T H E R EL A T IO N OF CHEMIC AL ST R U C T U R E T O BIOLOGICAL ACTIVITY IN C E R T A IN ORGANIC COMPOUNDS By JAG PAL SINGH A THESIS S u b m i t t e d to th e School f o r Ad va nc e d G r a d u a t e St udi es of M ic h i g a n S ta te U n i v e r s i t y of A g r i c u l t u r e and Applied Sc ience in p a r t i a l fu lf ill me nt of th e r e q u i r e m e n t s f o r t h e d e g r e e of DOCT OR OF PHILOSOPHY D e p a r t m e n t of H o r t i c u l t u r e 1956 P roQ uest Num ber: 10008687 All rights reserved IN FO R M ATIO N TO A LL USERS The quality o f this reproduction is dependent upon the quality of the copy subm itted. In the unlikely event that the author did not send a com plete m anuscript and there are m issing pages, these will be noted. Also, if material had to be rem oved, a note will indicate the deletion. uest ProQ uest 10008687 Published by P roQ uest LLC (2016). C opyright o f the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code M icroform Edition © ProQ uest LLC. ProQ uest LLC. 789 East E isenhow er P arkw ay P.O. Box 1346 Ann Arbor, Ml 48106 - 1346 A C KN OW LE DGE ME NT T h e a u t h o r w i s h e s to e x p r e s s his s i n c e r e s t a p p r e c i a t i o n to Dr Charles L H a m n e r f o r his kind guidance, e n t h u s i a s t i c e n c o u r a g e m e n t s an d n e v e r f a i l i n g help d u r i n g th e c o u r s e of t h i s investigation T h a n k s a r e due to D r H B T u k e y f o r h is v a lu a b l e a d v i c e s a nd s u g g e s t i o n s , which a r e r e f l e c t e d in t h i s t h e s i s A p p r e c i a t i o n i s due to Dr. C. E Dr L Wildon, Dr, H. M Sell, W, M e r i c l e a nd Dr. L, M. T u r k f o r t h e i r kind a d v i c e s T h e a u t h o r e x p r e s s e s a p p r e c i a t i o n a l s o to th e Upjohn C h e m i c a l Co mpany, whose f in a nc ia l help a nd c h e m i c a l su pply have m a d e t h i s w o r k p o s s i b l e L a s t l y , th e a u t h o r is de ep ly in d e b te d to his b r o t h e r s f o r t h e i r thoughtful e n c o u r a g e m e n t s in p r o s e c u t i n g the a d v a n c e d studies TABLE OF CONTENTS Page INTRODUCTION . 1 I. Biological A c tiv ity of O r g a n i c Co mp o un ds on C u c u m b e r R oots R ev ie w of L i t e r a t u r e . M e t h o d s and M a t e r i a l s 2 . 6 Results 12 D iscussion . 37 II. A c ti v it y of O r g a n i c Co mp ound s on A b s c i s s i o n of C ol e us P e t i o l e s R ev ie w of L i t e r a t u r e 41 M e th o d s and M a t e r i a l s 45 Results . 50 III. Biological A ct iv ity of O r g a n i c Co mp ound s on R oo tin g of Cu ttings R e v i e w of L i t e r a t u r e . 57 M e t h o d s and M a t e r i a l s . 58 Results . 59 IV. G r o w t h of T o m a t o P l a n t s a s A ffected by T r a n s p l a n t i n g T r e a t ­ m e n t s With O r g a n i c C h e m i c a l s R e v i e w of L i t e r a t u r e . 61 M e th o d s a nd M a t e r i a l s . 62 Tom ato T ran sp lan ts - Greenhouse 62 Tomato Transplant s - F ie ld . 64 Page Results 65 G r e e n h o u s e St udie s . 65 F i e l d S tu die s . 66 V. T h e T r e a t m e n t of Se e d li n g P la n ts with O r g a n i c C h e m i c a l s R ev ie w of L i t e r a t u r e . 69 M e t h o d s and M a t e r i a l s . 70 F o l i a g e Ap pl ic at io n . 70 Results . 71 Soil A pp lic at io n . 75 Results . VI 76 Bl o s s o m and F r u i t T h i n n i n g of F r u i t T r e e s with O r g a n ic Chemicals R ev ie w of L i t e r a t u r e , , „ 78 M et ho ds and M a t e r i a l s 79 R esu lt s 80 G E N E R A L DISCUSSION . 82 SUMMARY 84 L I T E R A T U R E C IT E D 89 INTRODUCTION D i s c o v e r y of th e effect of b e t a - i n d o l e a c e t i c a c i d on plant gr ow th o p e n e d an e x t e n s i v e field of r e s e a r c h fo r plant p h y s i o l o g i s t s As a re s ult m a n y i n v e s t i g a t i o n s have b e en m a d e to d i s c o v e r c o m po un ds which would s i m u ­ l a t e the a c ti o n of in d o l e a c e t i c a c i d T h e s t r u c t u r a l r e q u i r e m e n t s of c o m p o u n d s a c t i v e a s a u x in s o r a n t i - a u x i n s have be en i n v e s t i g a t e d e x t e n s i v e l y and s e v e r a l t h e o r i e s have b e e n f o r m u l a t e d R e c e n t l y m a n y d iff ere nt new sy n th e t ic c o m po un ds ha ve b e e n found to be a c t i v e a s plant g r o w th s u b s t a n c e s , and he nce have le d to a r e s t a t e m e n t of t h e s e s t r u c t u r a l r e q u i r e m e n t s for g ro w th r e g u l a t o r s . Since the d i s c o v e r y of high a c t i v i t y of 2, 3, 6 - t r i c h l o r o b e n z o i c acid, 2, 6 - d i c h l o r o b e n z o i c a c i d a nd 1 -n a p ht h oi c a c i d a s g ro w th r e g u l a t o r s , t h e s id e ch ain in the f o r m o r i g ­ i n a l l y p o s t u l a t e d is no l o n g e r a c r i t e r i o n for th e s t r u c t u r a l r e q u i r e m e n t The s t r u c t u r a l d i v e r s i t y of known g r o w th r e g u l a t o r s h a s p r o v e d to be a v a lu a b l e tool f o r i n v e s t i g a t i o n s into th e r e l a t i o n s h i p s a m o n g p h y s i o l o g i c a l a c t i v i t i e s . The m e c h a n i s m of a c ti o n c o n c e r n i n g the p h y s io lo g ic a l p r o c e s s e s which account fo r t h e c h e m i c a l c o n t r o l of gro w th is not yet c o m p l e t e l y u n d e r s t o o d Therefore, r e s e a r c h into the r e l a t i o n s h i p be tw e e n c h e m i c a l s t r u c t u r e and m o r p h o g e n e t i c a l a c t i v i t y m a y p r o v i d e a sh o rt cut to the d i s c o v e r y of o th e r highly a c t i v e c o m po un ds o r p r o v i d e fu n da m e nt al knowledge on m o d e of action T h e initial s c o p e of t h is w o r k w as to s c r e e n out c o m p o u n d s which might be of s o m e val ue in h o r t i c u l t u r a l p r a c t i c e s , and an a tte m pt wa s then m a d e to c o r r e l a t e th e s t r u c t u r e s and a c t i v i t i e s of s o m e t e s t e d c o m po un ds 2 Bio lo gic al A c tiv ity of O rg a n ic C h e m i c a l s on C u c u m b e r Root Grow th R e v i e w of L i t e r a t u r e B e t a - i n d o l e a c e t i c a c i d w a s i s o l a t e d f r o m huma n u r i n e in 1934 by Kbgl (36) a n d his c o l l a b o r a t o r s at U t r e c h t ; it w a s found to be m a r k e d l y a c t i v e in p r o m o t i n g c e ll el on ga ti on in p l a n t s F ol l ow i ng t h i s d i s c o v e r y , Z i m m e r m a n a nd H it c h c o c k (92) showe d that phenyl, alph a and bet a - n a p h t h a l e n e , a n t h r a c e n e , a c e n a p h t h e n e , a n d f l u o r e n e a c e t i c a c i d s all p o s s e s s e d g ro w th r e g u l a t i n g a c t i ­ v ity M a n y o t h e r co mp ound s, whic h in c lu d e d su ch i n d o l e - c a r b o x y l i c a c i d s a s a lp ha ( i n d o l e - 3)- p r o p i o n i c a c i d and y -( in d o le - 3 ) b u t y r i c a c i d have b e e n a n ­ n o u n c e d by Z i m m e r m a n et al. (90) to p o s s e s s gr o w th r e g u l a t i n g p r o p e r t i e s F o ll o w i n g th e d i s c o v e r y of I r v i n e (32) that b e t a - n a p h t h o x y - a c e t i c a c i d p o s s e s s e s act iv ity , Z i m m e r m a n et al. (91) e x a m i n e d a l a r g e n u m b e r of s u b ­ s t i t u t e d ph en oxy a nd naphthoxy aci ds , m a n y of which w e r e found to be highly active O t h e r t y p e s of c o m po un ds a r e now known to influence plant growth. S t r u c t u r e and A c tiv ity D u r i n g th e p a s t few y e a r s , m a ny o r g a n i c c o m po un ds w e r e found a c t i v e in r e g u l a t i n g th e g ro w th of p la nts , and a t t e m p t s w e r e m a d e to c o r r e ­ la t e th e m o r p h o g e n e t i c a l a c t i v i t y with th e c h e m i c a l s t r u c t u r e Koepfe, T h i m a n n a nd Went (35) post ula te d t hat c e r t a i n f e a t u r e s of m o l e c u l a r s t r u c t u r e and c o n fi g u ra ti o n a r e r e q u i r e d for a c t i v i t y These features b a s e d on th e pea t e s t , w e r e : (a) a r i n g s y s t e m nu cl eu s; (b) a double bond in th is 3 rin g; (c) a s id e chain; (d) a c a r b o x y l i c grou p (or a s t r u c t u r e r e a d i l y c o n ­ v e r t e d to a c a r b o x y l group) on t h i s side chain; at le a s t one c a r b o n a to m w a s r e m o v e d f r o m t h i s ring, and (e) a p a r t i c u l a r sp at ia l r e l a t i o n s h i p b e ­ tw e e n t h e r i n g s y s t e m and c a r b o x y l gro up A s m o r e c o m p o u n d s b e c a m e known, t h e s e five r e q u i r e m e n t s a p ­ p e a r e d to fall short Some c o m po un ds w e r e found to meet th e r e q u i r e ­ m e n t s , a lth oug h th e y w e r e inactive- while o t h e r s did not m e et t h e i r r e ­ q u i r e m e n t s e ve n though th e y w e r e a ct i v e. T h e s e d e v e l o p m e n t s have be en r e v i e w e d in a n u m b e r of p a p e r s by Audus (8), L i n s e r (42), N o r m a n et al (52), a nd T h i m a n n (70) A t t e m p t s w e r e th en m a d e by V e l d s t r a (76) to c o n d e n s e the five r e q u i r e m e n t s into two: (1) a b a s a l r i n g s y s t e m with high s u r f a c e activity; a nd (2) a c a r b o x y l gro up in a v e r y de finite s pa ti al p o s i t i o n with r e s p e c t to the ring system T h e s e r e q u i r e m e n t s w e r e l a t e r f o r m u l a t e d in g r e a t e r de ta i l by V e l d s t r a an d Booij (78), a s a b a s a l r i n g s y s t e m (non p o l a r p a r t ) with high i n t e r f a c e a c t i v i t y and a c a r b o x y l i c group (p ol a r p a rt ), in g e n e r a l a group of a c i d i c c h a r a c t e r , in a s p a ti a l p o s i t i o n with r e s p e c t to t h i s r i n g system T h e c l a s s i c a l e x a m p l e i l l u s t r a t i n g V e l d s t r a ' s t h e o r y of c o n f i g u r ­ ation c o n f e r i n g a c ti v it y of c in n a m ic acid, in which the c i s fo r m fulfills V e l d s t r a ' s r e q u i r e m e n t and is an auxin, w h e r e a s in the t r a n s f o r m th e si de ch ain cannot exist in any o t h e r p la n e than that of th e r i n g a nd is not an auxin In a n o t h e r in s ta n c e . 4 t e t r a h y d r o n a p h t h y l i d e n e a c e t i c a c i d has a c i s and t r a n s f o r m of which t h i s c i s f o r m i s a c t i v e and t r a n s f o r m is not In t h i s c a s e th e a c t i v i t y cannot be e x p l a i n e d by V e l d s t r a ' s s c h e m e , T h i m a n n (70) r e m a r k e d that both i s o m e r s m u s t e x is t with th e c ar b o x y l in th e s a m e p la n e a s the r i n g d i s c u s s e d by M u i r et al It w as f u r t h e r (47) th e p o s it io n on th e b e n z e n e r i n g a dj ace nt to the point of a t t a c h m e n t of the si de c hai n is d i r e c t l y invol ve d in the gro wth r e ­ acti on. It m e a n s if th e co m po und is to have activity, at l e a s t one of the o r t h o p o s i t i o n s n e e d s to be f r e e Op tical i s o m e r s c a n a ls o inf lu enc e auxin a c ti v it y a s is evident in 2, 4 - d i c h l o r o p h e n o x y - a l p h a - p r o p i o n i c a c i d which e x i s t s in d e x tr o and levo forms T h i m a n n (70) found that th e d e x t r o i s o m e r i s an a c t i v e auxin and lev o i s e s s e n t i a l l y i n a c t iv e It w a s a l s o c o n f i r m e d f r o m th e in v e s t i g a t i o n s of Mat ell (43) and A b e r g (1) in m a n y c a s e s w h e r e levo i s o m e r s w e r e found a s anti-auxins Some of the i m p o r t a n t w o r k s which a r e c o n n e c te d with t h i s i n v e s t i ­ ga tio n a r e d i s c u s s e d below T he Ring S y s te m N o r m a n and W e in t r a u b (52) e xp la i n e d that m o s t a c t i v e co m po un ds p o s s e s s a b e n z e n e n u c le u s o r fu s e d b e n z e n e nuc leu s hav ing an a p p r o p r i a t e s id e ch ain Booij (1 5) c o m p a r i n g n a p h t h a l e n e - 1 -, indo le -3, i n d e n e - 3 , and c o u m a r o n e - 3 - a c e t i c a c i d e s t a b l i s h e d that a fuse d nu c le us ha s a m a r k e d 5 effect on a c ti v it y T h e v a l u e s fo r indene and c o u m a r o n e w e r e p r a c t i c a l l y ide nti cal S u b s ti tu te d Benzoic Ac id Z i m m e r m a n et al (91) r e p o r t e d f i r s t of all a m i l d a c t i v i t y fo r cell elo n g at io n with 2 - b r o m o - 3 - n i t r o b e n z o i c a c i d an d f o r m a t i v e e f f e c t s with 2c h l o r o - 5 - n i t r o - and 2, 3, 5 - t r i iod ob en zoi c a c i d Bentley (13) found 2, 3, 6- t r i c h l o r o - b e n z o i c a c i d to be highly a c t i v e in s t r a i g h t gro wth L a t e r , the a c t i v i t y w a s a l s o n oti c e d by T h i m a n n (72), V e l d s t r a (80), and Z i m m e r m a n et al. (93) S e v e r a l o t h e r s u b s t i t u t e d be nzo ic a c i d s w e r e i n v e s t i g a t e d by M u i r and H a n sc h (48), V e l d s t r a et al (79), a nd Z i m m e r m a n et al. (93). N a p h t h a l e n e an d R e l a t e d Compou nds T h e i n t r o d u c t i o n of a s ec o n d c a r b o x y l group in th e s id e chai n was i n v e s t i g a t e d by V e l d s t r a et al. (79) T h e y o b s e r v e d no effect with ( na ph­ t h a l e n e - 1- m e th y l) m a lo n ic acid, ( n a p h t h a l e n e - 1-m et hyl ) b r o m o m a l o n i c acid, an d a l p h a - ( n a p h t h a l e n e - 2 -met. hyle) s u c c in ic a c i d in th e p e a t e s t V e l d s t r a (77) found a high a c t i v i t y with 1-nap hth oic a ci d tetra h y d ro derivatives w ere investigated Mitsui et al Its 1, 2, 3, 4 T h e high a c t i v i t y w a s no tic e d (46) had i n v e s t i g a t e d h y d r o g e n a t e d 1-na ph th oi c aci d The 1,4- dih y dr o and 1, 2, 3, 4 - t e t r a h y d r o d e r i v a t i v e s w e r e found to be s t r o n g l y active It i s evident f r o m th e above r e s u l t s that t h e s e c o m po un ds a c t e d in a m a n n e r s i m i l a r to auxin. However, th ey dif f e r e d widely in r e s p e c t to 6 t h e i r s p e c i f i c a c ti o n determination. T h e a c t i v i t y v a r i e d with the n a t u r e of th e a s s a y u s e d in th e T h i m a n n (68) h a s ev id en tl y shown in his w o r k that i d e n e - 3 - a c e t i c a c i d had a v e r y s m a l l and c u m a r y l - 2 - a c e t i c a c i d no a c t i v i t y in th e Avena C u r v a ­ t u r e t e s t , w h e r e a s c o n s i d e r a b l e a c ti v it y wa s shown both in Avena C ol e op til e s t r a i g h t g ro w th a nd pe a te st M etho ds and M a t e r i a l s C u c u m b e r Root T e s t T h e c u c u m b e r root t e s t , a s u s e d by R ea d y et al (55), an d A l a m e r c e r y (5) and e x t e n s i v e l y u s e d in t h i s l a b o r a t o r y , w a s found to be a f a i r l y a c c u r a t e a nd r a p i d b i o a s s a y . T h e r e f o r e , t h i s s i m p l e a nd r a p i d qua n ti ta ti v e m e th o d w a s d e e m e d d e s i r a b l e to d e t e r m i n e the e ff e ct s upon gro w th of a g r e a t n u m b e r of s o lu ti o n s of c h e m i c a l s . T h e u n if o r m s e e d s of c u c u m b e r ( C u c u m u s s a t i v u s v a r . M a r k e t e r ) w e r e u s e d for t h e s e e x p e r i m e n t s T h e c h e m i c a l s w e r e r e c e i v e d f r o m Upjohn C h e m i c a l and E a s t m a n Kodak C o m p a n i e s . T h e s t r u c t u r e s of s o m e co m po un ds u s e d in th e i n v e s t i ­ gation a r e given in F i g u r e s 1, 2, 3 and 4. T h e c h e m i c a l s w e r e f ir s t d i s ­ so lv e d in ethyl alcoh ol to f a c i l i t a t e t h e i r s o lu bi lit y in w a t e r T e n s e e d s w e r e u n i f o r m l y d i s t r i b u t e d upon a p i e c e of W h a tm a n No 1 f i l t e r p a p e r in p e t r i d i s h e s T h e fi l t e r p a p e r w a s then i m p r e g n a t e d with five m i l i l i t e r s of solution of a p r e d e t e r m i n e d c o n c e n t r a t i o n of th e com po un d to 7 be t e s t e d . p e r m il li o n T h e c o n c e n t r a t i o n s u s e d w e r e 25, 50. 100, 150, and 200 p a r t s L a t e r , t h e c o m p o u n d s which w e r e found a c t i v e w e r e ag ain t e s t e d at 1 and 10 pp m All p e t r i d i s h e s had be en p r e v i o u s l y c l e a n e d by s o a k in g ove rnig ht in a c t i v a t e d c h a r c o a l s u s p e n s i o n , th en r i n s i n g a nd w a sh in g with soap, and t h e n r i n s i n g a ga in with tap w a t e r followed by d i s t i l l e d w a t e r T h r e e p e t r i d i s h e s w e r e u s e d for e ac h t r e a t m e n t , p r o v i d i n g t h r e e replicates T h e s e e d s w e r e a llo w ed to g e r m i n a t e for four o r five days u n d e r l a b o r a t o r y c onditi on s 1 T e n s e e d l i n g s w e r e s e l e c t e d at r a n d o m fr o m e a c h t r e a t m e n t , and th e le ng th of th e p r i m a r y r o o t s w e r e m e a s u r e d n u m b e r of b r a n c h i n g s on t h e p r i m a r y root w as a l s o r e c o r d e d The To compare e a c h t r e a t m e n t s e p a r a t e l y , all dat a w e r e s t a t i s t i c a l l y an aly ze d, and the s i g n i f i c a n c e of d i f f e r e n c e s b e tw ee n a v e r a g e s of two t r e a t m e n t s w a s s t a t i s ­ t i c a l l y c o m p a r e d by th e " T ”" t e s t (60) In a r e s e a r c h l a b o r a t o r y at th e D e p a r t m e n t of H o r t i c u l t u r e of Michigan Sta te U n iv e rs it y , Eas t Lansing, Michigan, July to D e c e m b e r 1955 T h e t e m p e r a t u r e s r a n g e d b etw een 70° and 85° F T h e a l t e r n a t ing photo and d a r k p e r i o d v a r i e d with th e s e a s o n 8 F ig u re No. 1 OH COOH COOH COOH 2 -Nap hth oic a c i d 1-Naphthoic a c i d 1- H y d ro x y - 2 -naphthoic acid OH COOH s COOH COOH OH 3 - H ydroxy - 2 - naphthoic acid I- H y d ro x y -2 - naphthoic acid 6 - H ydroxy - 2 - naphthoic acid COOH I COOH COOH HO HO OH 7 - H y d r o x y - 1 - naph tho ic acid 6 - H y d r o x y - 1 - na phthoic acid 5 -H ydrox y - 1 - naphthoic acid OH OH COOH OH dl 1- H y d r o x y - 4 - c h l o r o 2 - Naphthoic a c i d 1 -Naphthol 2-Na pht hol 9 F ig u re No 2 OH OH S03Na 1 - H y d r o x y - 2 -n a p h t h a l e n e s ulfo nic a c i d (Sodium salt) 2, 4 - D i c h l o r o - 1 naphthol Quinaldinic a c i d OH HOOC COOH OH 6 - Q u i n o li n e c a rb o x y l ic acid 7 - C hlo ro - 4 - h y d r o x y 3 - q u in o l in e c a r b o x y li c a c id OH 8- Quinolinol O S03Na S03Na CH . OH OH 4, 5 - D i h y d r o x y -2, 7 - n a p h th - 1 - H y d r o x y - 2 - acetona i e n e d is ulf oni c a c i d aphthone (Di s o d iu m salt) 3, 4 - D i h y d r o - 1 - k e t o m ethyl-2-naphthoate i O— c — c h 3 OH ^/SC^Na T 6, 6 - D i h y d r o x y - 2n a p h th a l e n e su lfonic a c i d (Sodium salt) 5-I so quin oli no l 1 - 0 - Acetyl naphthoic acid 10 F ig u re No. 3 COOH O COOH OH ONa OH OH OH .OH CH COOH -OH -ONa O 4, 4 ' - M e t h y l e n e b i s - 3 - h y d r o x y - 2 - na pht hoi c a c i d HOO(^ H 2N / W 4, 4 T- M e t h y l e n e b i s - 3 - h y droxy-2-naphthoic acid (Dis odium salt) 4 ( 2 - H y d r o x y b e nza l amino) s a l i c y l i c acid COOH V / \ _ \ / - OH NH, HOOC' b i s ( 3 - C a r b o x y - 4 - h y d r o x y phenyl) m e t h a n e 4, 4 ' - D i a m i n o - 3, 3 - d i c a r b o x y bi phenyl O ii o L o ­ ch . n — c! h 2'2 o CH O O 'C O O H CH. O 2, 5 - D i p h t h a l i m i d o d im e th yl a d ip a t e 11 F ig u re No. 4 COOH OH COOH OH Benzoic a c i d S a lic yl ic a c i d COOH Phenol COOH OH OH JSh Cl 5 - Chlorosalicylic acid COOH 2 - P ic o l in ic a c i d CH3 2 - H ydroxy - 3 - m e th y l b e nzo ic a c i d 12 R es ult s Significant d i f f e r e n c e s in root g ro w th w a s o b s e r v e d with v a r i o u s chemical treatm en ts C u c u m b e r r o o t s m a d e si gn if ic a n tl y g r e a t e r gro w th without i n j u r y in s o lu ti o n s of 25 ppm of each of th e following: 1 - h y d r o x y - 2 - n a p h t h o i c acid, 3 - h y d r o x y - 2 - n a p h t h o i c acid, 4, 4 T- m e t h y l e n e b i s - 3 - h y d r o x y - 2 - n a p h t h o i c a c i d ( d is od iu m salt) th a n in c o n tr o l (Table 1). How eve r, 4, 4 ’ - m e t h y l e n e b i s - 3 - h y d r o x y - 2 -na p ht h oi c a c i d w a s found m o r e e ffe ct iv e on root elo nga ti on at 50 p p m N a p h t h a l e n e a c e t i c a c i d u s e d a s a s t a n d a r d gro wth r e g u l a t o r had m a r k e d l y in h ib it e d th e p r i m a r y ro o ts , though it s ig ni fi c a nt ly i n c r e a s e d the n u m b e r of root h a i r s S i m i l a r r e s u l t s w e r e o bt a in e d when the co m po un ds w e r e r e t e s t e d u n d e r c o n s ta n t t e m p e r a t u r e con dit ion s at 80° F, with the ex cep tio n of 3 - h y d r o x y 2 - naphthoic acid. T h e m a x i m u m g ro w th f o r t h i s co m po und w a s ob ta in e d at a c o n c e n t r a t i o n of 50 ppm (T ab le 1) When t h e s e m a t e r i a l s w e r e t e s t e d at a t e m p e r a t u r e of 90° F, i n h i ­ bition in a c t i v i t y of c u c u m b e r r o o t s o c c u r r e d with all t r e a t m e n t s No s i g n i ­ ficant d i f f e r e n c e s in root growth be tw ee n t r e a t m e n t s w e r e r e c o r d e d , although slight d i f f e r e n c e s w e r e found o v e r the c o n tr o l (Table 2) As a re s u lt of t he se te st s, two c om po un ds (1-naphthoic a c id and 6 - q u i n o l i n e c a r b o x y l i c acid) w e r e d i s c o v e r e d that c l o s e l y r e s e m b l e d the 13 a c t i v i t y of n a p h t h a l e n e - a c e t i c a c i d ( T a b l e s 3, 4 and 7, an d F i g u r e s 5 and 10) Root e lo ng at io n w a s s ig n if ic a n tl y inhibited, e ven at 1 pp m and an i n c r e a s e d n u m b e r of ro o t h a i r s w e r e n o ti c e d on th e p r i m a r y r o o t s T h i s is an effect which i s quite s i m i l a r to th e r e s p o n s e of n a p h t h a l e n e a c e t i c a c i d on c u c u m b e r root g r o w t h O t h e r c o mp ou nds , 2-n a p ht h ol a nd 8 - qu in ol in ol at 25 pp m and 1-naphthol an d 1-h y d r o x y - 2 -n a p h th a le n e sulfonic a c i d (s odiu m salt) at 50 ppm w e r e found to s ig n if ic a n tl y s t i m u l a t e root elo ngat ion (T ab le 3) Many c o m ­ pou n d s had no sig nifica nt effect (T ab le 3) T o c o m p a r e t h e a c t i v i t y of 4, 4 ’ - m e t h y l e n e b i s - 3 - h y d r o x y - 2 - n a p h t h o i c a c i d with o t h e r r e l a t e d compoun ds, two e x p e r i m e n t s w e r e c o nd uc te d and th e r e s u l t s a r e p r e s e n t e d in T a b l e 4 M any of t h e s e r e l a t e d m a t e r i a l s had p r o ­ n o u n c e d bi o lo g ic a l a ctivity, qui naldinic a c i d s ig ni fi c a nt ly in h ib ite d root gro w th at 25 p p m c o n c e n t r a t i o n , but th e root h a i r s w e r e a l s o in h ib ite d ( F i g u r e 6) Root g r o w th w a s a l s o s ig n if ic a n tl y r e t a r d e d at 25 p p m of 2 - n a p h th o ic a c i d Significant i n c r e a s e d root elongat ion w as o b s e r v e d with t r e a t m e n t by 4 - c h l o r o 1-h y d r o x y - 2 -n ap h th o ic a c i d at 25 pp m ( F i g u r e 8). T h e r e m a i n d e r of th e c o m ­ pounds u n d e r t h i s t e s t had no sig nific an t effect on th e c u c u m b e r root g ro w th (T a b le 4). Sin ce th e i n tr o d u c ti o n of an hydrox yl group on th e fu s e d n u c l e u s c o m p o u n d had m o d if ie d th e acti vity, it w a s thought d e s i r a b l e to t e s t si ngl e r i n g c o m p o u n d s with hydroxyl g r o u p s o r a c i d grou ps , o r both, on th e r i n g 14 to c o r r e l a t e t h e activity. tested Single r i n g h e t e r o c y c l i c co m p o u n d s w e r e a l s o G r o w t h of c u c u m b e r r o o t s w a s m a r k e d l y r e t a r d e d in s o lu ti o n s of 25 p pm of 2 - p i c o l i n i c a c i d and 5 - c h l o r o s a l i c y l i c a c i d (T ab le 5) An i n ­ t e r e s t i n g r e s p o n s e wa s n o t i c e d with 2 - p i c o l i n i c a c i d ( F i g u r e 11), the n u m ­ b e r of b r a n c h i n g s on t h e p r i m a r y root d e c r e a s e d m a r k e d l y by i n c r e a s e d c o n c e n t r a t i o n s ; a l s o an i n t e r e s t i n g r e s p o n s e of 2 - h y d r o x y - 3 - m e t h y l b e n z o i c a c i d w a s r e c o r d e d , th e p r i m a r y r o o t s w e r e un u s u al l y thin ( F i g u r e 12). Phenol t r e a t m e n t s h a d no sig nifica nt effect, how ev er, s a l i c y l i c a c i d m a r k e d l y r e t a r d e d root g ro w th at 10 pp m and at i n c r e a s i n g c o n c e n t r a t i o n s . Benzoic a c i d i n c r e a s e d root g ro w th at 1 ppm, but r e t a r d e d at h i g h e r c o n ­ centrations. T h e h yd rox yl group d oe s not ha ve an effect u n l e s s th e a c i d gro u p i s p r e s e n t , a nd it a p p a r e n t l y m o d i f i e s th e a c ti v it y of the a c i d group T h e co m p o u n d s sh owi ng th e g r e a t e s t a c t i v i t y on c u c u m b e r root w e r e r e t e s t e d at 1 an d 10 p p m to d e t e r m i n e t h e i r a c ti v it y in e x t r e m e d i l u ­ t i o n s (T a b le 7) 6 - q u i n o l e n e c a r b o x y l i c a c i d and 1 -nap hth oic a c i d r e t a r d e d root gro w th s ig n if ic a n tl y at 1 ppm, w h e r e a s 2 -p i c o l i n i c a c i d and quinaldinic a c i d w e r e found to inhibit g r o w th at 10 pp m Significant s t i m u l a t i o n on r o ot el ong at io n w a s o b s e r v e d at 10 p p m with c om pou nds 2, 4 - d i c h l o r o - l naphthoi, 3 - h y d r o x y - 2 -n ap h th o ic acid, and 1 - h y d r o x y - 2 - n a p h t h o i c a c i d An e x p e r i m e n t w a s d e s i g n e d to d e t e r m i n e w h e t h e r o r not root s t i m u l a t i o n with 4, 4 f - m e t h y l e n e b i s - 3 - h y d r o x y - 2 - n a p h t h o i c a c i d co ul d be 15 f u r t h e r e n h a n c e d by s i m u l t a n e o u s a p p li c a ti o n of a n i t r o g e n f e r t i l i z e r ( T a b le 9) It i s evident that u r e a and KH^PO^ had no sig nific an t a ddi tiv e effect on root elongation. In o r d e r to e xplai n why c e r t a i n s e e m i n g l y u n r e l a t e d c o m p ou nd s s t i m u l a t e d root growth, it w as s u g g e s t e d ( L e e p e r 40) a f t e r study of the c h e m i c a l s t r u c t u r e involved, that t h e s e c o m p o u n d s might f o r m a c o m ­ p l e x ion with c e r t a i n c h e m i c a l s an d he nce act a s c h e l a t i n g a g e n t s The m e t a l c h e l a t e co m poun d might r e m o v e e x c e s s q u a n ti ti e s of c e r t a i n c h e m ­ i c a l s f r o m t h e r o o t s and t h u s p e r m i t elongation. In o r d e r to t e s t t h i s th e o ry , s e v e r a l c h e l a t i n g m a t e r i a l s w e r e investigated activity It w a s found that s e v e r a l c o m p o u n d s s ho we d b io lo gic a l R e s o r c i n o l , b e n z o t r i a z o l , 2, 2T-biquinoline, di e th yl di th io - c a r b a m i c acid, 2, 4 - d i h y d r o x y - a c e t o p h e n o n e an d m e r c a r p t o a c e t i c a c i d at a c o n c e n t r a t i o n of 25 p p m w e r e a c ti v e in s t i m u l a t i n g root growth. T h i s w as highly si gnificant I - a m i n o - 4 - h y d r o x y a n t h r a q u i n o n e , fu ri l d io x im e a nd t h i a z o l e yellow a l s o i n c r e a s e d root growth; this , however, w a s sig nific an t only at th e L S. D. 5% le vel ( T a b le s 10 and 11) A re­ t a r d i n g effect on root elon gat ion w a s r e c o r d e d when th e c o m p o u n d s p h e n y l glyoxal a ld o x im e , and 2, 2, 4, 4, 6, 6 - h e x a n i t r o d i p h e n y l a m i n e w e r e u s e d ( T a b l e s 12 and 13) 16 £ u bo £ d *f-i 43 o d d o o CL d H <4-4 o bO Ch 3u d d d PQ XJ CO u CO I & ° § u £ .s <« c^tf 4—1 cn Q xt cd b2 °CL tru £ o u o *s d ’Z3 X o X X m X CN d •—i r~ CN CN X X X X X o d O vo ON CN d X ■—i X X 1/3 rCN ON r-H d X 1—1 X ON CN r- X m r- o d< CN ON i—H rCN X CN a o m X CN co 6 \ co • LO j »~h 2 2 r- OO CN ON CN ' CD X h- X o X o X '. on x oo d" X o CN X CN ON X X X CN X X d< x l6 r- d id r- d x CJ I=J 2 LO CN O ON oo x X3 •rH CO o 43 o CL £ o U u '£ d bo d O o d £ O U o CN 2 j£ CL d d 1 CN t b*'* X o d X5 >> 2 X 0 d X >n U d 0 d lo r—i d c *~ ) ^ d £ o d o w bo ON CN >—1 a. m a XI co LO CN CN ON o -Q o^ J °CO d o d d > *o ° ' CN O ^ oc d CD 'bo u t> v < d O m d & b d O d to CN CO CD bO d S X Ov X CN l_Q c2J to o o d CD 43 £ d 2 JP bo d d CD > «J # P4 w X 5 E-1 d X 1 d CQ o W is _4 n O X CN Ov cl d O 3* U »+-t o •rb ^ X CO LO a 3 43 d d d 1"oo >—1 X o 43 43 43 Od d 1 CN i Pd X 0 d XI kS X 1 co X 1 CO i 0 °? co •kH CO * i-d CD U d CD d CD "d 8 CD O 43 43 . d £ u d o -.— i CO & (j « CJ 0 X +-» CD 2 CL S d i d 1 d CN d o d 4-1 d o U X 0 d X CJ 43 % 3 CO CO O CN 2 0 X 0 x 43 43 CL d d 1 CN I >v X O CL d d 1 CN d X pN 2 CO u d x d 2 3 X X >» o ■4— 1 b^ X 0 1 3 i d 3 CO X 2 o s * CD 3 b*"! 3 X X d X 2 d x d 1 bO d 2 CL d d i CN 3 CJ d 3 d 3 *d X 4— ' X CL d 2 3 bO d d 3 > <3 -a- 17 P 00 vO -H CN r- CO p G in 0 P p CO <—1 f—i i—i o o CO p 1—( 00 OO I a 3 o B p a 1 1 CO QJ P o o a a > -H P CN 4-i CN CO i—I CN p t5b d a aj 5-1 CQ iO CO C3 CN p 1 CN •—1 CN o P -H 1 1 co v© NO O o i—i CN ON I CN CN ON CO CN i aj P -a g a> G O aj G QJ bO aj > < S? bO d o CQ On OO 4-J QJ P a, d as •H H co d o o £ o <3 H CO pi o bo P *i-H o o W I I OO .—I r-p CO p aj H v+-< cn > — < -* -S CN * CO 3 OO 0) P 4-> d o CO P G d co QJ e d CO o to P o a. 5 Bo U Q p a> P 2a -rH c 0j CO d aj bo >. cd 0 G t»—* •^ P ^ r g q g <* u d 2 d .2 § G G *2 — o ffi. ° c bl (U P P v d Q> ^ aj W co aj CJ aj U O 0 O Q O cl> co Jr! d P o H »rH a £ P CO P d d o p o co 0 o d U u aj 43 u a u b*% rd 1 bo g O o G +—i d o U 0 p +-1 p p aj d 1 CN i bo X o d P b*~> O CN X X 0 p co £ S' d 1 CN i b*N X 0 d P b’N X 1 CO sd 1 CN i b^ o aj •a d £ aj d 1 CN i >-. X S 0 P P QJ d 0 I— < b*N p +— 0 bo X =3 p I 0 0 co O aj CO u i p 0 d 0 1+-> 0 QJ o aj 0 d 0 aj P s £ '■f P aj z CO d 0 4-> VM o p bO aj d 0 > < •s & O Z J8 CN o 6 Dh o CN CN CN LO CO CO id vO CO VO CO bCN i —H r—( vO CN CN OO cd r- co VO CN u 0 bo CO d B d £ o d aj d CO o d CJ o 0 d: CO CO *-> o o o d 0 lO rQ di d 2 LO CN &> aj d 0 bo bO d "O d co 0) •d co d 3 P$h ^ rH x: .5 w -a d d o CO >> aj Q d d Q J 10 J ^ s> s o o CN CO CN 1—1 co N< CO Ov vO CN CN •“H CO r— vd CN CN B LO o co o o —( b- Ov o 1—L CO b- CN CN O id o CN OO CN 0 a dC <2 CJ •d 5 aj co d H-l bC .tj ° bO O d co d >% d trt ^ ^ d CN CN Ov CN oo CN CN lO vO b-io O d i—1 OO vO o o oO^-h QO i-H oo O 1—4 o vd CO Ov CO O^ CN oo vO vO CN vd i—l vO OO OO CO OO o b- CO VO lO cj **o r2 CJ o o So d CN o OO OO vO iO CN c o r-' CN CO VO o o lo oo id LO co id r- Ov vO N* Ov LO y—1 LO N* vO id LO CN CO jd o CO o £ CO CO O r’ aj H O r- B o Pu o CN 6, a 4-J o o pd co OO CN Q 04 d o JH E- LO OO * aj d CQ d CN vO CN O CO OO OO CO > < o d W -I CO OO 0 LO CN VO OO vd vd b- oo CN CN LO cd vd I>- Ov r— H 1 id LO oo VO OO LO LO CO CO ov O »—H rLO CN rr- bb~ CO vO cd vd LO OO r- CN b- aj d 0 CO > < b~ vO Ov vO CO vO o o•> * f"H+ c 0 U d ^ * I—I O aj CO TJ d d al d ^ O 6 o U o o *-> O CO o > <4 O-H ° co b r_ CO bo d 0 Cj VM 0 *+-« 0 W 00 d d ‘S aj bO d O d: O dS o a, d o U oCN X o d X! 0 x3 >> X 1 vO o U O CN 2 0 Bd 0 a, o d Q d o d al co jd d *-> d aj X £ Oh as d 0 d 0 o 0 d 0 -o d d o CO X) o JC £ Oaj 2 0 -d Jd du aj 21 CN d 0 2 0 51 CN o d 4-> d o U 1 -a CN X d3 d aj 0 0 X u 2 ‘S 13 O CN ‘r_l aj X o O >v % X o d -d >. x: i d •i-d =3 0 0 0 •i-H CO X O Jd d aj 0 0 d d 0 0 d t o o d ' o d d O i— H d d cr1 d i U i CO 1 r~OO cy 0 bo aj d 0 > < Observations were recorded after five days E- co CN o CN CN B S' d O LO CN 19 s O O 1 CN o t 1 \ i t— i H -G co Os >—< ro CO CN CN ft G G 3 tn O QJ G o CO Os r- lO id Os i—i i LO OO o CN o LO ■-H r- C5 CN CO CN CN CN CN r-~ LO t"- CO CN LO CN CN CN CN co LO CN sO CN [g oo CN CN cj CN G G G CQ mh O CN Os LO CO CO -H o sO lO CN OO oo O Os Os *—H G CN o CO CN G QJ G s z QJ 1—1 LO CN bo oj G QJ > LO LO o sO CN CN •» Q Q lo co fex c/i ^ . ► — i ^_, G G a CO +— o LO . ^ r- co o CO^ Lor-' —I Os sO sO LO CO 1 G t Jh s d ^ so id [ OO SO OO m in r» g N* si G c K— ^ £G o o f t CN .ft o CO o QJ o G CO O PCj a f t ■H G G 4—1 H QJ o U-l CL, LO O G *ch G CO G G QJ ■ ■fcj G G t O 9 C/5 G G QJ d G O <9 }L u cd CN i i sO 25 Effect of Various Concentrations of Organic Compounds on Elongation and Branching of Tap Roots of C uc um ber Seedlings Grown Under Laboratory Conditions for Four Days in Petri D ishes TABLE 4 bo co„ co CO G i—4 OO >—i OO LO CN CO G lO >—i Os Os OO Os CO Os CO O O LO CO CN OO io cd i—( Os rr- H G o id OS r- Os Os Os LO CN r—H r- ■N* CN cd LO sd G id Os G Os Os m CO r- cd IO OS CN OO G o r- sO G G G •f -H O G O TJ O G CJ O G G G *ri u G O O G G G G *— d G G G U G U * 1 “ H O G G ft G G CN CN r—i oo o co sO t—i r~ in r- bo > o r- OO lO CN sO ft CO G G G 1 CN i ►-G G G O ft £ o U u •a bO g o r- o 0 G £ G O g *-) G O U o CN X G U G o U ■ r — H G O G G O, G £ 0 g £ ft G £1 CN G O G 0 3 u1 X o G G co co G G O *r-H QJ i G G QJ O QJ * '3 O' o G G c y QJ - g G G G G o .2 o G QJ G •H i 1 X O ■ * “ H cj >> x 0 ■s ft G ^5 c CN O u (U ft S o CN £ G CN G +— « G ft G C t—< X o G ~o >> X in ft ft X >> X o -a X r- G X O G G >» X o G G X1 CO CO bO G § QJ cQJo C QJ • Sm O QJ bO G G QJ > < 20 o LO o CN LO CN OO iH O £ i i OO o CN r- >—1 o vd oo Ov OO CN CN Oh a bo CCOD O c X o Ov CO 2 0 r- o i O CO CN Ov i N* CN a cd j- i DQ o X OO rH LO O CO id CN LO r~ CN LO Ov Ov ’—i r^ LO o co rCN CO CN Ov CN >—i oo CN CN t—1 X Ov Ov CN O) X £ 2: 3 x CN 0 bo1 cd !h 0 OO CN LO > o < OO CN CO X o n CO CO ^ m . X X £ LO OV CN X cn cn j r- x o o x t" - o v r - ov X -H H LO i-H X oo Ov CN i Ov o o N* X O h CN a CO 0 o o xCO o o a O h OO I x o v LO t"- c > i—i o r~ CN X o 'd CN Ov x co cd CN LO CN Nf* N< r*- X X CN X CO r- N* —( Ov X CO Ov m CN X r- *— H id oo CN X 'd CN X X c cd H H—I 0 Oh o x o X r- cd p- OO OO X N* X co 3 Sb o c 0 J X o o X o X O X N-4’ X X vd X cd Ov X CD r- X r- X CD bO cd 01 LO vO f" LO r- pd 0 3 CO ~o 0 jq c 3 O a, cd Oh 3 i £ O U 0 3 ^ O co i T3 o u P-v ---J x y o £ o U O CN X ■3 P*V 3£ "3 co 10 =3 ■■ —< O cd U o ’£ X p*v X 0 u u 9L X cC 1 CN >v 3 •s p*-. x1 X 0 o £“ 3 ^ •In 0 £ ^ 5Cd XO h ^2 : 0 i— ( CO ^ X X 0 X CO H—* O h N cd 0 1 cd 1=1 0 0 u cd 1 CN ( P^ X o X O h X 'l—i o X £ 0 0 Pd X o ^ Q CN u 3 cd bo Sh O 3 0 i—f cd x U cd i o o 0 I I 3 to o U O CN X cd o u 0 3 U 1 io p^ CO I X o x X O 0 3 u >.■0 x d • cd CN 0 Cd 3 O ' X oo +-' > JD 0 CO r- Average of ten seedlings > < 21 £ ■a LO LO CM CO CO co Ov r-H LO LO 'd CM t—i o roo i—t i—1 »—i r-H cu 0 0) a> CO bo C0O o d X o H 3 CO t— 0 d s cd •rH d V-i CQ 4—> 0 Dh o LO C3 d *H 0) u a> X 3 3 0 U <4-1 O XI o o a 3 0 CTS OO to d £ o d cd d LO i-H LO LO CO CM CM 4 CM CM CM Ov •-H t"— LO CM co o LO CM CM b- X CM vd CM cd CM o OO LO CM id CM cd CM CM •—< O co CM CM CM Q bO CO cd d CD 0 > d o < o £ <4-1 P o ^ O w £ £P <4-4 d W X o o X Ov r- vd X i-H o CM LO CO CM o Ov X id OO LO -X X r- , CO a Pd CO OO , CO CO -rH 9* H d ■>-> 0 Oh pj jd & d bo cd d vO CU > < * O vO CO 0 -—^ X3 d o cu 3 o 3 4— CD 3 3 V u d cd bo d O o d •i-H X 0 1 O d d o U O CM PC CD % ° a ' £ S £ a s ? 4< " CO d X! X 0 0 cd "cd m 3 a X s cd •—< cd t3 a x 0) XH x •i— o >» cd X u o d X 0 >n PC Id CM co 3 CU X d o o t co 1X >> -rj g 8 cd 'S 0 1 £ a >> d a X =6 Q ^ ' CO X .,H x CM * X p <4-4 u cd o o X 4—i X cu cd d i —H >4 4-> 0 0 < o d *i—4 --I O d •H & O CO X Average of ten seedlings. W a 25 X rH d o CU o CM a Oh a bo d 3 o d cd u CQ CO 0 Os i—1 O r~ GO Os CN Os CN r- CO i-H o CN Os i—i Os CO co CN in CN CN CN in CN sO CN CO sO CO ~H m OO CN sO r- CO CN O CN CN CO —H m CN in CN CN CN CN CN in CN Os so oo 4b CO • i-H Q 0) CL, Jh O 42 e o 0 O bO CO d 0 u > d o < U cd co co in o CN CN in Q co in oo i—H i-H SO in sd CO Os CO in cb 6 3 CO 0 in o r- i-H m sd cb N" cb -j i-H m -* X CO sO o O SO rsO o Oh o o hO CN oo >-H i-H cb i-H m Os —1 N** SO sO i-H r- o t"- Os Os i-H sO so Os O Os cb o in i-H in in in so cb SO CO in Os m i-H sO i-H CO od O h Cd Jh H H0—' Oh O rC »rW co d d 0 o J 0 o bO co co Sh 0 J > C d o U sO CN CO in m CO 7>> bO o u +-> d o U O CN X 0 0 ib -l-H i < o 4b H—' 4b O h rO X o 42 O cd o 42 .i-H h u o 0 N d 0 0 T) cd CO bO 0 •I-H 0 cd O O a O U u ’S CO cd +-J 0 0 cd 0 •i-H d • r-H r— H d 3 O' O 0 £ so CN X! g 0 Oh 7d ct3 d O •pH Z K1 d CN O CN £ d •* H ♦i-H o 4b ■ l-H 4b o Sh O 4b 0 O h cd 2 CN 0 a o rC 4b* Oh cd d 0 0 0 cd 1 CN i >. X o Sh ~a b'S X 0 cd 0 0 4b Jb 0 0 0 4b £ cd Oh O h cd cd cb ■ CN 1 X X 0 S ■0 X1 h CO cb 1 CN i X o Sh TS X cb 0 =3 J 0 0 0 CO d in 0 cd ° cb 0 nJ bo u cd <+h i-H ‘rH g < S, CO Not significant. Effects of Various Concentrations of Organic Compounds on Elongation and Branching of Tap Roots of Cucumber S eed­ lings Grown Under Laboratory Conditions for Four Days in Petri D ishes. TABLE 7 22 23 vo o CN d cn I-H in m m 2 fcs in CNI oo Ov TjH CO CO g 0 43 £ G U G U CN o o o CN CN CN vO CN ■'f vO CN vO CN vb o o o od p 03 CO QJ 43 CO •H bO G 2 o c Cd Sh CQ T3 G cd G o • pH co 0 4d co CQ c H * r**H £ bo (D G P w CO g o cj ra Q 73 g G o P £ o u Q o •pH m G cu P G m OV vO vO Ov CN m co oo Gm r- CN m t h fc 'o cn <4-1 q o cn r—H G CO t— CO o CN Ov CO CO CN in m CN Ov O r— I m CN vO oo Ov O CN m CN m LO CN CN CN bo G 0 cd CL> CO G £ co CU a i-H G o U Ov in CO CN m m CO o CO vO m CN CN G 0) CN O co 4-11 o o g co _ o OO m “ 1 a, cd +-> CO CN <4-1 O § bo o u ® b 5 2 G 2 £ o ^ £u* 43 G cd 0 J °to 31 =3 ^ g £ Sh 03 o u o > O ° to CO =3 o ■iH ■p H o CO m O c cd <— i CN vO CO O VO in CO m a cd W X m r- £ p oo & I-H ® bo <4-H 0 *+-1 0 W CO 43 Sh 43 £ So cd CL) o G a )H o o Sh ■i—> c o U g ■i-> -i-i u o3 jd bo G 3CJ G CO ■a G G O P G C o U O 0 bO cd G 0) > < ' CN X bO G ••H M B 2d So G cd o 2 0) bo QJ OJ 43 CJ G cd Sh o 0 o CN > < CJ cd cn Sb g 0 Z QJ QJ > 73 'e Sh G3 g > , < P G cd g > < CN ■q o cd G 0 CQ 43 So G a; O 2 0 bO cd 0 bO cd Sh Sh 0 0 > > 0 •pH < 24 T3 d cd d o •rH >7 ^ cd bO 0 d £ « tl] °J ^ ja d o cd a CO bO d £ p £o cd 5h rH s § r- OO •—L rCN CN CN CN LO CO CO SO CO i—H o CN LO CN O b- CO CN CO LO CO c- CO o CN Os CN Os ■ '4h — ■-H sO LO Os •-H p-H i— H ■'tf s6 Os O O sO "d1 O CO sO CO OO p—H CO Os sO •—l U bo cd 0 d > 0 OO oo OO <1 X OO o o T— t lO LO I—H 1— 1 i—1 Oh co CN! Os w >-1 -2 £ ^ d O O o o CQ < CD) >H £ o cd —1 CO X03 D 0 d £ 2 CD 0 pd "O CO -3 bO a ^ 0 **"* r o O ^ CO ^ d O r cd ^ -5 2 d u o Ch 3 a U bi <1 CO d +=• d crJ 4-1 d 2 •p-l co o co _ CD cd H HH o d co 2 d 0 DH S|H 5 Cd In W CQ * 0i , M m 4- + 4- *h + 4- + 4- 2 CD CD 2 CD CD O 2 CD CD O o i— H 2 CD CD O 2 CD CD 2 CD CD O 2 CD CD O O 2 CD CD O lO LO CN lO m p“H LO CN LO 1— H u cd Sh *-> 0 0 Q*< 0 pd d • pH J2 CO CD d cd d o CO 1 bo d CN i >N o co X d co 4—' cd Sh H d 2 0 o CO 3 >4 pd 1 t o u d 0 0 0 co U ° O o CO cd CD CO ^ 2 aCD O w ► ' C3 ^ § 4- D J-J ' -2 CO T j *1-H Ch d X W CD CD O O LO -3 -5 H CN 2 Jh X 2 o i- H CU t o > * +3 S-i i-H CD g u 1 i-H '4* CN tP <4H f> c ^ 2 •§ -d O o Sh s O U O CN 2 CD CD O o m cd 0 Sh D CD CD O O t—H pQ 0 d 0 i—i K*~> rd 0 o Oh CN X d 0 __, 0 > 0 —i 1 0 > 0 ’—1 0 bO cd Sh 0 > LO •*—- < cd Q Q CO CO p -i j i 25 £ a. o o co a O r- i 1 vd vO 1 1 OO vo o iO ft vo vO LO o Ov O GO mq r- CO r-H r-H t- H i- H O VO CN ov vO uo LO CN vd i-H vO i-H •-H rH i- H Ov CN r- OO 00 id i-H ft i—( N" i-H OO i-H vo Ov lO r_ i CO >~H CJ 3 U P-l o *-> o o P CD o lo £ P 2 to a cd g OO O ( O vO v LO v o f t c o i d 1 CN c d c d I 'd OV o o CN CO CD ^ o o rH O o m Q£! LO CO oo r - [-— vO CO lo tt­ CN c d id r ed H cd CN lO i— H CO OO rH CN cd CN vd CN i-H CN ri-H co CN •d i-H CN i-H VO Ov Ov CO C"CN oo CN lO .j VO CN OO i-H CO OO CN CN rH oo CN • OO CN OO r- r- IO vd CO OO CO 00 CN oo CN CN co CO LO O co o r*- OO CO CN rCO a . „ CN i-H LO v o r- UOt"- cooo I - H CV H oodf coH CNCO CON LO Ov vo VO VO OO i-H cd CN uO i-H o CN O CN id CN LO VO O CN o CO cd co o I-H CO -=f CN o CN Ov CN i-H CO CN UO uo cd co OO CN hCO Ov "N* co„ vo OO i— H o vO CO rH CO CO vo -H CO S' co H P-l o -P 1sb| p cu - I CD bO o LO LO CN co - H5 CO CO a co „ co CO CO O CN cd p uo -N1 CD > < CO P H 3 O P CO p o •rH 4-> p j —> 4 -> o U CO p o •rH P 3 cr >V P o P p P p P o P ft P P ft P P P TJ f t P p > £ p-l o p o 4-> O o CO p bo PH PH p f t i— i o p 0 ‘£ 3 p p 0 P O o 1 CO T3 P P O 1 H ■! £ ft P p £ O u O £ 3 P o 3 co cd p 0 X o O 2 -3 +-* P^v i i O P VO *=i & § Wo p £ < ai x 0 p XJ >» u p N ..-H i "H p p * r-H P O' £ S ' p 1 CN i O P •rH £ C 31 vO cd i o p o 3 P 0 P O Q1 P ‘3 lO u* •rH CN CO bO C =6 p p •rH o b X O P P 0 p • tH 3 cr >> x 0 ■a>> p * rH D1 co CN 1 O p 3 p o p £ o o P o P u p p < u P p co O CO o p ft JQ P P p CO 0 p -f-M p s1 O P o ’£ p p p o CO p CN p p p - rH CN p p CO ft p O Pi p •H o 9 p CQ CP CQ •rH o N P P C Q P 3 +-> P r-H rC +-P CN 0> •rH CN p bo U O Q p > < 26 B 0 o o cC & CM CO bO G CO 0 x: 0 X) o o CO u O o ON Tf ON oo O' co r- vd id d ■'f CO O oo r- OO u CQ o G CU in On in 0 ON r-’ in co m t- On On vd d o OO id X B CJ n z: m ON cm p VO o ON ON LO on in i—l CM d bO 03 G CU CO o —i CM CM d i—1 o CM id d 0 X O CO o cd H -rH Q O o sH o -G m "Sb O' CM Hi CO i—^ m o O id CM no CM >—i CM O CO CM CM cd CM oo d i-H CM in CM OO Ov in co 0 OO CM d CM rCM vd 0 NO CM d CM id vd CM H 0 O O ON ON cd CO ON CM vd CO o CO cd o CM ON CM g 0 0 d 0 bo NO m OO CM CM oj in 0 0 LO > < CO co 0 0 0 0 0 ‘T S CO r-^ N 0 CJ CJ g 0 X! I O G o Ph 6 o U 0 4— a3 i—f 0 X u •rH 6 cb t" b*~» 0 •rH EM cb G 0 >. X 0 X Sh cb U rH G 0 JC P, S' § W U lo CO 'rH C! B cb O bJO G •H 0 0 cb b3 ■rH CJ cb 0 a o N d X G cb 0 •G o I — I •rH G Q 1 LO 0 9cb G O Q h 0 'cb £ 4-J G a U G 0 0 co G G cb 0 b~> 0 0 £ 04 cb G 1 CM 0 0 3 4—' 1 >4 jc 04 o G 0 rG CG c 0 0 Oh 0 P bO cb G 0 G O G G 0 M—i G CJ > < 27 o o CN £ "O 0 CO CJ G 3 U 3 u X O CQ CO Sh Sh X O x o o 0 £* £3 pel Oh 3 H x> r~ on 1 1 X x > i-H o oo r- 00 x X p -r— ( Sh ON 4 -1 o Oh LO 0 G X OO X r- I-H X d o o I— 1 ON i-H •— i •— t oo r- X X X x ^H •-H 3 " •-H *—H i-H X i-H -H r—4 o X X X co X >-H i— 1 i-H i-H i-H 3* »—H o *—H I-H ► i-H CO G O LO CN ON r- > < •rH X CN O CO 0 G o U X o o 3 CN CO CO <4H o 3 G O G O u CO 3 Sh bH Sh 4 — I O ■t-j 3 0 Sh G 0 O G X O 3 U J O ~o G Sh 3 D G X £ o O > Sh “ x x w 3 CO 0 G G O G G 3 O U 0 3 o £ o w g3 G ^ >, X D oo 0 XJ O 0 G 0 x: CL 0 4 — 1 0 U to 1cdI •i-H 0 CO X 0w t3 o Sh +-> G O o •rH £ 0 £ o r-H hC 3!>n s1 tu r>\ 3 CN seedlings. •rH X £ •rH Q 3 G 0 4—l 0 G 0 77 x 4 — > 0 £ 3 X 0 X 3 G 3 cr 0 X o X o 1 r1 >. X o p X kN X X £ x ~o o 3 X •1— 1 0 3 0 •rH G O < 4 -4 0 0 0 3 O 4— i QL 3 0 Sh 0 o N o -a 73 ON 73 x O z 3 4—> 4-J 0 CL G X O W U o >4 3) 77, G 0 X Qh 3 f— W G L-H 0 ■ 1 — 4 *-H 3 3 0 0 X CL 7u > o Sh < o X r—H 3 CO 1 X £ o N Qh e r a ge often W -I CO o o bO 3 o G CO 0 <4H r—4 CN 3< a , bO CO G 0 -G £ CO s3 CN VO Q h 0) cn u 0 G o "£ OO CN 3 •rH X d 28 X 3 £ 0 CL, 0 Sh 0 •i-H 1*0 G G G O SZ 0 CN On o 1—< I-H (U -C CO F" OO LO 1 1 2 t ' o o - CN i-H CN i-H i—H ON m Hf CN 2 in r— i—H 2 H H 2 I— H 2 r —H O o s G H I-H ( CO m ON ON o 2 LO CO in uo ■-H i-H i-H i—H i-H r~ vO O CO CN CO CO 2i—H On 2 2 m «—H i- H i— i —I •i-H G Sh CQ 4—i 0) o C l, <4H o g o 1-0 t" CO in i-H CN 2 CO oo i-H i-H OO LO i-H i-H i-H m r- NO ON CO I— o • rH CO CO CO G 3 On a CO bo CO r— CN i—H 2 i—H i-H ON o CO 2 ON ■ —i 0> 4—» o CO £ o QJ i-O 2 CN cu 50 G o o 3 O h cd 2 r-H ON T-H H CN i— i O ' c> i— H H — CO UO CN O o^ ON p—H i-H CN CN 2 I-H G 4H Sh O no 0 > bO o <1 G CN 2 O G CO cd 0 Sh hC CQ CO "O • rH G o *i-H cd W J 5 4—> 0 ■|—l W cd 0 Q g o Mh i- H cd 'X G T J G G cd G O O h G g G o O 0 CN NO 2 hf r- 2 oo o nG i—l CO 2 co 2 2 nO CO P u O 4 -H CO G rC O » rH o Qh c 3 2 OO LO i-H CO i-H 2 2 CO CN co CO CN CN UO ON NO CN ON 2 On 2 ON 2 2 CO o i- H i-H CN CN On o NO CN i-H hT H r~ o 1-0 4h o i CN 2 OO 2 CN G * o G OO On o o uo CO NO On co ■-H OO O ' 2 h- r~ 2 hF CN HP 2 2 Nf CO CO S o c cu LO CN - 1 OO NO ON CO O ON CO NO co ON 2 i-H uO o in NO UO ON 2 c6 o uo uo m 2 uo 0 in CO CU > n o IO < CD £ H - Uh O o G g CN 2 2 u u G W X N CJ CQ cd O cu -H & W T 3 CL) cd Sh * a o 2 bo rbo kH 0) a CO cu CN Qh O O o g I G ■ a g -Q 2 CU 4—* cd <4H a *Q o> g o o CO bO o ‘S o o V 4—I o *— ! 3 -Q o co o cu * r—( cu (Q h 5 cu cu Sh g ■a = 3 cd N X cu G v o QJ o 2 . 2 cd os 2 c O v d 2 2 4— CN s CN O N 2 4 XZ O h N cd bO G g b>* cu O h SZ & g X 2 5X cd 6 2 I a 2 2 a 2 i 2 2 cd cu X bO G 2 O 4> g *G 2 g "cd CO 'g cu NO cd Sh *4—( 2 Oh Oh cd co 4Q cu *G cd 2 2 a 6 CO CO •= 3 i cu g b n G u g a o cu i—H 4-J (O g cd i bn rC 0 r2 uo co i— 2 o 0 cd CN nO 2 CO i-H CN CO G O cd G O • pH Sh LO UO G ■i—H a o I-H 2 2 ON 2 CO u ON uo co CN <4H G O - rH 4-H cd G 2 0 3 o U o o CO o G 2 2 O 2 CO b ^ CO 4—> uo oo 2 2 co a co T 3 U h }4 o NO CM G bO G O i— ) rG 4—1 rH ^ 2 o CU o Q h cd co LOON G G O * iH 4 -J p-H a O 2 to 2 ^ XZ u a •r-J D cu CO 4—* c 2 G cd 4-— 1 G sz G Qh 'IH G -a G o i CO o 4Q CN 2 i O ' ' CO ~ o •— H O G i lO 2 CO i-H i 0 G o 0 cu g b o cd G 0 a cd i—H > . G CU t r~ | O h Q > < 100 soo COI F igure 5. M arketer cucumber seedlin gs grown in solutions of 25, 50, 100 and 200 ppm of 1-naphthoic acid for four days. 30. Figure 6. M arketer cucumber seedlings grown in solutions of 25, 50, 100 and 200 ppm of quinaldinic acid for four days. 31. Figure 7. M arketer cucum ber seedlings grown in solutions of 25, 50, 100 and 200 ppm of 2-naphthoic acid and 100 ppm of 4, 4 , -m ethylenebis-3-hydroxy-2-naphthoic acid for four days. 32. 2 5 s o T,Cr;1 % ' i f i i , * ■ r 2 0 0 I V ' f 1 1 H M Figure 8. M arketer cucumber seedlings grown in solutions of 25, 50, 100 and 200 ppm of 4 - chlor o -1 - hydroxy- 2 - naphthoic acid and 100 ppm of 4, 4 ’- m ethyl en eb is3 -hydroxy-2 -naphthoic acid for four days. 33, CONT F igure 9. M arketer cucumber seedlin gs grown in 50 ppm solutions of 4 -ch lo ro acid and 100 ppm of 4, 4*-m ethylen ebis-3 - hydroxy-2 - naphthoic a cid for four days. 1 - h y d r o x y - 2 -naphthoic 34. 5 0 IOO lO O CONT Figure 10. M arketer cucumber seedlings grown in solutions of 1, 10, 25, 50, 100 and 200 p p m of 6-quinolinecarboxylic acid for four days. 35. I IO 15 50 IOO lO O CONT Figure 11. M arketer cucumber seed lin gs grown in solutions of 1, 10, 25, 50, 100 and 200 ppm of 2-p ico lin ic acid for four days. A IS IOO zoo CONT Figure 12. M arketer cucumber seedlings grown in solutions of 1, 10, 25, 50, 100 and 200 ppm of 2-hydroxy-3-m ethylenebenzoic acid for four days. .37 D is c u s s io n T h e c o m p o u n d s r e p o r t e d in T a b l e s 1 to 9 a r e a r o m a t i c o rg a n ic c h e m i c a l s c o n ta in in g an h y d ro x y group, o r an a c id group, o r both A lso m o d if ic a tio n in s t r u c t u r e in v o lv in g o th e r s u b s titu e n ts and h e te r o c y c lic n itr o g e n w e r e in c lu d e d In v iew of th e g e n e r a l root inh ib itio n e n c o u n te re d at 200 ppm with a lm o s t a ll co m p o u n d s, it w a s b e lie v e d that t h i s w as th e u p p e r lim it fo r c o r r e c t l y e v a lu a tin g b io lo g ic a l a c tiv ity . T h e e f f e c tiv e n e s s of a com pound in in h ib itin g ro o t g ro w th of c u c u m b e r w a s d e te r m in e d by it s a c tio n at c o n ­ c e n t r a t i o n s of b e tw ee n 1 an d 100 ppm . It w a s found th at m a n y of th e n a p h ­ th o ic a c id c o m p o u n d s p r o d u c e d g e n e r a l roo t inhibition, s o m e at c o n c e n t r a ­ t io n s a s low a s 1 ppm . T h e in h ib itin g a c tiv ity a p p e a r e d to be c o r r e l a t e d w ith th e p o s itio n of th e c a rb o x y l gro u p on th e r i n g s t r u c t u r e It w as m o r e a c tiv e w hen in th e one p o s itio n th an in th e two p o sitio n . T h e a c tiv ity of naphthoic a c id w a s g r e a tly m o d ified by th e i n t r o ­ d uction of an h y d ro x y l g rou p on th e r i n g s t r u c t u r e ro o t s tim u la tio n i n s te a d of ro ot in hib ition by in tr o d u c tio n of an h yd ro xy l gro u p T h is te n d e d to p ro d u c e T h e a c tiv ity w as th u s r e v e r s e d When th is hydroxyl group w as in th e one, and t h r e e p o s itio n s , th e g r e a t e s t root s tim u la tio n o c c u r r e d T h e in tro d u c tio n of c h lo r in e into th e hydroxyl naphthoic s t r u c t u r e did not a p p e a r to g r e a tly m odify th e a ctio n of th e com pound in c o n c e n tr a tio n s b e tw e e n 1 and 100 ppm 38 If th e fu s e d r i n g n u c le u s c o n ta in s only hydroxyl group and no c a r b o x y l g ro up , g e n e r a l ro o t s tim u la tio n o c c u r s . T h u s , it a p p e a r s , when a n a p h th a le n e r i n g c o n ta in s an h yd ro xy l r a d ic a l th e com po un d is lik e ly to have a s tim u la tin g effect upon c u c u m b e r ro o t grow th. It sh o u ld be m e n tio n e d that n a p h th a le n e a c e tic a c id is an im p o rta n t g ro w th r e g u l a t o r and i s v e r y e ffe c tiv e in in h ib itin g ro o t g ro w th of c u c u m b e r at low c o n c e n tr a tio n s 1-n a p h th o ic a c id i s s i m i l a r in s t r u c t u r e to n a p h th alen e - a c e t i c acid, ex ce p t th a t it h a s only a c a rb o x y l group w h e r e a s in n a p h th a le n e a c e tic a c id th e c a rb o x y l g ro u p is a tta c h e d th ro u g h m e th y le n e on th e r i n g n u c leu s It is a ls o of i n t e r e s t to note th a t if th e b a s ic r i n g s t r u c t u r e is ch an g e d by s u b s tit u tin g a n itr o g e n fo r c a r b o n in th e r i n g s t r u c t u r e , it p r o d u c e s a h e t e r o ­ c y c lic n itr o g e n c o m po un d w ith a c tiv ity s i m i l a r to n a p h th a le n e a c e tic a c id If, on th e o th e r hand, an h y d ro x y l g roup i s a d d e d to th e h e te r o c y c le n itr o g e n c o m ­ pound, th e n th e a c tiv ity is r e v e r s e d , R o ots a r e g e n e r a lly in h ib ite d in t h e i r g row th by a d din g auxin, although s o m e t i m e s v e r y low c o n c e n tr a tio n s m a y slig h tly i n c r e a s e ro ot grow th. B u rs tro m (17) h a s s u g g e s te d two h is to lo g ic a lly d iffe re n t r e a c tio n s w hich a r e invo lved in th e r e s p o n s e of r o o ts a p p lie d w ith auxin F i r s t , is th e tim e in te r v a l betw een c e ll d iv is io n in th e m e r i s t e m and second, is in itia tio n of c e ll elongation B u r s tr o m (17) a d v o c a te d that t h is in te r v a l m a y be s h o r te n e d by low c o n c e n t r a ­ tio n of auxin. T h e s e c o n d s e n s itiv e p h a s e in root grow th is th e r a t e of cell 39 elo n g atio n , w hich i s d e c r e a s e d by th e a d d itio n of auxin In his l a t e r p a p e r B u r s t r o m (18) e x p la in e d how r e s p o n s e s of e x te r n a ll y a d d ed auxin and r e ­ l a te d c o m p o u n d s c an be d is tin g u is h e d : - (1) by p o s itiv e a ctio n on th e f ir s t p a r t o f c e ll e lo n g a tio n p r o c e s s , (2) an in h ib itin g a ctio n in c e ll elon gation p r o c e s s , (3) an a n ti- a u x in a c tio n e x e r t e d by c e r t a i n com pounds, and (4) u n s p e c ific to x ic a c tio n of both a u x in s and a n ti-a u x in s . On th e b a s i s of th e ab ov e h y p o th e sis, two v e r y p r o m i s i n g c o m ­ p o u n d s w e r e s tu d ie d in th is in v e s tig a tio n T h e y w e r e 1 - naphthoic a c id and 6 - q u in o lin e c a r b o x y lic a c id ( F ig u r e s 5 and 10) T h e s e c o m po un d s had in h ib ite d ro o t g ro w th in a v e r y c h a r a c t e r i s t i c m a n n e r w hich a p p e a r e d to be id e n tic a l to th a t in d u c e d by auxin. O th e r c o m p o u n d s found to inhibit roo t g row th s ig n ific a n tly w e r e 2 - n aphthoic acid, 6 - h y d r o x y - 2 -n a p hth o ic acid, quinaldinic a cid , p ic o lin ic acid, 5 - c h l o r o s a l i c y l i c acid, an d 1-h y d r o x y - 2 -a c eto n a p h th o n e . B u r s t r o m (20) o b s e r v e d th at a n ti- a u x in s , indole and p h e n o x y is o b u tric a c id d e r i v a t i e s c a u s e d an i n c r e a s e of m o r e th a n 100 p e r c e n t in th e root length by i n c r e a s i n g c e ll e lo n g atio n without ch an g in g cell m u ltip lic a tio n In th is i n ­ v e s tig a tio n , 2 -n a p h th o ic a c id w ith hydroxy at 1, 3 p o s itio n and s u b s titu te d c h l o r ­ ine, J -n a p h th o l, 2 -n a p h th o l, 2, 4 - d i c h l o r o - 1-naphthol, 8 - quinolinol and 1 - h y ­ d r o x y - 2 - n a p h th a le n e sulfonic a c id (so d ium salt), 4, 4 ' - m e t h y l e n e b i s - 3 - h y d ro x y 2 -n a p h th o ic a c id an d i t s d iso d iu m s alt have i n c r e a s e d root grow th r e m a r k a b ly It is, t h e r e f o r e , s u g g e s te d f r o m t h e i r b e h a v io r on g ro w th that th e y might have a n ti- a u x in p r o p e r t i e s T h e c o m p o u n d s r e p o r t e d in T a b l e s 10 to 13 a r e e s s e n t i a l l y m e ta l c h e la tin g c o m p o u n d s C e r ta i n of th e s e co m po un ds, l - a m i n o - 4 - h y d ro x y a n th ra q u in o n e , r e s o r c i n o l , b e n z o tr ia z o l 2, 2 ' -biquinoline, d ie th y ld ith io c a r b a m ic acid , 2, 4 - d ih y d ro x y a c eto p h e n o n e . m e r c a p to a c e tic acid , and th ia z o le yellow had s ig n ific a n tly i n c r e a s e d root grow th at th e lo w e st c o n c e n tr a tio n u n d e r in v e s tig a tio n It is p o s s ib le that t h e s e c o m p o u n d s act by r e m o v in g c e r t a i n to x ic s u b s ta n c e s th a t m a y be p r e s e n t in r o o ts and t h e r e b y e n c o u r a g in g grow th. It i s a ls o p o s s ib le th a t th e s e m a t e r i a l s a r e a c tin g a s a n ti- a u x in s M a r t e l l et al. (44) a d v o c a te d that s o m e t im e s c h e la tin g a g e n ts m a y c a u s e d e a th of o r g a n i s m s by in h ib itin g a m e ta l- e n z y m e function, if it i s p o w e rfu l enough to c o m p e te w ith th e e n z y m e fo r th e m e ta l T h is m ig ht e x p la in why c e r t a i n of th e c h e la tin g c o m po un ds had in h ib ite d root g ro w th Activity of Organic Compounds on the Ab sciss io n of Coleus blumei Petioles R ev iew of L i t e r a t u r e T h e d e ta c h m e n t, o r a b s c i s s i o n of v a r io u s p la n t o r g a n s is a w e llknown p h e n o m en o n . T h e s e p a r a tio n of i m m a t u r e flo ra l p a r t s , le a v e s , foliage b r a n c h e s , a n d f r u i t s of th e plant is of c o n s id e r a b le i n t e r e s t T h e re g u la tio n of a b s c i s s i o n by c h e m i c a l s h a s now b e c o m e an a g r i c u l t u r a l p r a c t i c e A g r e a t n u m b e r of c h e m i c a ls have been found to be e ffe c tiv e for r e t a r d i n g p r e ­ h a r v e s t d ro p of o r c h a r d f r u its , an d in d u c in g a b s c is s io n of b lo s s o m th in n in g of h e a v y s e t t i n g v a r i e t i e s T h e v a r i o u s u s e s of a b s c is s io n r e g u l a t o r s have b e e n e x te n s iv e ly r e v ie w e d by T u k e y (73), Audus (9), and T h a r p (65). L a ib a c h (37) s u s p e c te d th a t aux in p la y e d a p a r t in th e p h en om en on of o rg an a b sc issio n . He o b s e r v e d th a t a p p lic a tio n of o r c h id p o lle n ia r e t a r d e d a b s c i s s i o n of d e b la d e d p e tio le s . In 1936, L a R u e (39) d e m o n s tr a te d th at a p ­ p lic a tio n o f s y n th e tic a u x in s d e la y e d l e a f fall in C o le u s b lu m e i. He ap p lie d la n o lin p a s t e c o n ta in in g 50 p p m of in d o le a c e tic a c id to the tip s of deb laded p e tio le s of c o le u s p la n ts , and o b s e r v e d th at th e t r e a t e d p e tio le s s ta y e d on lo n g e r th a n th e c o n tr o ls . T h e s e r e s u l t s w e r e r e p e a te d ly c o n f ir m e d by A ddicott an d Lynch (2), G a r d n e r and C o o p er (21), M y e r s (50), Wet m o r e et_al_ (86). Beal and W hitin g (12) o b s e r v e d that th e a b s c is s io n of s te m s of M ir a b ilis ja la p a c o u ld be in h ib ite d by ap p ly in g in d o le a c e tic a c id in la n o lin to th e cut s u r f a c e of a b ra n c h . 42 A b s c is s i o n a c c e l e r a n t s have b e en in v e s tig a te d (3), and found that, in g e n e r a l, t h e i r m e c h a n is m of a c tio n is s i m i l a r . M any of t h e s e m a t e r i a l s a r e to x ic to th e le a v e s , e i t h e r k illin g o r i n j u r i n g th e m , th u s a c c e l e r a t i n g o rg a n a b s c i s s i o n without s e r i o u s l y a ffe c tin g o th e r p a r t s of th e p la n ts T h e known a c c e l e r a n t s a r e c e r t a i n u n s a tu r a te d h y d ro c a rb o n s , a n ti-a u x in s , e n z y m e i n ­ h ib ito r s , d e fo lia n ts , and fru it t h i n n e r s C r o c k e r (19) r e p o r t e d th at e th y le n e a m o n g th e u n s a tu r a te d h y d r o ­ c a r b o n s i s th e m o st potent a b s c i s s i o n a c c e l e r a t o r Gawadi a n d A v e ry (22) r e m a r k e d that only one d e riv a tiv e , e th y le n e c h lo ro h y d rin is a c tiv e in a c c e l ­ e r a t i n g a b s c is s io n . B onner an d B an du rsk i (14) p o s tu la te d th a t an a n ti- a u x in which c o m p e t e s b io c h e m ic a lly w ith auxin fo r a s ite on an a p o e n z y m e m ight induce a b s c is s io n . W ein trau b_ et ak (84), W hiting and M u r r a y (87) found that 2, 3, 5- t r iio d o b e n z o ic a c id and o th e r halogen s u b s titu te d b e n z o ic a c id s a p p lie d to th e a p ic a l bud o f a b e a n s e e d lin g in d u ced a b s c i s s i o n of th e l a t e r a l buds It was f u r t h e r r e p o r t e d by W e in tra u b et^al_ (84) that a b s c i s s i o n w a s p r e v e n te d by s im u lta n e o u s a p p lic a tio n of in d o le a c e tic a c id and 2, 3, 5 - tr iio d o b e n z o ic a c id H all (24) in cotton p e tio le a b s c i s s i o n s tu d ie s , n o tic e d that t r a n s - c i n n a m i c a c id a c c e l e r a t e d a b s c is s io n , and th is a c c e l e r a t i o n w as re d u c e d by s i m u l ­ t a n e o u s a p p lic a tio n of in d o le a c e tic a c id S e v e ra l m a le im id e s , which a c c e l ­ e r a t e th e a b s c i s s i o n of p e a c h le a v e s , have been r e p o r t e d by van O v e rb e e k et a k (75) T h e p h y s io lo g ic a l m e c h a n is m of a c tio n on a b s c is s io n is not c l e a r l y u n d e rs to o d , h o w e v er, m a n y t h e o r i e s have b e en p o s tu la te d Only two th e o r i e s th e h o rm o n e e th y le n e b a la n c e t h e o r y of G aw adi jst al_ (22), and th e auxin g r a d ient t h e o r y of A ddicott et al. (4) have b e en s u p p o rte d c o m p r e h e n s iv e ly T h e h o rm o n e e th y le n e b a la n c e t h e o r y p r o p o s e s that le a f a b s c is s io n is r e g u l a t e d by th e b a la n c e of h o rm o n e and e th y le n e in th e le a f p o s e d by G a w adi et al. (22) and s u p p o rte d by Hall (24) It w as p r o ­ Gawadi et al (22) r e m a r k e d th a t l e a f a u x in d im in is h e d w ith m a t u r i t y and a s s u m e d that eth y le n e w a s p r o d u c e d in le a v e s and s e r v e d to a c c e l e r a t e t h e i r a b s c is s io n . He c o n ­ c lu d e d th a t th e i n t e r a c t i o n of th e o p p o sin g fa c to r s , auxin and e th y le n e r e g u ­ la te a b s c i s s i o n H all (24) w o rk in g w ith d e b lad e d p e tio le s of c o le u s and cotton found th a t a ux in p r e v e n t e d th e a c c e l e r a t i o n o f a b s c i s s i o n by e th y le n e and e th y le n e c h lo ro h y d rin . M any of th e r e c e n t a d v a n c e s in a b s c i s s i o n p h y sio lo g y show s that a u x in h a s a dom inant r o l e in c o n tr o llin g th e i n t e r v a l s of le a f a b s c is s io n (W e tm o re jjt a k , 86), S h o ji_ e ta k (57) s u g g este d , by m e a s u r i n g th e auxin c o n c e n tr a tio n d is ta l and p r o x im a l to th e a b s c is s io n zone, that auxin g ra d ie n t a c r o s s a zo n e w as m o r e im p o r ta n t in th e re g u la tio n of a b s c is s io n th a n th e a ux in c o n c e n tr a tio n in th e a b s c i s i n g o rg a n . C o n s id e rin g all a v a ila b le i n ­ f o r m a tio n , A ddicott et ak (4) p r o p o s e d a th e o r y of auxin g ra d ie n t They r e m a r k e d th a t r a t e of a b s c i s s i o n is r e g u la te d by th e auxin g ra d ie n t a c r o s s 44 th e a b s c i s s i o n zone, a b s c i s s i o n d o e s not o c c u r when th e g ra d ie n t is steep, th a t is , high on th e d is ta l s id e and low on th e p r o x im a l side of th e a b s c i s ­ sio n l a y e r If th e auxin is high on th e p r o x im a l sid e and low on th e d is ta l sid e, a b s c i s s i o n w ould o c c u r T h i s t h e o r y w as s u p p o rte d by th e i n v e s t i ­ g a tio n s of R o s s e t t e r j?t ah (56), Jaco bs (34) T h e y found that th e a c c e l e r ­ a tio n of n e ig h b o rin g young le a v e s on th e a b s c i s s i o n of de b lad e d p e tio le s i s a t t r i b u t e d to th e aux in p r o d u c e d in th e le a v e s . S in c e m a n y of th e o rg a n ic co m p ou nd s, w hich w e r e u s e d in th e c u c u m b e r ro o t t e s t , had s tim u la te d root grow th, it w a s thought d e s i r a ­ b le to t e s t t h e i r r e l a t i v e r e s p o n s e on a b s c i s s i o n to f u r t h e r d e te r m in e t h e i r a c tio n a s a n ti- a u x in s H ence, a s e r i e s of e x p e r im e n t s w e r e in itia te d to d e t e r m i n e t h e i r effect on C o le u s b lu m e i p e tio le a b s c is s io n . 45 M eth o d s and M a t e r i a l s C o le u s b lu m e i L th e c o u r s e of in v e s tig a tio n s . var C h r i s t m a s G e m w as u s e d th roughout T h e e x p e r im e n t a l p la n ts w e re g row n fro m c u ttin g s w h ich w e r e ta k e n f r o m clo n al m a t e r i a l T h e p la n ts w e r e grow n u n d e r g r e e n h o u s e c o n d itio n s d u rin g th e p e r i o d fr o m A p ril to S e p te m b e r, 1955 w ith t e m p e r a t u r e flu c tu a tio n s of 65° to 80° F. A b sc issio n T est S e v en ty s i n g l e - s t e m m e d u p rig ht p la n ts w e r e g r a d e d fo r s iz e a n d th e l e a f b la d e s w e r e cut off in th e m a n n e r shown in F ig u r e 13b The t i p s o f th e p e t i o l e s of d iffe re n t lo ts of p la n ts w e r e th e n c o v e r e d with la n o lin p a s t e c o n ta in in g 10, 100 and 1000 p p m of 2, 3, 5 -tr iio d o b e n z o ic a c id (TIBA), 4, 4* - m e th y l e n e b is - 3 - h y d r o x y - 2 - n a p h th o ic acid, 3 -h y d ro x y 2 - n a p h th o ic acid , 1 -h y d r o x y -2 -n a p h th o ic acid, and 1 -n a p h th o ic a c id P u r e la n o lin p a s t e w as u s e d a s c o n tro l and a la n o lin p a s t e w ith 100 ppm of n a p h th a le n e a c e tic a c id (NAA) w a s u s e d a s a s ta n d a r d g ro w th r e g u la to r check. C o n c e n tr a tio n s of th e c om p ou n ds m e n tio n e d above w e r e d is s o lv e d in a s m a l l q u a n tity of ethyl a lco h o l b e fo re m ix in g into w a r m lanolin. E v e r y p r e c a u t i o n w a s ta k en to apply th e lan o lin p a s t e u n ifo rm ly on th e t ip s F iv e p la n ts w e r e u s e d fo r e ac h t r e a t m e n t . T h e n u m b e r of p e tio le s w hich did a b s c i s s w ith slight p r e s s u r e w e re r e c o r d e d a f t e r e v e r y tw elv e hours T h e p e r c e n t a g e drop of p e tio le s w a s d e te r m in e d for e a c h t r e a t ­ m ent (T ab le 14) (a) N orm al coleus branch (b) B ra n c h with d e bl ad e d p e t i o l e s F i g u r e 13. M et ho d of p r e p a r a t i o n of c o l e u s p l a n t s 47 S i m u l t a n e o u s A p p lic at io n of N a p h t h a l e n e a c e t i c Acid (NAA) and O rg a ni c Compounds Auxin u s u a l l y d e l a y s t h e a b s c i s s i o n of c o le u s p e t i o l e s ( G a r d n e r et al 21) a nd it is a l s o evid ent f r o m o u r p r e v i o u s a b s c i s s i o n t e s t e x p e r i m e n t that n a p hth al en e a c e t i c a c i d (NAA) ha s e ff e c t iv e ly d e la y e d th e d r o p s of p e t i o l e s Therefore, a s e r i e s of e x p e r i m e n t s w e r e i n i t i a t e d to i n v e s t i g a t e w h e t h e r the co mp ou nd s w h ic h w e r e found e ff e c t iv e in e n h a n c in g th e a b s c i s s i o n in th e p r e v i o u s te st , m ig ht have s o m e i n t e r a c t i n g effect on th e t r a n s l o c a t i o n a nd act io n of n a p h th ­ a l e n e a c e t i c aci d. T h e following p r o c e d u r e s w e r e a do pt ed fo r th e in v e s t i g a t i o n s : M ix e d app lic atio n: T r e a t m e n t u s e d f o r th e s i m u l t a n e o u s a p p l i c a ­ t i o n of a b s c i s s i o n co m p o u n d s a r e a s follows: 1 2, N a p h t h a l e n e a c e t i c a c i d 100 p p m N a p h t h a l e n e a c e t i c a c i d 100 p p m + 4, 4 ' - m e t h y l e n e b i s - 3 - h y d r o x y 2 - n a p h t h o i c a c i d 10 p p m 3 N a p h t h a l e n e a c e t i c a c i d 100 p p m + 3 - h y d r o x y - 2 -n ap hth oic a c i d 100 p p m 4 N a p h t h a l e n e a c e t i c a c i d 100 p p m + 1- h y d r o x y - 2 -naphthoic a c i d 1000 p p m 5 N a p h t h a l e n e a c e t i c a c i d 100 pp m + 2, 3, 5 - t r i i o d o b e n z o i c a c id 1000 pp m 6 2, 3, 5 - t r i i o d o b e n z o i c a c i d 1000 ppm. 7 2, 3, 5 - t r i i o d o b e n z o i c a c i d 1000 ppm + 4, 4 f - m e t h y l e n e b i s - 3 - h y - d ro x y -2- naphthoic acid 10 ppm 48 8 2, 3, 5 - t r i i o d o b e n z o i c a c i d 1000 pp m + 3 - h y d r o x y - 2 n ap hth oic a c i d LOO pp m 9 2, 3, 5 - t r i i o d o b e n z o i c a c i d 1000 ppm + 1- h y d r o x y l nap hth oic a c i d 1000 pp m 10 La no lin only (check) T h e above t r e a t m e n t s w e r e m ix e d in lanolin and w e r e a pp li e d on d e b l a d e d p e t i o l e s R e c o r d s w e r e ta k e n a f t e r e v e r y twe lv e h o u r s and t h e p e r c e n t a g e r a t e of p e t i o l e d r o p s w as u s e d a s an index fo r inhibition o r a c c e l e r a t i o n of a b s c i s s i o n (T a b le 15) Middle a ppli cat ion : ( F i g u r e 14a) A lanolin p a s t e c onta in ing n a p h t h a l e n e a c e t i c a c i d 100 p p m was p l a c e d on th e t i p s of the de bl ad e d p e t i o l e s a nd a r i n g of la nolin p a s t e s c o n ta i n in g 10 p p m of 4, 4 ■ ’-methyleneb i s - 3 - h y d r o x y - 2 - na p ht h oi c acid; 100 p p m of 3 - h y d r o x y - 2 -n ap hth oic acid; 1000 p p m of 1 - h y d r o x y - 2 - na phthoic acid; an d 1000 p p m of 2, 3, 5 - t r i i o d o b e n z o i c a c i d a p p l i e d a r o u n d th e p e t i o l e s be tw e e n the a b s c i s s i o n zone and th e t i p s a s shown in F i g u r e Nja A r i n g of pl a in lanolin was a pp lie d to the o t h e r grou p of p l a n t s which s e r v e d a s c o nt ro l. in e a c h t r e a t m e n t T h re e plants w ere used T h e r a t e of a b s c i s s i o n was th e c r i t e r i a u s e d to d e t e r ­ m i n e t h e effect if th e m a t e r i a l s a r e m o dif yin g th e acti on of n a p h th a l e n e a c e ti c acid S p i r a l ap plic atio n: ( F i g u r e 14b) In t h i s e x p e r i m e n t the m etho d of de sig na t ing l e a f n u m b e r s is th e s a m e a s u s e d by J ac ob s (33) Wet m o r e et al (a) Middle a p p li c a ti o n of o r g a n i c c o m poun ds a p p li e d at i n d i c a t e d spots, n a p h t h a l e n e a c e t i c a c i d in lano lin p a s t e a p p li e d at tips. (b) Sti pp led d e b la d e d p e t i o l e s t r e a t e d w ith n a p h t h a l e n e a c e t i c acid; n o n ­ s t i p p l e d t r e a t e d with o r g a n i c c o m ­ p o u n d s in lanolin. F i g u r e 14. M e t h o d s o f t r e a t m e n t of c o l e u s p l a n t s (86) h a s a l s o u s e d a s p i r a l a r r a n g e m e n t of d e bla din g l e a v e s in t h e i r a b s c i s ­ s io n s t u d i e s F i g u r e 14b T h e d e b la d e d p e t i o l e s w e r e t r e a t e d s p i r a l l y , a s shown in T h e p u r p o s e of t h i s in v e s t ig a ti o n was to d e t e r m i n e th e p o s s i b l e i n t e r a c t i o n of n a p h t h a l e n e a c e t i c a c i d and a b s c i s s i o n a c c e l e r a t o r s when a p ­ p l i e d at a d if f er en t lo c at io n on th e plant F o r e x ample , the de bla de d p e ti o le on t h e pla n t w e r e t r e a t e d in s u ch a m a n n e r that p e t i o l e tip which w as t r e a t e d with 100 p p m of n a p h t h a l e n e a c e t i c a c i d ha d a p e t i o l e t r e a t e d with 10 ppm of 4, 4 , - m e t h y l e n e b i s - 3 - h y d r o x y ~ 2 - n a p h t h o i c a c i d jus t above o r below and oppo i te it The other chemicals, 100 p p m of 3 - h y d r o x y - 2 -n ap hth oic acid, 1000 p p m of 1 - h y d r o x y - 2 - n a p h t h o i c acid, an d 1000 pp m of 2, 3, 5 - t r i i o d o b e n z o i c a c i d w e r e t e s t e d with n a p h t h a l e n e a c e t i c a c i d in a s i m i l a r m a n n e r l a n o li n w a s u s e d a s c o ntr ol . A pla in T h r e e plants w ere used for each tre a tm e n t T h e r a t e of a b s c i s s i o n wa s r e c o r d e d a f t e r e v e r y tw e lv e ho u rs , a nd u s e d a s a c r i t e r i o n to d e t e r m i n e th e effect of m a t e r i a l s in modif ying th e a c ti o n of n a p h t h a l e n e a c e t i c acid. Results In a t t e m p t i n g to a s c e r t a i n th e a c t i v i t y f o r a b s c i s s i o n r e s p o n s e , 4, 4*m e t h y l e n e b i s - 3 - h y d r o x y - 2 -n ap h th o ic acid, 1 - h y d r o x y - 2 -na phthoic acid, and 3 - h y d r o x y - 2 -na ph th oi c a c id c o m pou nd s w e r e t e s t e d (Tab le 14) A known a n t i - a u x i n , 2, 3, 5 - t r i i o d o b e n z o i c (TIBA) and n a p h t h a l e n e a c e t i c a c i d (NAA) an auxin, w e r e in c lu d e d a s s t a n d a r d c o m po un ds in each e x p e r i m e n t a s a 51 c h e c k on t h e c o n s i s t e n c y of r e s p o n s e . It w a s o b s e r v e d that 1- h y d r o x y - 2- na p h th o ic a c i d at 1000 p p m had i n j u r e d t h e t i s s u e s of de bla de d p e t i o l e t i p s i m m e d i a t e l y foll owi ng a p p li c a ti o n T h e o t h e r c o m po un ds used w e r e not i n ­ j u r i o u s to t h e p la n ts , a nd had a si gn ifi ca nt effect on a c c e l e r a t i n g a b s c i s s i o n t h u s i n d i c a t i n g tha t t h e s e s u b s t a n c e s a r e a c t i n g a s a n t i - a u x i n s E x p l o r a t o r y t e s t s w e r e c a r r i e d out with th e s a m e c o m po un ds to i n ­ v e s t i g a t e t h e i r s i m u l t a n e o u s a p p li c a ti o n (Tab le 15) When the a n t i - a u x i n 2, 3, 5 - t r i i o d o b e n z o i c a c i d w a s a p p li e d s i m u l t a n e o u s l y with th e above m e n ­ t i o n e d c om p o u n d s, it w a s found that a c c e l e r a t i o n of a b s c i s s i o n was enhanced, t h u s i n d i c a t i n g that t h e s e m a t e r i a l s had a s y n e r g i s t i c effect with 2, 3, 5 - t r i ­ iod o b e n zo i c a c i d T h e m o s t e ffe ct iv e m a t e r i a l in t h i s e x p e r i m e n t w a s 4, 4'- m e t h y l e n e b i s - 3 - h y d r o x y - 2 -n a phth oic a c i d followed by 3 - h y d r o x y - 2 -nap hth oic a c i d a n d 1- h y d r o x y - 2 - naphthoic a c i d It w a s a l s o n o ti c e d that 1- h y d r o x y l - n ap hth oic a c i d w a s tox ic to the plant t i s s u e s when a p p li e d with 2, 3, 5 - t r i ­ io do be nz oi c acid, When n a p h t h a l e n e a c e t i c acid, an auxin s i m u l t a n e o u s l y a p p li e d with t h e s e m a t e r i a l s , it w a s found that th e a c c e l e r a t o r s , 4, 4 T- m e t h y l e n e b i s - 3 h y d r o x y - 2 - naphthoic, 3 - h y d r o x y - 2 -naphthoic, 1 - h y d r o x y - 2 -naphthoic, 2, 3, 5t r i i o d o b e n z o i c a c id s , r e d u c e d th e e f f e c t i v e n e s s of NAA in p r e v e n t i n g a b ­ s c i s s i o n , t h u s a g a i n i n d ic a ti n g t h e i r a n t i - a u x i n p r o p e r t i e s In a n o t h e r e x p e r i m e n t th e a b s c i s s i o n a c c e l e r a t o r s w e r e ap pl ie d at a 52 point m id w a y b e tw e e n th e cut s u r f a c e and th e a b s c i s s i o n l a y e r (Tab le 16) N a p h t h a l e n e a c e t i c acid, which was a p p l i e d to th e cut s u r f a c e might thus be l e s s e ff e c t iv e b e c a u s e of i n t e r f e r e n c e by an a n t i - a u x i n and have it s t r a n s l o c a t i o n a nd a c ti o n modified. T h i s w a s found to be t r u e when an a n t i - a u x i n o r a b s c i s s i o n a c c e l e r a t o r w a s a p p li e d in such a m a n n e r , the a c t i o n of n a p h t h a l e n e a c e t i c a c i d w a s r e d u c e d In s til l a n o t h e r e x p e r i m e n t to d e t e r m i n e th e e f f e c t i v e n e s s of the a n t i - a u x i n on m o d if y in g the act io n of n a p h t h a l e n e a c e t i c acid, an e x p e r i ­ m e n t w a s i n i t i a t e d in which th e a n t i - a u x i n o r a b s c i s s i o n a c c e l e r a t o r s w e r e a p p l i e d u s i n g a s p i r a l a r r a n g e m e n t of th e de bla de d l e a v e s (Tab le 16) It w a s o b s e r v e d that th e a b s c i s s i o n a c c e l e r a t o r u n d e r t h e s e co nditions a l s o m o d i f i e d t h e a ct io n of n a p h t h a l e n e a c e t i c a c i d It i s evident f r o m t h e r e s u l t s th a t t h e s e co m p o u n d s have a n t i - a u x i n p r o p e r t i e s when i n v e s t i ­ g a t e d in d if f e r e n t w a ys 1 - n a p h th o ic a c i d which w o r k e d like n a p h t h a l e n e a c e t i c a c i d on c u c u m b e r r o o t s w a s t e s t e d f o r i t s a c t i v i t y on a b s c i s s i o n . It was found that at 10 pp m t h e a b s c i s s i o n w a s delayed, h o w e v e r at 1000 p p m it had c o n s i d e r a b l y a c c e l e r ­ a t e d t h e a b s c i s s i o n (T ab le 17) At a low c o n c e n t r a t i o n it m a y be a c ti n g a s an auxin, wh ile at high c o n c e n t r a t i o n 1000 pp m it m a y have s o m e in j u r i o u s effect on c e r t a i n t i s s u e s and h a s t e n a b s c i s s i o n . 53 a. 0) X w o P r*H O p P X o CM o o o —4 vd CO o o ——4 [— uO X o o CM O o On o o r- o I/O ["- id p OO o o I——1 X o o —-1 O OO OO o o — 1 o i— 4 o 00 o o —4 X OO o o o i i o o o o o •—4 o o o o 1 o o r—4 1 1 +-> i— 1 100.0 * rH Ip —I CM CO ON OO CM CM X CO ON o CM 1— 4 p CM O \ —-i OO o X CO P CO X X p X ON id r- X OO o OO X oo X OO OO X ON CO X p OO CO X p CO OO X OO l> r— I id X X p UO r- cd X X r- id r- o CO X X OO CM r— o X OO p p ON UO o a CO 6 o CO CO i 4 X O o ■a P bo P O tP XI CM P CM 1 1 1 CO CO OO CO o o i—4 b- o X o cm ON r- CM uo X CO CO X X p X X CM l—H X ON X o ’ OO o 78 0 cl 3 W X 56,7 0 •i-H 86.6 X 53 H i i 1 1 i i X OO o x> UO CM On 1 o 1— t i— 4 CO P P CO 0 i t i t 1 1 >“ 4 o O p cd ON CO cd 1 1 t 1 1 1 o 4 4 NO 1 1 -- w G o 0 P 53 P i—i a CO 3 0) o U XI 0 X P 30 Q mh O 0) r-H a CO X p p o a a o P P bo 5-4 O "P O ° p co ^ ■ 4 — J P cc; p o w to o P •—1 S P "n CD X ^ *-> 0 CL, X 0 s 5 « - p O o X G P p a a o o o a a o i— i a a o o X X X X G P G P G P G X i—4 G P -r-H G P G G G G O O O O O +-> X a X X X X p p p p p p CM CM CM (—1 £0 a a a a a a o o o i— i i— H X CO X P H G 0 X 3 & *i-H b*N N P 0 CO £ « U a a o o f-H ^ U a a o o o p a a o i— 4 ._ < C Q M a X X a p p p CM CM >i X X p o P X ►^N X —1 3 X b-. X o o p p X X >> >1 X X a >N X a o p X >. X X o p X b^ X X CO 3 -H yd ro xy - 2 - naphthoic acid 1000 ppm p 1L 0 XI » X oft X < X • 1~H CJ co d cd E f t ff tt f t O O o O o r-H xt < •rH C Q 0 t—\ cd d ft ft ft o o o *—I X < C Q l-H H < CQ >— i H ♦r H 0 cd 0 o cd 0 c 0 cd x ft cd 2; u E x 0 £7 x ^ _ ^ • E a Cg co o 'ft E ft £ cd ft e ft o o < < 2: cd a f t 1 CM O O i do — CX c 2 < X 2: <4H 0 X X f t f t cd cd cd cd CM CM & O Q X ---1 4-J ft. X 4 — I X 0 Cd r- O JO dd •rH CO E fEt o o o o o o 3 ft ft ft Z X d •---1 C X >. CO cd 0 • rH O O X X E a. o ft x X I o o o i dO X i >V x 1 o o CM ft E 1 t— H CM CM ft ft ft ft c1d 1 cd 0 •rH -J—» cd cd £ CO ft ft cd 0 CO a X 4-1 X X JO 0 CO X 0 0 JO ft 0 0 • i-H 0 X * >v X K*"! X o X O 0 X a ■ a >i 0 0 X Jh CO d CO CO £ dd 3 CO f t r— £ f t i—1 o o 1— 1 <: < cd :d o E cl a X ft e x r- £ f t f t o o ft o o r-H < < Z £ f t e x o o o £ o u •-H co 2u 3^ CU, a> Z o U X >> ^ X CU 4-j cd u 0 x cd X ^3 CU c D £ -4h CO o —I CO co CN X O lid I-H X CN lid o oo CN CN Z CO Ud CO CO CN o CN CN LO CN o o cu HJ cd ctf CO CO ‘ i-H u CO c (U 0 Jh G o o ud i-H o X _i X o r- X X " 'f Ov CN oo o o X o Lid r-H i—H o X o r- X X o ) 1 CO co CO co lid co co CO CO CO CO CN cn uo CN -5 O G 2 ob Jh O co 3 O !> G cd *£ Jh O H c o cu * ,~l cd u X “O O cd 0 cd >r*] u 0 X CJ co o o CO 0 X! M £ CU cd G t CN 1 c CQ i—i H i u cd CO cd A* H CO oo Ud S •i—i Jh CO CO o OO £ 0 X ■3 | *s ° X3 P-< £& £o Z U Dd o CN Is- CN X CU fX, 0 0 a; U 0 O cu x CO CN Is- co -- o 0 4—' co cd cd oi CN in oo -- & < hh CO OO -- 0 CO cn *r—1 X 0 a Co X G 3 O a. 6 o V o ‘2 cd bO Jh o G o N G CU X O X O 0 i— 1 >> cu cu X H 0 o 1 — 1 c G x Jh H G u o •r-H H> 0 4^ a oj cd O *r—1 0 i ■1 G Ou 0 Pu X 3 S 2 o o B cx cu 4—> 7d X Jh h cd CU ’Q CO Z < Z § ^H o cd cu cd G CN 2 CN >■> >i X o O G cd X O Jh X >. Jh X X O CO r-H o X X 4—‘ CU i CN O O r-H >> X o < Jh < X z £ cu cd G X X H X cu G cd CU G cx X £ •i-H 0 cd X £ r- *f-H Ph B X bn H cd a G O o o < < z < CQ 1— ( H X 4— 4—1 cd o 1— ^ cu cu cu cu o o o 2 rz G CU CU o o o < < z 2 cu cu 4— I o 0 To X CU cx o o o CU 3 (U =2 ■a 2 cx CU o ■—( o o 1—H < < < < o z z bn X I— 1 0 _ X •I—1 0cd -a b^ X 1 0 CO X 4— o X 4—> X '$ 2 72 cx Cu cu cu o X 0 G 0 2 c % 2 with 1-h y dr ox y- 2 -naphthoic acid X § co CO 0 o iid OO cu 2 cu cu o o 1 c § Jh cd c 1 CN b^ X o X X CU cu o o < < z c cu cu o o NAA 100 ppm 1000 ppm ^ ^ >i X ^ o o o CN CN r- 70.0 CU 75 0 55 56 CN CO o o o 4-1 O CO 1 o o m o C N ON o On O O C N C O C O O O C N U O O O 1 O O U O o a, • r“4 H o o cn C O O N C O o a cd CD Oh ■ft) CD TJ ■ft) CD N O O O o o N O cd ft CX < 3 CD Q o r~- o o o H O C CD 4H cd u •’—I o Xd •*-> Xd cd o CX * uo r-* co o r- o C N On r- r —( o n6 OO CO CO Cd 2 a co % -Q w -1 uo u N O o ON uo ptf cd -a a> o c 0 ■ ft! CD 'd 1 (D oo ft CD Pk r—H NO c I-H H CO cd co CN r- CD ON co ad oo o NO CN CD Ph CO d3 CD 'o U O T3 cd CD X3 cd 6 cd cx cx r —4 X! (S 4h o o CO ■ft) O o CD < < cx s o cd PCh cd CJ o ■a co u cd ■i-H co •r"ft CO CD CO -Q <5 o • f“H -i- j cd ■*—> ft 4—> CD o CD CD O o cd cd CD CD CD 4—* cd SH co CD CD Dh - g Xd CD H cx cd U »—» £ Cl Cl o O CX cx o o o "O O cd CD cd cd £ cx cx o cd cd CD cd cd xd i—* -cd cd cd r——i CX, cx o xd ■i—’ xd cx cd 2: o o xd -Ed -£ x: Cl cd 4—1 CL cd Biological Activity of O rganic Compounds on the Rooting of Cuttings R e v i e w of L i t e r a t u r e T h e u s e of gr o w th r e g u l a t o r s to p r o m o t e ro o t i n g in t h e plant p r o p a g a ­ tio n i n d u s t r y i s v e r y r e c e n t Befo re the d i s c o v e r y of auxin, m a ny c h e m i c a l c o m p o u n d s h a d b e e n r e p o r t e d to i n c r e a s e th e ro o t i n g of cuttings, such a s p e r m a n g a n a t e by C u r t i s (20), an d c a r b o n m onoxid e by Z i m m e r m a n et al (89) Van d e r l e k (74) m a d e e x t e n s i v e i n v e s t i g a t i o n s into th e f a c t o r s involved in th e r o o t i n g of c u t t i n g s He r e p o r t e d that in c u r r a n t , po p la r, g r a p e s , and willow t h e i n t e n s i t y of ro ot p r o d u c t i o n w as d i r e c t l y c o r r e l a t e d with the r a t e of bud d e v e lo p m e n t He s u g g e s t e d t h e f o r m a t i o n of h o r m o n e o r h o r m o n e s in th e d e v e lo p i n g buds, an d i t s t r a n l o c a t i o n to th e b a s e of th e c utt in g w h e r e it i n i t i a t e d th e r o o t s In 1929, Went (85) o b s e r v e d that n o n - s p e c i f i c , heat r e s i s t i n g s u b s t a n c e s co uld be e x t r a c t e d f r o m l e a v e s of b a r le y , which, when a p p l i e d to cu tti n gs , p r o m o t e d th e de v elop m en t of new r o o t s Later, Thimann a nd Went (67) d i s c o v e r e d that auxin e x e r t s a p r i m a r y c o n tr o l o v e r root f o r ­ ma tio n. R ec e ntly , a g r e a t n u m b e r of c h e m i c a l s p r i m a r i l y dif ferent d e r i v a - t i b e s a nd f o r m u l a t i o n of a r y l o x y - a l k y l - c a r b o x y l i c a c i d and a r y l - a l k y - c a r b o x y l i a c i d s w e r e t r i e d on a l a r g e v a r i e t y of differ ent s p e c i e s and un d e r diff erent conditions T h e s e w o r k s have been e x t e n s i v e l y d i s c u s s e d by T u k e y (73), T h i m a n n a nd Behnke (69), Audus (9), Le opole (41), A v e r y and Johnson (10) 58 An u n d e r s t a n d i n g of th e m e c h a n i s m by which gro wt h s u b s t a n c e s s t i m u ­ l a t e t h e r o o t i n g of c u tt in g s e m e r g e d v e r y r e c e n t l y T h e initial step in th e f o r m a t i o n of r o o t s i s t h e d i f f e r e n t i a t i o n of m e r i s t e m s into root p r i m o r d i a By a n a l y s i n g t h e d if f er en t p a r t s of cu tt in g s of young be an p la nt s, w ho se cur s u r f a c e s w e r e t r e a t e d with i n d o l e a c e t i c acid, Stuart (62) a nd A l e x a n d e r (6) found c a r b o h y d r a t e s a nd n i t r o g e n o u s food m a t e r i a l s w e r e t r a n s l o c a t e d to the tre a te d a re a T h e s e s u b s t a n c e s migh t s t i m u l a t e the root p r i m o r d i a Skoog (58, 59) d e m o n s t r a t e d that th e ty p e of d i f f e r e n ti a ti o n that o c c u r s in t h e m e r i s t e m is depen de nt upon t h e p r o p o r t i o n of auxin to o t h e r s u b s t a n c e s . He p o s t u l a t e d th a t t h e r a t i o of auxin to o t h e r plant c o n s t i t u e n t s sh ould be high f o r e n c o u r a g i n g root p r i m o r d i a . In a t t e m p t i n g to c o r r e l a t e c h e m i c a l s t r u c t u r e with bio log ic al activity, c e r t a i n c o m p o u n d s w e r e found w hose a c ti o n c l o s e l y r e s e m b l e d t h a t of n a p h t h a l e n e a c e t i c a c i d at l e a s t fo r t h e c u c u m b e r root t e s t It was thought d e s i r a b l e to e x t e n d t h e i n v e s t i g a t i o n s of t h e s e co m po un ds on p l a n t s o t h e r t h a n c u c u m b e r , and he nce an e x p e r i m e n t w as set up to d e t e r m i n e t h e i r a c t i v i t y on t h e r o o t i n g of c u tt in g s M et h o d s and M a t e r i a l s T w o c o m pound s, 1-n ap h th o ic and 6 - q u i n o l i n e c a r b o x y l i c a c i d s w e r e d i s c o v e r e d which w e r e s i m i l a r in r e s p o n s e to n a p h th a l e n e a c e ti c a c i d on c u c u m b e r ro ot growth. T h e s e w e r e u s e d to d e t e r m i n e t h e i r a c ti v it y on t h e r o o t i n g of c u tt in g s blumei L var One h u n d r e d a nd s i x t y - f i v e cu tti ng s of Co leus C h r i s t m a s G e m w e r e u s e d f o r th e study The chemicals w e r e f i r s t d i s s o l v e d in s m a l l q u a n ti ti e s of ethyl alcohol to f a c il it a te t h e i r s o lu b il it y in w a t e r 1000 p p m T h e c o n c e n t r a t i o n s u s e d w e r e 1, 10, 50, 100 and F i f t e e n c u tt in g s w e r e u s e d in e ac h t r e a t m e n t p l a c e d in a b e a k e r c o n t a i n i n g 50 cc of th e solution a nd a llo w ed to s o ak fo r 22 h o u r s A f t e r t r e a t m e n t , the c u tt in g s w e r e p l a n t e d in a g r e e n h o u s e bench. T h r e e r e p l i c a t i o n s w e r e u s e d c o n ta i n in g five cu tt in g s in e a c h t r e a t m e n t A f t e r 15 d a ys th e c u tt in g s w e r e ta k e n out and g r a d e d to a su b je c ti v e e v a l u a t i o n of n u m b e r of r o o t s in which t h e following s c a l e w a s employed; (1) He av y r o o t i n g (2) Good r o o t i n g (3) F a i r r o o t i n g (4) P o o r r o o t i n g (5) V e r y p o o r r o o t i n g Results T h e data i n d i c a t e tha t 1-na phth oic a c i d and 6 - q u i n o l i n e c a r b o x y l i c a c i d h a s c o n s i d e r a b l y s t i m u l a t e d th e root gro w th on Co le us c ut tin gs in all co nce n t r a t i o n s (T a b le 18) T h e m a x i m u m s ti m u la ti o n of root gro wth w a s a t t a i n e d at 100 p p m c o n c e n t r a t i o n of 1 -n ap hth oic a c i d and at 1000 pp m of 6 - quinoline carboxylic acid 60 TABLE 18 T h e P e r c e n t R oo ti n g of C o le u s C u tt in g s F i f t e e n Day s a f t e r T r e a t m e n t with V a r i o u s C o n c e n t r a t i o n s of O r g a n i c Co mpounds. C o n c e n t r a t i o n s of O r g a n i c Compounds A v e r a g e P e r c e n t of Rooting on Cuttings _________________ G ra d e s * _______ ________ 1 II III IV V C on tro l 33., 3 46 7 1 - Naphthoic a c i d - 1 p p m 66. 7 33 3 20. 0 1 - Naphthoic a c i d - 10 p p m 20, 0 60. 0 1 - Naphthoic a c i d - 50 p p m 53. 4 46 6 1 - Naphthoic a c i d - 100 p p m 80. 0 20, 0 1 - Naphthoic a c i d - 1000 p p m 33. 3 60. 0 6, 7 -- 40. 0 60. 0 6 - Q u i n o l i n e c a r b o x y l i c a c i d - 10 p p m 13 3 66. 7 20. 0 6 - Q u i n o l i n e c a r b o x y l i c a c i d - 50 p p m 26. 6 60.0 13.4 6 - Q u i n o l i n e c a r b o x y l i c a c i d - 100 p p m 46. 6 53. 4 6 - Q u i n o l i n e c a r b o x y l i c a c i d - 1000 p p m 86. 6 13. 7 6 - Quinolinecarboxylic acid - 1 ppm ^Grading r e f e r s to a s u b j e c t i v e ev al u a ti o n of n u m b e r s of r o o t s in which the followi ng s c a l e w a s employed : I - H e av y r o o t i n g II - Good r o o t i n g III - F a i r r o o t i n g IV - P o o r r o o t i n g V - Very poor rooting 61 G r o w t h of T o m a t o P la n ts a s A ffe ct ed by T r a n s p l a n t i n g T r e a t m e n t s with O r g a n ic C h e m i c a l s R evi ew of L i t e r a t u r e V e g e t a b l e c r o p s a r e often a f f e c t e d by a s e v e r e s h o ck in t r a n s p l a n t i n g a s r o o t s a r e u s u a l l y d i s t u r b e d a nd ex posed. If the e n v i r o n m e n t a l conditions a r e a d v e r s e d u r i n g t h e t r a n s p l a n t i n g p e r i o d , p l a n t s m a y be p e r m a n e n t l y i n ­ j u r e d o r e v e n kill e d T o m i n i m i z e t h e s e c h a n c e s , the s t a r t e r solution (66) a n d p u d d li n g m e t h o d (72) have been a d v o c a t e d with all t h e i r a d v a n ta g e s for b e s t c r o p yi e ld s. H ow ev e r, t h e s e m e t h o d s do not m a r k e d l y p r e v e n t w a t e r l o s s e s f r o m t h e pla nt a n d t h e s t i c k i n g of c l a y p a s t e to the r o o t s (puddling m e th od ) c a n c a u s e s e v e r e i n j u r y Hamner yet i n e x p e n s i v e m e t h o d of t r a n s p l a n t i n g (28) ha ve d e v i s e d a si mple, T h i s m e t h o d is a s u b s t i t u t e for t h e p u dd lin g m e t h o d a n d it in vo lv e s th e dipping of r o o t s in a m i x t u r e m a d e up of f in e ly d iv id e d p a p e r pulp a nd p e a t m o s s in s u ita ble p r o p o r t i o n s . They r e p o r t e d th at c r a n b e r r y b e an p l a n t s so t r e a t e d did not s u f f e r t r a n s p l a n t i n g s h o c k a n d s u b s e q u e n t l y m a d e s u p e r i o r growth, a s c o m p a r e d to u n t r e a t e d plants O t h e r t r i a l s c on d u c te d by H a m n e r and his c o - w o r k e r s in the g r e e n ­ h o u s e a nd fie ld s t r o n g l y s u g g e s t e d that it is d e s i r a b l e to i n c o r p o r a t e c o m m e r ­ c i a l f e r t i l i z e r s an d g r o w th r e g u l a t o r s with th e p a p e r pulp and peat m i x t u r e M cC a ll, Rai and H a m n e r (45) in t h e i r p r e l i m i n a r y t r i a l , usin g p a p e r and pe at m o s s with f e r t i l i z e r a s a t r a n s p l a n t i n g a id for t o m a t o p la nts , have 62 found tha t g r e a t e r gro w th of both t o p s and r o o t s r e s u l t e d f r o m such t r e a t ­ m ents It i s e v ident that t h i s new m e t h o d m a y h a ve be ne f ic ia l e ffe ct s in the t r a n s p l a n t i n g of m a n y v e g e t a b l e and f l o r i c u l t u r a l c r o p s which have v e r y s e n s i t i v e ro ot s y s t e m s . T h e r e f o r e , e x p e r i m e n t s w e r e co nd u cte d with t o m a t o p l a n t s u s i n g p a p e r pulp and peat m o s s a s a c a r r i e r f o r s o m e p r o m ­ i s i n g o r g a n i c c o m p o u n d s to d e t e r m i n e w h e t h e r o r not t h e y showed p r o m i s e a s ro o t p r o m o t e r s . M et h o d s a n d M a t e r i a l s T h e r e s p o n s e of m a n y c h e m i c a l s w a s found s i m i l a r to aux ins and a n t i - a u x i n s on c u c u m b e r root growth. T h e r e f o r e , it w a s thought d e s i r a b l e to e v a l u a t e s o m e of th e p r o m i s i n g c o m po unds in h o r t i c u l t u r a l p r a c t i c e s . Hence, e x p e r i m e n t s w e r e i n i t i a t e d in field and g r e e n h o u s e in which th e r o o t s of t h e t o m a t o s e e d l i n g s w e r e t r e a t e d with v a r i o u s c h e m i c a l s at th e t i m e of t r a n s p l a n t i n g T o m a t o T r a n s p l a n t s - G r e e n h o u s e Studi es T w o e x p e r i m e n t s inv o lv in g t r e a t m e n t s of t r a n s p l a n t s w e r e s i m u l t a n e o u s l y s t a r t e d in t h e g r e e n h o u s e with t o m a t o s e e d l i n g s U ni fo r m se e d li n g s , a p p r o x i ­ m a t e l y s e v e n c e n t i m e t e r s in height w e r e s e l e c t e d for the v a r i o u s t r e a t m e n t s In th e f i r s t e x p e r i m e n t , th e c o n c e n t r a t i o n s of 1-naphthoic, 6 - q u i n o l i n e ­ c a r b o x y l i c a n d 1 - h y d r o x y - 2 - n a p h t h o i c a c i d s u s e d w ere: 50. 100 and 1000 ppm. 63 F i v e s e e d l i n g s w e r e u s e d in e a c h t r e a t m e n t p l a c e d in b e a k e r s co nt ai nin g 50 cc of solution, a nd a ll o w e d to s o a k f o r 16 h o u r s A ft e r t r e a t m e n t th e s e e d l i n g s w e r e t r a n s p l a n t e d in 9 -i n c h p o ts c o n ta i n in g s t e r i l i z e d soil and p l a c e d on a g r e e n h o u s e be nch and grow n u n d e r g r e e n h o u s e co ndi tio ns for 15 days. T h e t e m p e r a t u r e r a n g e d f r o m 65° to 70° F at night, and fr o m 75° to 80° F d u r i n g th e day in th e g r e e n h o u s e In o r d e r to d e t e r m i n e the be n e f ic ia l e f f e c t s of p a p e r a nd peat m o s s a s a m e d i a fo r c h e m i c a l applic atio n, a n o t h e r e x p e r i m e n t was set up in th e g r e e n h o u s e . In t h i s e x p e r i m e n t , the s a m e p r o c e d u r e w a s ad op ted a s d e v i s e d by H a m n e r jet al. (28) U si n g a W a r i n g Blendor, a m i x t u r e of 1/4 p a p e r a n d 3 / 4 p e a t m o s s w a s m ad e, t h i s w a s u s e d a s th e s u b s t r a t e fo r the various chem icals. T r e a t m e n t s w e r e p r e p a r e d u s in g 1-naphthoic, 6 - q u i n o ­ l i n e c a r b o x y l i c , a nd 1 - h y d r o x y - 2 -na ph th oi c a c i d s at c o n c e n t r a t i o n s of 50, 100 and 1000 p p m T a p w a t e r only w a s u s e d a s check. T h e r o o t s of t o m a t o s e e d l i n g s w e r e dipp ed in th e v a r i o u s s l u r r i e s so that the p u l v e r i z e d m i x t u r e would a d h e r e to th e r o o t s T h e s e e d l i n g s w e r e then p l a n t e d in 9-i n c h po ts c o n ta i n in g s t e r i l i z e d soil. F i f t e e n day s a f t e r t r a n s p l a n t i n g , the p l a n t s of both e x p e r i m e n t s w e r e h a r v e s t e d at th e s a m e t i m e and t h e i r f r e s h weights w e r e r e c o r d e d (Table 19) 64 T o m a t o T r a n s p l a n t s - F i e l d Studies Tomato, v ar D e tr o it e a r l y s e e d l i n g s w e r e r a i s e d in the g r e e n h o u s e When t h e s e e d l i n g s w e r e eight w e e k s old, he al th y and u n if o r m p l a n t s w e r e s e l e c t e d a nd t r e a t e d August 6, 1955 T h e following t r e a t m e n t s w e r e c o n s i d e r e d ; (1) P a p e r pulp + pe at m o s s . (2) P a p e r pulp + peat m o s s + 4, 4 r- m e t h y l e n e b i s - 3 - h y d r o x y l naph tho ic a c i d 50 ppm. (3) P a p e r pulp + p e at m o s s + 4, 4' - m e t h y l e n e b i s - 3 - h y d r o x y l nap htho ic a c i d 100 pp m (4) P a p e r pulp -f p e a t m o s s + 4, 4 f - m e t h y l e n e b i s - 3 - h y d r o x y - 2 na phthoic a c i d 200 ppm E s s e n t i a l l y , t h e s a m e p r o c e d u r e w a s a d o p te d for p r e p a r i n g the m i x ­ t u r e of p a p e r pulp a n d pe at m o s s a s w a s a d v o c a t e d by H a m n e r et^aL (28) One oun c e of p a p e r pulp a nd t h r e e o u n c e s of pe at m o s s w e r e f i r s t m ix e d by hand T h e n t h i s m i x t u r e w a s p l a c e d in a W a r i n g Blendor with 500 m i l i - l i t e r s of ta p w a t e r T h e W a r i n g Blendor wa s o p e r a t e d for about 15 m i n u t e s until a pulp of t h i c k c o n s i s t e n c y was o bt a in e d In c a s e of t r e a t m e n t s 2, 3 a n d 4, 500 m i l i l i t e r s of solution of v a r i o u s c o n c e n t r a t i o n s w e r e u s e d in p l a c e of w a t e r T h e r o o t s of the p l a n t s w e r e dipped in m i x t u r e s so that the pulp t h o r ­ oughly c o v e r e d the r o o ts 65 T h e p l a n t s so t r e a t e d w e r e p l a n t e d in r o w s 4 feet by 4 feet in the field w h e r e t h e t r e a t m e n t s w e r e a r r a n g e d in a r a n d o m fashion s et p e r plot, a n d f o u r p l o t s for e a c h t r e a t m e n t . Eight p l a n t s w e r e Due to e x t r e m e l y d r y w e a t h e r c on di tio ns , it w a s thought d e s i r a b l e to w a t e r e ach t r a n s p l a n t e d plant No ad d it io n a l w a t e r w a s given to th e plant th rou gh out the e x p e r i m e n t 20 d a y s t h e height of e a c h plant in e v e r y t r e a t m e n t w as m e a s u r e d A ft e r The p l a n t s w e r e h a r v e s t e d a f t e r 37 day s in t h e fie ld and f r e s h weights of vine s w e r e r e c o r d e d (T a b l e 20) Results G r e e n h o u s e S tu di es When t o m a t o s e e d l i n g s w e r e s o a k e d in w a t e r s ol ut io ns of t h e v a r i o u s c h e m i c a l s , no m a r k e d s t i m u l a t i o n of vine g ro w th wa s o b s e r v e d (Tab le 19) On the c o n t r a r y , gr o w th was c o n s i d e r a b l y in h ib ite d with t r e a t m e n t at 100 ppm of all c o m p o u n d s and all s e e d l i n g s w e r e killed at 1000 p p m of 1-naphthoic a c i d a n d 1- h y d r o x y - 2 -n a phth oic acid. In e x p e r i m e n t 2, in which c h e m i c a l s w e r e a p p l i e d t h r o u g h t h e m e d i a of p a p e r an d peat m o s s , significant i n c r e a s e in vine g r o w t h w a s r e c o r d e d with t r e a t m e n t at 50 pp m of J - naphthoic a c id and 6 - q u i n o l i n e c a r b o x y l i c a c i d (T a b le 19) T h e s e e d li n g s w e r e i n j u r e d with 1000 p p m of 1 -n ap h th o ic a c i d and 1- h y d r o x y - 2 - maphtho ic acid. The results i n d i c a t e that th e p a p e r a nd p eat m o s s m i x t u r e had a b u ff e r i n g acti on on the c h e m i c a l s an d th e to xic a c ti on o b s e r v e d in the f i r s t experimen* at 100 pp m 66 with all t h e c o n c e n t r a t i o n s did not o c c u r . However, t h i s b u ff e ri n g effect w a s not s uf fic ie nt to o v e r c o m e th e to x ic effect of th e h ig he r c o n c e n t r a t i o n s It i s evid ent that th e m i x t u r e of p e a t m o s s , p a p e r pulp and gro wth r e g u l a t o r show p r o m i s e a s a c o m m e r c i a l m e th o d fo r ai d in g in t r a n s p l a n t i n g of t o m a t o s e e d l i n g s F i e l d St u di es Add ition of 50 and 100 p p m of 4, 4 ' - m e t h y l e n e b i s - 3 - h y d r o x y - 2 -naphthoic a c i d t o a m i x t u r e of p a p e r a nd p e a t m o s s has si gn if ic a n tl y i n c r e a s e d length of v i n e s 20 day s a f t e r t r a n s p l a n t i n g (T ab le 20) Also, a f t e r 37 da ys of t r a n s p l a n t i n g , sig nific an t i n c r e a s e in weight of t o p s wa s r e c o r d e d with a t r e a t m e n t of 50 p p m of t h e c h e m i c a l in p a p e r a nd peat m o s s (Tab le 20). R e s u l t s in d i c a t e that high c o n c e n t r a t i o n of c h e m i c a l s d a m a g e d the t e n d e r r o o t s a nd c o n s e q u e n t l y r e d u c e d t h e w a t e r a b s o r p t i o n c a p a c i t y of th e r o o t s 67 o CO ?a CN o o o Jl 3 +-» CO JH bO 7 d 0 CN o CN *r—( 0 O 2 £ LO i— 1 6 0) £ CD CN > • H-p .y. > 'A CN CN •— 1 0 O -'X CO CN & < JH 0 o 0 a cd bO G o CO co 0 JH JH CO 0 u 0 G 0 Eg ■a G 0 G lO 0 bO bO G G G o 0 w *-> so O N O 1 — 1 CN CN a o LO i-H • i-H o iO o 0 G O u o o NO cd g H 1 O cn 0 0 NO LO G O 0 G 6 ■4-p o G o H 1 p W 0 p CO G i 0 M-l 4-1 a x: bo O h *i—t 4_) ON i—H m £ jh CO 0 g 3 H P-4 G o cn 0 s bO CN O o CO bO i—H G o -i-H 2 0) CJ •f—P cn £ 0 JH CO B 0 G g 0 Eg ■ 0 bo G G 0 > & w J—' G 0 G 3 hG < *■ o o NO NO r—P i—1 ON CO CO o c G 0 JH O 0 •a G bO G 6 o m o o o CN 00 r- cd o bO g -i-H G o3 o Oh CO o ON 0* G OO co O NO co LO LO 4-1 £ G 0 JH CO co G JH O 0 Np-i <-i-i m 0 JO H G 0 O h G Oh 0 G G £ o 0 CO *^H *—*H a3 1 e 0 JO CJ o3 U 0 u o -a s? bo G O ( !>> X O a ■ 4 — < 0 G G JH 0 0 o3 T3 o ■ a G G G G H CO cd S-i 0 5-( O U G c 0 Oh JH o ■ p — ' c o o jn & 2 S3 g cd 0 0 a "o -t-H G •rH 0 O ' 1 NO a 0 0 03 0 0 JH 0 > 0 I g t 1 X -o 0 J4 G O JH Oh cd CN G G I G O 4-t "O 0 LO J4 +-J o3 cd c/5 O o G ~o Q Q 2 c/) co J Oh 0 > co CO bO C % 0 0 C/5 0 bo G G 0 > < 68 X D On cn CX to O P> 4-1 cd o o r— ?bO Jh c o * » H bo cd X 50 C • r-H ^ /* V Ud i-H *^H ( s cd r— I CO d 1— 1 x C u H CO 4-1 o CO TJ co CO CO o o B s O cd D B cd D cx ~ 0 o HH o iD w D X ! H cd D Jh h * 4n cd D CX CN i CX P i X o X T d x p c x cd CO cd ( d r—H CN i to > 4 CO o X o CX CO CO o P i x d P i x d i 4-H cd 4—* cd P i x d < CO ■ CX c o i CX T d id cd CX d c x X X r lO w D D d CX cd cd 6 T d -r-} bJ cd X D CX cd D h co * iH B c x c x X d D cd o D .— , o ~ o cd cd c x >— 1 d D i- H ~ o - i-H X p i x d 4H D D B o cd c x cd CX c x d D D P > D D r—H o 4— i d cr i c x c x O bo uO d D £ x o cO CO c t3 J D X cd > Q o 4 h o CN t d •i-H id O D o D 4h £ o S cd X to ■rH X d P i x d 4- J D D w X D X c o i D cd X u cx X o D CX cd CX cd .— i X f i D o CN t > 4 x d i D id cd i - a c x O f x CO 6 B c x r £ a O uO c x 1— 1 d CX cd cx, d i—H • p X 3 X) cd D r-H d ”d CX to id i J-. cd cx £ c x cd to cd ”3 H "1 • a cd a o • i-H O x d £ § - CO cd 4—f i x d £ cd d _ N "1 Cu Xd ( o x d u •»-X o < 69 T h e T r e a t m e n t of Se e dlin g P la n ts with O rg a n ic C h e m i c a l s R ev ie w of L i t e r a t u r e Plant g r o w th r e g u l a t o r s a p p li e d in v e r y dilute solution to r o o t s o r s h o o t s is a b s o r b e d by t h e p l a n t s If s u i t a b l e c o n c e n t r a t i o n s a r e used, c h a r a c t e r i s t i c g r o w th r e s p o n s e s m a y o c c u r Hit c h co c k and Z i m m e r m a n (31) r e p o r t e d that s y n th e t ic plant g ro w th r e g u l a t o r s a ppli e d a s solu tions to t h e soil of p l a n t s g r o w i n g in p o t s w e r e a b s o r b e d by th e ro o ts , and r e s p o n s e s s u c h a s e p i n a s t y of l e a v e s a nd f o r m a t i o n o f r o o t s on th e s t e m of t h e p la n t o c c u r r e d . P e a r s e (53) s p r a y e d young t o m a t o p l a n t s with a 0. 1 p e r c e n t s o lu tio n of p h e n y l a c e t i c a c i d an d in d o le b u ty ri c a c i d and note d i n ­ c r e a s e d height of t h e p l a n t s G r a c e (23) r e p o r t e d that gro w th of young s e e d l i n g s of t o m a t o , n a s t u r t i u m an d salvi a, w a t e r e d daily with nu tr i en t s ol ut io n c o n t a i n i n g s y n th e t ic g ro w th s u b s t a n c e s , was i n c r e a s e d c o n s i d e r ­ ably T h e r e a r e , ho w e v e r, s e v e r a l r e s u l t s that have been a d v o ca te d in w hic h t h e s y n t h e t i c c o m p o u n d s w e r e not abl e to show t h e i r s ig n if ic a n c e on t h e s u b s e q u e n t gro w th T e m p l e m a n (64) c a r r i e d out pot c u l t u r e e x p e r i ­ m e n t s in which s o lu ti o n s of in d o le a c e ti c acid, a - n a p h t h a l e n e a c e t i c , sk ato le a n d a s c o r b i c a c i d w e r e a ppli e d to p l a n t s by s p r a y i n g the foliage, and by w a terin g the sand No si gnificant r e s u l t s w e r e found. H a m n e r (26) o b ­ s e r v e d tha t a d d in g a l p h a - n a p h t h a l e n e a c e t a m i d e to the nutri ent solution 70 fo r g r o w i n g r e d kidney b e an p l a n t s r e s u l t e d in l e s s top growth, but i n c r e a s e d ro o t g r o w t h In l a t e r p a p e r s H a m n e r (30) r e p o r t e d that no p a r t i c u l a r b e n e ­ fits w e r e a c h i e v e d by a dd in g s m a l l q u a n ti ti e s of p h e n y l e a c e t i c a c i d o r naphtha l e n e a c e t a m i d e to t h e p l a n t s gro w n in p o t s S w a r t z (63) r e p o r t e d a l p h a - n a p h t h a l e n e a c e t i c acid, c o n ta i n e d in a c o m p l e t e n u tr i e n t solution fa ile d to s t i m u l a t e t h e g r o w t h of c h r y s a n t h e m u m , m a r i g o l d o r c o s m o s s e e d li n g s Z i m m e r m a n (88) s t a t e d th at t h e r e i s at p r e s e n t no e s t a b l i s h e d p r o o f that an y of t h e s y n t h e t i c gr o w th r e g u l a t o r s s t i m u l a t e t h e gr o wth of p la n ts A s e r i e s of e x p e r i m e n t s w e r e co n d u ct e d by t r e a t i n g dif ferent g ro w i n g p l a n t s w ith v a r i o u s c o n c e n t r a t i o n s of o r g a n i c c om pou nds found e f f e c ­ t i v e in r e t a r d i n g o r e lo n g a t in g c u c u m b e r r o o t s to d e t e r m i n e if t h e s e n e w e r m a t e r i a l s mi ght be e ff e c t iv e T h e s e t r e a t m e n t s , a ls o in c lu d e d m a n y c h e l a t i n g c o m p o u n d s, whic h w e r e found to s t i m u l a t e c u c u m b e r ro ot gro w th a n d it w a s b e l i e v e d that t h e i r c h e m i c a l s t r u c t u r e r e s e m b l e d that of th e anti - a u x i n s M eth od s and M a t e r i a l s F o l i a g e A pp li c at io n T o m a t o (v a r E a r l y D e tro it) s e e d li n g s grown u n d e r g r e e n h o u s e c o n ­ ditions'^ w e r e u s e d a s e x p e r i m e n t a l m a t e r i a l Seedlings, a p p r o x i m a t e l y 8 c m in height w e r e t r a n s p l a n t e d to 9 - in c h p o ts filled with s t e r i l i z e d r i c h soil ^T he g r e e n h o u s e con di tio ns w e r e s i m i l a r to t h o s e u s e d for the a b s ­ c i s s i o n s t u d i e s of co le us. 71 T e n d a y s a f t e r t r a n s p la n t in g , th e s e e d lin g s w e r e sp ra y e d , u s in g a hand s p r a y e r , w ith 1000, 5000, a n d 10, 000 ppm of 1-naphthoic acid, 6 -q u in o le n e c a r b o x y lic acid , 1- h y d r o x y - 2 -n a p h th o ic a c id sp ra y ed under each tre a tm e n t. w e re h a rv e ste d F iv e p la n ts w e re F if te e n days a f t e r tr e a tm e n t, the p la n ts T h e f r e s h w eig h ts of v in e s w e r e r e c o r d e d (T ab le 21) H a m n e r (29) r e p o r t e d that 1, 4 -n a p h th a le n e d io l is v e r y a c tiv e in i n ­ h ib itin g c u c u m b e r r o o t s e v en in m in u te d o s e s . T h e r e f o r e , it w as thought d e s i r a b l e to t e s t th e a c tiv ity of in h ib itin g g ro w th o f s e e d lin g o r g a n s of sen sitiv e p lan ts T o m a to (L y c o p e r s ic u m e s c u le n tu m v a r an d c o le u s (Co le u s b l u m e i L. v a r h o u s e w e r e u s e d fo r in v e stig a tio n . E a r l y D etroit) C h r i s t m a s G em ), grow n in th e g r e e n ­ T h e s e e d lin g s w e re t r a n s p l a n t e d to 6 - in c h p o ts c o n ta in in g r i c h s t e r i l i z e d soil. T o m a to and c o le u s see d lin g s, a p p r o x i m a t e l y 9 in c h e s an d 6 in c h e s in height re s p e c tiv e ly , w e r e s p r a y e d w ith a h a n d s p r a y e r , u s in g 1000 ppm , 5000 ppm , and 10, 000 p pm of 1, 4n a p h th a le n e d io l. Six p la n ts o f to m a to and fo u r p la n ts o f c o le u s w e re s p r a y e d under each tre a tm e n t. P i c t u r e s of th e s e e d lin g (F ig u re 15) w e r e ta k e n 10 d a y s a f t e r s p r a y in g and th e p la n ts w e r e h a r v e s t e d 23 days a f te r tr e a tm e n t T h e f r e s h w e ig h ts o f to p s w e r e r e c o r d e d (T able 22) R e s u lts It i s evident fro k i th e data that no m a r k e d d iff e r e n c e s in g row th o c c u r r e d due to d iffe re n t t r e a t m e n t s H ow ever, when to m a to p la n ts w e r e s p r a y e d with 72 TABLE 21 T h e A v e r a g e F r e s h Weight in G r a m s of T o m a to P la n ts F if te e n D a y s A fte r T r e a t m e n t w ith V a rio u s C o n c e n tr a tio n s of O rg a n ic C h e m ic a ls . C o n c e n tr a tio n s of O rg a n ic C om pounds C o n tro l * A v e ra g e F r e s h W eight (gm s p e r Plant 17. 2 1 - N aphthoic a c id - 1000 p pm 22. 8 1 -N a p h th o ic a c id - 5000 p pm 15. 2 1 -N ap h th o ic a c i d - 10000 p p m 14. 0 6 -Q u in o lin e c a r b o x y lic a c id - 1000 ppm 19 2 6 - Q u in o lin e c a r b o x y lic a c id - 5000 p p m 18. 4 6 -Q u in o lin e c a r b o x y lic a c id - 10000 p p m 12 0 1 -H y d r o x y - 2 - n a p h th o ic a c id - 1000 p p m 18. 0 1 - H y d r o x y - 2 -n a p h th o ic a c i d - 5000 p pm 10. 4 1 - H y d ro x y - 2 -n a p h th o ic a c id - 10000 ppm 8. 8 L, S. D. at 5% le v e l 4. 5 L. S D. at 1% le v e l 6, 0 sSe A v e ra g e of five p la n ts . 73 TABLE 22 T h e E ffe ct of V a r io u s C o n c e n tra tio n s of 1, 4 -N a p h th a le n e d io l upon th e G ro w th of S e e d lin g T o m a to an d C o le u s P la n ts. C o n c e n tr a tio n s Av e r a g e F r e sh W eight (g m sj_____ T o m a t o ’1'* C oleus*** C o n tro l 21. 71 23. 88 1000 p p m 12, 21 17. 38 5000 p p m 8. 04 11. 06 10000 p p m 4. 63 6, 81 D a ta r e c o r d e d a f t e r t w e n t y - t h r e e days of s p r a y of c h e m ic a l. ** A v e r a g e of s ix p la n ts in c a s e of to m a to s e e d lin g s . A v e ra g e of fo u r p la n ts in c a s e of c o leu s. 74. moon... j ooo CHECK I so o n . CHECK F i g u r e 15. R e s p o n s e of fo lia r a p p lic a tio n of 1000, 5000, and 10, 000 p p m of 1, 4 - n a p h th a le n e d io l on c o le u s an d to m a to p la n ts a f t e r t e n days of tr e a tm e n t. 75 LOOO p p m of 1 -n a p h th o ic acid, s o m e i n c r e a s e d g row th w a s noted w a s sig n ific a n t at th e 5% L S D T h is level S p r a y s of 1, 4 -n a p h th a le n e d io l at all c o n c e n tra tio n s c o n s id e ra b ly in h ib ite d th e g ro w th of c o le u s and to m a to s e e d lin g s P la n ts w e re k illed at i n c r e a s i n g c o n c e n tr a tio n s , a s is evident fro m F ig u r e 15- R e s u lts i n ­ d ic a t e th a t I, 4 -n a p h th a le n e d io l w as m a r k e d ly to x ic to plant t i s s u e s and t h e r e f o r e m ight be of s o m e v a lu e in u sin g a s a h e rb ic id e M eth o d s and M a te r ia ls Soil A p p lic a tio n S e v e r a l c h e la tin g com p ou nd s which s tim u la te d th e root gro w th of c u c u m b e r s e e d lin g s w e r e in v e s t ig a te d to d e te r m in e t h e i r a c tiv ity on t o m a to T o m a to (L y c o p e r s ic u m e s c u le n tu m v a r E a r l y D e tro it) s e e d lin g s a p p r o x i m a t e l y 6 c m in height w e r e t r a n s p l a n t e d in 9 -in c h p o ts co n tain in g s o il la c k in g in o r g a n ic m a t t e r an d n u tr i e n ts . It w a s b e lie v e d that any b e n e ­ fic ia l effect o f t h e s e c h e m i c a ls might be e x a g g e r a te d in th is typ e of soil One w e e k a f t e r th e s e e d lin g s w e r e tr a n s p la n te d , solu tio n s of 25 an d 100 ppm of v a r i o u s c h e la tin g co m pounds w e r e a p p lie d to th e soil s o a k e d w ith 500 m i l i l i t e r s of solu tio n E a c h pot w as F iv e p la n ts w e r e kept u n d e r each tre a tm e n t. C o n tro l p la n ts w e r e a ls o i r r i g a t e d with th e s a m e amount of ta p w a te r . T w e n ty d a y s a f t e r soil ap p licatio n , the p la n ts w e re h a r v e s te d a n d th e f r e s h w e ig h ts of v in e s w e r e r e c o r d e d (T able 23). R e s u lts T o m a to v in e g ro w th w a s s ig n ific a n tly s tim u la te d w ith 25 ppm of 4 - (p -e th o x y p h e n y la z o ) -m -p h e n y le n e d ia m in e , a s c o m p a r e d to th e c o n tro l No m a r k e d d if f e r e n c e s in f r e s h weight w e r e found with o th e r com pounds (T a b le 23) 77 TABLE 23 T h e E ffe ct of Soil A p p lic a tio n of V a r io u s C h e la tin g C om pounds Upon th e G row th of S e e d lin g T o m a t o P la n ts . C h e la tin g C o m p o u n d s C o n tro l Av e r a g e F r e s h W eight p e r Plant (gms) Cone. C h e la tin g C om pounds (ppm) 0 25 100 8 75 1 - A m in o - 4 -h y d r o x y a n th ra q u i none 12, 15 6. 20 1 - A m in o - 2 -n ap h th o l-4 - su lfo n ic a c id I T 10 7. 45 8. 80 10 55 D ie th y ld ith io c a r b a m ic a c id 11. 00 10. 75 2, 4 -D ih y d r o x y a c e to p h e n o n e 11 55 9. 45 4 - ( p - n itr o p h e n y la z o ) r e s o r c i n o l 12. 40 8 85 8, 85 14. 15 10. 25 I T 15 9. 50 I T 25 13 90 12. 70 R e s o r c in o l p, p - M e th y le n e b is (N , N -d im e th y la n ilin e ) D iphenyl g ly o x im e 2, 2, 4, 4, 6, 6 -H e x a n itro d ip h e n y la m in e 4 - (p - eth o x y p h en y laz o ) - m -p h e n y le n e d ia m in e Lo S. D at 5% le v e l 3. 48 L. S. D. at 1% le v e l 4. 62 *D ata ta k e n tw e n ty d ay s a f t e r t r e a t m e n t 78 B lo s s o m a n d F r u i t T h in n in g of F r u it T r e e s w ith O rg a n ic C h e m ic a ls R ev iew of L i t e r a t u r e E x c e s s i v e flo w e rin g in one y e a r a c c o m p a n ie d by heavy f r u itin g r e ­ s u l t s in b ie n n ia l b e a r i n g in m a n y fru it t r e e s T o a lle v ia te th is situation, h a n d th in n in g of flo w e r s an d young f r u i t s h a s be en p r a c t i c e d by g r o w e r s T h i s i s an e x p e n s iv e a n d te d io u s p r o c e s s . A u c h te r and R o b e r ts (7) f ir s t d e m o n s t r a t e d th a t c h e m ic a l s p r a y s co u ld be u s e d e ffe c tiv e ly to th in ap ple b lo sso m s. L a t e r B u rk h o ld e r and McCown (16) n o tic e d th at auxins, su ch a s n a p h th a l e n e a c e tic acid, w ould re d u c e th e fru it s et of a p p le s F o llo w ­ in g t h e s e d i s c o v e r i e s , m a n y s y n th e tic c h e m i c a ls w e r e e ffe c tiv e ly u tiliz e d to th in f lo w e r s a n d f r u i t s T h e u s e of t h e s e c h e m i c a ls h a s been s u m m a r ­ i z e d by T u k e y (73), L e o p o ld (41), A udus (9), B a tje r and Hoffman (11) T h e d e g r e e of th in n in g flo w e rs o r young f r u i t s r e s u l t i n g fr o m th e u s e o f c h e m i c a l s i s g r e a t l y in flu e n c e d by t r e e v ig o r, ti m e of a p p licatio n, e n v ir o n m e n ta l c o n d itio n s, and v a r i e t y Southw ick et_al_ (61), and L a n g e r (38) a d v o c a te d th a t no s a t i s f a c t o r y m e th o d of th in n in g p e a c h e s has yet be en e sta b lish e d L e o p o ld (41) d e m o n s t r a t e d that th in n in g o f b lo s s o m s and yo u n g f r u i t s by a u x in s a p p e a r s to be due to t h r e e p h y s io lo g ic a l fa c to r s : (1) p r e v e n tio n of n a tu r a l p o llin a tio n ; (2) a b o rtio n of young e m b ry o ; and i (3) d ir e c t a c c e l e r a t i o n of a b s c i s s i o n by a l t e r a t i o n of the auxin g ra d ie n t at th e a b s c i s s i o n zo ne 79 E x p e r i m e n t s w e r e c o n d u c te d to d e te r m in e if a ctid ion e, sodium azide, an d 1, 4 -n a p h th a le n e d io l w ould be e ffe c tiv e in th in n in g a p p les, p e a c h e s and c h e r r i e s on th e H o r tic u ltu r a l f a r m of M ich igan State U n iv e rs ity , E a s t L a n s in g , in th e s p r i n g of 1955. M etho ds and M a t e r i a l s Peaches T r e e s of eq u al v ig o r of two d iffe re n t v a r i e t i e s , H a lehaven an d R ed haven, w e r e u s e d fo r th e in v e s tig a tio n s . A queous s p r a y s at 50 an d 250 ppm o f 1, 4 - n a p h th a le n e d io l and so d iu m a z id e w e r e a p p lie d to th e lim b s d u rin g th e m id d le o f th e day on A p ril 28, 1955. w e re also used S p ra y s of a ctid io n e at 2. 5 an d 10 p p m E a c h t r e a t m e n t w a s a p p lie d to th e lim b s w hich w e r e s e le c te d in a ra n d o m fa sh io n on five d iffe re n t t r e e s of e a c h v a r i e t y at th e p e a k of full bloom . The tr e e s w ere T h e n u m b e r of f lo w e rs and flo w e r bud s on th e b r a n c h e s at th e t i m e of s p r a y in g w a s r e c o r d e d O b s e rv a tio n s w e r e ta k e n e a c h w eek on th e a b s c i s s i o n of flo w e rs, C h e rrie s M o n tm o re n c y s o u r c h e r r y t r e e s in full bloom w e re s p r a y e d with 50, 250, 500 a n d 750 p pm of 1, 4 -n a p h th a le n e d io l, 2 5 ppm and 10 p pm of a c t i ­ dione, a n d 5, 15, 30 an d 60 ppm of 2, 4, 5 -tr ic h lo ro p h e n o x y p ro p io n ic a c id on M a y 3, 1955 E a c h t r e a t m e n t w a s ap p lie d on a s m a ll lim b which w as s e le c te d 80 in r a n d o m fa s h io n on five t r e e s Since so d iu m a z id e w as found to be c o n s i d ­ e r a b l y p r o m i s i n g in th in n in g b l o s s o m s in e x p e r im e n t s of p e a c h t r e e s , it w a s thought d e s i r a b l e to d e te r m in e i t s e f f e c tiv e n e s s on s o u r c h e r r y b lo s s o m s H ence, o t h e r lo ts of c h e r r y t r e e s w e r e s p r a y e d with 500 ppm of so d ium a z id e at e a r l y p e ta l fall on M ay 5, 1955 on d iffe re n t t r e e s . T h e t r e a t m e n t w a s r e p l i c a t e d five t i m e s T h e b r a n c h e s w e r e ta g g e d an d t h e i r flo w e rs w e r e c o u n te d A p p le s T h r e e v a r i e t i e s of a p p le s (D elicio u s, in full bloom ; W ealthy, at e a r l y p e ta l fall; a n d M cIntosh, at la te p e ta l fall) w e r e s p r a y e d w ith 25, and 50 ppm o f 1, 4 - n a p h th a le n e d io l; and 50 and 250 p p m of so diu m a z id e on May 5, 1955 T h r e e t r e e s of e a c h v a r i e t y w e r e s e l e c t e d fo r t r e a t m e n t . s e l e c t e d in ra n d o m fa s h io n on t h e s e t r e e s w e r e u s e d S m a ll lim b s T h e n u m b e r o f flo w e rs on th e t r e a t e d b r a n c h e s w e r e c o u n ted at th e t i m e of s p r a y in g s and r e c o r d s w e r e kept in o r d e r to c o m p a r e th e effect of th e c h e m ic a ls . R e s u lts No c o n c lu s iv e r e s u l t s w e r e o b ta in e d due to a la te f r e e z e on th e t r e e w e r e fr o z e n an d d a m ag e d . All f r u its H ow ever, o u r e a r l y o b s e r v a tio n in d ic a te d th a t so d iu m a z id e at all c o n c e n tr a tio n s had e ffe c tiv e ly th in n ed th e b l o s s o m s on p e a c h e s . H ow ever, th e g r e a t e r th in n in g w as n o tic e d 81 w h en 250 p p m of th e c h e m ic a l w as u s e d Slight d iff e r e n c e s w e r e r e c o r d e d w ith 1, 4 -n a p h th a le n e d io l an d a c tid io n e at th e h ig h e r c o n c e n tra tio n s . The D e lic io u s a p p le v a r i e t y w a s m a r k e d ly a ffe c te d by so d iu m azide, a s c o m ­ p a r e d to M c In to sh an d W ea lth y v a r i e t i e s at high c o n c e n tr a tio n s . w ith th e d o s a g e a p p lie d T h e flo w e rs w e r e not in ju r e d T h e a c tiv ity of th e c o m po un d s v a r i e d som ew hat By p e r s o n a l o b s e r v a tio n s , it w a s found that so d iu m a z id e w a s m o r e p r o m i s i n g in b lo s s o m th in n in g th an w as 1, 4 - n a p h ­ th a le n e d io l. No m a r k e d d if f e r e n c e s w e r e r e c o r d e d w ith c h e r r y t r e e s H ow ever, a c o n s i d e r a b l e n u m b e r of flo w e rs w e r e in ju r e d w ith 500 ppm of sodium a z id e a n d 750 p p m of 1, 4 -n a p h th a le n e d io l. 82 G E N E R A L DISCUSSION , A n a tte m p t h a s b e en m a d e to d e te r m in e w h e th e r o r not t h e r e i s any c o r r e l a t i o n b e tw e e n s t r u c t u r e a n d a c tiv ity of v a r io u s o rg a n ic com pounds w h ic h w e r e t e s t e d A s a r e s u l t of t h is r e s e a r c h , m a n y new g ro w th r e g u l a t o r s have been d is c o v e r e d , a n d p e r h a p s s e v e r a l im p o r ta n t l e a d s have be en u n c o v e re d It h a s b e e n found th a t m a n y nap htho ic a c id c om p ou nd s a r e a c tiv e a s g r o w th r e g u l a t o r s T h e s e c o m p o u n d s a r e s i m i l a r in s t r u c t u r e to naph- t h a l e n e a c e t i c acid, ex cep t th e s id e c h ain c o n s i s t s only of a c a rb o x y l group, w h e r e a s in n a p h th a le n e a c e tic a c id th e c a rb o x y l group is a tta c h e d th ro u g h m e th y le n e on th e r i n g n u c le u s . If th e c a rb o x y l group is in th e 1-p ositio n , th e c o m p o u n d i s m o r e a c tiv e , a s c o m p a r e d to when it is in th e 2 -p o s itio n "When an h y d ro x y l g ro u p is a d d e d in d iffe re n t p o s itio n s on th e r i n g s t r u c t u r e , fo r e x a m p le 1 an d 3 p o s itio n s th e a c tiv ity i s r e v e r s e d , an d a p p a r e n tly th e c o m p o u n d s act a s an a n ti-a u x in , t h is i s in d ic a te d by t h e i r a ctio n in s t i m u ­ la tin g ro o t elon gation , an d on h a s te n in g a b s c is s io n It is b e lie v e d that th e in tr o d u c tio n of an h yd ro xy l g roup m ight effect th e two point a tta c h m e n t of th e c h e m ic a l on th e p r o t e i n s u b s tr a te , a s e x p lain ed by M u ir and H a n sc h (49) S u b s titu tin g n itr o g e n fo r c a rb o n in th e r in g s t r u c t u r e a p p a r e n tly does not c h a n g e th e a c tiv ity of th e com pounds, s in c e h e te r o c y c lic n itro g e n 83 c o m p o u n d s have a ls o been found to act a s an auxin, and when hydroxyl g r o u p s a r e a d d e d to th e h e te r o c y c lic n itr o g e n com pound, it then a c ts a s an a n ti- a u x in . T h e s t r u c t u r e s of t h e s e m a t e r i a l s h a s s u g g e s te d a ls o that p e r h a p s . . . i th e a c ti v ity m ig h t be c o r r e l a t e d w ith t h e i r a b ility to act a s m e ta l c h e la te s . M an y c h e la tin g m a t e r i a l s w e r e te s te d , and s o m e w e r e found to be a c tin g in p r o m o t i n g ro o t g ro w th and a ls o top g ro w th o f c e r t a i n p la n ts . It is b e lie v e d th a t p e r h a p s t h e s e c h e m i c a ls w e r e re m o v in g e x c e s s iv e q u a n titie s o f m e ta l f r o m th e r o o ts , an d th u s i n c r e a s i n g th e m e ta b o lic a c ti v itie s T h e fact th a t s o m e of t h e s e c h e la tin g a g e n ts i n c r e a s e root g ro w th m ight a l s o in d ic a te th a t th e y a r e a c tin g a s an a n ti-a u x in . It is thought p o s s ib le t h a t m a n y o f o u r s o - c a l l e d a n ti- a u x in s act lik e c h e la tin g a g e n ts and c o m p le x s o m e m e ta l e n z y m e s y s te m . In th e c o u r s e of th e stu d y o th e r m a t e r i a l s s e e m in g ly u n r e la te d w e r e a c tid io n e , 1, 4 -n a p h th a le n e d io l, and sod iu m a z id e T h e s e co m pounds h a d in h ib ite d th e ro o t g ro w th of c u c u m b e r s e e d lin g s ; t h e r e f o r e , it w as thought th a t t h e s e c o m p o u n d s p e r h a p s be a c tiv e a s b lo s s o m th in n e r s T h e s e m a t e r i a l s w e r e s p r a y e d on p e a c h e s , a p p le s and c h e r r i e s It w as o b s e r v e d th a t so d iu m a z id e i s v e r y p r o m i s i n g fo r flo w e r th in n in g 1, 4 - n a p h th a le n e d io l is a ls o an in h ib ito r of root grow th of c u c u m b e r a n d w a s o b s e r v e d a c tiv e a s a to x ic com pound fo r th e g ro w in g p la n ts It is , t h e r e f o r e , s u g g e s te d th a t t h i s com pound has a p r o p e r t y fo r h e rb ic id a l use. 84 SUMMARY A r o m a t i c o r g a n ic c o m p o u n d s c o n ta in in g an hydroxyl group o r an acid g ro u p , o r both, o th e r s u b s tit u e n ts an d h e te r o c y c le n itro g e n w e r e in v e s tig a te d f o r t h e i r a c t i v i t i e s upon c u c u m b e r ro o ts . p o u n d s w e r e a ls o t e s t e d fo r t h e i r a c ti v itie s A n u m b e r of m e ta l c h e la tin g c o m ­ P r o m is i n g co m pounds w e re t h e n t e s t e d on v a r i o u s c r o p s to d e te r m in e th e p o s s i b i l i t i e s fo r t h e i r h o r t i ­ c u ltu ra l use 1, C o m po u nd s th a t m o s t e ffe c tiv e ly s tim u la te d root gro w th o f c u c u m b e r s e e d lin g s g ro w n in p e t r i d is h e s w e re : 1 - h y d r o x y - 2- naphthoic acid, 3 - h y d ro x y 2 -n a p h th o ic acid, 4, 4*- m e th y le n e b is - 3 - h y d r o x y - 2 - n a p h th o i c a c id and its d i ­ s o d iu m s a lt, 1 -n a p h th o l,2 , 4 - d i c h l o r o - l - n a p h t h o l , 4, c h l o r o - 1 - h y d r o x y - 2 -nap hth oic a cid . Slight r e s p o n s e upon ro o t elo n g atio n w as o b s e r v e d with 2-naph tho l, 8- q u ino lin ol, b e n z o ic acid, an d 1-h y d r o x y - 2 -n a p h th a le n e sulfon ic a c id (sodium s a lt) 2. C om pounds, 1 -n a p h th o ic and 6 -q u in o lin e c a rb o x y lic a c id s in h ib ite d r o o t g ro w th of c u c u m b e r s e e d lin g s in a c h a r a c t e r i s t i c m a n n e r s i m i l a r to the r e s p o n s e of n a p h th a le n e a c e tic a c id on c u c u m b e r r o o ts O th e r a c tiv e ro ot i n ­ h ib itin g co m p o u n d s w e r e qu in aldin ic, 2 -p ic o lin ic , 2 - naphthoic a c id s , and 1 - h y d r o x y - 2 - a c e to n a p h t hone 3 No a d d itiv e r e s p o n s e upon c u c u m b e r root e lo ng atio n o c c u r r e d when u r e a and KH0PO , w e r e s im u lta n e o u s ly a p p lie d with 4. 4 f - m e th y le n e b is - 3 - h y d r o x y 2 -n a p h th o ic a c id in p e t r i d is h e s 85 4 M eta l c h e la te co m p o u n d s found to s tim u la te c u c u m b e r ro o t grow th s ig n if ic a n tly at th e 25 p p m d ilu tio n w e r e : r e s o r c i n o l , b e n z o tria z o l, 2, 2 fb iq u in o lin e , d ie th y ld ith io c a r b a m ic acid, 2, 4 -d ih y d ro x y a c e to p h e n o n e and m e r c a p t o a c e t i c a c id Slight effect w as o b s e r v e d with 1 - a m in o - 4 - h y d r o x y - a n th ra q u in o n e , th ia z o le yellow , and fu r il dio x im e co m pounds in p e t r i d is h e s 5. A m o n g th e m e ta l c h e la te com po un ds t e s t e d that s tr o n g ly in hib ite d c u c u m b e r ro o t g ro w th w e r e p h e n y l- y - th io h y d r a n to ic acid, phenylglyoxal a ldo xim e a n d 2, 2, 4, 4, 6, 6 - h e x a n itro d ip h e n y la m in e . Somewhat l e s s inh ib itio n w as found w ith 1, 5 -( p -d im e th y la m in e b e n z y lid e n e ) and 2, 3 -b u ta n e d io n e o x im e th io s e m icarbazone 6 O th e r m e ta l c h e la tin g a n d o th e r o rg a n ic com pounds u n d e r in v e stig a tio n h ad no m a r k e d effect on c u c u m b e r ro ot grow th. Somewhat to x ic effect w as n o tic e d at h ig h e r c o n c e n tr a tio n s . 7 C o n c e n tr a tio n s of 10, 100 and 1000 ppm of 2, 3, 5 -triio d o b e n z o ic , 4, 4 ' - m e t h y l e n e b i s - 3 - h y d r o x y - 2 - naphthoic, 1 -h y d ro x y -2 -n a p h th o ic , and 3h y d r o x y - 2 -n a p h th o ic a c id s a p p lie d in la n o lin to th e cut s u r f a c e s tim u la te d th e a b s c i s s i o n of d e b lad e d c o le u s p e tio le s T h e r a t e of a b s c is s io n w a s d ir e c tly p r o p o r t i o n a l to th e d o s a g e a p p lie d 8 When 2, 3, 5 -tr iio d o d b e n z o ic a c id 1000 ppm w as ap p lie d s i m u l t a n e ­ o u s ly on th e d e b la d e d p e tio le s with e ith e r 4, 4 ?- m e t h y le n e b is - 3 - h y d r o x y - 2 -naphthoic a c id 10 ppm , 3 - h y d r o x y - 2 - n a p h th o ic a c id 100 ppm, o r 1- h y d r o x y - 2 -naphthoic 86 a c i d 1000 p p m i n c r e a s e d s tim u la tio n of a b s c i s s i o n w as noted 9 S im u lta n e o u s a p p lic a tio n of n a p h th a le n e a c e tic a c id at 100 ppm with e i t h e r 2, 3, 5 - tr iio d o b e n z o ic a c id 1000 ppm , o r 4, 4 * -m e th y le n e b is - 3 -h y d ro x y 2 -n a p h th o ic a c id 10 ppm , o r 3 - h y d ro x y - 2 - naphthoic a c id 100 ppm , o r 1 -h y d ro x y 2 -n a p h th o ic a c id 1000 w as found to i n c r e a s e th e a b s c is s io n a s c o m p a r e d to n a p h th a le n e a c e tic a c id when a p p lie d alon e. It in d ic a te s that th e a c tio n of n a p h th a le n e a c e tic a c id on a b s c i s s i o n w a s c o u n te r a c te d by t h e s e m a t e r i a l s sh o w in g th a t t h e s e c o m p o u n d s m a y be a n ti-a u x in s . 10. W hen 2, 3, 5 - tr iio d o b e n z o ic a c id 1000 ppm , o r 4, 4 r - m e th y l e n e b i s 3 - h y d r o x y - 2 -n a p h th o ic a c id 10 pp m , o r 3 - h y d r o x y -2 -n a p h th o ic a c id 100 ppm o r 1 - h y d r o x y - 2 -n a p h th o ic a c id 1000 p p m w as a p p lie d m idw ay be tw ee n the a b s c i s s i o n z o n e an d th e cut s u r f a c e w ith n a p h th a le n e a c e tic a c id 100 ppm a p p lie d on th e tip s of d e b la d e d p e tio le s , th e r e s p o n s e of n a p h th a le n e a c e tic a c id w a s re d u c e d . A s i m i l a r a c tio n w as r e c o r d e d when t h e s e m a t e r i a l s w e r e a p p lie d in a s p i r a l fashion; th u s in d ic a tin g that th e s e m a t e r i a l s have a n ti- a u x in p r o p e r t i e s 11 T h e co m po u nd 1 -n a p h th o ic a c id at a 10 p pm c o n c e n tra tio n ap p lie d on th e cut s u r f a c e of d e b lad e d p e tio le s d e lay e d th e a b s c i s s i o n of p e tio le s o f c o le u s . H ow ever, 1000 p pm c o n c e n tra tio n w as found to a c c e l e r a t e th e a b scissio n . 12 Soaking c o le u s c u ttin g s in a 100 ppm solution of 1 -n ap htho ic acid a n d a 1000 p p m so lution of 6 -q u in o lin e c a rb o x y lic a c id b e fo re rooting, in- 87 c r e a s e d th e p e r c e n t a g e of c u ttin g s w hich r o o te d 13 No s tim u la tio n on g ro w th o c c u r r e d w ith 1-naphthoic, 6 -q u in o ­ l i n e c a r b o x y l ic , and 1 - h y d r o x y - 2 -n a p h th o ic a c id s when th e s e e d lin g s w e re s o a k e d fo r 16 h o u r s b e f o r e tr a n s p la n t in g , but th e y w e r e in ju r e d at h ig h e r c o n c e n tr a tio n s . H ow ever, when t h e s e c h e m i c a ls w e r e a p p lie d th ro u g h the m e d i a of p a p e r a n d p e at m o s s , v in e g ro w th w as s tim u la te d except in the p l a n t s t r e a t e d w ith 1 -h y d r o x y - 2 - n a p h th o ic acid. 14. T o m a to p la n t r o o t s t r e a t e d w ith 50 p p m of 4, 4 ' - m e th y le n e b is - 3 h y d r o x y - 2 -n a p h th o ic a c id th ro u g h th e m e d ia of p a p e r and pe at m o s s and t r a n s p l a n t e d in th e open fie ld e x h ib ite d g r e a t e r f r e s h weight of v in e s a s c o m p a r e d to c o n tro l. 15 S p r a y of 1000 p p m of 1 -n a p h th o ic a c id on to m a to p la n ts s t i m u ­ la t e d th e v in e gro w th. D ilution of 10, 000 p pm of 6 -q u in o lin e c a rb o x y lic and 1 - h y d r o x y - 2 -n a p h th o ic a c id s c o n s id e r a b ly r e d u c e d th e grow th of v in e s a s c o m p a r e d to th e c o n tro l. 16 C o le u s and to m a to p la n ts s p r a y e d w ith 1000 ppm, 5000 ppm and 10, 000 p p m s o lu tio n s o f 1, 4 -n a p h th a le n e d io l w e re s e r i o u s l y in ju re d , At high c o n c e n tra tio n , p la n ts w e r e killed. 17 Soil a p p lic a tio n w ith 25 p p m dilution of 4 - ( p -e th o x y p h e n y la z o )-m - p h e n y le n e d ia m in e gave s ig n ific a n tly g r e a t e r f r e s h weight of v in e s a s c o m ­ p a r e d to c o n tro l O th e r m e ta l c h e la te com pounds u n d er in v e stig a tio n had no s t i m u l a t i n g r e s p o n s e upon vine grow th. 18 C h e m ic a ls , 1, 4 -n a p h th a le n e d io l, so d iu m a zid e , a ctid io n e and 2, 4, 5 - tr ic h l o r o p h e n o x y p r o p io n ic a c id s p r a y e d on p e a c h e s , c h e r r i e s and a p p le s g a v e no c o n c lu s iv e in d ic a tio n s of t h e i r r e s p o n s e due to la te snow fall in s p r i n g All f r u its and flo w e rs w e r e d a m a g e d H ow ever, so diu m a z id e s p r a y e d w ith v a r i o u s d ilu tio n s on d iffe re n t fru it t r e e s sig n ific a n tly r e d u c e d th e n u m b e r of b l o s s o m s on th e t r e a t e d lim b s a s c o m p a r e d to th e c o n tro l. 19 An a tte m p t w a s m a d e to c o r r e l a t e th e c h e m ic a l s t r u c t u r e w ith th e a c ti v ity o f th e o r g a n ic c o m p ou nd s t e s t e d 89 L IT E R A T U R E C ITED L A b e rg , B. S tu d ie s on p la n t g ro w th re g u la to rs., VIII On o p tic a lly a c tiv e p la n t g ro w th r e g u l a t o r s . Ann. R oyal A g ric , Coll, Sweden 20: 241-295. 1953. (A b s tra c t) 2. A d dicott, F . T. , an d R S. Lynch. A c c e le r a t io n and r e t a r d a t i o n of a b ­ s c i s s i o n by in d o le a c e tic a c id . S c ie n ce 114: 688-689 1951, 3. A dd icott, F , T , an d R. S. L ynch. P h y sio lo g y of a b s c is s io n . P lant P hys. 6: 211-238* 1955 4. A dd icott, F , T . , R S. L y nch and H by A ddicott_et aL Ref. 3. 5 Ann R, C a r n s , S cien ce (in p r e s s ) Rev. quoted A l a m e r c e r y , J, I n t e r a c t i v e e ffe c ts of c o u m a rin , dithiooxim e, a s c o r b ic a c id an d a u x in s upon th e e a r l y d e v elo p m en t of ro o ts . Ph. D, T h e s is , M ich ig an S ta te C ollege. 1952. 6. A le x a n d e r, T . R. 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G az, 106: 420-431 1945 13. Bentley, J A G ro w th r e g u la tin g effect of c e r t a i n o rg a n ic com pounds. N a tu re 165: 44 9-450. 1950. 90 14 B onner, J , an d R. S B and ursk i. S tu dies of th e physiology, p h a r m a ­ co lo g y an d b i o c h e m i s t r y of aux ins. Ann Rev. Plant Phys 3' 59-86 1952, 15, Booij, H, L P r o c , Koninkl Ned (quoted by V e ld s tr a , r e f 82). 16 Akad. W eten schap. 52: 1100. 1949 B u rk h o ld e r, C, L. , an d M. M cCown. E ffect of s c o r in g and of a -n a p h th y la c e tic a c id an d a m id e s p r a y upon fru it set an d of th e s p r a y upon p r e - h a r v e s t fru it drop. P r o c , A m e r. Soc H orL Sci, 38: 117-120 1941. 17. B u r s tr d m , H. S tu d ie s on g ro w th an d m e ta b o lis m of ro o ts . III. P o s itiv e a n d n e g a tiv e a u x in e ffe c ts on c e ll e lo ng atio n. Physiol P la n ta ru m . 3: 2 7 7 -2 9 2 . 1950o 18 B u r s tr b m , H. 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