THE EFFECT OF SELECTED HALOG-ENATED BENZOIC ACIDS ON FLOWERING Howard G. A p p le g a te A THESIS S u b m itte d to th e S ch o o l o f G ra d u a te S tu d ie s o f M ich ig an S t a t e U n i v e r s i t y o f A g r i c u l t u r e and A p p lie d S c ie n c e i n p a r t i a l f u l f i l l m e n t o f th e re q u ire m e n ts f o r th e d e g re e o f DOCTOR OF PHILOSOPHY D e p artm en t o f H o r t i c u l t u r e 1956 ProQuest Number: 10008683 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. west ProQuest 10008683 Published by ProQuest LLC (2016). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code Microform Edition © ProQuest LLC. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 4 8 1 0 6 - 1346 J -----------------------------t i LIBRARY Michigan State University ^ ACKNOWLEDGEMENTS The a u th o r w is h e s to e x p r e s s h i s In d e h te d n e s s an d s i n c e r e a p p r e c i a t i o n t o D r. C. L. Hanaier f o r h i s g u id a n c e , e n co u rag em en t an d n e v e r f a i l i n g h e lp w h ich made t h i s i n v e s t i g a t i o n p o s s i b l e . To th e members o f my c o m m itte e , D r. R. B a n d u r s k i, D r. W. Haney a n d D r. H. S e l l g o e s my a p p r e c i a t i o n . T hanks a r e a l s o due to D r. R. L e a p e r f o r s y n t h e s i z i n g c e r t a i n com pounds u s e d i n t h i s e x p e rim e n t an d to D r. 0 . E. W ildon f o r n e v e r f a i l ­ i n g i n t e r e s t and f r i e n d s h i p . To a man who h a d no a c t i v e p a r t i n t h i s r e s e a r c h m ust go th e g re a te s t c re d it. In my u n d e r g r a d u a te me t o t h e b e a u ty o f s c i e n c e . th a n k s . days a t C o lo rad o A&M h e aw akened To G eorge B each g o es my m ost h e a r t f e l t TABLE OF CONTENTS p ag e INTRODUCTION.................................................................................................................................1 REVIEW OF LITERATURE .................................................................................................................3 P h o to p e rio d is m an d F lo w e rin g . . ........................................................................ 3 G row th R e g u la to r s and F lo w e rin g ...................................................................... . 4 ............................................................................................. 4 In d o le a c e tic a c id 2 . 3 .5 - T r iio d o h e n z o ic a c i d .......................................................................... 6 O th e r Grow th R e g u l a t o r s .....................................................................................7 Growth R e g u la to r s and M o r p h o l o g y ........................................................................... 9 I n d o l e a c e t i c a c i d ........................... 9 2 .3 .5 - T r iio & o b e n z o ic a c id and R e la te d S u b s t i t u t e d B en z o ic A c id s . . 9 O th e r Growth R e g u l a t o r s ....................................................................................... 11 Grow th R e g u la to r s a n d P h y s io lo g y ........................... I n d o l e a c e t i c a c id . . . 13 ...........................................................................13 2 ,3 »5“ T riio d o l> e n z o ic A cid a n d R e la te d S u b s t i t u t e d B en z o ic A cid s . . 13 O th e r G row th R e g u l a t o r s ................................ 14 Mode o f A c t i o n In d o le a c e tic a c id . 15 . 15 2 , 3 » 5 ~ T riio d o b e n z o ic A c id an d R e la te d S u b s t i t u t e d B e n z o ic A cid s .■ . 15 O th e r Growth R e g u l a t o r s ....................................................... I6 MATERALS AND METHODS.............................................................................................................1? EXPERIMENTAL RESULTS.............................................................................................................20 E f f e c t o f D i f f e r e n t C o n c e n tr a tio n s o f S u b s t i t u t e d B en z o ic A cid s When S p ra y e d on P e tu n ia h y b r i d a ................................................... 20 TABLE OF CONTENTS (C o n tin u e d ) E f f e c t o f D i f f e r e n t A c i d i t y L e v e ls o f S u b s t i t u t e d B e n z o ic A cid s When S p ra y e d on P e t u n i a h y b r i d a ..................................................................... 29 E f f e c t o f D i f f e r e n t C o n c e n tr a tio n s o f S u b s t i t u t e d B e n z o ic A cid s ................................................................................................ 38 On Z in n ia e le g a n s E f f e c t o f D i f f e r e n t A c id i ty L e v e ls o f S u b s t i t u t e d B e n z o ic A c id s S p ra y e d on Z in n ia e l e g a n s .............................................................................. . 4 5 E f f e c t o f D i f f e r e n t C o n c e n tr a tio n s o f S u b s t i t u t e d B e n z o ic A cid s On C a l l i s t e p h u s c h i n e n s i s .................................................................................. 48 DISCUSSION ............................................................................................................................ 57 SUMMARY................................................................................................................................................... 64 LITERATURE CITED.................................................................................................................................65 INTRODUCTION The in d u c t i o n o f f lo w e r in g i n p l a n t s h a s a t t r a c t e d th e a t t e n t i o n o f i n v e s t i g a t o r s f o r many y e a r s . I t i s p e rh a p s n o t s u r p r i s i n g t h a t d i f f e r e n t w o rk e rs h a v e c h o se n to em p h asize d i f f e r e n t a s p e c t s (35» 3 8 » ^ 1 ) o f t h i s com­ p l e x phenom enon. T h u s, i n t h e i r c l a s s i c a l work on c a r h o h y d r a t e - n i t r o g e n r e l a t i o n s h i p s , K raus and K r a y h i l l (1 9 ) c a l l e d a t t e n t i o n t o th e n u t r i t i o n a l s t a t u s o f p l a n t s a s a f a c t o r in flo w e r p r o d u c tio n . u p o n th e e f f e c t o f C/N r a t i o on f r u i t f u l n e s s r a t h e r o f f lo w e r p r im o r d ia . Em phasis was p la c e d th a n on th e i n i t i a t i o n I t was s t a t e d t h a t *The c o n d itio n s f o r i n i t i a t i o n o f f l o r a l p r im o r d ia and even b lo o m in g a r e p ro b a b ly d i f f e r e n t fro m th o s e a c ­ com panying f r u i t s e t t i n g . The g r e a t e s t number o f f lo w e r s a r e p ro d u c e d n e i t h e r by c o n d i t i o n s f a v o r i n g h i g h e s t v e g e t a t i o n n o r b y c o n d it io n s m a rk e d ly s u p p re s s in g v e g e ta tio n ” . Mel c h e rs (2 5 ) a l s o i n v e s t i g a t e d th e C/N r a t i o . W orking w ith M aryland Mammoth to b a c c o , G a rn er an d A l l a r d (9 ) f o c u s s e d a t t e n t i o n on p h o to p e r io d ic f a c t o r s le a d i n g to f lo w e r in d u c tio n . P l a n t s i n e a r l y s t a g e s o f d ev elo p m en t may re s p o n d d i f f e r e n t l y to a g iv e n p h o to p e r io d th a n s i m i l a r p l a n t s a t l a t e r s ta g e s o f d e v e lo p m e n t. C a jla c h ja n ( 4 ) h a s shown c o n c l u s i v e l y t h a t i t i s th e le a v e s w hich a r e th e r e c e p t o r s o f t h e p h o to p e r io d ic s tim u lu s . As h a s b e e n shown by S te in b u r g an d G a rn er (3 7 ) many p l a n t s re s p o n d t o t h e r m o p e r i o d i c i t y b y f lo w e r in g . The s tu d y o f th e i n t e r r e l a t e d n e s s o f C/N r a t i o , p h o to p e r io d and t h e r m o p e r io d ic ity h a s p ro v e n v e r y p r o d u c tiv e and h a s show n th e t h r e e f a c t o r s a r e c l o s e l y r e l a t e d i n t h e i r a f f e c t on f l o r a l d e v e lo p m e n t. H itc h c o c k an d Zimmerman (1 6 ) in d u c e d f l o w e r in g b y a c h e m ic a l 2 coxf^ound h a v in g th e p r o p e r t y o f a g ro w th r e g u l a t o r . Tobacco p l a n t s t o w h ich i n d o l e p r o p i o n i c a c i d was a p p l i e d to th e s o i l i n a n aq u eo u s s o l u t i o n flo w e r e d much q u ic k e r th a n n o n t r e a t e d p l a n t s . T h ese same w o rk e rs (5 0 ) r e p o r t e d t h a t a n a q u eo u s s o l u t i o n o f 2 , 3 , 5 - t r i i o d o b e n z o i c a c i d (TIBA) a p p l i e d a s a f o l i a r s p r a y w ould in d u c e l e a f y s h o o ts o f to m a to e s t o grow f lo w e r c l u s t e r s an d c a u s e th e m ain s h o o t to te r m in a t e i n a f lo w e r c l u s t e r . C la rk and K ern s (6 ) in d u c e d f lo w e r in g b y s p r a y in g s o l u t i o n s o f n a p h th a l e n e a c e tic a c i d on p in e ­ a p p le . Many i n v e s t i g a t o r s , s t i m u l a t e d by th e w ork o f Zimmerman a n d H itc h ­ c o c k an d C la rk a n d K e r n s , h a v e t r i e d v a r io u s c h e m ic a ls f o r t h e i r a b i l i t y to in d u c e f lo w e r in g . To d a t e , h o w e v er, no s y s te m a ti c s tu d y o f th e e f f e c t o f TIBA an d i t s d e r i v a t i v e s h a s b e e n made on co m m ercial g re e n h o u se c r o p s . The p u rp o s e o f t h i s i n v e s t i g a t i o n was to s tu d y th e e f f e c t o f f o l i a r a p p l i c a t i o n s o f TIBA an d i t s d e r i v a t i v e s on a s t e r s ( C a l l i s t e p h u s c h i n e n s i s ) , p e t u n i a s ( P e t u n i a h y b r i d a ) an d z in n ia s ( Z in n ia e l e g a n s ) . REVIEW OF LXTERATURB P h o to p e rio d is m and F lo w e rin g The l i t e r a t u r e on p h o to p e rio d is m i s v e r y e x t e n s iv e an d num erous e x c e l l e n t g e n e r a l re v ie w a r t i c l e s a r e a v a i l a b l e ()5 » 15» 29 an d I ? ) a r e i n a d d i t i o n many re v ie w s o f more r e s t r i c t e d s c o p e , T h e re P a r k e r and B o rth - w ic k ( 3 1 ) r e p o r t e d on w ork done w ith econom ic c ro p s an d fo u n d p h o to p e r io d ic r e s p o n s e s to in c lu d e v e g e t a t i v e e x te n s i o n ( o n i o n s ) , tu b e r f o r m a tio n ( s u g a r b e e t s ) an d c h an g es i n w i n t e r h a r d in e s s (s u g a r c a n e ) a s w e ll a s i n i t i a t i o n o f f l o r a l p r im o r d ia an d d e v elo p m en t o f f l o w e r s , f r u i t s and s e e d s . Hamner ( I 5 ) r e v ie w e d i n v e s t i g a t i o n s o f t h e p o s t u l a t e d h o rm o n e -p h o to p e rio d r e l a t i o n s h i p . He c o n c lu d e d t h a t a horm one o r horm ones may be in v o lv e d i n th e f lo w e r in g p r o c e s s o f many p l a n t s ; t h a t , w h a te v e r t h i s horm one i s , i t s a c t i v i t y i s n o t c o n f in e d to tie p a r t i c u l a r p l a n t i n w h ich i t i s fo rm ed b u t may be t r a n s ­ f e r r e d t o o t h e r s p e c ie s and t h e r e r e s u l t i n f lo w e r in g ; and t h a t th e e n v ir o n ­ m e n ta l c o n d itio n s l e a d i n g t o i t s m a n u fa c tu re d i f f e r w ith d i f f e r e n t p l a n t s . T h u s , l a some p l a n t s th e horm one seems to be m a n u fa c tu re d u n d e r s p e c i a l p h o t o p e r i o d i c c o n d itio n s and i n o t h e r p l a n t s u n d e r d i f f e r e n t , b u t s t i l l s p e c i a l , p h o to p e r io d ic c o n d i t i o n s . A c o m p re h e n siv e symposium by M urneek an d Whyte (2 9 ) sum m arizes t h e in f o r m a t io n a v a i l a b l e on v e r n a l i z a t i o n and p h o to p e rio d is m a s th e y r e l a t e to f l o r a l in d u c tio n . I t i s g e n e r a l l y a g re e d t h a t th e p h o t o p e r io d ic in d u c ­ t i o n o f f lo w e r in g i s h o rm o n a lly c o n t r o l l e d , t h a t th e s i t e o f in d u c tio n i s i n t h e le a v e s ; and t h a t f lo w e r in d u c tio n i s a p h a s ic d e v e lo p m e n t. Grow th R e g u la to r s an d F lo w e rin g A. I n d o l e a c e t i c a c i d (lAA) Two r e c e n t re v ie w s on f lo w e r in g h av e b e en p r e p a r e d by B o n n er an d L lv e rm a n (2 ) and L iverinan ( 2 4 ) , tu re B onner and L iv e r man re v ie w e d th e l i t e r a ­ on h o rm o n al c o n t r o l o f f lo w e r i n i t i a t i o n . They s u b d iv id e d th e p h o to p e rio d ic re sp o n se o f p la n ts in to a s e r ie s o f s e q u e n tia l p a r t i a l o r com ponent p r o c e s s e s and a tte m p te d to a s s o c i a t e th e s e p r o c e s s e s w ith p a r t i c u ­ l a r b io c h e m ic a l o r p h y s i o l o g i c a l s t a g e s o f th e p l a n t . T h ese b io c h e m ic a l o r p h y s i o l o g i c a l s t a g e s a r e b e l i e v e d t o be c o n t r o l l e d , a t l e a s t i n p a r t , by a u x in s . W ith s h o r t - d a y p l a n t s i n p a r t i c u l a r , p h o to p e r i o d ic i n d u c tio n may b e a s s o c i a t e d w ith re d u c e d l e v e l s o f e f f e c t i v e a u x in i n t h e p l a n t an d th e i n t e r p l a y o f l i g h t an d d a rk i n t h e p h o to p e r io d ic p r o c e s s may b e m e d ia te d , i n p a r t a t l e a s t , th ro u g h i n f l u e n c e s upon th e a u x in economy. F lo w e rin g i n s h o r t - d a y p l a n t s i s n o t a s im p le m a tte r o f a u x in economy, h o w e v er, an d two o r p o s s i b l y more horm ones o f q u i t e d i f f e r e n t c h e m ic a l n a t u r e s may be in v o lv e d . I t f o ll o w s t h a t th e i n f l u e n c e o f a u x in on f lo w e r in g i s n o t d i r e c t b u t a p p e a rs r a t h e r to b e e x e r t e d t h r o u ^ c o n t r o l an d r e g u l a t i o n o f th e s y n t h e s i s o f a s p e c i f i c f lo w e r in g horm one o r horm ones o f unknown c h e m ic a l n a t u r e . I t is t h i s m a t e r i a l , t h e f l o w e r in g horm one o r ho rm o n es, an d n o t th e a u x in , w h ich h a s b e e n s t u d i e d by v i r t u e o f t h e tr a n s m is s io n o f th e f lo w e r in g s tim u lu s th r o u g h t h e p l a n t an d fro m p l a n t t o p l a n t . I n v e s t i g a t i o n o f f lo w e r in g i n lo n g -d a y and d a y - n e u t r a l p l a n t s h a s shown th e c o n c e p t o f r e g u l a t i o n o f f lo w e r in g b y a u x in l e v e l to be o f w id e a p p l i c a b i l i t y . L iverm an (2 4 ) em p h asized t h e im p o rta n c e o f p h y s i o l o g i c a l f a c t o r s o n flo w e rin g * E s s e n t i a l l y th e same c o n c lu s io n s w ere re a c h e d a s w ere r e a c h e d by B onner an d L iv erin an ( 2 ) . g ra p h ic a lly T hese c o n c lu s io n s a r e b e s t shown (D iagram I ) ; RYTHMICAL CHANGES IN lAA LEVEL II AUXIN RESPONSES o D*S S>D O t-t I-» 6-t I—I CO DARK s g o g g M 1-4 to Ji, J a H4 The h i ^ - i n t e n s i t y l i g h t p r o c e s s i s c h a r a c t e r i z e d i n p a r t by th e f o r m a tio n o f a u x in p r e c u r s o r s . The n e t c o n c e n tr a tio n o f a u x in (A) d ep en d s on th e b a la n c e b etw een i t s s y n t h e s is (S ) and i t s d e s t r u c t i o n (D) by t h e a d a p ti v e f o r m a tio n a n d t h e d e - a d a p tiv e d is a p p e a r a n c e o f lAA o x id a s e . A uxin fo rm ed d u r in g th e d a rk p r o c e s s com bines w ith th e a u x in r e c e p t o r (E ) i n l i g h t to fo rm th e g r o w th - a c tiv e a u x i n - r e c e p t o r co m p lex (A S ). The com plex may le a d to g ro w th r e s p o n s e s o r may be decom posed t o fo rm an a u x in - n o n r e c e p tiv e e n t i t y (Bp) p lu s some 6 compound (A ^ ), The a u x in - n o n r e c e p tiv e e n t i t y (B p) i s a g a in a c t i v a t e d by r e d l i g h t to fo rm ( B ) . may p a r t i c i p a t e i n t h e b i o s y n t h e s i s o f f l o r i g e n . N e i t h e r B onner and L iv erm an (2 ) o r L iv erm an (2 4 ) d is c u s s o r c i t e t h e w ork done on a u x in tr e a tm e n t o f s e e d w h ich h a s r e s u l t e d i n h a s t e n in g o f f lo w e r in g . Thim ann and Lane (4 2 ) so a k e d to m ato s e e d i n a n aq u eo u s a u x in s o l u t i o n and r e p o r t e d , u n d e r g re e n h o u se c o n d i t i o n s , t h r e e to s e v e n d ay s q u ic k e r f lo w e r in g o f p l a n t s fro m t r e a t e d s e e d com pared to p l a n t s fro m non­ tre a te d seeds. S t 1 e r a n d duBuy (3 9 ) d u s te d to m ato s e e d w ith an a u x i n - t a l c m ix tu r e a t tim e o f sow ing i n q u a r tz s a n d . A f te r g e r m in a tio n p l a n t r o o t s w ere d ip p e d i n t o s o l u t i o n s o f n a p h th a l e n e a c e ti c an d i n d o l e b u t y r i c a c i d s a n d t h e n t r a n s p l a n t e d i n t o th e f i e l d . e a r l i e r th a n n o n t r e a t e d p l a n t s . T r e a te d p l a n t s f lo w e re d t h r e e d ay s T h is h a s te n in g o f f lo w e r in g i s n o t e x p l i c ­ a b l e b y t h e i n t e r a c t i o n o f a u x in l e v e l and p h o to p e r io d h y p o th e s iz e d by B o n n er an d L iv erm an (2 ) an d L iverm an ( 2 4 ) . A re v ie w o f th e l i t e r a t u r e on p h o to p e r io d h a s shown no r e p o r t s o f l i ^ t o r d a rk a f f e c t i n g s e e d s p r i o r to g e r m in a tio n . I t i s d i f f i c u l t , t h e r e f o r e , to s e e any r e l a t i o n s h i p b etw een a u x in t r e a t e d s e e d and f lo w e r in g i f f lo w e r in g i s c o n t r o l l e d by p h o to p e r io d ­ i c a l ly in d u c e d ch an g e s i n th e a u x in economy. B. 2 .3 t5 - T r iio d o b e n z o ic a c i d (TIBA) A r e l a t i o n s h i p b etw ee n TIBA and f lo w e r in g was f i r s t r e p o r t e d by Zimmerman and H itc h c o c k ( 5 0 ) . They o b s e rv e d t h a t a p p l i c a t i o n o f a f o l i a r s p r a y o f TIBA to to m ato p l a n t s in d u c e d n o rm a lly v e g e t a t i v e a x i l l a r y buds t o grow f lo w e r c l u s t e r s . The te r m i n a l v e g e t a t i v e bud o f th e m ain a x i s was a l s o in d u c e d to grow flo w e r c l u s t e r s . T h is d is c o v e r y by Zimmerman an d 7 H itc h c o c k : s t i m u l a t e d c o n s id e r a b le i n t e r e s t and th e y l a t e r (5 2 ) r e p o r t e d w id e s p r e a d c o n f ir m a tio n o f t h e i r i n i t i a l o b s e r v a t io n o f TI3A a c c e l e r a t i n g f l o w e r i n g I n to m a to p l a n t s . On th e o t h e r h% id. G als to n (8 ) r e p o r t e d t h a t TIBA h a d no f l o r a l g e n e ic p r o p e r t i e s s i n c e i t d i d n o t in d u c e v e g e t a t i v e so y b ean p l a n t s to flo w e r. H ow ever, i t g r e a t l y augm ented t h e f lo w e r in g r e s p o n s e due to p h o t o p e r i o d i c i n d u c tio n . I t h a s b e e n r e p o r t e d by G o r te r (1 1 ) t h a t t h e a p p l i c a t i o n o f TIBA to th e s o i l o f P h a s e o lu s v u l g a r i s r e s u l t e d i n a n in c r e a s e d num ber o f f lo w e r s an d f r u i t and an i n c r e a s e i n t h e f r e s h w e i ^ t o f th e f r u i t . e a r l y f lo w e r in g was p ro m o ted . In a d d itio n , I t was a l s o fo u n d t h a t t h e number o f f lo w e r s on L y c o p e rs ic o n e sc u le n tu m was in c r e a s e d by s o i l a p p l i c a t i o n o f TIBA. C. O th e r Growth R e g u la to r s The f i r s t l a r g e s c a l e p r a c t i c a l u s e o f gro w th r e g u l a t o r s i n in d u c ­ in g f lo w e r in g was made p o s s i b l e a f t e r C la rk and K ern s (6 ) in d u c e d f lo w e r in g o f p in e a p p l e s by s p ra y s o f n a p h th a l e n e a c e ti c a c i d . I t h a s b e e n r e p o r t e d t h a t i f n a p h th a l e n e a c e ti c a c i d so a k e d to m ato s e e d s w ere g e rm in a te d a t t h r e e d e g re e s c e n ti g r a d e th e num bers o f d ay s to f lo w e r was s h o r te n e d when com pared to n o n tr e a te d p l a n t s ( 2 2 ) , Hamner a n d B onner (1 4 ) p la c e d v e g e t a t i v e c u t t i n g s o f X anthium p e n n su Iv a n ic u m i n s o l u t i o n s o f v ita m in s ®6* a s c o r b i c a c i d , p a n to ­ t h e n i c a c i d , n i c o t i n i c a c i d , i n o s i t o l , lAA., th e e l i n and t h e e l o l to t e s t t h e i r a c t i v i t y on f l o r a l i n i t i a t i o n . A ll th e s e s u b s ta n c e s when t e s t e d o v e r a w id e ra n g e o f c o n c e n tr a tio n s p ro v e d i n e f f e c t i v e i n p ro m o tin g f l o r a l p r im o r d ia . 8 D orm ant Thompson s e e d l e s s g ra p e c u t t i n g s t r e a t e d w ith a s p r a y o f t h e th io s e m ic a r b a z o n e s o f 2 ,4 - d ic h lo r o b e n g a ld e h y d e , 3 » 4 - d lc h lo r o b e n z a ld é ­ h y d e , 4 - c h lo ro b e n z a ld é h y d e and p h e n y la c e to n e w ere s u c c e s s f u l l y in d u c e d to f lo w e r ( 3 3 ) . 9 G row th R e g u la to r s an d M orphology A. I n d o l e a c e t i c a c i d The a c t i o n o f n a t u r a l an d s y n t h e t i c g ro w th r e g u l a t o r s on m o rp h o lo g i­ c a l c h a n g e s h a s b e e n r a t h e r w id e ly i n v e s t i g a t e d ( 2 0 ,3 ,1 8 ,4 4 ) . K ra u s , Brown a n d Hainner (2 0 ) t r e a t e d d e c a p i t a t e d Red K idney b e a n s w i t h lAA i n l a n o l i n . D i f f e r e n t t i s s u e s v a r i e d i n t h e i r re s p o n s e to lAA b u t in d u c e d o r p ro lo n g e d m e r is te r a a t ic a c t i v i t y was th e f i r s t r e a c t i o n n o te d i n a l l t i s s u e s . d e rm a l c e l l s u n d e rw e n t a few d i v i s i o n s i n t h e r a d i a l p l a n e . t h e c o r t i c a l parenchym a e n la r g e d and became m e r is te r a a tic . E p i­ The c e l l s o f N u c le a r d i v i s i o n was g r e a t l y s p e e d e d up i n e p id e rm a l c e l l s and w a lls fo rm ed i n a l l p l a n e s . The c e l l s o f th e p e r i c y c l e and parenchym a o f p rim a ry phloem p r o l i f e r a t e d s l i g h t l y w h ile th e parenchym a o f th e s e c o n d a ry phloem p r o l i f e r a t e d m a rk e d ly . Numerous tum ors and g a l l s form ed on th e stem and le a v e s . S im ila r r e s u l t s w ere o b ta in e d by B o rth w ic k , Hamner an d P a r k e r (3 ) u p o n t r e a t i n g to m a to e s i n t h e above f a s h i o n . B. 2 , 3 ,5 - T r ilo d o b e n z o ic A cid an d R e la te d S u b s t i t u t e d B en z o ic A cid s I n g e n e r a l , b o th a p p l i c a t i o n o f TIBA an d r e l a t e d m a t e r i a l s p ro d u c e some d e g re e o f f o r m a tiv e e f f e c t s i n m ost p l a n t s . Zimmerman an d H itc h c o c k ( 5 0 ) r e p o r t e d t h a t TIBA a p p l i e d a s a f o l i a r s p ra y to to io ato p l a n t s in d u c e d s h o r t e n i n g o f in te r n o d e s and m alform ed le a v e s . A ls o , TIBA a p p l i e d a s a f o l i a r s p r a y c a u s e d a b e r r a t i o n s w i t h i n so y b ea n p l a n t s w hich r e s u l t e d in s h o r t e n i n g o f i n te r n o d e s ( 8 ) . A p p lic a t io n o f TIBA to b e an le a v e s ch eck ed e l o n g a t i o n o f i n t e r n o d e s , a f f e c t e d te r m in a l and a x i l l a r y b u d g ro w th and 10 c a u s e d d w a rfin g and c u r l i n g o f le a v e s ( 2 1 ) . When TIBA was a p p l i e d in l a n o l i n p a s t e to d e c a p i t a t e d b e a n p l a n t s , d i s c o l o r a t i o n o f t i s s u e , n e c r o s i s o f t r e a t e d t i s s u e , tum or f o r m a tio n an d d w a rfin g r e s u l t e d (4 7 ) Zimmerman and H itc h c o c k (5 3 ) an d Z e i s t an d K o ev o ets (4 9 ) r e p o r t e d t h a t TIBA an d 2 - c h lo r o - 3 ,5 - d .iio d o b e n z o ic a c i d when s p r a y e d on K a lan c h o e p l a n t s le a d to f u s i n g o f o p p o s ite l e a v e s , f u s i n g o f m ain a x i s an d l a t e r a l s h o o t s , I n c r e a s e d l e a f s u c c u le n c e and s to p p a g e o f m ain a x is g ro w th . A p p lic a t io n o f TIBA t o to m ato le a v e s r e s u l t e d i n s to p p a g e o f l o n g i­ t u d i n a l g ro w th o f r o o t h a i r s w h ereas p r o d u c tio n o f c e l l - w a l l m a t e r i a l c o n tin u e d . The g ro w in g p o i n t s o f to m ato p l a n t s t r e a t e d w ith TIBA grew in a co n e-sh ap e. C o r r e la te d w ith t h i s phenomenon was t h e i n a b i l i t y o f th e p l a n t to p ro d u c e new le a v e s and th e a b i l i t y to p ro d u c e f lo w e r s ( 1 2 ) . R o o tin g o f C o leu s b lu m e i was i n h i b i t e d by tr e a tm e n t o f th e c u t t i n g s w i t h TIBA pow der ( 3 6 ) . f lo w e r s o f to m ato p l a n t s s p ra y e d w ith TIBA w ere c h a r a c t e r i z e d by s h o r t t o lo n g , h e av y p e d u n c le s and by f a s e l a t e d , o f t e n a b n o rm a lly la r g e flo w e rs . The f lo w e r s had c i r c u l a r o v a r ie s ( 5 2 ) . L a t e r , Zimmerman and H itc h c o c k (5 4 ) showed t h a t a f o l i a r a p p l i c a ­ t i o n on to m a to p l a n t s o f 2 , 3 , 5 = t r i c h lo r o b e n z o ic a c i d an d i t s a ld e h y d e h ad s i m i l a r b u t more s e v e r e f o r m a tiv e e f f e c t s th a n TIBA a t th e same c o n c e n tr a ­ tio n . R eady, e ^ . (3 4 ) r e p o r t e d t h a t t h e a p p l i c a t i o n o f 3 - n it r o ~ 4 — h y d ro x y b e n z o ic a c i d , 3” ^ ilb ro -4 -m e th o x y b e n z o ic a c i d , 3 - i:^ ltr o - 4 - e th o iy b e n z o ic a c i d a n d 3 - n i t r o - 4 - a c e t o z y b e n z o i c a c i d to th e s o i l c a u s e d a lb in is m i n emerg­ i n g b a r l e y s h o o ts . 3 -M itro b e n z o ic a c i d , 4 -m e th o z y b e n z o ic a c i d , 4 - e th o x y - 11 b e n z o ic a c i d , 4 - a c e to x y b e n z o ic a c i d and 4—h y d ro x y b e n z o ic a c i d w ere i n ­ e f f e c t i v e i n c a u s in g a lb in is m . The e f f e c t o f TIBA on m o rp h o g e n e sis o f Lemna m in o r was s t u d i e d by W ager man and L acey ( 4 6 ) . They r e p o r t e d t h a t f r o n d s grow n i n n u t r i e n t s o lu ­ t i o n s c o n t a i n i n g TIBA h a d a much more e x te n s iv e v a s c u l a r s y ste m th a n c o n t r o l fro n d s. A s i m i l a r i n v e s t i g a t i o n was made by W ardlaw (4 6 ) who fo u n d t h a t t h e a p p l i c a t i o n o f a f o l i a r s p ra y o f TIBA on to m ato p l a n t s c a u se d a cessart i o n o f g ro w th i n th e m ost d i s t a l c e l l s o f th e a p ex and r e t a r d e d g ro w th o f t h e s u b ja c e n t r e g i o n s . As a r e s u l t o f t h i s t r e a tm e n t a p ic e s o f u n u s u a l c o n f i g u r a t i o n and o r g a n i z a t i o n w ere p ro d u c e d and some o f th e s e a s p i c e s gave r i s e t o h o llo w o r r i n g - f a s e l a t e d s h o o ts w ith a d o u b le v a s c u l a r sy ste m . T r ic h l o r o b e n z o ic a c i d a p p lie d a s a f o l i a r s p r a y on b e an p l a n t s c a u s e d com­ p l e t e o r p a r t i a l s u p p r e s s io n o f a p i c a l g ro w th an d l e a f f o r m a tio n , b u t g r e a t l y i n c r e a s e d r o o t f o r m a tio n . P i l l a i an d C h a k r a u a r ti (3 2 ) s t u d i e d th e e f f e c t o f TIBA on l e a f fo rm o f B r a s s i c a cam past r i s and Lens e s c u l e n t a and fo u n d t h a t s o a k in g m u sta rd s e e d i n TIBA s o l u t i o n s p r i o r to g e r m in a tio n c au se d c o a le s c e n c e o f th e le a v e s t h u s fo rm in g a n a sc id u m . T re a tm e n t o f Lens e s c u l e n t a s e e d i n th e same m anner in d u c e d s h o r te n in g o f th e r a c h i s and c o a le s c e n c e o f th e l e a f l e t s r e ­ s u l t i n g i n p a lm a te l e a v e s . C. O th e r Growth R e g u la to r s The m o rp h o lo g ic a l e f f e c t s o f th e p h e n o x y a c e tic a c i d s ( p a r t i c u l a r l y 2 ,4 - d i c h lo r o p h e n o z y a c e tic a c i d ) an d n a p h th a l e n e a c e t ic a c id s h a v e b e e n s tu d ie d in d e t a i l . W hile th e s e compounds show s m a ll d i f f e r e n c e s from th e 12 r e s p o n s e o f lAA on b e a n s a n d to m a to e s ( l 4 ) , th e o v e r a l l r e s p o n s e i s s im ila r. I n g e n e r a l , th o s e t i s s u e s t h a t a r e l e a s t d i f f e r e n t i a t e d h av e t h e g r e a t e s t p o t e n t i a l f o r r e s p o n s e , and w ith i n c r e a s i n g d e g re e s o f d i f f e r e n t i a t i o n , r e s p o n s iv e n e s s d e c l i n e s (L e o p o ld , 2 3 ). 13 G row th R e g u l a to r s a n d P h y s io lo g y A# I n d o l e a c e t i c A cid E f f e c t s o f lAA on th e g e n e r a l p h y s io lo g y o f t h e p l a n t h a v e b e e n th e s u b je c t o f in te n s iv e in v e s tig a tio n . L i t e r a t u r e r e s u l t i n g fro m th e s e i n v e s t i g a t i o n s i s v o lu m in o u s an d f r e q u e n t l y c o n t r a d i c t o r y . None o f th e l i t e r a t u r e r e a d i n p r e p a r a t i o n f o r t h i s e x p e rim e n t o f f e r e d c o n c lu s iv e ex­ p e r i m e n t a l e v id e n c e l i n k i n g an a u x in in d u c e d p h y s i o l o g i c a l r e s p o n s e s o f i n t a c t p l a n t s to s u b s e q u e n t f lo w e r in g . B» 2 , 3 « 5 -T rilo d o b e n z o ic A c id an d R e l a te d S u b s t i t u t e d B e n z o ic A cid s Zimmerman and H itc h c o c k (5 0 ) h av e c o n c lu d e d t h a t TIBA d o es n o t c a u s e im m e d ia te ( w i t h i n a few h o u r s ) c e l l e lo n g a t i o n o f t e s t o b j e c t s . The u l t i m a t e r e s u l t s o f a p p ly in g TIBA to p l a n t s re s e m b le d th o s e o f t r u e horm ones m ore th a n th e in d o le and n a p h th a le n e compounds commonly r e f e r r e d to a s a u x in s , C a r r o l l (5 )* i n s tu d y in g th e a n t i - a u x i n p r o p e r t i e s o f TIBA i n A vena t e s t s , c o n c lu d e d t h e r e was a la g o f f o u r h o u rs b e tw ee n th e a p p l i c a ­ t i o n o f TIBA an d i t s a n t i - a u x i n a c t i o n . G a ls to n (8 ) r e p o r t e d TIBA i t s e l f was w ith o u t a c t i v i t y i n Avena t e s t s b u t i t s a c t i v i t y a n ta g o n iz e d an d n e g a te d t h e e f f e c t s o f lAA. Wangerman and L acey (4 5 ) a p p l i e d f o l i a r s p ra y s o f TIBA t o Lemna m in o r an d r e p o r t e d no e f f e c t on le n g th o f l i f e o r r a t e o f ag in g th e f r o n d s . Lower a u x in l e v e l s w ere fo u n d i n t r e a t e d f r o n d s when com pared to n o n tre a te d fro n d s , Audus and Q jia s te l (1 ) fo u n d t h a t c e r t a i n su lp h o n a m id e s a p p l i e d to t h e s o i l a t 10 p .p .m . i n h i b i t e d r o o t g ro w th o f c r e s s . p -A m in o b en zo ic a c i d of 14 s o l u t i o n s when a p p l i e d t o th e s o i l l e s s e n e d t h e i n h i b i t i o n . When t h e s u lp h o n a m id e s a n d p -a m in o b e n z o i c a c i d w ere a d d ed i n e q u a l c o n c e n t r a t i o n s r o o t g ro w th was n o rm a l, C. O th e r Grow th R e g u la to r s M ost o f t h e w ork h a s b e e n done w ith p h e n o x y a c e tic a c i d s an d n a p h th a le n e a c e tic a c id s . R e p o r te d r e s u l t s a r e v a r i e d an d do n o t p e rm it p i n p o i n t i n g o f t h e p rim a ry a c t i v i t y o f th e s e g ro w th r e g u l a t o r s . r e s u l t s a r e a b n o rm a l m e ta b o lism an d a b n o rm al g ro w th p a t t e r n s . S e c o n d ary T h ere i s s t r o n g e v id e n c e (L e o p o ld , 23* R eady e t . a l . , 3 4 ) o f a r e l a t i o n s h i p b e tw ee n t h e s e g ro w th r e g u l a t o r s and a u x in l e v e l s . 15 Mode o f A c tio n A. I n d o l e a c e t i c A c id An e n z y m a tic mode o f a c t i o n f o r lAA i n s t r a i g h t g ro w th t e s t s h a s b e e n a d v a n c e d by B onner and L iv erm an ( 2 ) , f o ll o w s M ic h a e lis -M e n te n k i n e t i c s . They show t h a t lAA in d u c e d g ro w th I t is p o s tu la te d t h a t th e carb o x y l g ro u p an d o r t h o r i n g c a rb o n com bine w ith a s u l f h y d r y l g ro u p o f a n amino a c i d to fo rm a com plex. T h is com plex d i s s o c i a t e s to r e g e n e r a t e th e s u l f h y d r y l g ro u p a n d fo rm p r o d u c ts . L i t t l e in f o r m a tio n i s a v a i l a b l e on th e mode o f a c t i o n o f lAA on flo w e rin g . B onner an d L iverm an (2 ) h av e a tte m p te d to c o r r e l a t e t h e ob­ s e r v a t i o n s o f low a u x in l e v e l s i n f lo w e r in g p l a n t s w ith p h o to p e r io d . E s s e n t i a l l y t h i s in v o lv e d p o s t u l a t i n g th e e n z y m a tic c o m b in a tio n o f a u x in w ith compounds p h o t o p e r i o d i c a l l y in d u c e d i n l e a v e s , t h e d i s s o c i a t i o n o f t h e co m plex, and f o r m a tio n o f one o r more f lo w e r in d u c in g h o rm o n es. B. 2 . 3 .5 - T r iio d o b e n z o ic A cid an d r e l a t e d S u b s t i t u t e d B e n z o ic A cid s M uir and H ansch (2 ? ) h av e p o s t u l a t e d a n a n t i - a u x i n mode o f a c t i o n f o r TIBA on f lo w e r i n g . They s a i d th e f o llo w i n g s t r u c t u r a l r e q u ir e m e n ts m ust b e met f o r a c t i v i t y a s g ro w th r e g u l a t o r s : 1. The o r th o p o s i t i o n m ust b e s u b s t i t u t e d w ith a n e l e c t r o ­ n e g a t i v e g ro u p c a p a b le o f d is p la c e m e n t by a n e l e c t r o n - r i c h s u b s tra te , 2. I f o n ly m e ta a n d /o r p a r a p o s i t i o n s e r e s u b s t i t u t e d th e compound w i l l be i n a c t i v e . 3. I f th e o r th o p o s i t i o n i s s u b s t i t u t e d w ith a n e l e c t r o n - 16 p o s i t i v e g ro u p th e compound w i l l b e i n a c t i v e . I t i s th o u g h t t h a t any s u b s t i t u t e d b e n z o ic a c i d p o s s e s s i n g th e n e c e s s a r y s t r u c t u r a l r e q u ir e m e n ts w i l l com bine w ith th e same s u b s t r a t e a s lAA. F a i l u r e to m eet t h e s e r e q u ir e m e n ts g iv e s TIBA i t s commonly a s c r i b e d a n ti- a u x in a c tio n . C. O th e r G row th R e g u la to r s The mode o f a c t i o n o f t h e s e compounds h a s b e e n th e s u b j e c t o f in te n s iv e in v e s tig a tio n . I t i s th o u g h t t h e i r a c t i v i t y d ep en d s on a s t r u c t u r a l re s e m b le n c e to lAA w h ich p e r m its i n t e r f e r e n c e w ith lAA c a t a ­ ly s e d r e a c tio n s . The s t r u c t u r a l re q u ire m e n ts n e c e s s a r y a r e a f r e e o r p o t e n t i a l l y f r e e c a r b o x y l g ro u p an d a f r e e o r p o t e n t i a l l y f r e e p o s i t i o n h a v in g a s p a t i a l r e l a t i o n t o th e c a rb o x y l g ro u p w hich p e r m its t h e i r b e in g l i n k e d by a s u l f h y d r y l g ro u p . S e v e r a l r e c e n t re v ie w s on t h i s s u b j e c t a r e b y M uir an d H ansch (28) an d Gordon ( 1 0 ) . 11 MATERIALS AND METHODS I n o r d e r t o d e te r m in e t h e e f f e c t i v e n e s s o f v a r io u s s u b s t i t u t e d b e n z o ic a c i d s a s f lo w e r in d u c in g a g e n ts a v a r i e t y o f f l o r i c u l t u r a l c ro p s w e re grow n u n d e r g re e n h o u s e c o n d it io n s p r e v a i l i n g a t E a s t L a n s in g , M ic h ig a n , d u r in g F a l l , W in te r and S p r in g m onths o f 1 9 5 5 -5 6 . S eeds o f Z in n ia ^ ( Z in n ia e l e g a n s ) v a r i e t y E n c h a n t r e s s , a s t e r ^ ( C a l l i s t e p h u s c h i n e s i s ) v e u rie ty Queen o f t h e M arket A zure B l u e , an d p e t u n i a ^ ( P e t u n i a h y b r id a ) v a r i e t y Dream G i r l , w ere p l a n t e d i n s t e r i l i z e d f l a t s a n d l a t e r t r a n s p l a n t e d to 3 - in c h s t e r i l i z e d p o t s . The c h e m ic a ls u s e d ^n t h e s e e x p e rim e n ts w ere o b ta in e d fro m v a r io u s s o u r c e s (T a b le I ) . The s o l u t i o n s V e re p r e p a r e d , f i r s t , d i s s o l v i n g t h e s e compounds i n a minimum amount o f 95 p e r c e n t a lc o h o l ( u s u a l l y 0 .0 5 g ram /lO m l, ) an d made to volum e w ith d i s t i l l e d w a te r . C o n c e n tr a tio n s o f 100 and 1000 p .p .m . w ith a s m a ll amount o f w e tti n g a g e n t ( D r a f t ) w ere em ployed f o r a l l t h e c h e m ic a ls , l i s t e d i n T a b le 1 , and f o l i a r a p p l i c a t i o n s w ere made a t a s t a g e when t h e f i r s t t r u e le a v e s w ere o n e - h a l f ex p an d ed . I n a n o th e r s e r i e s o f t r i a l s , th e r e l a t i v e e f f i c a c y o f th e v a r i o u s c h e m ic a ls was d e te r m in e d i n r e l a t i o n t o i t s pH v a lu e . S o lu tio n s o f 100 p .p .m , c o n c e n t r a t i o n s w ere a d j u s t e d to 3 , 4 , 5 , 6 , 7 , 8 and 9 pH by 0 .5 N KOE en d 0 .5 N HCl on a Beckman m odel H -2 l i n e o p e r a te d . pH m e te r. L a te r o n , t h e s e s o l u t i o n s w ere u s e d a s f o l i a r s p r a y s . S in c e m o d if ic a tio n s o f s o i l r e a c t i o n s h a s a g r e a t e f f e c t on p l a n t g ro w th i t was th o u g h t a d v is a b le t o in c lu d e th e e f f e c t o f s o i l a p p l i c a t i o n s o f c h e m ic a ls , s u b s t i t u t e d b e n z o ic a c i d g ro u p a s g iv e n i n T a b le I , on p l a n t S e e d s o b ta in e d from ( l ) V aughans an d (2 ) H a r r is Seed Company 18 s o o •H O N a •H U (g *d •rH ü % f-t o N Ü •H % es O •iH O M a 0> rCJ Q S O m en 6 & » ü •H iH (S t/i O H •H c •H A A s ■d •H o cS o •H rH O •rH rH cS en -d O •tH •ri A s •d •rH O (S o •rH rH >b O •H '3 vn g a o m A s *d •rH O c6 o •H rH >» ü •H d 00 o s o m s •d •rH O cS ü •H rH ü •H rH cS m O a o •H A m •H d •H o es o •H rH >> o •rH rH cS m o P, o rH d Q) A3 A3 O O d o d •ri •ri d 1 en 1 o d A3 •H d g 1 o d d •H o eS d •H O N d o> A3 O o a u A3 •H Fh EH •iH •H A 4 4 cî, CM cîi nd •H 0 01 o •H O N Ü _produced i n d i c a t e d t h a t m a g n itu d e o f t h i s p h a se o f b i o l o g i c a l a c t i v i t y was i n f l u e n c e d by th e r a t e an d n a t u r e o f t h e c h e m ic a l u s e d (T a b le V I ) , A c c o rd in g ly , p l a n t s t r e a t e d w ith 100 p .p .m d e v e lo p e d more a x i l l a r y s h o o ts th a n p l a n t s t r e a t e d w ith 1000 p .p .m . D i f f e r e n c e s in p l a n t g ro w th b e h a v io r , when a n a ly z e d i n te rm s o f c h e m ic a l a c t i v i t y , f o llo w e d th e same g e n e r a l t r e n d a s e x p re s s e d p r e v io u s ly f o r t h e i n i t i a t i o n o f in c r e a s e d number o f f lo w e r s a n d b u d s . T hat i s , th e m ore e l e c t r o - p o s i t i v e o r th o s u b s t i t u t e d compounds p ro d u c e d more a x i l l a r y s h o o ts th a n t h e e l e c t r o - n e g a t i v e o r th o s u b s t i t u t e d compounds; th e e f f e c t was e n h a n c e d b y an e l e c t r o - n e g a t i v e g ro u p o r th o to th e e l e c t r o - p o s i t i v e g ro u p . A l l p l a n t s e x c e p t th o s e s p ra y e d w ith 2 , 3 •5“ t r i c h l o r o b e n z o i c a c i d an d 2 , 5 d ic h lo r o p h e n o x y a c e tic a c i d h a d more a x i l l a r y s h o o ts th a n p l a n t s r e c e i v i n g no t r e a t m e n t . The c h e m ic a l tr e a tm e n ts and th e c o n c e n tr a t io n s o f th e a p p l i c a t i o n s a f f e c t e d th e p e t u n i a p l a n t s i n su ch a m anner t h a t t h e f lo w e r in g phenom ena 25 TABLE V EFFECT OF SUBSTITUTED JPNZQIC ACIDS ON FLORAL INITIATION OF PETUNIA HYBRIDA* C h e m ic a l C heck 2 . 3 .5 - t r i i o d o 'b e n z o i c a c i d 2 . 3 .5 - tr ib r o m o h e n z o ic a c i d 2 . 3 .5 -tr io h lo ro b e n z o ic a c id p - io d o b e n z o ic a c i d o - io d o b e n z o ic a c i d m -io d o b e n z o ic a c i d 2 . 3 - d iio d o b e n z o ic a c i d 2 .5 - d ii o d o b e n z o ic a c i d 3 .5 - â .iio d o b e n z o ic a c id 2 - i o d o - 3 - n i t r o b e n z o i c a c id p -a m in o b e n z o ic a c i d 2 - a m in o -5 - io d o b e n z o ic a c id 2 - a m in o -3 » 5 -d iio d o b e n z o ic a c i d 2 -a m in o -3 » 5 -d ib ro m o b e n z o ic a c i d 2 .4 -d ih y d r o iy b e n z o i c a c id 2 .5 - d ih y d r o x y b e n z o ic a c id 3 ,5 - d iio d o s a lic y lic a c id 3 - b r o m o s a l i c y l i c a c id 3 . 5 - d i b r o m o s a l i c y l i c a c id 3 . 5 - d i c h l o r o s a l i c y l i c a c id 2 . 5 - d ic h lo r o p h e n o x y a c e tic a c i d Number o f F lo w e rs 1000 p .p .m , 100 p .p .m . 4.33 4.83 8 .0 0 4.67 6.58 6.50 5.92 7 .0 0 6.17 5.83 9.83 6.65 8.33 9.17 9.35 1 2 .0 0 5.17 6 ,8 3 8.17 5.00 5.25 4.92 L .S .D . 5$5 = 0 .8 8 155 = 1 . 1 6 ♦Average of three replicates of four plants each 4.33 4.08 4.50 1.50 5.33 3.92 4 .6 9 5.83 7.17 7.08 4.17 7.58 6.33 8 .4 2 6.92 10.75 5.25 7.08 6.17 3.83 3.58 2.83 26 TABLE VI EFFECT OF SUBSTITUTED BENZOIC ACIDS ON NUMBER OF AXILLARY SHOOTS OF PETUNIA HYBRIDA* C h e m ic a ls C heck 2 ,3 » 5 - tr iio d o b e n z o ic a c i d 2 , 3 * 5 -trib ro m o b e n z o ic a c i d 2 , 3 ,5 “ t r i c h l o r o b e n z o i c a c i d p - io d o b e n z o ic a c i d o - io d o b e n z o ic a c i d m -io d o b e n z o ic a c i d 2 , 3 - d ii o d o b e n z o ic a c i d i 2 ,5 - d ii o d o b e n z o ic a c i d 3 » 5 - d iio d o b e n z o ic a c i d 2 - i o d o - 3 - n i t r o b e n z o i c a c id p -a m in o b e n z o ic a c i d 2 - a m in o -5 - io d o b e n z o ic a c i d 2 - a m in o - 3 ,5 - d iio d o b e n z o ic a c i d J 2 -am ino—3 * 5 -d ib ro m o b en z o ic a c i d 2 , 4 - d ih y d r o x y b e n z o le a c id 2 , 5 -d ih y d r o x y b e n z o ic a c i d 3 ,5 - d iio d o s a lic y lic a c id 3 -b r o m o s a lic y lic a c id 3 , 5 -d ib ro m o s a lic y lic a c id 3 . 5 - d io h lo r0s a l i o y l i c a c id 2 ,5 - d ic h lo r o p h e n o x y a c e tic a c id Number o f a x i l l a r y s h o o ts 100 p .p .m . 1000 p p.m . 4 .6 0 4 .0 8 6 ,5 0 5 .9 2 6 .2 5 6 .9 2 6 .2 5 6.50 6.92 6 .0 0 7.25 5 .4 2 7 .5 8 7 .6 6 7 .7 8 9.25 6.17 5.83 7 .7 5 5 .6 6 5.83 4.50 L .S .D . 5^ = 0 .6 0 1^ = 0 . 8 0 ♦Average of three replicates of four plants each 4.50 4.50 4 .6 6 3.75 6 .0 0 4.50 5.08 5.58 6.83 6 .4 2 5.58 6.08 6.25 7.08 6 .4 2 1.50 6 .3 3 5 .6 6 6 .6 6 5.00 5.08 4 .4 2 27 was i n f l u e n c e d . T h e re w ere h ig h ly s i g n i f i c a n t v a r i a t i o n i n t h e num ber o f d a y s to f lo w e r (T a b le V I I ) . H ow ever, t h e r e a p p e a re d to b e no 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 o f th e c h e m ic a l compound an d t h e i r a b i l i t y t o e i t h e r h a s te n o r d e l a y f lo w e r i n g . O b s e rv a tio n s seem ed t o i n d i c a t e t h a t o r th o s u b s t i t u t i o n te n d e d t o c a u s e more d e la y i n f lo w e r in g a t 1000 p .p .m . th a n m eta o r p a r a s u b s t i t u t i o n s a t t h e same c o n c e n t r a t i o n . No t e r a t o l o g i c a l ch an g es in P e t u n i a h y b r id a w ere o b s e rv e d w ith a n y o f th e c h e m ic a l t r e a t m e n t s . M o rp h o lo g ic a l ch an g es w ere l i m i t e d to t h e f o r m a ti o n o f s u c c u le n t le a v e s an d more l e a f h a i r s on p l a n t s s p ra y e d w ith o r th o e l e c t r o - p o s i t i v e s u b s t i t u t e d b e n z o ic a c i d s . When P e t u n i a h y b r id a was t r e a t e d w ith 100 p .p .m . o f e i t h e r 2 , 3 » 5 - tr i c h l o r o b e n z o ic a c i d o r 2 ,5 “ d i c h l o r o p h e n o z y a c e t ic a c i d , a s l i g h t t o s e v e r e e p i n a s t y o c c u r r e d w i t h i n tw e lv e h o u r s a n d p e r s i s t e d f o r two to s i x day s a f t e r t r e a t m e n t. E xtrem e e p i n a s t y a n d d w a rfin g r e s u l t e d when p l a n t s w ere t r e a t e d w ith t h e above c h e m ic a ls a t c o n c e n t r a t i o n s o f 1000 p .p .m . 28 TABLE V II EFFECT OF SUBSTITUTED BEÎTZOIC ACIDS ON DAYS TO FLOWER IN PETUNIA HYBRIDA* Dsqts to F lo w e r 1000 p .p .m . 100 p .p .m . C h em ica l C heck 2 ,3 » 5 “ t r i i o d o b e n z o i c a c i d 2 , 3 tS - tr ib r o m o b e n z o ic a c id 2 , 3 »5“ t r i c h l o r o b e n z o i c a c i d p - io d o b e n z o ic a c i d o - io d o b e n z o ic a c i d m -io d o b e n z o ic a c i d 2 , 3 - d iio d o b e n z o ic a c i d 2 ,5 - d ii o d o b e n z o ic a c i d 3 ,5 - d ii o d o b e n z o ic a c i d 2 - i o d o - 3 - n i t r o b e n z o i c a c id p -a m in o b e n x o ic a c i d 2 -a m in o -5 - io d o b e n z o ic a c i d 2 - a m in o - 3 ,5 - d iio d o b e n z o ic a c id 2 -a m in o -3 ,5 -d ib ro m o b e n z o ic a c id 2 , 4 - d ih y d r o x y b e n z o ic a c i d 2 ,5 - d ih y d r o x y b e n z o ic a c i d 3 ,5 - d ii o d o s a lic y lic a c id 3 -b ro m o s a lic y lic a c id 3 ,5 -d ib ro m o s a lic y lic a c id 3 ,5 - d ic h lo r o s a lic y lic a c id 2 ,5 - d ic h lo r o p h e n o x y a c e tic a c i d L .S .D . * 1^ = 8 9 .3 3 8 8 .0 8 91.00 8 9 .5 8 9 3 .5 8 8 9 .4 1 8 0 .0 0 8 7 .6 6 8 9 .0 8 8 8 .3 3 9 1 .4 1 8 8 .5 8 8 9 .3 3 91.66 9 0 .7 5 9 1 .1 6 8 7 .2 5 92.91 85.83 8 2 .7 5 8 7 .0 0 79.75 1 .1 5 1 .5 3 ♦A verage o f th r e e r e p l i c a t e s o f f o u r p l a n t s eac h 89.25 88.33 8 9 .5 8 92.66 92.83 89.75 7 8 .5 8 89.25 8 9 .1 6 89.00 91.50 86.83 8 4 .4 1 91.75 8 4 .0 8 92.25 86.08 90.58 8 0 .4 1 83.58 85.66 8 4 .4 1 29 EFFECT OF DIFFERENT ACIDITY LEVELS OF SUBSTITUTED BENZOIC ACIDS WHEN SPRAYED ON PETUNIA HYBRIDA The s y n t h e s i s o f d r y m a tte r i n a e r i a l p o r t i o n s o f P e tu n ia h y b r i d a was h i g h l y s i g n i f i c a n t l y a f f e c t e d by t h e c h e m ic a l t r e a t m e n ts (T a b le V I I I ) , T h e re w ere no s i g n i f i c a n t a f f e c t s o f pH n o r p H -c h em ica l in te ra c tio n s . W ith th e e x c e p tio n o f 2 , 3 ,- d ii o d o b e n z o ic and 3 , 5 - d i i o d o s a l i ­ c y l i c a c i d t h e r e was no s i g n i f i c a n t d i f f e r e n c e b etw een th e c h e m ic a ls i n t h e i r e f f e c t on to p g ro w th . T h e re was a s i g n i f i c a n t d i f f e r e n c e b etw een t h e c h e m ic a l t r e a t e d p l a n t s and c o n t r o l s . A ll c h e m ic a l tr e a tm e n ts r e s u l t e d i n r e d u c e d s y n t h e s i s o f d ry m a tte r a s com pared t o c o n t r o l p l a n t s . T h e re w ere h i ^ l y s i g n i f i c a n t c o r r e l a t i o n s b e tw e e n d ry w e i ^ t i n gram s o f P e t u n i a h y b r id a r o o t s an d c h e m ic a l t r e a t m e n ts b u t no c o r r e l a ­ t i o n s b e tw e e n d ry r o o t w e i ^ t an d pH o r ch em ica l-p H i n t e r a c t i o n s (T a b le IX ), No s i g n i f i c a n t d i f f e r e n c e s w ere n o te d b etw een c h e m ic a ls i n t h e i r a c t i o n on r o o t g ro w th a n d a l l c h e m ic a ls re d u c e d r o o t g ro w th a s com pared to c o n t r o l p la n ts . H ig h ly s i g n i f i c a n t c o r r e l a t i o n s w ere n o te d b etw een th e d ry w e ig h t o f t o p / r o o t r a t i o o f P e tu n ia h y b r id a sind c h e m ic a l t r e a t m e n t s , pH and pHc h e m ic a l i n t e r a c t i o n s (T a b le X ), A l l c h e m ic a ls s u b s t i t u t e d i n th e p a r a p o s i t i o n a f f e c t e d p l a n t s more th a n p l a n t s t r e a t e d w ith n o n -p a ra s u b s t i t u t e d c h e m ic a ls . A l l c h e m ic a ls a p p l i e d t o p l a n t s in s o l u t i o n s a t pH 6 a f f e c t e d s u b s e q u e n t g ro w th and p ro d u c e d th e lo w e s t v a lu e f o r t o p / r o o t r a t i o ( F ig u r e 1) The h i g h e s t r a t i o was o b ta in e d a t pH 4 w ith a s l i g h t l y s m a l le r r a t i o a t pH 8, H i ^ l y s i g n i f i c a n t c o r r e l a t i o n s w ere o b s e rv e d b etw een c h e m ic a l t r e a t m e n t s and f l o r a l i n i t i a t i o n a n d s i g n i f i c a n t c o r r e l a t i o n s b e tw e e n pH an d Figure 1 E f f e c t o f pH o f s u b s t i t u t e d B e n z o ic A c id s on T op/R oot R a tio Dry W eight o f P e t u n i a H y b rid a Jo.9* t s >. Q (O 99.M è o •H Ÿé.oê •S O u eu f-R e p . o Eh gt.où ■5ÿ,M 8 pH 30 TABLE V I I ï EFFECT OF SUBSTITUTE BENZOIC ACIDS AT 100 P .P .M , CONCENTRATION ON DRY WEIGHT OF PETUNIA HYBRIDA TOPS* C h em ica l Grains D ry W eight Check 2 , 3 , 5 " t r i i o d o 'b e n 2 o ic a c i d 2 , 3 » 5 -tv i'b ro in o 'b en zo ic a c i d 2 . 3 . 5 - t r i c h l o r o b e n z o l c a c id o - io d o b e n z o ic a c i d m -io d o b e n z o ic a c i d p - io d o b e n z o ic a c i d 2 , 3 ,- d ii o d o b e n z o ic a c i d 2 .5 - d i i o d o b e n z o i c a c i d 3 .5 - d ii o d o b e n z o ic a c i d 2 -io d o -3 -n itro b e n z o ic a c id 2 - a m in o -5 - io d o b e n z o ic a c i d 2 -a m in o -3 ,5 - < iiio d o b e n z o ic a c i d 3 .5 - d iio d o s a lic y lic a c id L .S .D . 5^ 1^ = = 19.01 12.53 13.60 1 4 .0 7 1 5 .3 7 1 6 .4 8 1 5 .7 8 1 9 .5 0 16.23 16.03 13.99 16.26 16.16 17.83 3.94 5.20 ♦Average of three replicates of twenty-eight plants each 31 TABLE IX EFFECT OF SUBSTITUTED BENZOIC ACIDS AT 100 P .P .M . CONCENTRATION ON DRY WEIGHT OF PETUNIA HYBRIDA ROOTS* C h e m ic a l Grams D ry W eight C heck 2 , 3 »5“ tr i io d o 'b e n z o ic a c i d 2 , 3 ,5 " tr ih r o m o h e n z o ic a c id 2 . 3 . 5 - t r i c h l o r o ‘b e n z o ic a c i d o - io d o b e n z o ic a c i d m -io d o b e n z o ic a c i d p - io d o b e n z o ic a c id 2 , 3 - d ii o d o b e n z o ic a c id 2 .5 - d ii o d o b e n z o ic a c id 3 .5 - d ii o d o b e n z o ic a c i d 2 -io d o -3 -n itro b e n z o ic a c id 2 - a m in o -5 - io d o b e n z o i c a c i d 2 - a m in o - 3 ,5 - d iio d o b e n z o ic a c i d 3 . 5 - d i i o d o s a l i c y l i c a c id L .S .D . 5^ = 2 .8 4 = 3.74 H 8 .3 2 2.80 3 .3 8 2 .61 3.08 3.26 2 .5 3 3 .0 7 3 .0 5 2.68 3 .0 1 3 .3 1 2.86 2 .9 3 ♦Average of three replicates of twenty-ei^t plants each 32 TABLE X EFFECT OF SUBSTITUTED BENZOIC ACIDS AT 100 P .P .M . CONCENTRATION ON TOP/ROOT DRY WEIGHT RATIO OF PETUNIA HYBRIDA* R a tio Grams D ry W eight T op/R oot C h em ical Check 2 , 3 » 5 - t r iio d o b e n z o ic a c i d 2 . 3 . 5 - tr ib r o m o b e n z o ic a c i d 2 , 3 *5 - t r i c h l o r o b e n z o i c a c i d o - io d o b e n z o ic a c i d m -io d o b e n z o ic a c i d p - io d o b e n z o ic a c i d 2 , 3 - d io d o b e n z o ic a c i d 2 .5 - d ii o d o b e n z o ic a c id 3 .5 - d ii o d o b e n z o ic a c i d 2 -io d o -3 -n itro b e n z o ic a c id 2 -a m in o -5 - io d o b e n z o ic a c i d 2 - a m in o - 3 ,5 - d iio d o b e n z o ic a c id 3 . 5 - d i i o d o s a l i c y l i c a c id L .S .D . = vjL - 33.86 3 8 -1 6 3 4 .2 6 4 5 .3 6 4 1 ,5 3 4 0 ,5 1 52.07 4 8 .8 5 4 2 .8 4 4 9 .4 3 3 9 .5 5 43*99 4 4 ,6 8 4 5 .0 0 0.59 0.78 ♦A verage o f t h r e e r e p l i c a t e s o f t w e n ty - e ig h t p l a n t s eac h 33 flo ra l in itia tio n (T a b le X I ) . T h e re w ere no c o r r e l a t i o n s b e tw ee n pfl—c h e m ic a l i n t e r a c t i o n s and f l o r a l i n i t i a t i o n . Any r e l a t i o n s h i p s b etw een c h e m ic a l s t r u c t u r e a n d a c t i v i t y ( a s ju d g e d by th e number o f f l o r a l i n i t i a l s ) w ere n o t e v id e n t. P l a n t s s p ra y e d w ith c h e m ic a ls i n s o l u t i o n a t pH? r e s u l t e d i n t h e lo w e s t i n c r e a s e o f f l o r a l i n i t i a l s . T re a tm e n t w ith s o l u t i o n s a t pH 9 r e s u l t e d i n t h e g r e a t e s t p r o d u c tio n o f f l o r a l i n i t i a l s i n P e t u n i a h y b r i d a . P l a n t s t r e a t e d w ith c h e m ic a ls a t pH 4 o r 5 p ro d u c e d an i n t e r m e d i a t e i n c r e a s e o f f lo r a l, i n i t i a l s in P e tu n ia h y b r id a .P l a n t s t r e a t e d w ith c h e m ic a ls pH 4 o r 5 p ro d u c e d an i n te r m e d ia te in c r e a s e o f f l o r a l i n i t i a l s ( F ig u r e 2 ) , The num ber o f a x i l l a r y buds on P e tu n ia h y b r id a w ere h i g h l y s i g ­ n if i c a n tly c o rre la te d at w ith t h e v a r io u s c h e m ic a l t r e a tm e n t s an d pH b u t no s i g n i f i c a n t d i f f e r e n c e s w ith p H -c h em ica l i n t e r a c t i o n s w ere r e c o r d e d (T a b le X II). T h e re a p p e a re d to b e no c o r r e l a t i o n b e tw ee n c h e m ic a l s t r u c t u r e an d a b i l i t y to e i t h e r i n h i b i t o r e n h an ce th e a x i l l a r y s h o o t p r o d u c tio n o f Pe­ tu n ia h y b rid a . The l e a s t num ber o f a x i l l a r y s h o o ts wae o b ta in e d on p l a n t s s p r a y e d w ith s o l u t i o n s a t pH 6 ( F ig u r e 3 )» and t h e g r e a t e s t number o f a x i l l a r y s h o o ts was n o te d on p l a n t s t r e a t e d w ith s o l u t i o n s a t pH 9* There were highly significant correlations between days to flower and chemical treatments in Petunia hybrida. (Table XIII), well as sig­ nificant correlations between days to flower and pH (Table XIII). No correlations between days to flower and pH-chemical interactions were ob­ served. In general, compounds with a para substitution (either alone or in conjunction with other position substitutions) were the least effective in hastening flowering. Ortho-meta substitutions had the greatest affect in accelerating flowering. As far as acidity levels were concerned, greatest 1 0 2 .OQ 1 0 0 .0 0 R ep . I 9 8 . Op 9 4 .0 0 rH as *H -P d H kitf o I— I k 44 O 9 2 .0 0 9 0 .0 0 u «> .q 88.00 F ig tire 2 E f f e c t o f pH o f S u b s t i t u t e d B e n z o ic A cid s on Number o f F lo ra l i n i t i a l s of P e tu n i a H y b rid a 86.00 8 4 .0 0 - 6 2 .0 0 o Rep. Ill Rep. II Rep. I Effect of pH of Substituted Benzoic Acids on Number of Axillary Shoots of Petunia hybrida z ÏÏ 34 TABLE XI EFFECT OP SUBSTITUTED BENZOIC ACIDS AT 100 P .P .M . CONCENTRATION ON THE NUMBER OF FLORAL INITIALS OF PETUNIA HYBRIDA* C h em ica l Number o f F l o r a l I n i t i a l s C heck 2 , 3 t 5 *“t r i i o d o b e n 2 o ic a c i d 2 , 3 »5“ ‘t ri'b ro in o b e n z o ic a c id 2 ,3 »5“ t r i c h l o r o 'b e n z o i c a c i d o - io d o b e n z o ic a c i d m -io d o b e n z o ic a c i d p - io d o b e n z o ic a c i d 2 , 3 - d iio d o b e n z o ic a c i d 2 .5 - d ii o d o b e n z o ic a c i d 3 .5 - d ii o d o b e n z o ic a c i d 2 -io d o - 3 -n itro b e n z o ic a c id 2 -a m in o -5 - io d o b e n z o ic a c i d 2 - a m ln o - 3 ,5 - d iio d o b e n z o ic a c i d 3 . 5 - d i i o d o s a l i c y l i c a c id L .S .D . - 156 = 3 1 .9 2 4 0 .6 5 43.83 49.50 4 0 .3 3 51.00 52.25 52.83 43.33 43.25 44.83 49.50 47.92 47.17 0.95 1 .2 5 •Average of three replicates of twenty-eight plants each 35 TABLE X II EFFECT OF SUBSTITUTED BENZOIC ACIDS AT 100 P .P .M . CONCENTRATION ON THE NUMBER OF AXILLARY SHOOTS OF PETUNIA HYBRIDA* Ohemi c a l Number o f A x i l l a r y S h o o ts C heck 2 .3 .5 - t r i i o d o 'b e n z o i c a c i d 2 , 3 »5 “ irib ro jn o b e n 2 o ic a c i d 2 ,3 ,5“ i r i c h l o r o b e n z o i c a c i d o - io d o b e n z o ic a c i d m -io d o b e n z o ic a c i d p - io d o b e n z o ic a c i d 2 ,3 “ d iio d o b e n z o ic a c i d 2 .5 - d i i o d o b e n z o i c a c i d 3 .5 - d ii o d o b e n z o ic a c id 2 -io d o - 3 -a itro b e n z o ic a c id 2 - a m in o -5 - io d o b e n z o ic a c i d 2 - a m in o - 3 ,5 - d iio d o b e n z o ic a c i d 3 .5 - d iio d o s a lic y lic a c id L .S .D . 55^ = « 3 1 .7 7 2 3 .9 8 2 6 .1 5 27.50 2 8 .6 7 31.58 29.08 36.33 27.75 30.33 2 4 . 50 31.50 29.92 3 2 .4 2 0 .5 9 0 .7 8 *Average of three replicates of twenty-eight plants each 36 TABLE XIII EFFECT OF SUBSTITUTED BENZOIC ACIDS AT 100 P .P .M . CONCENTRATION ON DAYS TO FLOWER OF PETUNIA HYBRIDA* C h e m ic a l Days C heck 2 , 3 i5 “ t i ‘l i o d o ‘b e n z o ic a c i d 2 . 3 .5 -* tri'b ro m o b en z o ic a c i d 2 ,3 fS -tric h lo ro b e n a o ic a c id o - io d o h e n z o ic a c i d m -io d o b e n z o ic a c i d p - io d o b e n z o ic a c id 2 ,3 - d ii o d o b e n z o ic a c i d 2 .5 - d ii o d o b e n z o ic a c i d 3 .5 - d i i o d o b e n z o i c a c i d 2 -io d o -3 -n itro b e n z o ic a c id 2 - a m in o -5 - lo d o b e n z o ic a c i d 2 -o in in o -3 t 3 “ d iio d o b e n z o ic a c i d 3 ,5 - d iio d o s a lic y lic a c id L .S .D . 5^ 1^ « = to F lo w e r 122.30 8 2 .4 2 8 6 .7 0 83*50 89.51 8 1 .4 5 93*94 83*29 8 9 .0 3 93*00 8 7 .1 0 88 . 8 5 9 2 .2 6 89.62 2.92 3*84 *Average of three replicates of twenty-eight plants each 37 a c c e l e r a t i o n o f f lo w e r in g o c c u r r e d when p l a n t s w ere t r e a t e d w ith s o l u t i o n s on pH 7 an d l e a s t a c c e l e r a t i o n w ith s o l u t i o n s o f pH 4 ( F ig u r e 4 ) . A c id ity l e v e l s a p p a r e n t l y d id n o t a f f e c t th e c h e m ic a l i n in d u c in g m o r p h o lo g ic a l ch an g es i n P e tu n i a h y b r i d a . A ll m o rp h o lo g ic a l ch an g es d i f f e r ­ in g fro m c o n t r o l p l a n t s w ere p r e v i o u s l y n o te d and r e c o r d e d i n th e s e c t i o n u n d e r c o n c e n tra tio n a f f e c t s . T hese ch an g es w ere i n c r e a s e d l e a f s u c c u le n c e an d i n c r e a s e d l e a f h a i r s on a l l p l a n t s t r e a t e d w ith e l e c t r o - p o s i t i v e o r th o s u b s t i t u t e d b e n z o ic a c i d s . T h e re w a s, in a d d i t i o n , s l i g h t to s e v e r e e p i n a s t y a n d s l i g h t to s e v e r e d w a rfin g o f p l a n t s s p ra y e d w ith 2 , 3 , 5 - t r i c h l o r o b e n z o i c a c i d an d 2 , 3 ,5 - b r iio d o b e n z o ic a c i d . F ig u r e 4 Effect of pH of Substituted. Benzoic Acids on Days to Flower of Petunia Hybrida U i o +» 09 >» S Rep. Ill Rep. II / & 38 EFFECT OF DIFFERENT CONCENTRATIONS OF SUBSTITUTED BENZOIC ACIDS ON ZINNIA BLEGANS D ry w e ig h ts i n gram s o f Z in n ia e le g a n s to p s was h i ^ l y s i g n i f i ­ c a n t l y c o r r e l a t e d w ith c h e m ic a l t r e a t m e n t s , c o n c e n t r a t io n s and c h e ra ic a lc o n c e n t r a t i o n i n t e r a c t i o n s (T a b le X I 7 ) . r e l a t i n g c h e m ic a l s t r u c t u r e to a c t i v i t y . T h e re w ere no a p p a r e n t t r e n d s In g e n e r a l , th e p a r a and m eta s u b s t i t u t e d compounds showed g r e a t e r a c t i v i t y th a n o r th o and c o m b in a tio n s o f 2 ,5 s u b s t i t u t i o n s a s ju d g e d by in c r e a s e in d ry m a tte r o v e r c o n t r o l p l a n t s . No tr e a tm e n t r e s u l t e d i n an y d i f f e r e n c e o f number o f nodes to flo w e r. A lm ost u n if o r m ly p l a n t s f lo w e re d a t th e f i f t h n o d e . O c c a s io n a lly a p l a n t w ould flo w e r a t th e s i x t h node an d r a r e l y a t t h e f o u r t h node. The f i r s t p l a n t flo w e re d i n f o r t y - s e v e n day s and th e l a s t p l a n t f lo w e r e d i n f i f t y - e i g h t d a y s . T h ere w ere no s i g n i f i c a n t d i f f e r e n c e s b e tw ee n d a y s to f lo w e r and c h e m ic a l t r e a t m e n t s , c o n c e n t r a t io n s o r c h e m ic a l-c o n c e n ­ tr a tio n in te ra c tio n s . P ro fo u n d m o rp h o lo g ic a l and t e r a t o l o g i c a l ch an g es w ere in d u c e d i n Z i n n ia e le g a n s b y s e v e r a l o f th e tr e a tm e n ts w ith s u b s t i t u t e d b e n z o ic a c i d s . W ith in tw e n ty - f o u r h o u rs f o lio v /in g s p r a y in g , 2 , 3 , 5 - t r i c h l o r o b e n z o i c a c i d a t 1000 p .p .m . in d u c e d e p i n a s t y . c a s e s to u c h e d th e s o i l . The g ro w in g p o i n t tu r n e d down and i n s e v e r a l At th e end o f 120 h o u rs a f t e r s p r a y in g th e p l a n t s h a d s t r a i g h t e n e d up b u t th e le a v e s s t i l l showed e p i n a s t y . g ro w th o f t h e s e p l a n t s i s shown in F ig u r e 5 . The s u b s e q u e n t The f i r s t t r u e le a v e s w ere n o rm a l and th e r e m a in in g le a v e s a p p e a re d i n a c l u s t e r due to much s h o r te n e d in te rn o d e s . L eav es w ere ab n o rm al i n s i z e ( s m a l l e r , s t r a p - l i k e o r ro u n d . F ig u r e 8 ) and h a d much v a s c u l a r t i s s u e p r o l i f e r a t i o n . P l a n t s w ere a p a le to 39 TABLE XIV EFFECT OF 100 AIJD 1000 P .P .M . CONCENTRATIONS OF SUBSTITUTED BENZOIC ACIDS ON DRY WEIGHT OF ZINNIA ELEGANS TOPS* Grams D ry W eight 1000 p 100 p .p .m . Chemi c a l C heck 2 , 3 »5 “ t r i i o d o b e n z o i c a c i d 2 , 3 , 5 - t r i T 3rom o'benzoic a c i d 2 , 3 , 5 - t r i c h l o r o 'b e n z o i c a c id o - io d o b e n z o ic a c i d p - io d o b e n z o ic a c i d 2 ,3 - d li o d o b e n z o ic a c i d 2,5*“i i t o d o b e n z o i c a c i d 3 , 5 -(iiio d .o b e n z o ic a c id 2 - i o d o - 3 - n i tr o b e n z o 1c a c i d p -a m in o b e n z o ic a c i d 2 -a m in o -5 “ io d o b e n z o ic a c id 2—a m in o -3 io d o b e n zo i c a c i d 2 -a m in o -3 ,5 ” d ib ro m o b e n z o ic a c id 2 ,5 " d ih y d r o x y b e n a o ic a c id 3 , 5 ” < i iio â .o s a li c y lic a c id L.S.D 1^ = = 27.2 2 4 .9 3 7 .2 2 7 .5 3 4 .9 3 4 .2 3 6 .0 2 9 .8 2 8 .1 4 1 .7 2 9 .8 3 0 .9 45.8 29.1 27.3 33.2 0 .9 0 1 .2 0 ♦ A verage o f t h r e e r e p l i c a t e s o f f o u r p l a n t s each 23.6 35.8 33.3 8.3 2 6 .1 45.0 33.1 34.2 38.9 2 4 .7 4 1 ,5 2 8 .9 25.2 36.2 28.3 67.5 Figure 5 Z i n n i a e le g a n s s p r a y e d w ith s o l u t i o n s o f 1000 p .p .m . o f 2 ,3 * 5 tric h lo ro b e n z o ic a c id . N o te s h o r te n e d i n t e r n o d e s l e a d i n g to a t e r m i n a l l e a f c l u s t e r ; p l a n t on l e f t i s c o n t r o l . 40 "bright yellow color and soon died. A 100 p.p.m. spray of 2,3,^-Trichloro- benzoio acid induced similar but less severe symptoms than the 1000 p.p.m. spray. Orov/th of these plants is shovm in Figure 6. were normal. The first nodal leaves The basal portions of the second nodal leaves were much re­ duced or strap-like (Figure 8), Proliferation of vascular tissue occurred and par enchymous tissue was almost lacking in the strap-like leaves. Third nodal leaves were either strap-like or else lacking in distal parenchymous tissue, Vascular tissue was much proliferated and confined to the middle of the leaf. The fourth node leaves were fused into a cone-shape and varied from a tight tube to a slight cup (Figure 4 ) . Internodal distances were much shortened coiiqpared to control plants. A spray 1000 p.p.m, spray of 2,3,5-Triiodobenzoic acid induced slight to medium epinasty. Seventy-two hours after spraying all plants appeared normal. Leaves on plants treated with 2,3,5-tribromobenzoic acid at 1000 p.p.m, showed naich swollen parenchymous tissue with sunken veins on all leaves. Leaves at the lower nodes were more severely affected than those leaves at the upper nodes. Profound changes, as compared with check plants, were induced by 2-Iodo-3-nitrobebzoic acid (Figure 7 ) . Plants treated with 100 p.p.m. of the chemical caused the second pair of leaves to be strap-like with some proliferation of the vascular tissue (Figure 8). The usual three midribs were coalesced into one and the third nodal leaves were lobed at the base. The three midribs were loosely interlaced. One side of the basal portion of the leaves was Joined at node four and in addition, the three midribs Figure 6 Z i n n i a e le g a n a s p r a y e d w ith 100 p .p .m . 2 , 3 ,3 - t r ic h l o r @ b e n z o ic a c id . N o te t i g h t to lo o s e t e r m i n a l c o n e , p r o l i f e r a t e d v a s c u l a r t i s s u e (lig h t c e n t e r p o r t i o n o f l e a f ) , s t r a p - l i k e le a v e s an d le a v e s d e f i c i e n t i n p a re n ­ chym ous t i s s u e ; p l a n t on l e f t i s c o n tro l. Figure ? Z i n n i a e le g a n s s p r a y e d w ith ( l e f t t e r i g h t ) w a t e r , 2 -ie d o -3 * ’ n i t r e ’o e n z e ic a c i d (100 p . p . m . ) a n d r e m a in in g p l a n t s w i th 2 - i e d e - 3 n i t r o b e n z e i c a c i d (1 0 0 0 p . p . m . ) , lik e On p l a n t B (1 0 0 p . p . m . ) n o te s t r a p ­ l e a v e s a t s e c o n d n o d e , lo o s e c e a le a c e n s e o f t h r e e m id v e in s a t t h i r d n ode a n d c o m p le te c o a l e s c e n s e o f t h r e e m id v e in s a t f o u r t h n o d e ; on p l a n t s C a n d D n o te s t r a p - l i k e s e c o n d n o d a l l e a v e s w ith v a s c u l a r t i s s u e p r o l i f e r a t i o n , s h o r t e n e d t h i r d —f o u r t h i n t e r n o d e , c o a le s c e n s e a n d p r o ­ l i f e r a t i o n o f v a s c u la r ti s s u e a t t h i r d n o d e, l o s t t i p a t f o u r th node. 1 Figure 8 Z i n n i a e le g a n s le a v e s s p r a y e d w ith s u b s t i t u t e d b e n z o ic a c i d s . Row 1 i s c o n t r o l l e a f ; row 2 ( l e f t to r i g h t ) l e a v e s A, B a n d C h a v e l o o s e t o t i g h t cone o f t e r m i n a l g ro w th o f 100 p .p .m . 2 , 3 . 5 - t r l c h l o r o h e n z o ic a c i d s p r a y e d p l a n t s ; l e a f S i s s t r a p - l i k e w ith p r o l i f e r a t e d v a s c u l a r t i s s u e fro m 1000 p .p .m . 2 , 3 • 5 - t r i c h l o r o h e n z o i c a c i d s p r a y e d p la n ts ; l e a f 5 show s p r o l i f e r a t i o n a n d c o a l e s c e n s e o f v a s c u l a r t i s s u e , l a c k o f d i s t a l p aren ch y m o u s t i s s u e i n 1000 p .p .m . 2 - i o d o - 3 - n l tr o b e n z o I c a c i d s p r a y e d p l a n t s ; Row 3 l e a f A show s lo o s e c o a le s c e n s e o f t h r e e m ain v e i n s i n 100 p .p .m , 2 -io d o -3 * ’2 ii" tro b e n z o ic a c i d s p r a y e d p l a n t s ; le a f B show s f u s i o n o f o p p o s i t e l e a v e s o f 100 p .p .m . 2 - io d o - 3 - * ^ itr o b e n z o ic a c i d sp ra y e d p la n ts ; l e a f 0 show s v a s c u l a r p r o l i f e r a t i o n a n d c o a l e s c e n s e i n 1000 p .p .m . 2 - i o d o - 3 ” ^ i t r o b e n z o i c a c i d s p r a y e d p l a n t s . 41 w e re c o a le s c e d * P l a n t s t r e a t e d w ith 1000 p .p .m , o f th e c h e m ic a l w ere a l s o a f f e c t e d a n d th e s e c o n d p a i r o f l e a v e s w ere s i m i l a r to th o s e r e c e i v i n g 100 p .p .m . a lth o u g h t h e a b n o r m a litie s w ere somewhat more p ro n o u n c e d ( F ig u r e s 7 a n d 8)* T h ir d n o d a l le a v e s h ad much v a s c u l a r t i s s u e p r o l i f e r a t i o n w h ich c o a le s c e d to form m id r ib s . I n t e r n o d a l d i s t a n c e s b etw een th e t h i r d and f o u r t h , an d f o u r t h an d f i f t h no d es w ere much s h o r te n e d . t i o n o f t h e f o u r t h p a i r o f le a v e s was common. A much re d u c e d d i s t a l p o r­ The f i f t h l e a f - p a i r was n o rm a l, n o rm a l f lo w e r in g o c c u r r e d a t b o th c o n c e n t r a t i o n s . To f u r t h e r t e s t t h e e f f e c t o f c o n c e n tr a tio n o f o th e r s u b s t i t u t e d b e n z o ic a c i d s more s e e d o f Z in n ia e la g a n s was sown on December t w e n ty - s e v e n th , 1 955. C h em ica ls u s e d i n t h i s t e s t w ere m -io d o b e n z o ic a c i d , o - c h lo r o b e n z o i c a c i d , m -c h lo ro b e n z o ic a c i d , o -b ro m o b en z o ic a c i d , m -brom obenzoic a c i d , m - n itr o b e n z o ic a c i d , 2 ,5 - d ic h lo r o b e n z o i c a c i d , 3 ^3 - d ic lilo r o b e n z o ic a c i d , 3 ,5 " " d in itr o b e n z o ic a c i d , 3 ~ ° ^ l o r o s a l i c y l i c a c i d , 5 - c b . l o r o s a l i c y l i c a c i d , 3 - b r o r a o s a l i c y l i c a c i d , 5 - b r o m o s a li c y lic a c i d , 3 , 5 - d i i o d o s a l i c y l i c a c i d , 3»5~ d i c h l o r o s a l i c y l i c a c i d , 3 ,5 - d i b r o m o s a l l c y l i c a c i d and 3 , 5 - d i n i t r o s a l i c y l i c a c id . T h e re w ere no c o r r e l a t i o n s b etw een d ay s to f lo w e r and c h e m ic a l t r e a t m e n t s , c o n c e n t r a t i o n s , o r c h e m ic a l- c o n c e n t r â t io n i n t e r a c t i o n s . The f i r s t p l a n t f lo w e r e d i n tw e n ty - n in e days and th e l a s t p l a n t flo w e r e d i n f o r ty - n in e d ay s. S t a t i s t i c a l a n a l y s i s r e v e a le d no c o r r e l a t i o n b e tw ee n d r y w eig h t o f a e r i a l p o r t i o n s and c h e m ic a l t r e a t m e n t s , c o n c e n tr a tio n s o r c h e m ic a lc o n c e n tra tio n in te r a c tio n s . R o n - tr e a t e d p l a n t s w ere u n if o r m ly lo w e r i n 42 w e ig h t th a n t e s t p l a n t s b u t th e d i f f e r e n c e was n o t s i g n i f i c a n t a t th e f i v e p e rc e n t le v e l. Nodes to f i r s t f lo w e r i n b o th n o n t r e a t e d p l a n t s an d t r e a t e d p l a n t s w e re u s u a l l y f o u r an d i n a few c a s e s t h e r e w ere f i v e nodes to f i r s t flo w e r. E ach p l a n t u n d e r tr e a tm e n t h a d one o r two a x i l l a r y s h o o ts p e r p l a n t w h ile no c o n t r o l p l a n t p ro d u c e d any a x i l l a r y s h o o ts . As i n th e p r e v io u s tr e a tm e n t o f Z in n ia e le g a n s w ith s u b s t i t u t e d b e n z o ic a c i d s , t h i s tr e a tm e n t a l s o p ro d u c e d p ro fo u n d m o rp h o lo g ic a l an d t e r a t o l o g i c a l ch an g e s w i t h i n th e p l a n t , A c o n c e n t r a t i o n o f 1000 p .p .m . o f 2 ,5 “ d i c h l o r o b e n z o i c a c i d p ro d u c e d a d v e n t i t i o u s buds o r i n t e r n o d a l d ich o to m o u s b r a n c h in g ( F ig u r e 9 ) i on t h r e e o u t o f tw e lv e p l a n t s . T h is i s b e l i e v e d to be t h e f i r s t tim e a g ro w th r e g u l a t o r h a s b ro u g h t h a s b ro u g h t a b o u t t h i s r e s p o n s e . F u rth e r e f f e c ts o f 2 F ig u r e s 10 and 11. c h l o r o b e n z o i c a c i d a t 1000 p .p .m . a r e shown on L eaves a t th e sec o n d node a r e e i t h e r n o n -ex p an d ed a t th e b a s e o r e l s e s t r a p - l i k e w ith p r o l i f e r a t i o n o f v a s c u l a r t i s s u e . At th e seco n d n o d e ,( F ig u r e 1 0 ) , e i t h e r a s t r a p - l i k e l e a f a r o s e d i r e c t l y fro m th e node o r a c l u s t e r o f s t r a p - l i k e le a v e s on a stem a r o s e from th e n o d e. The te r m i n a l g ro w in g p o i n t e i t h e r p ro d u c e d a y e llo w a n t h e r - l i k e f r i n g e ( p l a n t A) o r a m ass o f m alform ed (m o s tly b ilo b e d ) le a v e s w ith p r o l i f e r a t e d v a s c u l a r t i s s u e ( l i g h t b a n d s on l e a f ) . F ig u r e 1 1 . Two p l a n t s a t a l a t e r s t a g e o f g ro w th a r e shown i n P l a n t A h a s th e y e llo w a n t h e r - l i k e f r i n g e on to p a n d i n a d d i t i o n , a t t h e t h i r d n o d e , a n a x i l l a r y s h o o t h a s b ra n c h e d a f t e r p ro d u c in g one l e a f . P l a n t B h a s f u s e d le a v e s a t t h e sec o n d n o d e , a m is s in g l e a f a t th e t h i r d n o d e , two a x i l l a r y s h o o ts on t h e same s i d e o f th e node a t th e t h i r d node and a m is s in g l e a f a t th e f i f t h n o d e. The e f f e c t o f 2 ,5 - d i c h l o r o b e n z o ic a c id a t 100 p .p .m . i s shown In F ig u re 9 Zinnia, e l e ^ a n s t r e a t e d sh ow in g a d v e n t i t i o u s vâth 2 , 5 - d i c h lo r o b e n z o ic a c i d a t 100 0 p . p . m . bud; bud on l e f t i s u s u a l t e r m i n a l bud. Figure 10 Z i n n i a e le g a n s t r e a t e d w i t h 2 ,5 -= d ic h lo ro 'b e n z o ic a c i d a t 1000 p .p .m , R o te s t r a p - l i k e l e a v e s w ith p r o l i f e r a t e d v a s c u l a r t i s s u e a t s e c o n d node on p l a n t s A a n d B w i t h b a s a l u n e x p a n d e d le a v e s a t s e c o n d n o d e o f p l a n t C. P l a n t A h a s much s h o r te n e d a x i l l a r y s h o o t a t s e c o n d n ode an d p l a n t s B an d C h a v e u p r i g h t g ro w in g s t r a p - l i k e l e a f a t s e c o n d n o d e . On p l a n t s B a n d C n o te t e r m i n a l l e a f c l u s t e r o f b i l o b e d , h e a v i l y v a s c u l a r l e a v e s . Figure 11 Z i n n i a e le g a n s s p r a y e d w i t h 1000 p .p .m . 2 , 5 ~ d ic h lo r o b e n z o ic a c i d p i c tu r e d a t th e flo w e rin g s ta g e . On p l a n t A n o t e b a s a l u n e x p e n d e d le a v e s a t s e c o n d n o d e , s t r a p - l i k e le a v e s a t t h i r d n o d e a n d f u s e d le a v e s a t f o u r th node. A x i l l a r y s h o o t a t t h i r d node h a s much r e d u c e d i n t e r n o d e s . On p l a n t B n o t e f u s e d s e c o n d a n d t h i r d n o d e l e a v e s Eind m is s in g l e a f a t fifth node. N o te much r e d u c e d a x i l l a r y s h o o t a t t h i r d n o d e . c 43 f i g u r e 1 2, F i r s t n o d a l le a v e s a r e n o rm a l an d le a v e s a t t h e se c o n d node a r e n o n -e x p a n d e d a t t h e b a s e an d h av e p r o l i f e r a t e d v a s c u l a r t i s s u e . D is ta l p aren ch y m o u s t i s s u e i s la c k i n g on le a v e s a t t h e t h i r d n o d e , v a s c u l a r t i s s u e i s g r e a t l y p r o l i f e r a t e d and fo rm s a more o r l e s s m a ssiv e m id r ib . On p l a n t D t h e i n t e r n o d a l d i s t a n c e b e tw ee n th e f o u r t h an d f i f t h node i s l a c k i n g an d t h e f o u r le a v e s a r e f u s e d a s a u n i t . The e f f e c t s o f 5 - c h l o r o s a l i c y l i c a c i d a t 1000 p .p .m . a r e shown in F ig u r e 13- I n a d d i t i o n to ab n o rm al le a v e s ( s t r a p - l i k e , p r o l i f e r a t i o n o f v a s c u l a r t i s s u e , f u s i n g ) p l a n t A h a s t h r e e a d j o i n i n g b lo sso m h e a d s w h ile p l a n t B h a s two a d j o i n i n g b lo sso m h e a d s . M o rp h o lo g ic a l an d t e r a t o l o g i c a l ch an g es in d u c e d by compounds in a d d i t i o n t o t h e s e d e s c r i b e d above a r e shown i n T a b le XV, A p a ra p o s itio n s u b s t i t u t i o n a p p e a rs to c o n fe r more f o r m a tiv e a c t i v i t y on a compound th a n an y o th e r s u b s ti t u t i o n . Figure 12 ^ s p r a y e d w ith 100 p .p .m . 2 , 5 - d i c h l o r o b e n z o i c a c i d . P l a n t o n l e f t i s a c o n t r o l ; p l a n t s B an d C show b a s a l u n e x p a n d e d s e c o n d n o d e l e a v e s , t h i r d node le a v e s h a v e t i g h t t o l o o s e l y c o a le s c e d p r o l i f e r ­ a tio n o f v a s c u la r tis s u e . P l a n t on r i g h t h a s f o u r t h an d f i f t h c o m p le te ly l a c k i n g w i t h t h e f o u r l e a v e s f u s e d . in t e r n o d e Figure I3 Z i n n i a e le g a n s s p r a y e d w ith 1000 p .p .m . o f 5 - c h l o r o s a l i c y l i c a c i d . P l a n t A h a s t h r e e a d j o i n i n g bloom s a n d p l a n t B h a s two a d j o i n i n g b lo o m s. ? 44 O CO O f H C v l O O O O O O O O O O C V l c ^ O f H O O O r H O C ^ O O i H C v J O O OM CO N to O Ul M OO Ï3Î M E-i EH CO 0) % *4 Pi W o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o «H fH i- t rH iH M "d •H Ü (0 •H O cO o •H O M d Q) rO o § 1 o F-. O (D O •d 1 o o «H Ü (A O •H O N d o 'd o •H 1 a o •H O N d •ri d •ri 'd 1 » d m o d o 1—4 € 1 tn •iH cO tn o d o rH rH •g I d •H Ü aS o •H rH W o •H 1—1 tO CO o a o d t d •H Ü cO d •H Ü <0 Ü •iH o (—1 >s r*) O rH •H rH •rH rH cO to o o d a rO t Ü •H (Ù CO o d o •cH •rH d 1 44 A UAUkHMiaiNM Q) I—I P» •H «H d o o o o o o -d’ -d- -d- -d- -j- o r\ o o o o o o -d- -4- o o & cd CO r4 +3 rH O d ® II I +3 ti o o O CM ■ g "S ^rH 0O d0) O d 00 CO r t *H Pi > CO (D O CM EH o o â .3 X na i ^ •H o d o O ®. A • Pi o oo o o o si rH rH §§ ) 40-3 o •H d rH tH 0 •H (d rH d •iH od •H «ri rH ■iH & 03 •H rH g 03 O g 1 •H c3 1 0 d •H d S 0) 1 g C~\ & to w 10 -P H3 d d (d § rHdcd rHcd rH Pt Pi Pi Pi 'H - n fi % i ii rH CM C A ^ 45 EFFECT OF DIFFERENT ACIDITY LEVELS OF SUBSTITUTED BENZOIC ACIDS SPRAYED ON ZINl'TIA ELEG-ANS The f o ll o w i n g compounds w ere u s e d i n t h i s e x p e r im e n t: 2 , 3 , 5 t r i i o d o b e n z o i c a c i d , 2 , 3 ,5 - tr ib r o m o b e n z o i c a c i d , 2 , 3 , 5 - t r i c h l o r o b e n z o i c a c i d o - io d o b e n z o ic a c i d , m -io d o b e n z o ic a c i d , p - io d o b e n z o ic a c i d , 2 ,3 - d i i o d o b e n z o i c a c i d , 2 - a m in o -5 -io d o b e n z o ic a c i d , 2 -a m in o -3 » 5 “ d iio d o b e n z o ic a c i d an d 3 , 5 - d i i o d o s a l i c y l i c a c i d . 2 ,5 - d il o d o b e n z o lc a c i d , 3 ,5 -d .ilo d .o b e n z o ic a c i d an d 2 - i o d o - 3 - n i t r o b e n z o i c a c i d . Due to c u l t u r a l d i f f i c u l t i e s many p l a n t s d i e d an d i t becam e n e c e s s a r y to r e g r o u p th e r e p l i c a t i o n s i n t o two r a t h e r th a n t h r e e s e t s . J u s t b e f o r e f l o w e r i n g o c c u r r e d , i t becam e n e c e s s a r y to rem ove t h e p l a n t s fro m th e b e n c h a n d p l a c e them i n f o u r g ro u p s on th e g re e n h o u s e f l o o r . No s t a t i s t i c a l a n a l y s i s was p o s s i b l e b u t s e v e r a l t r e n d s w ere o b serv ed . N o n - tr e a te d p l a n t s w ere n o t i c a b l y t a l l e r th a n th e t r e a t e d p l a n t s . P l a n t s t r e a t e d w ith 3 ,5 - d . i i o d o s a l i c y l i c a d d a p p e a re d to b e s l i g h t l y t a l l e r th a n t h e o t h e r t r e a t e d p l a n t s b u t n o t a s t a l l a s c o n t r o l p l a n t s . P la n ts s p r a y e d w ith o r th o a n d o r t h - p a r a s u b s t i t u t e d b e n z o ic a c i d s a p p e a re d t o f lo w e r a few d a y s e a r l i e r th a n th e c o n t r o l p l a n t s o r p l a n t s t r e a t e d w ith b e n z o ic a c i d s s u b s t i t u t e d i n o t h e r p o s i t i o n s . M o rp h o lo g ic a l and t e r a t o l o g i c a l ch an g es w ere e v id e n t i n t r e a t e d p la n ts . The ch an g e s seem ed to b e r e l a t e d more c l o s e l y to c h e m ic a l s t r u c t u r e th a n to a c i d i t y o r c h e m ic a l-p H i n t e r a c t i o n s . Changes in d u c e d i n p l a n t s s p r a y e d w ith 2 , 3 , 5 - t r i c h l o r o b e n z o i c a c id a t 1000 p .p .m . c o n c e n t r a t i o n a r e shown i n f i g u r e s l 4 and 15. T e rm in a l g ro w th fo rm ed a t i g h t t o lo o s e cone w i t h v a s c u l a r t i s s u e p r o l i f e r a t i o n a n d a b se n c e o f d i s t a l parenchym ous t i s s u e . Figure 14 Z in n ia e le g a n s s p ra y e d w ith 1000 p .p .m . 2 , 3 » 5 - t r ic h l o r o 'b e n z o ic a c id . N o te c o n e -s h a p e d t e r m i n a l l e a v e s , p r o l i f e r a t i o n a n d c o a l e s i n g o f v a s c u l a r tis s u e . c lu s te r. P l a n t A shows te r m in a l t i p g ro w in g down a n d t e r m i n a t i n g i n a l e a f Figure 15 Z i n n ia e le g a n s s p r a y e d w ith 1000 p . p .m . 2 , 3 . 5 - t r i c h l o r o 'b e n z o i c a c id . T h is p l a n t a t an e a r l i e r s t a g e o f g ro w th i s shown i n F ig u r e 1 0 , p l a n t A. TTote a l t e r n a t e l e a v e s . m # % 46 L e a v e s a t lo w e r n o d e s w ere c h a r a c t e r i s t i c a l l y s t r a p - l i k e w ith nmch v a s c u l a r tis s u e p ro life ra tio n . A d d itio n a l le a v e s a p p e a re d a t th e node ( p la n t B, F ig u r e 14) a n d grew s t r a i g h t u p . I f a p i c a l g ro w th c o n tin u e d th e p o l a r i t y was r e v e r s e d c a u s in g th e new g ro w th to grow down an d te r m in a te in a l e a f c lu s te r. U s u a lly a l a t e r a l s h o o t ( F ig u r e 14) assum ed dom inance an d p ro ­ d u c e d a f lo w e r h e a d . C h a r a c t e r i s t i c a l l y le a v e s w ere a l t e r n a t e and n o t o p p o s i t e on th e l a t e r a l s h o o t. At a l l pH l e v e l s compounds w ith p a r a o r o r t h o - p a r a s u b s t i t u t i o n s te n d e d to p ro d u c e p l a n t s w ith a l t e r n a t e an d n o t o p p o s i t e le a v e s from t h e t h i r d node u p . To t e s t a c id s t h e m o rp h o lo g ic a l e f f e c t s o f a d d in g s u b s t i t u t e d b e n z o ic t o th e s o i l , Z i n n ia e le g a n s s e e d was sown on F e b ru a ry t w e n t y - f i f t h , 195^1 d i r e c t l y i n t o t h r e e - i n c h p o t s . 1956, 10 m l. o f 50 added t o th e s o i l d a i l y . T a b le XVI. S t a r t i n g on F e b ru a ry tw e n ty - e ig h th , p .p .m . o f s u b s t i t u t e d b e n z o ic a c id s (T a b le XVI) w ere D a ily o b s e r v a ti o n s w ere made and a r e r e c o r d e d i n I n g e n e r a l , m o rp h o lo g ic a l an d t e r a t o l o g i c a l c h an g es p r e v i o u s l y r e c o r e d e d f o r Z i n n ia e le g a n s w ere e v id e n t : f u s e d l e a v e s , p r o l i f e r a t i o n o f v a s c u l a r t i s s u e an d s t r a p - l i k e l e a v e s . One new o b s e r v a tio n was t h a t p l a n t s t r e a t e d w ith s o l u t i o n s o f 3 ,5 - d iio d o b e n z o ic a c i d and 2 -a m in o -3 ,5 “ d iio d o b e n z o ic a c i d l o s t t h e i r p o l a r i t y a n d grew p r o s t r a t e . A l l s u c h p l a n t s d ie d a s so o n a s , o r im m e d ia te ly a f t e r , t h e t h i r d n o d a l le a v e s ex p an d ed . 47 > 0) k -*-> • C O 0> h cd d 0> d rHi cd r4 d A (D •H •d d § +> +3 S 1 to 1— O R M (D § •a I I cd I d •H W«H a <0 cd 4-4 d co •H c3 «JÎ .d 4-3 Q) t—1 "d 'd 0) d -p o cd 'd 'd (D Q ) o d d +> o 4J> d ta CO o O o +» +> q d 0) W OT RCO +5 o o «M O R ro C rH 03 R i> 03 cd rH (A d 0) O d d d O d -d 43 o u 4^ i N o I V) 1 —1 . d (d 03 CO 03 C O•r4 03 43 03 ■P O 1— 1 d > •H CD cd d 03 03 CO 03 d 03 cd d d 0 — I1 0 — 1 0 0 Pi cd 3 1 s R d a d R 0 flû ü 0 d m 43 43 !>a 43 CO •rH cd CO 03 d d 0 ■H •H d t> •iH £d Cd d «H (H d 1—1 03 e 03 1 03 d 43 - P cd o t— 03 d d Cd cd - P R 1— t CD CO *5Û cd rca tu] fiÛ d d d 0) *rH d d •rH •H 0 03 •H •H •H d d M M 0) CD C d .d Œ cd 43 4 3 C D 0) 03 cd Pi d O d 1—t d d d •iH > d CD o d 4 3 03 d 03 (0 03 - P 03 d 43 43 rH C D d P (0 d cd > CD C h 03 cd •H rH rH CO 03 - P 43 R R 03 03 ;d % rH 1— t cd Cd 03 d rH rH 03 rH • 03 0 Cd cd rH W CQ m H to to M Cet g t o CO CO "d •H ü 'd •d 5 § d •H C3 d d •rH ü ë E4 cd 0 •r4 d 0 d d N • r t •r4 •rH ü 0 ü d 03 c d d cd o g .H I 0 •r4 0 N d 03 d 0 d 0 e n nH 1 CM 0 0 d 0 •rH •H d 43 1 VT\ ü 0 •H •H 0 0 N N d d 03 CD rP 0 0 d d 0 0 -rH •rH 1 g à R d d d •rH •rH •H 0 0 0 cd Cd P ü ü •rH •rH 0 0 N N P P 03 03 rP 0 0 d d 0 0 •rH •rH •rH •rH d d : 1 en CM N ü •r4 0 M P 03 rO 0 d 0 •iH •rH d 1 m ü •rH 0 N P 03 rP 0 d 0 rH JA 0 •H d 43 f en CM (D t^ a R o m (H cd (-4 d CD rH 03 rH § 43 0 1—1 d > •rH 0) d 03 f-4 0) Cd 03 d •H o -P ,d d -H 4^ rd TO fclÛ •r4 d 43 rO O > cd cd 1 — 1 d « tn d (D (0 > 03 cd •H (D 1 +3 1— I § § 1 I d o d o d d d iH O rH O > d m -P > . d d CD a (D W ■P d O •H o -P R cù O 'd t—4 0) O to CO R 4 0 0 •fH •rH f—1 rH p P CO CO 0 0 d d d •H ü d P •rH Ü ü P •rH rH ü •rH ü H •rH rH ü Cti •H CO rH 0 P CO d 0 0 rH d 0 •3 •rH •H •rH ü • rt 43 P ü P w q P 03 Si R 0 d 0 1— t -P 0 •rH d d 1 1 1 P ü Ü V AV AV A 1 1 en »Aen en cvj 0 0 rH cH 46 EFFECT OF DIFFERENT CONCENTRATIONS OFSUBSTITUTED BENZOIC. ACIDS ON CALLISTEFHUS CHINENSIS T h e re w ere h i ^ l y s i g n i f i c a n t c o r r e l a t i o n s b e tw ee n d ry w e ig h t o f a s t e r to p s an d c h e m ic a l tr e a tm e n ts b u t no c o r r e l a t i o n s b etw ee n co n cen ­ t r a t i o n s an d c h e m ic a l- c o n c e n t r â t io n i n t e r a c t i o n s (T a b le X V II). T h e re w ere h i ^ l y s i g n i f i c a n t c o r r e l a t i o n s b e tw ee n d ry w e ig h t i n gram s o f a s t e r r o o t s and c h e m ic a l t r e a t m e n t s , c o n c e n t r a ti o n s and c h e m ic a lc o n c e n t r a t i o n i n t e r a c t i o n s (T a b le X V III ). I n g e n e r a l , c h e m ic a l s p ra y s a t 1000 p .p .m . c o n c e n t r a t i o n te n d e d to i n h i b i t r o o t g ro w th more th a n d id s p r a y s a t 100 p .p .m . c o n c e n t r a t i o n . T h ere a p p e a re d to be l i t t l e re la tio n ­ s h i p b e tw e e n c h e m ic a l s t r u c t u r e and d ry w e i ^ t o f r o o t s . T h e re w ere h i g h l y s i g n i f i c a n t c o r r e l a t i o n s b etw een t o p / r o o t ra tio o f a s t e r an d c h e m ic a l tr e a tm e n t b u t no c o r r e l a t i o n s b etw een c o n ce n ­ t r a t i o n s o r c h e m ic a l- c o n c e n tr â t io n i n t e r a c t i o n s (T a b le XIX ). p l a n t s h a d a lo w e r v a lu e th a n d id c o n t r o l p l a n t s . A ll t r e a t e d No g e n e r a l i z a t i o n c o u ld b e draw n r e l a t i n g c h e m ic a l s t r u c t u r e to t o p / r o o t r a t i o in a s t e r s . T h e re w ere h i # i l y s i g n i f i c a n t c o r r e l a t i o n s b etw ee n number o f f l o r a l i n i t i a l s , c h e m ic a l tr e a tm e n ts and c o n c e n tr a tio n s b u t no c o r r e l a t i o n s b e tw e e n number o f f l o r a l i n i t i a l s an d c h e m ic a l- c o n c e n tr a tio n i n t e r a c t i o n s ( T a b le XX), P l a n t s s p ra y e d w ith compounds s u b s t i t u t e d i n th e o r th o p o s i t i o n w i t h an e l e c t r o - n e g a t i v e g ro u p h a d th e most f l o r a l i n i t i a l s an d w ere fo llo w e d b y p l a n t s s p ra y e d w ith compounds s u b s t i t u t e d in th e p a r a p o s i t i o n w ith an e l e c t r o - n e g a t i v e g ro u p . The t r e n d was f o r 100 p .p .m . s p ra y e d to h ave more f l o r a l i n i t i a l s th a n p l a n t s s p ra y e d w ith 1000 p .p .m . The node number o f f i r s t flo w e r was c o r r e l a t e d h ig h ly s i g n i f i c a n t l y 49 TABLE XVIî EFFECT OF SUBSTITUTED BENZOIC ACIDS AT 100 AND 1000 P .P .M . CONCENTRATIONS ON DRY WEIGHT OF CALLISTEPHUS CHINENSIS* Grams Dry W e i ^ t 100 p .p .m . 1000 p .p .m . C h em ica l C heck 2 , 3 »5-'t3:*iiodo'benzoic a c i d 2 . 3 .5 - tr ib r o m o b e n z o ic a c i d 2 , 3 .S ^ tric h lo ro b e n z o ic a c id o -io d o "b e n z o ic a c i d p - io d o b e n z o ic a c i d 2 ,3 -â .iio d o 'b e n z o ic a c i d 2 .5 - d i i o d o b e n z o i c a c i d 3 .5 - d ii o d o b e n z o ic a c id 2 - io d o - 3 “ i i i t r o b e n z o i c a c i d p -a m in o b e n z o ic a c i d 2 - a m in o -5 - io d o b e n z o ic a c i d 2 - a m in o - 3 ,5 - d iio d o b e n z o ic a c i d 2 - a m in o -3 ,5 -d ib ro m o b e n z o ic a c i d 2 . 5 -d ih y d ro % y b e n z o ic a c i d 3 .5 - d iio d o s a lic y lic a c id L .S .D . 5^ 1^ 7 .4 2 8 .1 5 8 .9 0 2 .1 5 7*50 7 .5 8 7 .2 3 8 .7 7 8 ,6 9 7# 77 1 0 .8 4 9*52 7*33 1 0 .6 3 1 0 .4 2 9 .5 8 - 2 .8 0 = 3.72 *Average of three replicates of four plants each 7*52 7*69 8 .3 8 d ead 8 .0 9 8 .5 4 7*39 8 .0 2 8 .2 3 5# 83 9 .7 3 9 .5 9 8 .1 9 1 1 ,1 0 9 .8 4 8 .6 7 50 TABLE X V III EFFECT OF SUBSTITUTED BENZOIC ACIDS AT 100 P .P .M . AND 1000 P .P .M , CONCENTRATIONS ON DRY MATTER OF CALLISTEPHUS CHINENSIS ROOTS* Grams D ry W e i ^ t 100 p .p .m . 1000 p .p .m . C h e m ic a l C heck 2 . 3 . 5- 1r i i o d o h e n z o i c a c i d 2 . 3 . 5 - tr ib r o m o b e n z o ic a c i d 2 . 3 .5- tr lc h l o r o b e n z o ic a c id o - io d o b e n z o ic a c i d p - io d o b e n z o ic a c i d 2 , 3 - d ii o d o b e n z o ic a c i d 2 , 5 “" d iio d o b e n z o ic a c i d 3 . 5 - d ii o d o b e n z o i c a c i d 2 - i o d o - 3- u l t r o b e n z o i c a c i d p -a m in o b e n z o ic a c i d 2 m-amino-5 - io d o b e n z o ic a c i d 2 - a m in o - 3 , 5 “ d iio d o b e n * o ic a c i d 2—am ino—3 , 5 ~ d ib ro m o b e n z o ic a c i d 2 . 5 - d ih y d r o x y b e n z o ic a c i d 3 . 5- d i i o d o s a l i c y l i c a c i d L .S .D . 5^ 1$ = = 2 ,4 6 2 .4 2 2 .3 8 0 .7 3 2 .5 3 2 .6 5 2 .3 6 3»04 2 .9 1 3 »09 3*42 2 .3 9 3 »54 4 ,0 9 3 .4 8 2 .8 6 0 .2 8 0 .3 7 ♦Average of three replicates of four plants each 2 .4 8 2 .0 2 2 .2 5 d ead 1 .3 3 2 .4 6 2 .5 8 2 .8 1 2 .8 1 1 .5 8 2 .8 9 2 .0 2 3 *81 4 .0 8 3 » 86 2 .1 5 31 TABLE XIX EFFECT OF SUBSTITUTED BENZOIC ACID AT 100 AND 1000 P .P .M . CONCENTRATIONS ON DRY WEIGHT OF CALLISTEPHUS CHINENSIS TOP/r OOT RATIO* Grams Dry W eight 100 p .p .m . 1000 p .p .m . C h e m ic a l C heck 2 , 3 »5 - t r i i o d o h e n z o i c a c i d 2 . 3 . 5 - t r i ’b rom o'benzoic a c id 2 . 3 . 5 - t r i c h l o r o b e n z o l c a c id o - io d o h e n z o ic a c i d p - io d o h e n z o ic a c i d 2 , 3 “ d iio d o b e n z o ic a c i d 2 . 5 - d ii o d o b e n z o i c a c id 3 . 5 - d ii o d o b e n z o i c a c i d 2 - i o d o - 3 —a i t r o b e n z o i c a c i d p -a m in o b e n z o ic a c i d 2 -a m in o - 5 - io d o b e n z o ic a c id 2 - a m in o - 3 , 5 - d ii o d o b e n z o ic a c i d 2 -a m in o - 3 , 5 -d ib ro m o b e n z o ic a c i d 2 . 5 -d ih y d r o x y b e n z o ic a c i d 3 , 5“ d i i o d o s a l i c y l i c a c i d L .S .D . 3i 1^ = = 3 .3 0 3*51 4 .5 0 2 .6 1 3 »45 3 -0 1 3*39 3*04 3*31 2 .9 9 3*55 4 ,0 7 2 .5 2 2 .8 1 3*71 3*74 1 .3 0 1.72 *Average of three replicates of four plants each 3 .3 6 4 .2 7 3*74 d e ad 3»04 3» 75 3*15 3*29 2 .8 4 3*08 3*55 4 .6 1 2 ,6 6 3* 77 3* 14 3*93 52 TABLE XX EFFECT OF SUBSTITUTED BENZOIC ACIDS AT 100 AU) 1000 P .P .M . CONCENTRATIONS ON NUMBER OF FLORAL INITIALS OF CALLISTEPHUS CHINENSIS* Number o f F l o r a l I n i t i a l s 100 p .p .m , 1000 p .p .m . C h e m ic a ls Check 2 . 3 .5 - t r iio d .o b e n z o ic a c i d 2 .3 .5 - tr i'b r o m o ‘b e n z o ic a c i d 2 , 3 » 5 - t r i c h l o r o ’b e n z o ic a c i d o - io d o b e n z o ic a c id p - io d o b e n z o ic a c i d 2 ,3 - d il o d o b e n z o ic a c i d 2 .5 - d ii o d o b e n z o ic a c i d 3 .5 - d ii o d o b e n z o ic a c i d 2 - io d o - 3 - i i i t r o b e n z o l o a c i d p -a m in o b e n z o ic a c i d 2 - a m in o -5 - io d o b e n z o ic a c i d 2 -a m in o -3 » 5 “ d iio d o b e n z o ic a c i d 2 -a m in o -3 ,5 -d ib ro m o b e n z o ic a c id Z ,5 - dihydro% ybe n z o ic a c i d 3 .5 - d ii o d o s a lic y lic a c id L .S .D . 5^ 1^ = - 1 0 .0 8 1 2 .3 3 1 4 .5 8 4 .9 2 1 0 .7 5 15*67 1 2 .1 ? 1 5 . 1? 1 6 .0 0 1 2 .4 2 17*92 1 4 .5 0 1 6 .2 5 2 0 .2 5 I 6 .O 8 15*87 1 .7 2 2 ,3 8 *Average of three replicates of four plants each 1 0 .1 3 1 2 .0 0 1 1 .9 2 dead 1 3 -3 3 1 4 .2 5 1 2 .3 8 15*08 1 4 .7 5 1 0 .6 3 15*33 1 4 .5 4 1 6 .2 9 2 0 .0 4 1 5 .2 1 1 4 .3 8 53 w ith c h e m ic a ls and c o n c e n tr a tio n s b u t n o t c o r r e l a t e d w ith c h e m ic a l— c o n c e n t r a t i o n i n t e r a c t i o n s (T a b le X X I), No t r e n d was d i s c e r n a b l e a s to w h e th e r 100 p .p .m . o r 1000 p .p .m . c o n c e n t r a t i o n c a u s e d th e lo w e s t nodes to flo w e r. P l a n t s s p ra y e d w ith compounds h a v in g o r th o —m eta s u b s t i t u t i o n s h a d t h e lo w e s t num ber o f n o d es to f lo w e r . n o t seem t o be a f a c t o r i n f lo w e r in g , The ty p e o f s u b s t i t u t i o n d id P a r a s u b s t i t u t e d compounds when s p r a y e d on p l a n t s seem ed to g iv e t h e h i p e s t number o f n o d es to f lo w e r . Number o f d ay s to flo w e r i n t h e a s t e r i s h i g h l y s i g n i f i c a n t l y c o r r e l a t e d w ith c h e m ic a l t r e a tm e n t s an d c h e m ic a l- c o n c e n t r â t io n i n t e r a c t i o n s b u t i s n o t c o r r e l a t e d w ith c o n c e n tr a tio n s (T a b le X X II), In g e n e ra l, p la n ts s p r a y e d w ith compounds o r t h o - s u b s t i t u t e d w ith a n e l e c t r o - n e g a t i v e g ro u p f lo w e r e d i n th e s h o r t e s t tim e ; e l e c t r o - n e g a t i v e 5” P O S itio n s u b s t i t u t i o n s w e re a lm o s t a s e f f e c t i v e i n h a s t e n i n g f lo w e r in g . M o rp h o lo g ic a l and t e r a t o l o g i c a l c h an g es in d u c e d in th e a s t e r b y s u b s t i t u t e d b e n z o ic a c i d w ere fe w . The e f f e c t s o f 2 , 3 , 5 - t r i c h l o r o - b e n z o ic a c i d (100 p .p .m .) a n d 2 - i o d o - 3 - u i t r o b e n z o i c a c i d (1000 p . p . m . ) a r e shown in F ig u r e l 6 . T e rm in a l g ro w th h a s s to p p e d and a s a r e s u l t o f s h o r t e n i n g o f i n t e r n o d a l d i s t a n c e , a l e a f c l u s t e r i s fo rm ed . L eav es i n t h e c l u s t e r a r e s m a l l, e n t i r e m a rg in e d and a r e m o s tly v a s c u l a r t i s s u e . Par en chymous t i s s u e i s l i m i t e d t o a m a rg in a ro u n d t h e v a s c u l a r t i s s u e . L e a v es a t t h e s e c o n d , t h i r d an d f o u r t h n o d es a r e u s u a l l y s t r a p - s h a p e d , h av e p r o l i f e r a t e d v a s c u l a r t i s s u e and l i t t l e p a re n c h y mous t i s s u e . The e f f e c t o f 2 , 3 , 5 - t r i c h l o r o b e n z o i c a c i d a t 1000 p .p .m . on p l a n t g ro w th i s shown i n F ig u r e 1 ? . T e rm in a l g ro w th h a s s to p p e d and a l e a f c l u s t e r , o r m ore commonly, a ro u n d knob w ith s m a l l , s t i p u l e - l i k e le a v e s a r i s e fro m th e knob. T h ese le a v e s t u r n a b r i g h t y e llo w an d so o n d i e . Nodes b elo w th e knob CO fd •H g (g 0 •H 0 N d d +> •1— 1 4-> m rO d {/} «H 0 ro 4^ ü (D «H (D hO d > 0 si m m' w g d si 0 •d 43 •H > 'd (D & R 0) 43 •d *H u R 0 43 43 •d 0 *H 0 N d Q) d 0 0 (H 0 d ta 0 d d 43 rH rH cd d •H E M q) 43 .3 t 0 *§ 0> A «D S m •H 1 d 43 •H > m •g •r4 d CO 43 S A CM I d •H 0 cd "S 6 ü iH O k R Figure 1? C a l l i s t e p h u s c h ilie n s i s s p r a y e d w ith 1000 p .p .m , 2 , 3 , 5 - t r i c h l o r o b e n z o ic a c i d . C o n tr o l p l a n t i s r i g h t row c e n t e r ; n o te d w a r f in g , e n t i r e m a r g in s , c u p -s h a p e d le a v e s an d f u s e d le a v e s on t r e a t e d p l a n t s . f 54 h a v e l a r g e , m a lfo rm e d , c u p -s h a p e d l e a v e s . e n t i r e , a c h a r a c t e r i s t i c o f th e young l e a f . y e llo w an d d i e d . M ature l e a f m arg in s a r e o f te n A ll p l a n t s tu r n e d b r i g h t 55 TABLE XXI EFFECT OF SUBSTITUTED BENZOIC ACIDS AT 100 AND 1000 P .P .M . CONCENTRATIONS ON NUMBER OF NODES TO FIRST FLOWER IN CALLISTEPHUS CHINENSIS* Nodes to F i r s t F lo w er 100 p .p .m 1000 p .p .m . C h e m ic a l C heck 2 . 3 . 5 - ‘t r i i o d o b e n z o i c a c id 2 . 3 .5 -tri'b ro m o 'b e n z o ic a c i d 2 . 3 .5 -tr ic h lo ro h e n z o ic a c id o - io d o h e n z o ic a c i d p - io d o h e n z o ic a c i d 2 ,3 - d ii o d o h e n z o ic a c i d 2 .5 - d ii o d o h e n z o ic a c i d 3 .5 - d ii o d o b e n z o ic a c i d 2—io d o - 3 " " ^ ltr o b e n z o ic a c i d p -a m in o b e n z o ic a c i d 2-am ino-5*“io d o b e n z o ic a c i d 2 - a m in o - 3 ,5 - d iio d o b e n z o ic a c i d 2 -a m in o -3 ,5 -d ib ro m o b e n z o ic a c i d 2 . 5 - d ih y d r o z y b e n z o ic a c i d 3 .5 - d ii o d o s a lic y lic a c id L .S .D . 5^ i$é = = 3 7 .4 2 3 1 .9 2 31*87 17 * 8 6 3 0 .5 8 3 0 .9 2 2 8 .3 3 3 8 .2 5 2 8 .5 0 2 5 .2 5 35*17 3 4 .3 3 25*50 3 2 .0 1 3 2 .0 1 3 4 .8 3 3 .7 2 4 .9 5 *Average of three replicates of four plants each 3 7 .1 7 31*83 3 1 .0 0 d ead 33*00 31*33 29*58 31*17 3 0 .2 5 2 7 .0 0 3 4 .6 ? 34*33 25*75 3 0 .0 0 3 0 .0 0 3 0 .5 0 56 TABLE XXII EFFECT OF SUBSTITUTED BENZOIC ACIDS AT 100 AND 1000 P.P.M . CONCENTRATIONS ON DAYS TO FLOWER IN CALLISTEPHUS CHINENSIS* Days to F lo w er 100 p .p .m . 1000 p .p .m , C h em ical C heck 2 . 3 .5 - t r i i o d o 'b e n z o i c a c i d 2 .3 .5 - tr ib r o m o b e n z o i c a c i d 2 ,3 » 5 -tric h lo ro b e n a o ic a c id o - io d o h e n z o ic a c i d p - io d o h e n z o ic a c i d 2 ,3 - d ii o d o h e n z o ic a c i d 2 .5 - d ii o d o h e n z o ic a c i d 3 .5 - d ii o d o h e n z o ic a c i d 2—io d o —3“ n i t r o h e n z o i c a c id p —a m in o h e n z o ic a c i d 2 -a m in o -5 “ io d o h e n z o ic a c i d 2 -a m in o -3 » 5 ~ d iio d o h e n z o ic a c i d 2 -a m in o -3 ,5 “ d ih ro m o h e n z o ic a c i d 2 .5 - d ih y d r o x y h e n z o ic a c i d 3 .5 - d iio d o s a lic y lic a c id L .S .D . 1^ = 1 3 8 .1 3 1 3 0 .4 2 1 4 0 .0 0 1 2 8 ,6 ? 1 3 7 .0 0 1 4 5 .6 ? 143*83 143*58 145* 83 1 4 0 .9 2 1 4 4 .0 0 1 4 3 .4 2 144 .8 3 1 4 8 ,6 ? l 4 l . 92 143* 83 1 1 .6 6 15*48 ♦Average of three replicates of four plants each 1 4 8 .2 5 136 .3 3 139*00 dead l4 l,5 0 1 4 2 .9 2 137*92 1 3 8 .9 2 1 4 2 .6 ? 139. 6? 1 4 1 .9 2 143-17 143*92 155* 83 142*75 l4 0 .0 8 57 DISCUSSION I t i s o b v io u s ly d i f f i c u l t t o d is c u s s i n d e t a i l th e many e f f e c t s ^4e t h i r t y —f o u r c h e m ic a ls a t t h r e e c o n c e n t r a t i o n s , s e v e n d i f f e r e n t a c i d i t y l e v e l s and two modes o f a p p l i c a t i o n on t h r e e su ch d i f f e r e n t p l a n t s h y b r i d a , Z in n ia e l e g a n s , and C a l l i s t e p h u s c h i n e n s i s . Even w ith t h e a i d o f s t a t i s t i c a l a n a l y s i s i t i s d i f f i c u l t to p in p o in t d i f f e r e n c e s among th e ^000 p l a n t s in v o lv e d in t h i s e x p e rim e n t. C e r t a i n tr e n d s a r e e v i d e n t , h o w e v e r, and i t i s p o s s i b l e to c o r r e l a t e th e s e tr e n d s so as to fo rm a c o h e r e n t h y p o th e s is f o r r e s u l t s r e p o r t e d in t h i s e x p e rim e n t. P l a n t g ro w th was d i v i d e d , i n t h i s e x p e rim e n t, i n t o two b ro a d p h a s e s — th e v e g e t a t i v e p h a se and th e r e p r o d u c tiv e p h a s e . By m e a su rin g t h e v a r i o u s p h a s i c com ponents i t was p o s s i b l e to d e te rm in e th e e f f e c t s o f s u b s t i t u t e d b e n z o ic a c i d s on each p h a s e . The v e g e t a t i v e p h a se grow th was d e te r m in e d by m e a s u rin g th e d ry r o o t w e ig h t, d ry a e r i a l w e ig h t, d ry r o o t / d r y a e r i a l r a t i o , num ber o f a x i l l a r y s h o o ts an d number o f f l o r a l i n i t i a l s . F l o r a l i n i t i a l s , w h ile c o n s id e r e d by some i n v e s t i g a t o r s a s b e in g p a r t o f t h e r e p r o d u c t i v e p h a s e , a n a to m ic a lly s-nd p h y t o g e n e t i c a l l y b e lo n g to th e v e g e ta tiv e p h ase. The r e p r o d u c t iv e p h a se o f p l a n t g ro w th i s , s t r i c t l y s p e a k in g , o n ly t h a t p o r t i o n o f t h e p l a n t ' s l i f e l i z a t i o n c a n ta k e p l a c e . c y c le d u r in g w hich f e r t i ­ I t i s u n u s u a l f o r f e r t i l i z a t i o n to ta k e p la c e w i t h i n f l o r a l i n i t i a l s and o n ly r a r e l y does f e r t i l i z a t i o n ta k e p la c e b e f o r e a n th e s is . D e s p ite r e p e a te d a tte m p ts no s e l f o r c ro s s f e r t i l i z a t i o n c o u ld b e a c h ie v e d b e f o r e a n t h e s i s i n th e a s t e r s , p e tu n ia s and z in n ia s u s e d in th is e x p e r im e n t. a c h ie v e d . A f t e r a n t h e s i s b o th s e l f and c r o s s f e r t i l i z a t i o n was T h e r e f o r e , a l l g ro w th com ponents o c c u r r in g d u r in th e p e r io d 58 fro m s p r a y a p p l i c a t i o n to a n t h e s i s w ere u s e d a s a m easure o f th e v e g e t a t i v e p h a s e ; th e num ber o f d a y s fro m s p r a y a p p l i c a t i o n to a n t h e s i s was u s e d to d e te r m in e th e change fro m th e v e g e t a t i v e p h a se to th e r e p r o d u c tiv e p h a se . Two o b s e r v a tio n s l e d t o th e c o n c lu s io n t h a t t h e s u b s t i t u t e d b e n z o ic a c i d s h a d two a c t i o n s i n p l a n t s . T hese o b s e r v a tio n s w ere (1 ) o rth o e l e c t r o —n e g a t i v e s u b s t i t u t e d b e n z o ic a c i d s a f f e c t e d r e p r o d u c t iv e g ro w th w h ile o r th o e l e c t r o - p o s i t i v e s u b s t i t u t e d b e n z o ic a c id s a f f e c t e d v e g e t a t i v e g ro v rth , a n d (2 ) d i f f e r e n t and r e c i p r o c a l a c i d i t y optimums w ere o b s e rv e d f o r v e g e t a t i v e and r e p r o d u c tiv e g ro w th . The M u ir-H an sch h y p o th e s is o f o rth o e l e c t r o - n e g a t i v e s u b s t i t u ­ t i o n s a c t i v a t i n g s u b s t i t u t e d b e n z o ic a c id s more th a n o th e r ty p e s o f s u b s t i t u t i o n s i s s u p p o r te d by a l l d a t a r e p o r t e d h e r e on r e p r o d u c tiv e g ro w th . As f a r a s v e g e t a t i v e g ro w th i s c o n c e rn e d , b e n z o ic a c id s s u b s t i t u t e d w ith a n o r th o e l e c t r o - p o s i t i v e g ro u p g av e b e t t e r g ro w th (th o u g h s t i l l n o t as good a s c o n t r o l p l a n t s ) th a n o rth o e l e c t r o - n e g a t i v e s u b s t i t u t i o n s . T h is le n d s s u p p o r t to th e id e a o f s u b s t i t u t e b e n z o ic a c i d s h a v in g two r e a c t i o n s in p la n ts . One r e a c t i o n , when th e b e n z o ic a c id i s o rth o e l e c t r o - n e g a t i v e s u b s t i t u t e d , a f f e c t s r e p r o d u c ti v e g ro w th ; a n o th e r r e a c t i o n , when th e b e n ­ z o i c a c i d i s o r th o e l e c t r o - p o s i t i v e s u b s t i t u t e d , a f f e c t s v e g e t a t i v e g ro w th . A c id ity optimums w ere a l s o d i f f e r e n t f o r th e v e g e t a t i v e a n d r e ­ p r o d u c t i v e p h a s e s o f g ro w th . V e g e ta tiv e g ro w th was most en hanced a t pH 9 a n d m ost i n h i b i t e d a t pH 6 o r 7; r e p r o d u c tiv e g ro w th was most en h an ced a t pH 7 and m ost i n h i b i t e d a t pH 8. At pH 4 ( th e pH r e g io n w here h a lo g e n a te d b e n z o ic a c id s a r e a t t h e i r i s o - e l e c t r i c p o i n t ) th e a c t i o n o f b e n z o ic a c id s c o u ld b e e x p e c te d to b e an o m alo u s. T h is was e x p e r im e n ta lly co n firm e d when 59 slight inhibition of both vegetative and reproductive growth occurred at pH 4. There is overwhelming evidence that the degree of ionisation of a compound profoundly affects its penitration into a leaf# A nonmionlsed molecule will enter a leaf much faster than an ionised molecule of the same sise# In addition, a non— ionised compound will reach a higher con­ centration in a leaf than an ionised compound if their other characteristics are similar# Compounds applied as a foliar spray at pH 6 or 7 lead to the lowest top/root ratio, lowest number of flowers and lowest number of axillary shoots but to the greatest acceleration of flowering (as measured by days from spray application to anthesis)# Conversely, com­ pounds applied as a foliar spray at pH 4 accelerated flowering the least while, at the same time, giving the highest top/root ratio# The affect of compounds at pH 4 was anomalous as far as number of flowers and number of axillary shoots was con­ 60 c ern ed . Coiiç)omds s p r a y e d on p l a n t s a t pH 9 c a u se d th e h i p e s t num ber o f f l o w e r s , t h e h i p e s t number o f a x i l l a r y s h o o ts w h ile a c c e l e r a t i n g f lo w e r in g t o some d e g re e . The hypothesis put foreward by Thimann and Bonner (43 ) is the basic assumption upon which is beaed both the acidity reactions and the ortho substituted reactions. They assume that an anti-auxin may react with lAA substrate mole­ cules to a large extent but still leave enough substrate molecules open to react with IA to cause growth with the ex­ penditure of a smaller number of auxin molecules. The rapid reaction in the leaves with lAA substrate molecules of both ortho electro-negative substituted benzoic acids and substi­ tuted benzoic acids at pH 7 goes almost to completion and seriously lowers the auxin content in the leaves. to florigen production. This leads The slow reaction in the entire plant with lAA substrate molecules of both ortho electro-positive 61 s u b s t i t u t e d b e n z o ic a c i d s a t pH 9 d o e sn * t l i m i t a u x in con­ c e n t r a t i o n i n an y one o r g in v e r y d r a s t i c a l l y . T h ere a r e eno u g h s u b s t r a t e m o le c u le s f r e e t o combine w ith lAA t o p ro ­ d u c e n o rm a l v e g e t a t i v e g ro w th . The r e c e n t o b s e r v a tio n o f N ie d erg an g —Kamien and Skoog ( 3 0 ) t h a t TIBA d e s tr o y s p o l a r i t y and th u s l i m i t s move­ m ent o f ZAA w i t h i n e x c is e d p l a n t t i s s u e i s d i f f i c u l t t o i n t e r p r e t i n te rm s o f r e a c t i o n m echanism s. The o b s e r v a tio n o f s u b s t i t u t e d b e n z o ic a c i d s a f f e c t i n g p o l a r i t y i n i n t a c t p l a n t s h a s b e e n r e p o r t e d u n d e r e x p e r im e n ta l r e s u l t s . T h is l o s s o f p o l a r i t y was o f t r a n s i e n t n a t u r e , h o w ev er, an d th e p l a n t s so o n grew n o r m a lly . Two com pounds, 3 ,5 - d iio d o b e n z o ic a c i d a n d 3 - a m in o - 3 ,5 - d iio d o b e n z o ic a c i d , w ere n o ta b le i n c a u s­ i n g a p ro lo n g e d l o s s o f a p i c a l dom inance w hich u l t i m a t e l y r e s u l t e d i n th e d e a th o f a l l t r e a t e d p l a n t s . S tre e t (4 0 ), 62 who a l s o w o rk ed w ith e x c is e d t i s s u e , fo u n d e v id e n c e o f p o la r ity re v e rs a l. T h is e x p e rim e n t a f f o r d s s t r o n g s u p p o rt f o r two way movement o f s u b s t i t u t e d b e n z o ic a c i d s i n p l a n t s . Star- t i s t i c a l a n a l y s i s shows th e compounds a f f e c t r o o t s even when s p r a y e d on t h e f i r s t node shows th e compounds move u p . The f i r s t n o d a l le a v e s o f z i n n i a s , a s t e r s an d p e tu n ia s a r e ap­ p a r e n t l y fo rm ed i n t h e s e e d s i n c e no e f f e c t was n o t i c e d on th e m . L e a v es a t t h e s e c o n d node a r e a p p a r e n tl y w e ll d e v e lo p e d i n i t i a l s s i n c e o n ly t h e m ost f o r m a t i v e ly a c t i v e compounds ( T r i h a lo g e n a te d and 2 -io d o —3—n l t r o b e n z o i c a c id ) c a u se d p ro fo u n d c h an g e s i n t h e i r m orpholo g y . T h ese c h a n g e s , w hich r e s u l t e d i n a s t r a p - l i k e l e a f , w ere c h i e f l y t h e la c k o f parenchym ous t i s s u e an d p r o l i f e r a t i o n o f v a s c u la r t i s s u e . When a 100 p .p .m . s p r a y o f 63 tlie l e s s fo rm a t i v e l y a c t i v e comrpounds w ere u s e d p r o l i f e r a t i o n o f v a s c u la r t i s s u e s t i l l o c c u r r e d b u t parenchym ous t i s s u e was c h a r a c t e r i z e d by p e r ­ s i s t e n t m a rg in a l m e riste rn s w h ich le a d to b a s i l a r l y f u s e d l e a v e s . P la n ts s p r a y e d w ith c o n c e n t r a t i o n s o f 1000 p .p .m , o f th e l e s s fo rm a t i v e l y a c t i v e com pounds w ere c h a r a c t e r i z e d by c l u s t e r i n g o f le a v e s due to s h o r te n in g o f i n t e r n o d e s , p r o l i f e r a t i o n o f v a s c u l a r t i s s u e , an d l a c k o f parenchym ous tis s u e . T h e se o b s e r v a tio n s a r e c o n s i s t e n t w ith l e a f h i s t o g e n e s i s . E sa u ( 7 ) (p a g e 4 4 4 , F ig u r e 1 6 ,1 3 ) shows a l e a f p rirao rd iu m w ith th e v e in a l n e t w ork w e ll d e v e lo p e d w h ile parenchym a t i s s u e i s s t i l l o n ly p a r t i a l l y d iffe re n tia te d . When h ig h c o n c e n tr a tio n s o f fo rm a t i v e l y a c t i v e b e n z o ic a c id s a r e s p r a y e d on f u r t h e r g ro w th o f m e tis te m a tic t i s s u e i s s to p p e d an d o n ly e l o n g a t i o n o f t i s s u e a l r e a d y p r e s e n t ta k e s p l a c e . l i k e le a v e s w ith p r o l i f e r a t e d v a s c u l a r t i s s u e . T h is r e s u l t s i n s t r a p - W hether th e v a s c u l a r t i s s u e i s a c t u a l l y p r o l i f e r a t e d o r m e re ly more p ro m in a n t due to la c k o f parenchym a t i s s u e i s u n d e te r m in e d . S in c e W ardlaw (4 6 ) who f i r s t r e p o r t e d th e phenom ena u s e d th e te rra p r o l i f e r a t i o n th e te rm i s u s e d h e r e . At lo w er c o n c e n tr a tio n s t h e d i s t a l r e g i o n o f th e p rim o rd iu m re m a in s m e r is te m a tic and r e s u l t s in a lo o s e cone o r f u s e d b a s a l le a v e s w ith p r o l i f e r a t e d v a s c u la r t i s s u e . Any s t u d y , t h e r e f o r e , o f th e a f f e c t s o f s u b s t i t u t e d b e n z o ic a c id s on l e a f h i s t o g e n e s i s m ust in c lu d e th e m o rp h o lo g ic a l ag e o f th e p l a n t a s w e ll as th e s t r u c t u r e o f th e c h e m ic a l. 64 SUMMARY 1, S u b s t i t u t e d b e n z o ic a c i d s have two e f f e c t s on p l a n t s . At pH 9 an d w ith o r th o e l e c t r o —p o s i t i v e s u b s t i t u t e d compounds v e g e t a t i v e g ro w th i s a f f e c t e d ; a t pH 7 a n d w ith o r th o e l e c t r o - n e g a t i v e s u b s t i t u t e d compounds r e p r o d u c t i v e g ro w th i s a f f e c t e d . Low pH a f f e c t s b o th v e g e t a t i v e and r e p r o ­ d u c t i v e g ro w th r e g a r d l e s s o f th e ty p e o f s u b s t i t u t i o n . T hese a f f e c t s w ere l i n k e d to th e i o n i c s t r u c t u r e o f th e conpounds a t v a r io u s a c i d i t y l e v e l s . 2, The M uir-H ansch h y p o th e s is o f s u b s t i t u t e d b e n z o ic a c i d m echanism i s a p p a r e n t l y v a l i d f o r r e p r o d u c tiv e g ro w th b u t may n o t be v a l i d f o r v e g e t a t i v e g ro w th . 3, S u b s t i t u t e d b e n z o ic a c id s have th e f o ll o w in g e f f e c t s on p la n ts : 4, 1) i n h i b i t r o o t g ro w th 2) h a s te n d a y s to f lo w e r in g 3) in c r e a s e number o f a x i l l a r y s h o o ts S u b s t i t u t e d b e n z o ic a c id s h ave no e f f e c t on w e ig h t o f a e r i a l p o rtio n s of p la n ts . 5, M o rp h o lo g ic a l ch an g es o f le a v e s o f p l a n t s s p ra y e d w ith sub­ s t i t u t e d b e n z o ic a c i d s can b e e x p la in e d i n te rm s o f l e a f h i s t o g e n e s i s . 65 LITERATURE CITED 1* A u d u s, L. 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