STUDIES OF CATION ABSORPTION BY SOME FLORICULTURE CROPS BY CHARLES WARREN DUNHAM A THESIS S u b m itte d to th e School of G raduate S t u d i e s of M ichigan S t a t e C o l l e g e of A g r i c u l t u r e and A p p l i e d S c i e n c e in p a r t i a l f u l f i l l m e n t of the re q u ire m e n ts f o r the degree of DOCTOR OF PHILOSOPHY Department of H o r tic u ltu r e 19?U ProQuest Number: 10008295 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. uest ProQuest 10008295 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 481 06- 1346 ACKNOWLEDGEMENTS The a u t h o r w i s h e s Doctors Hamner, and s u p e r v i s i o n He i s also Asen, this to e x p r e s s h i s the greatly indebted t o D o c t o r Ma c k D r a k e for his help exchange c a p a c i t i e s acknowledgement i s also due a u th o r's c o m m itte e and t h e staff H orticulture of M ichigan S t a t e College fo r ance and g u i d a n c e , W ildon, Haney, at deter­ of plant ro o ts. to members o f of th e Department of their assist­ Steinbauer, and T e u b n e r . including his valuable in the i n c lu d i n g D octors Kenworthy, The a u t h o r a l s o w i s h e s tioned to i n v e s t i g a t i o n was c o n d u c t e d . the c a tio n G rateful thanks and E r i c k s o n u n d e r whose g u id a n c e the U n iv e r s ity of M assach u setts m ination of sincere to t h a n k ma ny o t h e r s fellow graduate students n o t men­ for their suggestions. Last but not le a s t, the a u th o r is w ife f o r her encouragement during th e vestigation and f o r typing indebted course the m a n u sc rip t. ii of to h i s the in­ C h a r l e s W a r r e n Dunham candidate for the degree of D octor of P h ilo so p h y F in a l exam ination, S e m i n a r Room D issertation: O utline A u g u s t 1 3 , 1951i, 3 : 3 0 A . M . , H orticulture S t u d i e s o f C a t i o n A b s o r p t i o n b y Some F l o r i c u l t u r e Crops of Studies M ajor s u b j e c t : H o r t i c u l t u r e M inor s u b j e c t s : S o i l s , P l a n t P h y sio lo g y B io g ra p h ic a l Items B o r n , May 9 , 1 9 2 2 , Norwich, Vermont U ndergraduate S tu d ie s , Graduate S tu d ie s , Experience: U n iv e rs ity of M a ssa c h u se tts, 191-1-0-L[.3, c o n t . 1914.6 U n i v e r s i t y o f W i s c o n s i n , I 9 I1 6 -I 4.8 M i c h i g a n S t a t e C o l l e g e , 1 9 5>2-5li- R esearch A s s i s t a n t , U n i v e r s i t y of W isc o n sin , I 9 I4-6 -J4.8 , I n s t r u c t o r o f F l o r i c u l t u r e , U n i v e r ­ s i t y of M a ss a c h u se tts , 19U3-^2, Graduate A s s i s t a n t , M ichigan S t a t e C o lle g e , 19^2-9U, U n i t e d S t a t e s A r m y , 9l| .th I n f a n t r y D i v i s i o n , 1 9! | 3 - 1| 6 Me mb e r o f P h i K a p p a P h i , Society iii o f Sigma Xi TABLE OF CONTENTS INTRODUCTION 1 REVIEW OF LITERATURE 3 MATERIALS AND METHODS 12 P lan t M aterial 12 S o lu tio n C ulture 13 S o lu tio n Composition 15 E xp erim en tal Design 16 Growth M ea su re m e n ts and H a r v e s t i n g M ethods 18 A n a l y t i c a l Methods D eterm ination of Roots 18 the Exchange C a p a c ity o f P l a n t 20 The E f f e c t o f E l e c t r o d i a l y s i s Factors A ffecting P l a n t Roots Sources of E rro r C apacity the on P l a n t Roots 21+ Exchange C a p a c i ty o f 28 i n D e t e r m i n a t i o n o f Exchange 29 The E x c h a n g e C a p a c i t y of F r o z e n R oo ts 32 3b RESULTS The C a t i o n Exchange C a p a c ity of P l a n t Roots The E f f e c t o f t h e D i f f e r e n t N u t r i e n t S o l u t i o n s P l a n t Growth and C hem ical C o m p o s itio n o f t h e P l a n t Tops Corn v a r i e t y Golden C ro s s Bantam Snapdragon v a r ie ty Chrysanthemum Stock v a r i e t i e s S p a r t a n Ro s e v a r i e t y W h i t e Mefo Shasta and L a v e n d e r L a r k s p u r v a r i e t y L i g h t Blue iv 3lf on 1+0 1+0 1+2 1+1+ 1+7 1+9 Discussion 52 The R e l a t i o n s h i p B e t w e e n R e l a t i v e C a t i o n E x c h a n g e C a p a c i t y o f P l a n t R o o t s and P o t a s s i u m A b s o r b t i o n 52 The R e l a t i o n s h i p B e t w e e n R e l a t i v e C a t i o n E x c h a n g e C apacity of P l a n t R oots and C alciu m A b s o r p t i o n 56 The R e l a t i o n s h i p B e t w e e n R e l a t i v e C a t i o n E x c h a n g e C apacity of P l a n t R oots and Magnesium A b s o r b t i o n 58 D eterm ination o f the R elative Capacity of P l a n t Roots 61 P ractical A pplications C a t i o n Exchange 61j. SUMMARY 68 BIBLIOGRAPHY 71 v L IS T OF TABLES TABLE 1 TABLE 2 TABLE 3 TABLE k TABLE 5 The M o l a r C o m p o s i t i o n o f t h e D i f f e r e n t N u t r i e n t S o l u t i o n s Employed i n th e Experim ent 17 F a c to r s A f f e c tin g the Exchangeable A c id ity of S w e e t P e a R o o t s a s M e a s u r e d by t h e pH o f t h e S o l u t i o n 21 H o u r s A f t e r 1 0 M i l l i l i t e r s o f . 0 2 N NaOH Was A d d e d 30 The E x c h a n g e C a p a c i t y o f D i f f e r e n t P o r t i o n s o f t h e R o o t S y s t e m o f S w e e t Pea W hic h D iffered in Physiological M aturity R e l a t i v e C a tio n Exchange C a p a c ity o f Roots o f D i f f e r e n t P l a n t S p e c ie s Plant The E f f e c t o f V a r i o u s N u t r i e n t S o l u t i o n s o n th e R e l a t i v e C a tio n Exchange C a p a c ity of P la n t Roots 35 37 TABLE 6 The G r o w t h a s M e a s u r e d b y D r y W e i g h t a n d t h e p e r c e n ta g e Com position of Calcium, P otassium , a nd M ag nes iu m i n t h e Tops o f Co r n V a r i e t y G o l d e n C r o s s B a n t a m Gr own i n V a r i o u s N u t r i e n t Solutions 1+1 TABLE 7 The G r o w t h a s M e a s u r e d b y D r y W e i g h t a n d t h e P e r c e n ta g e C om position of Calcium , P o ta ss iu m , a n d M a g n e s i u m i n t h e To p s o f S n a p d r a g o n V a r i e t y S p a r t a n R o s e Grown i n V a r i o u s N utrient Solutiohs I4.3 The G r o w t h a s M e a s u r e d b y D r y W e i g h t a n d t h e P ercen tag e Com position of Calcium, P otassium , a n d M a g n e s iu m I n t h e Tops o f C h r y s a n th e m u m V a r i e t y W h i t e Me f o Grown i n V a r i o u s N u t r i e n t Solutions 1+5 TABLE 8 TABLE 9 The G r o w t h a s M e a s u r e d b y D r y W e i g h t a n d t h e P e rc e n ta g e Com position of Calcium, P otassium , a n d M a g n e s i u m i n t h e To p s o f S t o c k V a r i e t i e s S h a s t a a n d L a v e n d e r Grown i n V a r i o u s N utrient Solutions 1+8 vi TABLE 10 The G r o w t h a s M e a s u r e d b y Dr y W e i g h t a n d t h e P ercen tag e Composition of Calcium, Potassium , and M agnesium i n t h e Tops o f L a r k s p u r V a r i e t y L i g h t B l u e Grown i n V a r i o u s N utrient Solutions 50 TABLE 1 1 The P o t a s s i u m C o n t e n t o f t h e To p s o f Some P l a n t S p e c i e s With D i f f e r e n t Root C a tio n E x c h a n g e C a p a c i t i e s Gr own i n N u t r i e n t S o l u t i o n s W i t h I n c r e a s i n g P o t a s s i u m Con ­ centrations 55 The C a l c i u m C o n t e n t o f t h e T o p s o f Some P la n t S p e c ie s With D i f f e r e n t Root C a tio n E x c h a n g e C a p a c i t i e s Gr own i n N u t r i e n t S o l u t i o n s W ith I n c r e a s i n g Calcium Concen­ trations 57 The M a g n e s i u m C o n t e n t o f t h e T o p s o f Some P la n t S p e c ie s With D i f f e r e n t Root C atio n E x c h a n g e C a p a c i t i e s Grown i n N u t r i e n t S o lu tio n s With D i f f e r e n t C o n c e n tra tio n s o f C a lc iu m and P o t a s s i u m 60 A R elativ e E valuation of the A vailable P o t a s s i u m Needed i n S o i l by th e P l a n t S p e c i e s S t u d i e d on the B a s i s o f S p e c i e s C haracteristics 67 TABLE 1 2 TABLE 1 3 TABLE 11+ v ii L IS T OF FIGURES Figure I The n u t r i e n t s o l u t i o n c u l t u r e e q u i p m e n t showing the t a b l e w ith the g a l l o n j a r s c o n t a i n i n g the d i f f e r e n t n u t r i e n t so lu tio n s enclosed in a L ig h t- tig h t com partment. Figure II A cu rv e showing th e amount t o m a i n t a i n a pH o f 7 i n t a i n i n g 2 0 0 m l . o f N KC1 w eight of d i a l i z e d sweet Figure III T i t r a t i o n curves of the a c id s d isp la c e d fro m d i a l i z e d and u n d i a l i z e d s w e e t pea r o o t s i m m e r s e d i n N KC1 f o r 30 s e c o n d s and 18 h o u r p e r i o d s i n N KC1. Figure IV D i f f e r e n c e s i n th e g r o w th and t e x t u r e o f corn ro o ts in n u trie n t so lu tio n s w ith d i f f e r e n t pH a n d c a l c i u m c o n c e n t r a t i o n s . v iii of base necessary a so lu tio n con­ and £ gm s. f r e s h pea r o o t s . INTRODUCTION An u n d e r s t a n d i n g o f t h e s e l e c t i v e a b s o r p tio n o f m ineral n u t r i e n t s by p l a n t s I s one o f t h e c h a l l e n g i n g problem s o f p lan t n u tritio n * I n v e s t i g a t o r s h a v e em p loy ed many a p p r o a c h e s i n an a t t e m p t t o s o l v e t h i s problem * I t was i n e v i t a b l e w i t h i n c r e a s i n g k n o w l e d g e o f i o n i c e x c h a n g e , and w i t h t h e p r o m i n e n c e o f e x c h a n g e phenomena i n so il stu d ies, t h a t a t t e m p t s be made t o r e l a t e r e a c t i o n o f p l a n t r o o t s to s e l e c t i v e the exchange absorp tion * v e s t i g a t o r s h a v e b e e n aware o f t h e f a c t Many i n ­ th a t exchange r e a c ­ t i o n s m ig h t be Im p ortant in n u t r i e n t a b s o r p t io n by p l a n t roots* u n til However, t h e r e was no way to t e s t t h e h y p o t h e s i s some means o f e v a l u a t i n g t h e e x c h a n g e c a p a c i t y o f p l a n t r o o t s was d e v e l o p e d * first M attson e t a l (2 9 ) were the t o d e v e l o p a m ethod f o r q u a n t i t a t i v e l y e v a l u a t i n g t h e rela tiv e exchange c a p a c i t i e s o f p la n t r o o ts* Drake (10) and Graham ( 1 6 ) b o t h h a v e d e v e l o p e d m o d i f i e d m e t h o d s f o r use w ith f r e s h t is s u e * The p u r p o s e o f t h i s i n v e s t i g a t i o n was to d e t e r m i n e t h e rela tiv e e x c h a n g e c a p a c i t y o f t h e r o o t s o f some f l o r i c u l t u r e c r o p s and t r y t o r e l a t e c a t io n ab sorp tion * th is A r e l a t i o n s h i p between the r e l a t i v e c h a n g e c a p a c i t y and s e l e c t i v e In p r e d i c t i n g in fo rm a tio n to t h e i r s e l e c t i v e ex­ c a t io n a b s o r p tio n could aid the f e r t i l i z e r n eed s o f f l o r i c u l t u r e 1 crops 2 under v a r y in g s o i l co n d itio n s. I n f o r m a t io n about the a c tu a l n u t r ie n t requirem ents o f f l o r i c u l t u r e crops together w i t h I n f o r m a t i o n a b o u t t h e f e e d i n g pow er o f r o o t s o f these crop s f o r d i f f e r e n t n u t r i e n t elem en ts could aid in a b e t t e r un d erstan d in g of the n u t r i t i o n a l grow ers• problem s o f com m ercial REVIEW OP LITERATURE T h eories o f Ion A bsorption One o f the m ost w i d e l y s t u d i e d tio n in p la n ts i s th eories o f t h e a n i o n r e s p i r a t i o n or s a l t r e s p i r a t i o n t h e o r y o f L u n d e g a r d h (7* 2 J ) . Lundegardh found i n w heat t h a t a n i o n i n t a k e was r e l a t e d to a e r o b i c n e u t r a l s a l t such as potassium c h l o r i d e , p ir a tio n rate ion absorp­ in the c e l l s resp iration * increased A the r e s ­ o f p l a n t r o o t s w i t h a n accompany in g i n c r e a s e in s a l t absorp tion * The f r a c t i o n o f t h e r e s p i a t i o n o f r o o t c e l l s w h i c h was s t i m u l a t e d b y t h e added s a l t , was v e r y s e n s i t i v e to c y a n i d e . C y a n id e i n h i b i t e d b o t h t h i s f r a c t i o n o f t h e c e l l r e s p i r a t i o n and s a l t a c c u m u l a t i o n i n the r o o t c e l l s . Lundegardh co n c lu d e d t h i s was p r o b a b l y t h e c y t o c h r o m e - c y t o c h r o m e o x i d a s e s y s t e m w h i c h was i n v o l v e d . He p o s t u l a t e d t h a t a t t h e cytochrom e s t a g e , hydrogen i o n s , and e l e c t r o n s d e r i v e d from h y d r o g e n atom s o f r e s p i r a t o r y s u b s t r a t e s , were s e p a r a t e d . The c y t o c h r o m e c o u l d p a s s e l e c t r o n s i n one d i r e c t i o n and a n i o n s i n t h e o p p o s i t e d i r e c ­ t i o n thru the cytoplasm o f th e c e l l due t o t h e v a l e n c e c h a n g e o f t h e i r o n atom i n t h e c y t o c h r o m e * hydrogen io n s could p a ss out o f the c e l l The l i b e r a t e d In exch ange f o r ca tio n s. If th is h yp oth esis is v a lid , the q u o t i e n t (eq u ivalen t a b s o r b e d a n i o n s / m o l e c u l e s o f o x y g e n consu m ed) sh o u ld have k a constan t valu e. Sin ce tw en ty -fou r ste p s of e le c tr o n t r a n s f e r are concerned i n the com plete o x i d a t i o n o f g l u c o s e , q ( a n / 0 2 ) s h o u l d h a v e a v a l u e o f I4.. This t h e o r e t i c a l v a lu e was a p p r o a c h e d i n e x p e r i m e n t s w i t h s t o r a g e t i s s u e o f c a r r o t r o o t s b y R o b e r t s o n and W i l k e n s (l|l). L u n d e g a r d h f o u n d much low er v a lu e s f o r the q ( a n /0 2 ) w ith wheat r o o ts . He a t t r i b u ­ t e d p o s s i b l e s o u r c e s o f e r r o r to l o s s o f a n i o n s b y b l e e d i n g o f the e x c is e d r o o t s , p o s s i b l e and o r g a n i c a n i o n s , in d if f e r e n t i n t e r n a l tr a n s p o r t o f m ineral and d i f f e r e n t t y p e s o f a n i o n r e s p i r a t i o n zones o f the r o o t s y s t e m . O v e r s t r e e t and J a c o b s o n (3i|) h a v e r e v i e w e d d i f f e r e n t t h e o r i e s o f i o n a b s o r p t i o n by p l a n t r o o t s and h a v e p r o p o s e d a t h e o r y which th e y f e e l b e s t e x p l a i n s known o b s e r v a t i o n s . A c c o r d i n g t o O v e r s t r e e t and J a c o b s o n , a b s o r p t i o n by r o o t s p lan t tis s u e s i s an i o n i c the f i r s t step in ion exchange r e a c t i o n between and t h e s u b s t r a t e . C a t i o n and a n i o n e x c h a n g e a r e so m e w h a t i n d e p e n d e n t o f e a c h o t h e r , b u t o f a s i m i l a r m echanism . H y dr o gen i o n s o f t h e p l a n t r o o t s a r e e x c h a n g e d f o r c a tio n s o f the s u b s t r a t e . The e x c h a n g e r e a c t i o n i n v o l v e d in an ion exchange i s n o t u n d erstood . connected allow The c e l l v a c u o l e i s t o t h e c u l t u r e medium b y a s y s t e m w h i c h f a i l s to the p a s sa g e o f m in e r a l io n s e x c e p t in c o n n e c tio n w ith an o r g a n i c c a r r i e r . M ineral t o o r g a n i c c a r r i e r s and p a s s the c e l l v a c u o le c a t i o n s and a n i o n s a r e bound thru the c o n n e c tin g l i n k i n t o w h er e t h e y a r e a g a i n r e l e a s e d . The i o n t r a n s p o r t a c r o s s t h e c o n n e c t i n g l i n k and r e l e a s e on t h e 5 In n ersid e in to the c e l l resp iratory rea c tio n s. vacuole i s a c c o m p l i s h e d by c e r t a i n I o n s w h i c h a r e t r a n s p o r t e d by t h e same o r g a n i c compounds i n t e r f e r e w i t h t h e a b s o r p t i o n o f e a c h o ther. S c h u f f e l e n (1^3) a l s o p r o p o s e d i o n e x c h a n g e b e t w e e n t h e p l a n t r o o t s and t h e s u b s t r a t e a s sorp tion . Ion a b so r p tio n i s the f i r s t s t e p i n i o n a b ­ the r e s u l t o f the p h y s i c a l- c h e m i c a l a c t i v i t y o f t h e i o n s on t h e p e r i p h e r y o f t h e r o o t and t h e i o n s o f t h e s u b s t r a t e . cau ses a flow of io n s A d ifferen ce in ion a c t i v i t y to move i n t h e d i r e c t i o n o f t h e r o o t and t h e f l o w i s m a i n t a i n e d by t r a n s p o r t and i n a c t i v a t i o n o f ion s taken in t o the p l a n t . A com p lication of the p rocess i n q u e s t i o n a r i s e s from e x c h a n g e r e a c t i o n s b e t w e e n t h e c e l l w a l l o f t h e r o o t and t h e s u b s t r a t e w h i c h S c h u f f e l e n r e f e r a to as the su r fa c e f u n c t io n . reaction is The s u r f a c e f u n c t i o n o r s u r f a c e o f a n o n - l i v i n g n a t u r e and i s r e g u l a t e d by the c o m p o s i t i o n o f th e plasma o f t h e r o o t w a l l . The c o m p o s i t i o n o f t h e plasma o f t h e r o o t c e l l w a l l s i s h i g h l y im p o r ta n t i n c o n n e c t i o n w i t h a s t u d y o f the s i g n i f i c a n c e o f the Ion r a t i o o f th e s u b s t r a t e In r e l a t i o n to p la n t grow th. The t r a n s p o r t o f i o n s i n t o t h e p l a n t i s r e l a t e d m e t a b o l i s m o f t h e p l a n t and a f f e c t s to the the o v e r a l l i o n i n ta k e by th e p l a n t . E p s t e i n and Hagen ( 1 3 ) h a v e d e r i v e d a t h e o r y , I n many r e s p e c t s t o t h a t o f J a c o b s o n and O v e r s t r e e t sim ila r (3*4-)* fro m o b s e r v a t i o n s o f t h e v e l o c i t y o f t h e a b s o r p t i o n r e a c t i o n 6 of ex cised b arley roots fo r a lk a li c a tio n s . fixed sites They v i s u a l i z e on t h e r o o t c e l l w h i c h b i n d s p e c i f i c C a t i o n s w h i c h c o m p ete f o r t h e same s i t e s ca tio n s. i n t e r f e r e w it h the a b so r p tio n o f each o th e r . C oo p er (8 ) arran ged the s o i l e le m e n ts i n the o r d e r o f d e c r e a s in g standard e le c tr o d e p o t e n t i a l s . He o b s e r v e d t h a t t h e i n t e n s i t y o f r e m o v a l o f i o n s f r o m s o i l c o l l o i d s and p l a n t t i s s u e b y e l e c t r o d i a l y s i s was i n t h e same o r d e r a s t h e i r standard e le c t r o d e p o t e n t i a l s . He o b s e r v e d t h a t t h e a v e r a g e p e r c e n t c o m p o s i t i o n o f a g r e a t many s p e c i e s o f p l a n t s a l s o tends to f o l l o w t h e same g e n e r a l o r d e r o f d e c r e a s i n g s t a n d a r d electro d e p o t e n t ia ls . He a t t e m p t e d t o r e l a t e n u t r i e n t a b s o r p t i o n t o w h a t he t e r m s c a p a c i t y and i n t e n s i t y o f ifche i o n s i n the s o i l . c i t y w o u ld be t h e amount a v a i l a b l e i n t h e s o i l the s o l u b i l i t y o f s o i l m i n e r a l s . a c t i v i t y of the s p e c i f ic related Capa­ to I n t e n s i t y w o u ld be t h e ions r e la te d to th e stan dard e l e c ­ trode p o t e n t i a l s . B reazeale e t al in p lan ts is (6 ) have p ro posed t h a t i o n a b s o r p t i o n an e l e c t r i c a l p la n t ro o ts in response by t h e p l a n t . I o n s m i g r a t e to w a r d t o an e l e c t r i c a l im pulse g en era ted U s i n g t h e p l a n t a s one e l e c t r o d e , a b l e t o show t h a t a l l w hich i s phenomena. th e y were i o n s p o s s e s s a h a l f wave p o t e n t i a l , a b o u t h a l f t h e i r s t a n d a r d e l e c t r o d e p o t e n t i a l , and a t w hich e l e c t r o m o t i v e f o r c e v e l o c i t y r e a c h a maximum. t h e i r c o n d u c t a n c e and m i g r a t i o n 7 Theories K unin and M ey e rs exchange i n (25) d e s c r i b e s e v e r a l in tern al than in t e r n a l cien t t h e o r i e s o f ion The c r y s t a l l a t t i c e to io n exchange between i o n i c surrounding s o l u t i o n . a ttra ctiv e Ion Exchange regard to exchange r e s i n s . theory a p p lie s has l e s s of so lid s The i o n a t t h e s u r f a c e o f t h e c r y s t a l a t t r a c t iv e fo r c e s hold in g i t ion s. and t h e in the l a t t i c e P o l a r m o l e c u l e s , s u c h a s w a t e r , e x e r t an f o r c e on t h e s e s u r f a c e i o n s w h i c h may be s u f f i ­ to d i s l o d g e them from t h e c r y s t a l structure so t h a t a n o t h e r i o n from t h e s o l u t i o n c an e n t e r t h e c r y s t a l l a t t i c e . Th e d o u b l e l a y e r theory of ion exchange, p r o p o s e d by H e lm h o l tz and m o d i f i e d a colloidal particle as p article the a t t r a c t e d thru the are co ntin u ally W hile fied, is the ions. This solution. lattice on t h e e x te n t of Ions atmosphere from th e f r e e ionic particle the solution ionic atm osphere. number o f which must be s a t i s ­ atmosphere of the double l a y e r a n d pH o f the sur­ solution. A third theory of Donnan d i s t r i b u t i o n particle atmosphere th e o ry assumes a f i x e d colloidal the visualizes w a t e r s o f h y d r a t i o n moves w i t h d e p e n d e n t b o th upon th e c o n c e n t r a t i o n rounding ionic exchanging w ith ions of th e the c r y s t a l exchange s i t e s b y Gouy ( 3 0 ) , s u r r o u n d e d by an i o n i c of electrostatically attra c te d along w ith originally is io n exchange a p p lie s to c o l l o i d a l considered systems the n o n - d if f u s ib le the (30). Ion. Theory of The c o l l o i d a l Transfer of 8 ions must occur between tion u n til ed a s of the concentrations activities, different the c o llo id a l are the ions w ith in of a l l m icelle and diffusible ions, s a me i n b o t h p h a s e s . the colloidal m icelle colloidal is attraction specific and t h e l a w s o f Donnan d i s t r i b u t i o n . P l a n t R o o ts and I o n i c Deveux that in (9)* a French plant roots the exhibit r o o ts were chem ist, cation thought th e n pov- particle for the Exchange wa s a b l e to show i n 1 9 1 6 exchange p r o p e r t i e s . to be t h e express­ The r a t i o o r n e d by t h e ion of the the s o l u ­ seat of Pectins th e exchange si te s , M attson e t al f o r determ ining r o o t s were Pea, in dried and t i t r a t e d and b a r l e y r o o t s the o rd e r o f in M attson the 29), were found to 7 1 , 2 9 *5 , the v a le n c e greater have and 2 5 .3 m i l l i e q u i v a l e n t s I t was s u g g e s t e d cations cation-exchange of the attraction exchange capa­ that the cation. occurence (12) i n low c o n c e n t r a t i o n capacity of the have is colloid High exchange c o l l o i d s for divalent the of the r o o t s . a n d E l g a b a l y and W i k l a n d e r shown t h a t a b s o r p t i o n o f of th e A weighed w ith potassium hydroxide. surface layers (28, The i n normal p o ta ss iu m c o n t e n t o f t h e p l a n t r o o t s was due t o of p ectin function to d e v e l o p a method and g r o u n d . was t h e n p l a c e d p e r 100 grams o f d r y w e i g h t . acidoid the f i r s t exchange c a p a c i ty o f p l a n t r o o t s . roots solution rye, cities the electrodialized, amount o f d r i e d chloride (28) were a and show a than m onovalent io n s . 9 M attson e t the addition al (28) observed that in dilute of calcium chloride increased the a b s o r p tio n of p h o s p h o r o u s more w i t h p ea and b a r l e y r o o t s tio n of potassium c h lo rid e . distribution of cations The p r e s e n c e of the of the anions the from th e of the r o o t would a p p ly to the than did They a t t r i b u t e d the m ic e lle s cations acidoid it in allow s external surface. cytoplasm of would be more i m p o r t a n t i n of this While the in regard to addi­ t o Donnan colloids. concentration the r e g i o n these cell, the the ro o t a greater solution solutions, of considerations M attson suggests the pectins in the cell w alls. J e n n y and O v e r s t r e e t governing the able to soil adsorbed the interactions plant cell a d s o rb e d on a s p e c i f i c tio n w ith ions the adsorbed by s l i p p i n g lations. in close systems tion Jenny is t h a t laws m ust be a p p l i c ­ about its the o s c i l l a t i o n cell. colloid. Ions from the The v o l u m e external sm aller o s c illa tio n volumes on th e larger o sc illa tio n between c o llo id w ith the l a t t e r contact overlap, so t h a t and the c o l l o i d systems as soil individual ions solu­ volumes during o s c i l ­ and p l a n t o c c u r so t h a t tend ion to d i s p l a c e the o s c i l l a t i o n volumes ion exchange w i l l of the tend each attraction a constant fo r a p a rtic u la r When two c o l l o i d a l volumes out (2l(.) h a s v i s u a l i z e d as o s c i l l a t i n g a space c a lle d oscillation have p o in te d between c o l l o i d s system s. io n on a c o l l o i d point w ithin of (23) of the the are two oscilla­ to become a minimum. 10 D irect c o n t a c t e x c h a n g e ma y o c c u r b e t w e e n on s o i l colloids process w ithout and t h o s e the the a d s o r b e d on p l a n t exchanged ions passing ions roots thru adsorbed by t h i s the s o il solution# W illiam s root surfaces and Coleman possess t h e l o w e r pH o f natent liquid rounding the to the p la n t ro o ts to t o be e v i d e n c e o f a n i o n i c the s a me change m a t e r ia ls # segment in c lu d in g By r e p l a c e m e n t o f root t h a n more m a t u r e that nature of the and e n l a r g e m e n t w e r e and probably accounted series all of w alls the cation root# probability not for differences in the in a s many e x ­ two m i l l i m e t e r in regions differences th e y were cesium and u s i n g had a h i g h e r regions cell in that tip sur­ the r o o t double type of l y o t r o p i c capacity cells, into super- the hydrogen cations, t h e y showed t h e f i r s t the plant They i n t e r p r e t e d double la y e r Employing r a d i o a c t i v e co rn and bean r o o t s , show t h a t com parison w ith the ro o t su rfaces w ith d if f e r e n t la y e r follow s m ature in show t h a t e n t r y o f c a t i o n s the able exchangeable hydrogen# root surface. on t h e p l a n t able (5>1) w e r e exchange They s t a t e d of c e ll the root surface division s a me a s in epiderm is exchange p r o ­ perties # Drake e t a l number o f economic pl ant roots dialized tion. (10) and determ ined Drake found exchange capacity of and weed c r o p s by e l e c t r o d i a l i z i n g titrating r o o ts were the placed the a the e x c h a n g e a b l e h y d r o g e n when t h e i n normal p o tassiu m c h l o r id e t h a t monocotyledonous plants solu­ had c o n s id e r a b l y 11 low er and cation exchange th a t legum es, cities after as capacities a group, exchange ideas absorption of soil such as of M attson capacity of of the root and E l g a b a l y colloids the are grasses w ith high (16) th re e hours a t 100 v o l t s the p la n t exchange levels in a b s o rp tio n of potassium such as by a h i g h c o n t e n t of and 0 .3 the They f o u n d l i t t l e barley, rye, ature and an i n c r e a s e They a l s o m e a s u re d root surfaces age o f p l a n t s , in an in c r e a s e in for roots difference and w h e a t . The e x c h a n g e c a p a c i t y o f s o y b e a n i n c r e a s e d w i t h a g e o f twelve d a y s ), the calcium , p lan t roots amperes w ith capacity of oats, (betw een f o u r and the exchange c a p a c i t i e s electrodialized tops. that the r a t i o a t low r o o t exchange c a p a c i t i e s characterized Graham a n d B a k e r to favored postulated, (12), determ ines P l a n t s w i t h low r o o t plants, exchange capa­ Drake has o f mono- a n d d i v a l e n t c a t i o n s legum es which a r e attached (29) plants, fertility . over plants in the possessed high among t h e d i c o t y l e d o n o u s the than dicotyledonous plants growing te m p e r­ co n cen tratio n of n u tr ie n t s o lu tio n . the p e r c e n t hydrogen s a t u r a t i o n of th e and found i t varied w ith n u trie n t plant species, treatm ents, and grov/ing t e m p e r a t u r e . EXPERIMENTAL METHODS P lan t M aterial The r e l a t i v e c a t i o n e x c h a n g e c a p a c i t i e s o f r o o t s o f a number o f f l o r i c u l t u r e p l a n t s w e r e d e t e r m i n e d by t h e method o u t l i n e d by Drake (10). P l a n t s were s e l e c t e d f o r a c a t i o n a b s o r p t i o n s t u d y w h o se r o o t s had a r a n g e o f c a t i o n e x c h a n g e ca p a cities and w h i c h a s f a r a s p o s s i b l e w e re o f e c o n o m i c im p o r ta n c e to t h e f l o r i c u l t u r e were u sed : v a r i e t y H. L a v e n d e r , v a riety The f o l l o w i n g p l a n t s snapdragon v a r i e t y Spartan R ose, v a r i e t y W hite M efo, L igh t B lue, industry* stock v a r ie ty Shasta, (a colu m n t y p e ) , ch rysa nthem um (a b r a n c h i n g t y p e ) , and l a r k s p u r v a r i e t y To i n c l u d e a m o n o c o t y l e d o n o u s p l a n t , sw eet corn G o ld en C r o s s Bantam was u s e d * O rdinary c u l t u r a l p r a c t i c e s were f o l l o w e d i n p r o p a g a ­ t i o n and h a n d l i n g o f t h e s e e d p r o p a g a t e d s p e c i e s b e f o r e t h e y were p l a c e d In t h e n u t r i e n t s o l u t i o n s * i n a m i x t u r e o f s c r e e n e d sa n d and s o i l * one to two i n c h e s ta ll, The s e e d s w e r e sown When s e e d l i n g s were un iform p l a n t s were s e l e c t e d , o u g h l y w a s h e d u n d e r t a p w a t e r t o remove s o i l and p l a c e d im ent* thor­ from t h e r o o t s , in the d i f f e r e n t n u t r i e n t s o l u t i o n s o f the e x p e r ­ An e x t r a p l a n t was p l a c e d i n e a c h j a r and removed as soon as t h e p l a n t s became e s t a b l i s h e d , l e a v i n g most un iform p l a n t s . the t h r e e Corn and s w e e t p e a s w ere g e r m i n a t e d i n s a n d and s e e d l i n g s t r a n s f e r r e d d i r e c t l y 12 to the n u t r i e n t 13 so lu tio n c u ltu r es. Chrysanthemum was p r o p a g a t e d by t e r m i n a l s o f t w o o d c u t t i n g s from s t o c k p l a n t s grown u n d e r c o n t i n u o u s lig h t. The c u t t i n g s w e r e r o o t e d i n s a n d and s e l e c t e d p l a n t s t r a n s f e r r e d d i r e c t l y from t h e c u t t i n g be n c h t o so lu tio n s the n u t r i e n t o f the e x p e r im e n t. S o l u t i o n C ulture B ecause the d e t e r m in a tio n o f r o o t exchange c a p a c i t y r e ­ q u i r e d p l a n t r o o t s y s t e m s f r e e from a l l s o i l m a t e r i a l , e n t s o l u t i o n c u l t u r e was em ployed* hold t h i r t y - f o u r w ide-m outh g a l l o n j a r s w ere f i t t e d n u tri­ A t a b l e was c o n s t r u c t e d to jars. (F igu re I . ) * The i n t o a c o v e r o v e r t h e t a b l e so t h a t the n u t r i e n t s o l u t i o n s were i n a l i g h t - t i g h t compartment to p r e ­ v e n t the grow th o f a l g a e . 3* 6 l i t e r s Each j a r was c a l i b r a t e d of n u trien t so lu tio n . to h o l d P l a n t s w e r e s u p p o r t e d by n o n - a b s o r b e n t c o t t o n p a c k e d ar o u n d t h e s t e m s i n s i d e o f one i n c h d i a m e t e r r u b b e r t u b i n g w h i c h was f i t t e d d r ille d in to the jar l i d s . A eration o f in to h oles t h e s o l u t i o n s was a c c o m p l i s h e d b y a q u a r iu m a e r a t i n g stones^*and by s e c t i o n s of p la stic n eed le. t u b i n g p e r f o r a t e d on t h e end w i t h a d i s s e c t i n g The a i r l i n e i n t o e a c h j a r was r e g u l a t e d by a s c r e w cla m p and a c o n t i n u o u s f l o w o f a i r was b u b b l e d t h r u a l l tion s at a ll tim es. so lu ­ S o l u t i o n s w e re m a i n t a i n e d a t c o n s t a n t v o l u m e by f r e q u e n t a d d i t i o n s o f d i s t i l l e d w a t e r . ^-Purchased fro m Wards B i o l o g i c a l E s t a b l i s h m e n t o f R o c h e s t e r , New Y o r k . ib Figure X The n u t r i e n t s o l u t i o n c u l t u r e e q u i p m e n t s h o w i n g t h e t a b l e w ith the g a llo n j a r s c o n ta in in g the n u t r i e n t s o lu tio n s enclosed i n a l i g h t - t i g h t com partm ent. 15 Solution The n u t r i e n t ( 2 1 ) was u s e d s o lu tio n developed f o r as a s ta n d a rd s o l u t i o n potassium v a rie d stant from as p o s s i b l e . ratios Once p l a n t s this w ith a ll the d i f f e r e n t were p la c e d to have l i m i t e d were renewed. absorption and th e was r e d u c e d In could ratio a s was p r e s e n t to it In In order w ithin the the p l a n t solution solution, containing solutions if the the r a t i o of a t which grow th With the f i r s t series of plants th e low c a lc iu m and low p o ta s s iu m to d i s t i n g u i s h between the a n d l o w p H, the s e r i e s cium and p o t a s s i u m a t ammoni um n i t r a t e the low est c o n c e n tra tio n t h e a d d e d ammoni um n i t r a t e to added. s ame c o n c e n t r a t i o n o f n i t r o g e n standard and low p o t a s s i u m , th en added nutrient and p o t a s s i u m a v a i l a b l e t w e e n 3 a n d [j. w h i c h wa s v e r y d e t r i m e n t a l was treatm ents, i t was d e s i r e a b l e t h i s manner, b o t h was o b s e r v e d t h a t so lu tio n w ith calcium calcium -potassium treatm ents. grew, however, of calcium and p o ta ssiu m . grown, as n e a r c o n ­ be a s c e r t a i n e d . in the the o f c a l c i u m and n o t have been p o s s i b l e o r d e r to m a i n t a i n wa s a d d e d the in the d if f e r e n t amounts o f c alciu m p l a n t s which would solutions in ions t h a t c o m p o s i t i o n a n d pH o f t h e would change as t h e p l a n t s the and r a t i o s were n e i t h e r renewed n o r a d d i t i o n a l I t was r e a l i z e d to t o m a t o e s by H o ag lan d other Wide v a r i a t i o n s were used in solutions Composition of d e v e l o p e d a pH b e ­ t o s o me s p e c i e s . effects a seventh o f low solution t r e a t m e n t s which had c a l ­ t h e same c o n c e n t r a t i o n as t h e standard 16 Hoagland. s o l u t i o n , but one-fourth of the n itro g en supplied b y ammo ni u m i o n s . All had the of the nutrient solutions potassium (21) except for iron* e th y le n e diam ine tetra-acetate Jacobson solution contained approxim ately m etallic iron. experim ent is (22). The c o m p o s i t i o n given in Table block co n sisted o f one jar of 5 per Each l i t e r of o f v a r i a n c e was u s e d cent le v e ls . the of n u t r i e n t solutions employed i n the Design to plants three Each f o r each t r e a t ­ tim es. analyses of for each re p lic a te between to 5 p a rts per m illio n of three The d r y w e i g h t a n d c h e m i c a l differences according by f e r r i c t h e e x p e r i m e n t was a r a n d o m b l o c k . and b l o c k s w ere r e p l i c a t e d were d e te rm in e d recommended by 1. Experim ental Th e d e s i g n o f the experim ent I r o n wa s s u p p l i e d recommendations of A nalysis in s a me m i c r o n u t r i e n t c o m p o s i t i o n a s Hoagland ment, used the p l a n t s of each tre a tm e n t. determ ine significant t r e a t m e n t means a t t h e 1 p e r c e n t and 17 TABLE 1 THE MOLAR COMPOSITION OF THE DIFFERENT NUTRIENT SOLUTIONS EMPLOYED IN THE EXPERIMENT 1 2 Treatm ent 9 KNO3 Low Ca:Low K S a l t s E x p r e s s e d as Mol e s / L i t e r x 1 0 “ -^ C a (NO3 >2 KH2 P0 ^ MgSo^ K2 S 0 ^ nh^no^ h 1+ 8 Low C a:H lg h K k9 b k 8 1 H o a g la n d 20 20 b 8 H ig h CarLow K 30 k 8 H ig h C a : H ig h K 30 b 8 60 12 2k 20 it- 8 60 3 H oagland 1 H o a g la n d NHj^ ■^M icronutrients 26 12 10 10 s u p p l i e d by H o ag lan d m i c r o s o l u t i o n A ( 2 1 ) . ^ I r o n s u p p l i e d by f e r r i c p o t a s s i u m t e t r a - a c e t a t e . 01; g r a m s / l i t e r . ethylene diamine IS Growth M e a s u r e m e n t s and H a r v e s t i n g M eth ods Dry w e i g h t o f p l a n t P l a n t s were h a r v e s te d were h a r v e s t e d t o p s was u s e d and grams change capacity. of roots for the It ch an g es w i t h age plant that (I4.8 ) , the root ex­ forty- on a T o r s i o n b a l a n c e a gram. the n u t r i e n t however, s p e c i e s was d e s i r e d furnish 70° 0 , f o r Dry w e i g h t s were d e t e r m i n e d wa s r e a l i z e d to Plants in p e r f o r a t e d p ap er bags a d r y in g oven a t the n e a r e s t hundredth of growth. from r o o t s . determ ination of Tops w e r e p l a c e d and i m m e d i a t e l y p u t i n t o to separated evaluate when r o o t g r o w t h was s u f f i c i e n t 7 5 -1 0 0 eig h t hours. tops to com position of p la n ts a com parison between d i f f e r e n t and i t was f e l t between d i f f e r e n t s p e c i e s w ould be o f slig h t variations in physiological that differences such magnitude age a t that time o f h a r v e s t c o u l d be n e g l e c t e d . All c r o p s were in the v e g e ta tiv e e x c e p t s n a p d ra g o n w hich had v i s i b l e c o n d i t i o n when h a r v e s t e d flow er buds. A n a l y t i c a l Methods Calcium, was d e t e r m i n e d terial by f l a m e was g ro u n d screen. 70^ c . potassium , in The g r o u n d overnight, and magnesium c o n t e n t of p l a n t spectrophotom etry. a Wiley M ill t i s s u e was p l a c e d cooled in a m uffle furnace in In a d is s ic a to r weighed in p o r c e l a i n c r u c i b l e s . ashed to p a s s at tissue D r ie d p l a n t ma­ t h r u a 20 m e s h a d r y in g oven a t and one gram s a m p l e s The w e i g h e d s a m p l e s w e r e 5 5 0 ° C. f o r ten hours. The d r y 19 a s h was d i s s o l v e d Perchloric the l e a s t a slight excess of perch lo ric a c i d was u s e d b e c a u s e H i n s v a r k e t amount o f spectrophotom etric filtered in interference flasks determ inations. a n d ma d e t o (20) from p e r c h l o r a t e t h r u a Whatman # 2 f i l t e r volum etric al The m a t e r i a l paper into acid. found ions wa s in then 100 m i l l i l i t e r volume. C a l c i u m a n d p o t a s s i u m w e r e d e t e r m i n e d w i t h a B e c k ma n Model B spectrophotom eter using acetylene wa s d e t e r m i n e d on t h e using hydrogen as f u e l . Standard the ion to samples give be d e t e r m i n e d u s i n g c a r b o n a t e by excess trial to p ro v id e spectrophotom eter salts of perch lo ric a c id . and com parison w ith th e a standard readings w ithin sam ples. B e c k m a n M o d e l D. U. This p o r t i o n Maximum r a n g e wa s d iffere n t plant c u r v e w h i c h c o u l d be u s e d the m iddle t wo t h i r d s for w i t h i n one duplicate to the p l a n t o f t h e c u r v e was a s t r a i g h t l i n e Sam ples were a n a ly z e d u n t i l of neutralized c a l c i u m and magnesium and f o l l o w e d a sm ooth cu rv e sium. Magnesium c u r v e s w e r e made f r o m known c o n c e n t r a t i o n s w ith a s li g h t selected as f u e l . for fo r potas­ readings agreed transm ission u n it. Th e o n l y i n t e r f e r e n c e w h i c h was o f s u f f i c i e n t m a g n i t u d e to w a r r a n t c o r r e c t i o n was t h e m is s io n due interference to in potassium . increase A standard i n magnesium t r a n s ­ curve f o r potassium t h e magnesium d e t e r m i n a t i o n s was e s t a b l i s h e d f r o m known a m o u n t s made a c c o r d i n g l y . of potassium and m agnesium and c o r r e c t i o n s 20 D eterm in atio n of The r e l a t i v e the Exchange C a p a c i ty o f P l a n t R oots catio n exchange cap acity of th e was d e t e r m i n e d b y t h e m e th o d d e v e l o p e d by D r a k e s lig h t m o d ificatio n s. p la n t ro o ts (10) w i t h The d e t e r m i n a t i o n w a s c a r r i e d out as f o llo w s : 1. The l o w e r tw o -th ird s washed in ta p w a te r and th e c o a r s e s t r o o ts The r o o t s were b l o t t e d $0 gram s r o l l e d w ith 2. e la stic of in cheese a t e a c h end o f th en p la c e d a M attso n d i a l i a i n g d istille d t h e p l a n t r o o t s y s t e m was dry w ith a paper lo o sely bands The r o o t s w e r e of w ater. in cell the clo th rem oved. tow el and and s e c u r e d the r o l l . cen ter and th e The M a t t s o n c e l l cell com partm ent fille d was c o n n e c t e d 15$ v o l t s o u rc e o f d i r e c t c u r r e n t . The c e n t e r c a th o d e co m p artm e n ts w ere f l u s h e d f r e q u e n t l y b eg in n in g of the d i a l y s i s n o t ex ceed 2 am peres c e e d l4,0 ° C . u n til near .1 am pere w i t h i n 3. The r o o t s req u ired m o istu re a t the am perage d id the The d i a l y s i s am perage f a i l e d p erio d . to exceed The c o m p l e t e a b o u t $0 m in u te s . th at co n ten t. and c o m p a r t m e n t was n o t f l u s h e d w ere th e n c e n t r i f u g e d and so the to tem p e ra tu re did n o t ex­ a f iv e m inute a t 2000 r e v o l u ti o n s -m o istu re th at end o f t h e d i a l y s i s . was c o n t i n u e d u n t i l d ialy sis and t h e The a n o d e th e so w ith p er m inute for to f iv e m inutes remove e x c e s s th e y w ould h av e a uniform 21 1+ ♦ A f i v e the gram sam p le ro o ts ch lo rid e u sin g a b e a k e r w i t h 200 m i l l i l i t e r s c h lo rid e . th e titratio n to in potassium to a pH o f S ince tim e, 7 the f iv e m inu tes p laced any sm all to in the A mat o f l a r g e r bottom o f broken p ie c e s . the b e a k e r, the cru cib le The r o o t s w e r e covered w ith d i s t i l l e d w a t e r w i t h a few d r o p s o f 1 : 3 h y d r o c h l o r i c acid and l e f t in w eighed o v ern ig h t. and o v e n - d r i e d p laced They w e r e Gooch c r u c i b l e , The d r i e d at th en p la c e d washed w ith d i s t i l l e d r o o ts w ere by th e u s e th e n rem oved from to c o o l . Dry w e ig h ts w ere b alan ce. The e x c h a n g e c a p a c i t y w a s c a l c u l a t e d from th e used in the the l e n t s /1 0 0 w ater th e o v e n and of an a n a l y t i c a l w eight o f a o 70 C . f o r t w e n t y - f o u r h o u r s . in a d is s ic a to r o b tain ed end a Gooch c r u c i b l e w h ic h a su ctio n f la s k . was f i r s t then re tu rn e d 7. i n a 1*00 co n v en ien ce. attach ed to r e t a i n from o f norm al and th e changed w ith The r o o t s w e r e t h e n p l a c e d ro o ts 6. The r o o t s .0 2 n o rm a l sodium h y d r o x id e . was u s e d f o r was was t a k e n and p l a c e d s o l u t i o n was t h e n t i t r a t e d p o in t of 5# gram) .1 t h a t w ere c e n tr ifu g e d m illilite r potassium (w ith in ro o ts, titra tio n the m i l l i e q u i v a l e n ts dry o f base and e x p r e s s e d as m i l l i e q u i v a - grams o f d r y r o o t s . 22 M o d ificatio n s of co n v en ien ce. o f D rake*s p r o c e d u r e w ere l a r g e l y C h e e s e c l o t h was e a s i e r v isk in g bags. ing anode com partm ent a f t e r the cru cib les The d i a l y s i s elim in ated the p o ta ssiu m c h lo rid e so lu tio n th a t of the Gooch c r u c i b l e s the dry r o o ts son w ith in place th at be sh ifts of the p o tassiu m its w e ig h t from t h a t by u s i n g sm all t h e l a r g e Lj.00 m i l l i l i t e r titra te d from tim e k eeping beakers, the amount o f i n i t i a l as f a s t as seemed sodium h y d r o x id e to be d e r i v e d II). acid i­ could from e q u i ­ r o o t s a n d was v e r y s m a l l i n c o m p a r i ­ volum e. F iv e m in u tes proved i n w hich to t i t r a t e and t h e p lo ttin g m illilite r s t h e pH a t 7 ( S e e F i g u r e t h e r e was a l a r g e the o r i g i n a l n atan t liq u id evap orating a l s o was f e l t F u rth e r a c id ity co n v en ien t surface. It tim e w h ile ty w hich co u ld lib riu m of a c c u ra te ly p ip e ttin g c u r v e s were o b t a i n e d , of base v ersu s be a d d e d . so lu tio n , E m p l o y i n g Gooc h c o u l d be w e ig h e d more a c c u r a t e l y . T itratio n I t was f o u n d each ru n . to d ry n e s s and s u b t r a c t i n g ro o ts. th a n the tim e was s h o r t e n e d by n o t f l u s h ­ th e n e c e s s ity c h lo rid e to h a n d le a m atter read ily to be a the acid ity of the super­ av ailab le acid ity of the root 23 .20. 1 8 1- NaOH ADDED . 1 6 j- 12 10 06 02 - 0 1 2 6 3 7 8 9 10 TIME IN MINUTES F ig u re II A c u r v e s h o w in g t h e am ount o f b a s e n e c e s s a r y to m a i n t a i n a pH o f 7 i n a s o l u t i o n c o n t a i n i n g 2 0 0 m l . o f N KC1 a n d 5 gms • f r e s h w e i g h t o f d i a l i z e d s w e e t pea ro o ts * 2k E ffect of D ia ly sis on P l a n t H oots The p l a n t r o o t s w e r e d i a l i z e d exch an g eab le b ases and le a v e the in order to rem ove a l l exch an g e com plex s a t u r a t e d w ith hydrogen io n s . S h rin k ag e of th a t the cell absorbed catio n s. d ialized ro o ts o u ter la y e rs the sap of th e the the cell exam ination of s e c tio n s o f the titra tio n ro o ts len d s th at cell c o n s t i u e n t s w ere rem oved i n F ive gram s o f b o th d i a l i z e d liq u id in filte re d a second of stro n g acid s. of p o tassiu m root to the 30 seconds 30 s e c o n d s and t h e n and t i t r a t e d . ro o ts and ch lo rid e show t i t r a t i o n the rap id ity o th er (See F i g u r e III). ch lo rid e sup ern atent and l e f t curves in acid d ialized of f o r 18 h o u r s , titra te d . on t h e The l a r g e r v o l u m e o f the the sw eet pea r o o t s the su p ern aten t liq u id im m ersion o f to The r o o t s w e r e t h e n p l a c e d f o r hydrogen io n s in d icated of d ia liz e d o f norm al p o ta ssiu m second 18 h o u r im m ersio n i n so lu tio n s the the d i a l y s i s T h is w ould be e x p e c te d io n s co llo id s. first for and t h e Th e d i a l i z e d in and p o s s i b l e and u n d i a l i z e d volum e o f p o t a s s i u m again f i l t e r e d curves sap o f the v acuole off the c e l l s f u r t h e r ev idence i n 200 m i l l i l i t e r s stirre d in d icated v a c u o l e was rem oved a l o n g w i t h fact so lu tio n , process co rtex . sw eet pea w ere im m ersed d ialy sis showed a d i s a r r a n g e m e n t o f of the in M icroscopic A com parison of u n d ialized ro o ts ch a ra c te ristic a sim ple exchange surface of the d i s p l a c e d by th e ro o ts com pared the p o tassiu m ch lo rid e th e exchange r e a c tio n . T his r a p i d e x c h a n g e w ould be p o s s i b l e of th e p la n t tre atm e n t. so lu tio n th at eq u ilib riu m sh ift of to th at change w ith in the the d isp laced how ever, as the the tim e. to keep sh arp ly ch lo rid e titra tio n , system . N eu tral­ cau sed an e q u i l i b r i u m from the to d i s p l a c e . t h e c u r v e w h ic h was u s e d o f th e p la n t ro o ts ro o t exchange of This a s s u m p tio n cap acity sodium h y d r o x id e the pH o f t h e as th e easily resu lts of p la n t ro o ts w hich to conduct T his makes in m easuring by s e l e c t i n g the (See off to a v e ry g r a d u a l i t p o ssib le the r e l a t i v e a d e fin ite titra tio n . The c u r v e d is p la c e d hydrogen io n s th e h y d r o g e n i o n s become m ore d i f f i c u l t d u ceab le in added were s o l u t i o n a t 7* but then le v e ls c o llo id s. to Enough b a s e was ad d e d a t one m i n u t e at firs t n eu traliz ed , root to be d i s p l a c e d the t i t r a t i o n M illilite rs ag ain st in te rv a ls are ch lo rid e hydrogen io n s shape o f in the d e te r m in a tio n of p lo tted the p o ta s s iu m the rem ain in g hydrogen io n s on the r o o t c o llo id s e l e c t an end p o i n t II). the d i a l y s i s th e d i s p l a c e d h y d ro g e n io n s were n e u t r a l ­ w ould a c c o u n t f o r t h e F ig u re the p e r m e a b ility and h y d ro g en io n s w ere in an d a l l o w e d m ore h y d r o g e n to As in tim e p r i o r ro o t-p o tassiu m w ere p r o g r e s s i v e l y h a r d e r rises t h e pH o f th e potassium root c o llo id s . ized, had been d e s tro y e d The f a c t fa ile d in d icated izatio n cells only i f slo p e to d isp lace from to o b tain rep ro - exchange c a p a c ity tim e i n t e r v a l in 0 1____________ I____________ I_____ _ _____ I __________ I_____ .02 .Oil.06 .0 8 .10 M. E . NaOH ADDED F ig u re III T i t r a t i o n c u r v e s o f th e a c i d s d i s p l a c e d from d i a l i z ­ e d a n d u n d i a l i z e d s w e e t p e a r o o t s i m m e r s e d f o r 30 s e c o n d a n d 1 8 h o u r p e r i o d s i n N KC1. x - d ia liz e d ro o ts placed i n N KC1 f o r 30 s e c o n d s , x-, - s a m e s a m p l e s p l a c e d i n N KC1 f o r 1 8 h o u r s , y - u n d i a l i z e d r o o t s p l a c e d i n N KC1 f o r 30 s e c o n d s , y ^ - s a m e s a m p l e s p l a c e d i n N KC1 f o r 18 h o u r s . HC1 - h y d r o c h l o r i c a c i d . 27 Th e s e c o n d t i t r a t i o n cu rv e,(S ee F ig u re when t h e d ialized r o o t s w ere reim raersed in c h lo rid e so lu tio n for curve. T h is w ould 18 h o u r s , in d icate sa p w ere n o t in v o lv e d The tire ly titra tio n d ifferen t h o u r im m ersion second curves for in the for the u n d ia liz e d 30 s e c o n d s as ch lo rid e curve f o r is by W i l l i a m s type in to the (33) seeds a t stu d ied resu lt tio n g erm in a tio n . curve. (5 l) as ev id en ce The the p o ta ss iu m the type curve s a p a c i d i t y was e n t e r i n g potassium q u an tity d ialy sis, e ffe c t of of concluded from of bases the s e e d s . Loss of before than a c id s and p o s t u l a t e d surface anions the s e e d s was a r e d u c ­ the e f f e c t on g e r m in a ­ by s o m e t h i n g o t h e r t h a n t h e th at of the w hich c o u ld rem oval o f the power o f g e rm in a ­ any g r e a t amount o f c a lc iu m , o r m agnesium was re m o v e d . on th e tio n w ith e l e c t r o d i a l y s i s on o .I| a m p e r e s , a n d 2L|_ C. The m o s t N elly t i o n was m a r k e d l y r e d u c e d sorbed The 30 ro o t surface. This i s cell of e le c tro d ia ly sis t i o n was c a u s e d ele c tro ly te s the 80-15>0 v o l t s , obvious in the t h e 18 reactio n . N elly pea if to titratio n and C olem an type c u r v e . t h a t w ould be e x p e c te d the c e l l so lu tio n . th e 18 h o u r im m ersion i n a buffered type r o o t s w ere e n ­ compared o f e x c h a n g e a b le h y d ro g e n on th e e x t e r n a l titra tio n of acid titra tio n . a stro n g ac id T h i s was i n t e r p r e t e d th e potassium acids the p o ta s s iu m c h l o r id e im m ersion i s obtained was a g a i n a s t r o n g th a t organic in th e III), N elly removed from the catio n s p ro to p lasm not pass observed the seeds w ere o r were th ru the a rreater durin g eith er ad­ in com bina­ cell rtem branes. 28 S eifriz current (I4.I4.) s t u d i e d th ru fru it breakdow n o f the b l a c k mass w i t h the cause e f f e c t of p assin g and v e g e t a b l e tissu e a t the a uniform o c c u r r e d when th e b u ted the tissu e tissu e. cathode of d egen eration by enzymes r e n d e r e d a c t i v e to by th e He o b s e r v e d a to a d a r k brown to pH o f 1 2 . 2 . was p l a c e d en e l e c t r i c Ho s u c h r e a c t i o n a t th e anode. He a t t r i ­ breakdow n o f th e p r o t e i n red u cin g c o n d itio n s of the cath o d e. F acto rs A ffectin g The e f f e c t s ch lo rid e acid ity tilled of so lu tio n , E x c h a n g e C a p a c i t y of. P l a n t R o o t s freezin g , w ater, b lo tted dry, I4.OO m i l l i l i t e r Ten m i l l i l i t e r s p ip etted in to and t h e pH o f then each in crease of th e th e in .0 2 norm al in in acid ity titratab le the or d is tille d treatm en t (See T a b le 2 ) . for to stan d from recorded. the r o o ts frozen T h is m i g h t be e x p l a i n e d of the ro o ts the f r e e z i n g and over the ro o ts the then ov ern ig h t due to so lu tio n . in the by an a d iso rg an izatio n thaw ing p r o c e s s . The f r o z e n i n w a t e r w ould th e d isp la c e m e n t of adsorbed hydrogen of p o tassiu m w a t e r and s o d iu m h y d r o x i d e was e a c h s o l u t i o n was so lu tio n . in d is ­ gram s a m p le s w e ig h e d b e a k e r and a llo w e d p erm eab ility cytoplasm in crease due to ch lo rid e to ta l and c o v e r e d w i t h 200 m i l l i ­ ch lo rid e T he l o w e s t pH w a s r e c o r d e d p o tassium on t h e and fiv e a c c o rd in g to of and o f p o t a s s i u m The r o o t s w e r e w a s h e d beakers o f norm al p o ta ss iu m fro zen o r b o iled b o ilin g w ere o b s e rv e d of sw eet pea r o o t s . out in to lite rs th e The e f f i c i e n c y the r o o ts be by of potassiu m 29 in d isp la c in g th e h y d ro g e n from s e e n from t h e h i g h pH o f p o tassium ch lo rid e a f t e r b e i n g f r o z e n and po tassiu m c h lo rid e so lu tio n . B o ilin g the ro o ts the the r o o t c o l l o i d s ro o ts reduced w hich w ere washed w ith the s u p e r n a t e n t s o l u t i o n when com pared ro o ts. T h is m i g h t be due p e rm eab ility of th e o r on th e c h e m i c a l co u ld also reduce to cells, 70°C, tio n , able and acid ity to and u n f r o z e n frozen the root c o llo id s. (2 9 ) was a b l e by f i n e l y and o v e n - d r i e d fa ile d to ch lo rid e the exchange the tissu e at so lu ­ show a n y m e a s u r e - T his w ould i n d i c a t e had been d e s tro y e d g rin d in g B oiling acid . the r o o ts to d e te r m in e the by d r i v i n g o f f v o l a t i l e t h e n im m ersed i n n o rm a l p o ta s s iu m exchange c a p a c ity . in e f f e c t o f b o i l i n g on th e sw eet p eas w ere d i a l i z e d A f t e r JL p Q h o u r s , the amount o f th e m easured a c i d i t y of the r o o t c o llo id s ro o ts thaw ed i n upon c o a g u l a t i o n o f th e p r o t e i n s , co m p o sitio n of compounds s u c h as c a r b o n i c R oots o f the c a n be the p e r m e a b i l it y in d ry in g , M attson c a p a c ity of d rie d and em ploying s e r i a l titra tio n s• Sources o f E rro r i n D e te r m in a tio n o f th e Exchange C a p a c ity D ifferen ces in p h y sio lo g ic a l m atu rity cause v a r ia tio n s W illiam s of in and Colem an exchange for T h is w ould be the the th e m easured (51) w ere tip reg io n the ro o ts exchange c a p a c i t i e s , able p o rtio n s of to show th e h i g h e s t r a t e o f b e a n and c o r n r o o t s . i n w hich th e e p i d e r m i s was l e a s t 30 TABLE 2 FACTORS AFFECTING THE EXCHANGEABLE ACIDITY OF SWEET PEA ROOTS AS MEASURED BY THE pH OF THE SOLUTION 21 HOURS AFTER 1 0 M IL LILITE RS 01* . 0 2 N NaOH WAS ADDED S u p ern aten t L iquid pH N KC1 7.33 2. F rozen N KC1 6.66 3. F r o z e n and w ashed w i t h t h e KC1 N KC1 9 .56 k. Frozen H2° 7.14-8 5* B o i l e d N KC1 9.32 6. N KC1 9.70 Treatment*'** 1. U n treated ro o ts B o ile d and w ashed w i t h t h e KC1 **A11 s a m p l e s w e r e $ g r a m s f r e s h w e i g h t a n d i n 200 m i l l i l i t e r s o f s u p e r n a t e n t l i q u i d . 31 developed for and th e en tran ce of In tra -c e llu la r Io n s from Sweet pea r o o ts cu ltu res in g of after reg io n s w ere h a r v e s te d m id d le, f o r both th e from n u t r i e n t three of the placed o f sodium h y d r o x i d e 2lf h o u r s . d ialized R esu lts ro o ts for ch lo rid e , root the shown i n three The T able r o o ts were and an e x c e s s Th e s o l u t i o n w a s b a c k are c o n sist­ w as d e t e r m i n e d by The u n d i a l i z e d potassium added. the and u n d i a l i z e d r o o t s . p rev io u sly . i n norm al so lu tio n p o rtio n s and u pper re g io n s o f d ialized th e m ethod d e s c r i b e d after so lu tio n . T h e e x c h a n g e c a p a c i t y w as d e t e r m i n e d exchange c a p a c ity washed, the e x t e r n a l one m onth and c u t i n t o th e lo w er, system . s p a c e s were m ost a c c e s s i b l e titra te d 3. TABLE 3 THE EXCHANGE CAPACITY OF DIFFERENT PORTIONS OF THE ROOT SYSTEM OF SWEET PEA WHICH DIFFERED IN PHYSIOLOGICAL MATURITY D i s t a n c e From R oot Tip In I n c h e s D i a l i zed*'5. U n d i a l i z e d " ' 5, 0-3 39.86 1+26.0 3 -k 3U.38 367.0 6-9 28 .?5 268.0 '^ E x p re sse d a s m i l l i e q u i v a l e n t s / 100 grams o f d r y w e i g h t . 32 A lthough, b o t h d i a l i z e d same tren d for an i n c r e a s e reg io n n e a re s t the and u n d i a l i z e d In the grow ing t i p , ro o ts. ev id en ce in creases th at d ia ly sis by d i s r u p t i n g resu lted the in lo ss cytoplasm of change c a p a c ity o f due to the the in sap. more m a t u r e r e g i o n s o f t h e a g reater w ould te n d to decrease the grow ing A nother the r o o t The d e c r e a s e r o o t system In of e rro r ro o ts nearest reac tio n . t h e n be per The be e x p e c t e d to in reg io n s sim ila r No a n s w e r h a s so me d i a l y s e s . certain the to th at rep o rted b ecam e brow n and d i s c o l o r e d gave a l k a l i n e to the the e n c o u n t e r e d was a b reak d o w n o f d u rin g d ia ly s is so lu tio n . o th e r crops ex­ tip . pH r e a d i n g w h e n p l a c e d S h asta could r o o t com pared to caused a b asic v ariety the and im m a tu re c e l l s . The r o o t s occurred in re g io n s m ight S eifriz only ro o ts c o r t e x w hich th e m easured exchange c a p a c i ty o f of th e source tissu e c h lo rid e of the the d ry w e ig h t p e r u n i t o f f r e s h w e ig h t w hich m ore m a t u r e r e g i o n s nearer cells of the c o n te n t o f exchange m a t e r i a l u n i t o f d ry w eig h t betw een m atu re have the w as a c c e n t u a t e d the p e r m e a b ility th e m ore m a t u r e d ifferen ce d ifferen ce for T h is m ig h t be ta k e n as f u r t h e r of the cell showed th e exchange c a p a c ity the m ore by t h e u n d i a l i z e d ro o ts runs in the been found Two s e p a r a t e pH r e a d i n g s occurred and potassium as t o why t h i s crops of from a l l sto ck tre atm e n ts. in w hich p a r t o f c a th o d e w ere d i s c o l o r e d by and b a s i c the in 33 The E x c h a n g e C a p a c i t y o f F r o z e n R o o t s R o o ts o f s w e e t p e a s w ere f r o z e n and year. ly Th e e x c h a n g e h arv ested le n ts sto red c a p a c i t y wa s d e t e r m i n e d sw eet pea r o o t s . A v alu e p e r 1 0 0 g ra m s was o b t a i n e d 37.1+1 m i l l i e q u i v a l e n t s for f o r one along w ith fresh­ of i;2 .0 m i l l i e q u i v a - th e fro z e n r o o ts , and p e r 100 g r a m s . f o r f r e s h l y h a r v e s t e d roo t s . An a t t e m p t w a s m a d e t o of the p l a n t r o o t c o l l o i d s io n s in stead then thaw ed of in 5 m illilite rs allow ed to Th e r o o t s d isp lace the adsorbed c a tio n s by th e m ass a c t i o n the u s u a l d i a l y s i s . 200 m i l l i l i t e r s The r o o t s w e r e f r o z e n , of d i s t i l l e d o f norm al h y d r o c h lo r ic stan d w ith o ccasio n al i n norm al p o ta ssiu m cap acities of 5 1 . 3 # 5 0 .2 , to w hich stirrin g ch lo rid e t h i r t y m in u tes. w ater, cen trifu g ed , so lu tio n . and 2 8 .3 m i l l i e q u i v a l e n t s 100 gram s w ere o b t a i n e d f o r dragon r e s p e c ti v e ly . w ater a c i d was a d d e d a n d w ere th e n washed i n d i s t i l l e d and p la c e d of hydrogen sto ck , sw eet p eas, Exchange per and s n a p ­ RESULTS The C a t i o n E x c h a n g e C a p a c i t y o f The r e l a t i v e catio n exchange c a p a c it ie s o f a number o f f l o r i c u l t u r e The e x c h a n g e of C ollege (See of d if f e r e n t p la n t sp ecies from a h ig h o f 1 0 1 .8 7 m i l l i e q u i v a l e n t s o f dry tissu e ro o ts 1 9 .3 0 m i l l i e q u i v a l e n t s of p lan t fa m ilie s. th a t p lan ts ca p acities. sim ila r fa m ily had about exchange related th a t th e th e p la n t ro o ts of the in so il, as the ob tain ed of the in the su b stra te the in d icated s im ila r exchange the showed same p l a n t same r a n g e . in w hich the r e l a t i v e lo n g as group to sam e s p e c i e s and members o f the p l a n t s exchange c a p a c itie s p h y sio lo g ical m atu rity s a m p l e s was c o m p a r a b l e . gravel in b o t a n i c a l l y have cap acities w e re grown d i d n o t a l t e r of a low o f exchange c a p a c ity of d i f f e r e n t the r e s u l t s cap acities I t was fo u n d root the D ifferen t v a rie tie s exchange to f o r snapdragon v a r i e t y S unray. However, clo se ly p e r 100 grams annual la rk sp u r Not enough s p e c ie s w ere r e p r e s e n te d make g e n e r a l i z a t i o n s the T a b l e 1+). ranged the at A d d itio n a l v a lu e s were d e t e r ­ cap acities for the r o o ts c ro p s were d e te rm in e d U n iv e rs ity of M assach u setts* m ined a t M ic h ig a n S t a t e P l a n t R oots When p l a n t s w e r e g r o w n c u ltu re , w ater c u ltu re , and a m ix tu re of sa n d and e x ch an g e r e s i n , s im ila r values for the the same s p e c i e s . cap acity of the ro o ts w ere o b ta in e d 3U for exchange 35 TABLE RELATIVE CATION EXCHANGE CAPACITY OF PLANT ROOTS OF DIFFERENT PLANT SPECIES P lan t D elphinium M ath io la ajacis incana C u ltu re C ation Exchange. B lue B lue B lue resin so il w ater 10 1 .3 7 91j . 35 88.05 L ila c Lavender Lavender so il wa t e r 5 3 .082 £4<-.5l wa t e r w ater gravel U 5.22 U 3.20_ U o.73 V a rie ty annua C hrysanthem um h o r to r u m I n d i a n a p o l i s Mef o C o u rtier C allistephus ch in en sis Pink Queen o f M k t.,A z u re w a t e r kb*?! L i m o n i urn s i n u a turn M a rk e t G row ers B lu e s o i l l* .6 3 2 L ath y ru s o d o ra tu s C u t h b e r t s o n M ix. C u t h b e r t s o n M ix. C u t h b e r t s o n M ix. gravel w ater resin l( . 2 . 7 6 2 39.36 35 Jt-6 L upinus R u s s e l H ybrid sand l|0 .5 l2 G lad io lu s h y b rid a C apeheart gravel 3 8 . 902 N arcissu s P a p e r W hite P ap er W hite gravel so il 37.0 5 2 27 . I + 8 2 Hosa h y b r i d a B etter w ater 3U.39 L iliu m lo n g iflo ru m C roft C roft gravel wa t e r 3 0 .5lF 29.61 so il gravel 32.60 2 9 . 232 wa t e r gravel 3 1 . 3k 0 2 I4..29 p o ly ph yllus ta zetta Times P e la rg o n iu m dom esticum W allin g fo rd P elarg oniu m h o rto ru m -o K ing C a r d in a l D ianthus caiy o p h y llu s N o rth lan d Z ea mays G o ld e n C r o s s Bantam w a t e r A n tir r h in u m m ajus S k y s c ra p e r A laska Sunray S p a r t a n Rose S p a r t a n Rose S p a r t a n Rose gravel gravel wa t e r wa t e r resin 28.79 2 6 .6 9 | 1 9.30 14.0 . 0 2 25.21; 26.13 p e r 100 gram s o f d ry t i s s u e and a l l v a l u e s a r e a v e r ­ a g e s o f two o r m o r e d e t e r m i n a t i o n s * ^D ata from e x p e r im e n ts c o n d u c te d a t th e U n i v e r s i t y o f M assach u setts• 36 W ater c u l t u r e g reater had the a d v an tag e p o rtio n of the d e te rm in a tio n of the root th a t o lder ro o ts , and a sy stem co u ld be u t i l i z e d exchange c a p a c ity than in in the the o t h e r m ethods o f c u l t u r e . It root (See T a b le system n e a r e s t the change tip was show n cap acity to a d i f f e r e n c e erences grow ing than p o rtio n s whose c e l l s f e r e n t reg io n s 3) fa rth er catio n back from th e grow ing the r o o t of exchange cap acity t u r e w ere n o t i n cells of d i f ­ t h e r o o t o r i t may h a v e b e e n d u e t o w ith of the the c e ll w alls the cells. ro o ts agreem ent, d if- p e r u n i t o f exchange W here v a l u e s for the from v a r i o u s m ethods o f c u l ­ i t was f e l t c o u ld be e x p la in e d by v i s i b l e the ex­ in p erm eab ility of asso ciated th at d ifferen ces the d i f f e r e n c e in the m a tu rity sam ples. O ne d i s c r e p a n c y th e had a h i g h e r T h i s may h a v e b e e n d u e in dry w eight of the r o o t tip of w ere m ore m a t u r e . m ateria l of th a t younger p o rtio n s d ifferen ce in f o r w h i c h no e x p l a n a t i o n the exchange snapdragon v a r ie ty S p arta n is offered c a p a c ity o b tain ed fo r w as the Rose grow n i n w a t e r c u l t u r e w ith two c r o p s * An a t t e m p t w a s m ade io n on ratio s and s a l t the r e l a t i v e resu lts of the d eterm in e co n cen tretio n s of the e f f e c t of v ario u s the n u t r i e n t s o lu tio n the p l a n t r o o t s . (See T a b le 5 )» em ployed had v a r i o u s p la n t ro o ts the in exchange c a p a c ity of proved v a r ia b le ent so lu tio n s to The The d i f f e r e n t n u t r i ­ effects d iffe re n t crops. on the grow th 37 13 £ co X rH bd C\J co o 0 s oo v o co cm o CD N O O r\vD * • « • m in C E » * _h - h o OSCOCM _zfOJ 13 g IX °5 I—I v D lA O J i n C*- rH • n j bD • o • •H ■P u Is o Eh bO o “C to P £ TO rH CO > S D4 0) Eh O w H Ph > EH Eh CO_zj-S'COrH 13 13 P PI TO TO fl3 rH cm h bO & f « • O M O • M CO O cO t'-vO • • o m SC M TO oo o M Eh O is; <*J w PH EH * < w O EH « < • • »r— 1 X bO £ is Eh w £ £> w IS o ! +3 X X bG bCl oo £ Eh w CO *r! vD CMS O vO c\j CO CO COvO vO CO * * • • • » CS o in TO J W s • • vO C\J o ''S S °n n-xo O' * • * £ bOl vo cor^TO TO S c o _ s -P O CO W TOfcd O TO P O E Pi O O O S m s cm X is rH C O in CO CM S * • *

» TO TO P P. TO P i CO > TO 00 CO TO o U 0) oo TO TO Pi P. X w 13 W £ o o *X tX i n • • cOvX) O CO CO S ^ r H O ' CM • • 6 TO g P £ X O £ O bO bu TO TO g TO Pi Pi p TO Pi TO so cMm l O 1 0 1 /1 rH 1 rH X £ o o * Cl ro X TO S U JX o to Cl £■< O TO Pi O Pi T TO P XI c c tX CO o co CO o TO CO rH CO vO S • » • \ b0| rH TO O c o CM -S C M S ' O IS S P G CO rH PH e TO X p P. TO P CO £ TO TO TO Pi Pi tH X o X O o o TO Pi TO CO TO £ I—1 TO > rH rH < rH P TO • £ . iH Pi • O <*H TO ss TO P •rH X TO P P O P TO £ TO P X £ M CO Pi O P • to> to X p p P -H TO TO £ o •H *H TO TO Pi Pi rH TO TO Pi > > CM CO s 38 Two s o l u t i o n s grow th o f in p artic u la r several p lan t c a lc iu m ; low p o ta s s iu m t w e e n 3 a n d I4. a s grown i n in the th is ro o ts of p la n ts so lu tio n breakdow n o f th e One o f i n w hich grew . in the root tex tu re developm ent o f e f f e c t on t h e sium s o l u t i o n . m ad e n o t i c e a b l y l e s s change M ost p l a n t s com pared to cap acities w ere m ent f o r some p l a n t s th is the was h ig h er ro o ts t h e pH o f t h e from the w ere p la c e d the in ro o ts in T his sto ck , gave the m ost d i f f i c u l t y city . ft other in it is was n o t e d catio n s satu ratio n tre a t­ t h a t when th at was so lu ­ w ere n o t e a s i l y p r o c e s s when t h e of adsorbed calcium by t h e f a c t calcium d eterm in in g not f e lt th is the p otassium c h lo rid e a c r o p w h ic h showed a h i g h How ever, Low e x ­ t r e a t m e n t s when t h e the d i a l y s i s in r o o t grow th so lu tio n s. h y p o t h e s i s m i g h t be s t r e n g t h e n e d th at low p o t a s ­ su p ern aten t liq u id th a t the r o o ts had a h ig h p e rc e n ta g e io n s. the o th e r o b t a i n e d from r o o t s T his m ig h t i n d i c a t e rem oved from the h ig h c a lc iu m : (See T a b le 5) # than fo r ro o ts d ialized tio n . case, sh o rt, tip . s o l u t i o n w hich had an a d v e r s e so lu tio n IV ). to be a c c o m p a n ie d by a was th is n o t found (See F i g u r e r o o t g r o w t h o f many s p e c i e s in to b e ­ o f m an y s p e c i e s so lu tio n s i n p a r t by t h e was t h e l o w t h e pH d e c r e a s e d The r o o t s o th er w h ic h seemed e f f e c t on t h e th ese developed a co a rse was c a u s e d branch ro o ts The o t h e r sp ecies. p lan ts so lu tio n Th e c o a r s e n e s s stu b b y , the had an a d v e r s e from ab so rp tio n , ro o t exchange c a p a ­ th ese lo n g term F ig u re IV D i f f e r e n c e s i n t h e g r o w t h a nd t e x t u r e o f c o r n r o o t s i n n u t r i e n t s o l u t i o n s w i t h d i f f e r e n t pH a nd c a l c i u m c o n c e n t r a t i o n s . L e f t t o r i g h t : l o w C a l l o w K, pH 3 . $ 2 ; s t a n d a r d H o a g l a n d , pH 7 . 0 2 s t a n d a r d H o a g l a n d w i t h NH. , pH 3 * 2 9 . ko experim ents effects nature of of upon t h e It is the the possible organic to d ifferentiate com position adsorbed c a tio n s cation exchange in capacity of the between roots and regard to t h e i r of roots. the the the effect The E f f e c t o f t h e D i f f e r e n t N u t r i e n t S o l u t i o n s o n t h e P l a n t G ro w th and C h e m i c a l C o m p o s i t i o n o f t h e P l a n t Tops Corn v a r i e t y ical ent an aly ses of so lu tio n s used In the G olden C ro ss B antam . tops o f corn p la n ts showed t h a t i n ex p erim en t, p e rc e n ta g e s o f p o tassiu m (See T a b le 6 ) . to p s the calcium tio n s the young c o rn p l a n t s acid grown i n the n u t r i e n t in p lan ts of calciu m the c o n c e n tr a tio n s so lu tio n . the n u t r i e n t the o f the However, h i g h s o lu tio n low ered c o n te n t in th e p la n t to p s , w hile high c o n c e n tra ­ in over in the n u t r i e n t c o n ten t of the the p o ta ss iu m s o lu tio n had l i t t l e tops (3)* effect O f I n t e r e s t w as c o n t e n t of co rn p l a n t s w hich per m illio n of in d o le- t h o s e w h ic h w ere u n s p r a y e d when b o t h w ere s ta n d a r d H oagland In c o n tr a s t to so lu tio n # po tassiu m c o n c e n t r a t i o n was c o n s t a n t th ird to s p r a y e d w e e k ly w i t h 1000 p a r t s acetic n u tri­ co n tain ed high b u t low p e r c e n t a g e s o f potassium potassiu m in crease w ere in of calcium on th e grown i n v a r i o u s The c a l c i u m a n d p o t a s s i u m c o n t e n t o f ions co n cen tratio n s o f chem­ com parison w ith th e o t h e r o f c o r n p l a n t s was r e l a t e d resp ectiv e The r e s u l t s in and c a lc iu m , all and 3 X H oagland s o l u t i o n s . so lu tio n s th e m agnesium except D ifferen ces the one- i n m agnesium 1+1 T A B LE 6 THE GROWTH AS MEASURED BY DRY WEIGHT AND THE PERCENTAGE COMPOSITION OF CALCIUM, POTASSIUM, AND MAGNESIUM IN THE TOPS OF CORN VARIETY GOLDEN CROSS BANTAM GROWN IN VARIOUS NUTRIENT SOLUTIONS (A# I n t o so lu tio n :F eb ru ary 1, T reatm ent 1 9 5 U ; h a r v e s t e d : M a r c h 2 3 , 1951*.) Dry W e ig h t* E x o r e s s e d a s % Dry W e ig h t * %YL $Ca $Mg Low C a : L o w K 1+.72 3.5 3 .22 .20 Low C a : H i g h K 5 .2 0 6.91 .23 .27 1 H oagland 3 .5 9 5 .2 9 ♦ 31+ .33 H ig h Ca:Low K 2.56 3.96 .63 .33 High C a :H ig h K 5 .1 2 6 .7 3 .33 .27 3 H oagland li.3 5 5 .6 8 .1+6 .31 2i«16 5 .7 3 .21 .23 1.1+1+ 2 .0 2 1 .1 5 1 .6 1 .07 .10 .03 .0l|. 1 H oagland NH^ L .S .D . ,05 L . S «D* . 0 1 (B. In to so lu tio n :A u g u st 6, 1953; T reatm ent D r y Weight''*1 h a r v e s t e d : A u g u s t 20 Expressed 1953! a s ^ Dry W e ig h t %Ca $Mg 1 / 3 H oagland 1+.1+3 5 .2 0 .36 .36 1 H oagland 3.96 6.98 .29 .25 3 H oagland 3.20 5 .5 3 .29 .2 9 H ig h Ca:Low K 2 .90 1 .6 9 .33 .36 Low C a : H i g h K 3.90 3.1+9 .27 .39 1 H oagland l+.O l 8.63 .27 .26 .71+ 1.01+ 1 .0 0 1.1+3 .05 .07 .03 . 0)4 L .S .D . L .S .D . .05 .01 I*A .A ^A verage d ry w e ig h t o f th ree p lan ts in gram s• k 2 c o n t e n t o f p l a n t t o p s I n t h e d i f f e r e n t t r e a t m e n t s c a n be ascrib ed to th e d i f f e r e n t p o t a s s i u m :c a lc iu m c o n c e n t r a t i o n s in the n u t r i e n t s o lu t io n s * potassium in Increased concen trations of t h e n u t r i e n t s o l u t i o n s d e c r e a s e d th e magnesium c o n ten t of the tops of corn p l a n t s . The c o n c e n t r a t i o n o f c a l c i u m I n t h e n u t r i e n t s o l u t i o n had l i t t l e e f f e c t on t h e a b s o r p t i o n o f m a gnesium by c o r n . Corn p l a n t s grown i n d i f f e r e n t n u t r i e n t s o l u t i o n s w i t h d i f f e r e n t c o n c e n t r a t io n s o f potassium * p r o d u c e d more g r o w t h a s m e a s u r e d by t h e d r y w e i g h t o f t h e t o p s i n t h e s o l u t i o n s w ith the h ig h er potassium c o n c e n tr a tio n s* n o ticea b le T h i s was e s p e c i a l l y i n t h e c r o p grown i n t h e w i n t e r and i n d i c a t e s a high p otassium req uirem en t fo r corn . Snapdragon v a r i e t y S p artan R o se. The r e s u l t s of chem ical a n a l y s e s o f t o p s o f s n a p d r a g o n p l a n t s grown i n v a r i o u s n u t r i ­ ent s o lu tio n s in d ica ted t h a t t h e c o n t e n t o f p o t a s s i u m and c a lc iu m In the p l a n t t i s s u e rem arkably c o n s t a n t i n t h e d i f f e r e n t t r e a t m e n t s was (S e e T a b l e ? ) • T h is w o u ld i n d i c a t e that t h e maximum p o t a s s i u m and c a l c i u m c o n t e n t f o r s n a p d r a g o n was a p p r o a c h e d by p l a n t s grown i n t h e s t a n d a r d H o ag lan d s o l u t i o n . H igh c o n c e n t r a t i o n s o f p o t a s s i u m i n t h e n u t r i e n t s o l u ­ t i o n low ered th e c a lc iu m c o n te n t o f snapdragon. c o n c e n t r a t i o n i n t h e n u t r i e n t s o l u t i o n had l i t t l e the p o ta s siu m c o n t e n t o f the p l a n t t i s s u e . The c a l c i u m e f f e c t on 1*3 T A B LE 7 THE GROWTH AS MEASURED BY DRY WEIGHT AND THE PERCENTAGE COMPOSITION OF CALCIUM, POTASSIUM, AND MAGNESIUM IN THE TOPS OF SNAPDRAGON VARIETY SPARTAN ROSE GROWN IN VARIOUS NUTRIENT SOLUTIONS (A, I n t o so lu tio n :S ep tem b er 18, 1 9 5 3 ;h arv ested :O cto b er 2 9 , 1953) T rea tm ent Dry W eight'* E xpressed %K as % Dry W e ig h t a Low Ca :Lov/ K 3.85 1.1*9 .3 3 .1*0 Low C a : H i g h K 5 .6 9 5 .5 5 .1*1 .5 7 1 H oagland 5 .3 5 11.89 1.1 0 . 66 H ig h Ca:Low K 5.21*. 2.1*-7 1.6 3 .72 H igh C a:H igh K 5 .3 3 5.6 9 .76 .1*0 2 H oagland 3.69 1+.99 1.1 3 .66 L .S .D . .0 5 L «S «D • *01 1 .3 9 1 .8 8 .76 1 .0 8 .10 .1 4 .05 .08 (B. In to s o l u t i o n : F e b r u a r y 1 8 , 1 9 5 1 * - > h a r v e s t e d : A p r i l 1 0 , 1951}-) Trea tm ent Dry W eight* E x p re s sed as % Dry W e ig h t $Ca $Mg Low C a :L o w K 3 .0 9 1 .9 3 •44 .47 Low C a : H i g h K lp . 0 0 U-83 •47 .5 2 1 Ho a g l a n d 7.5 3 3.50 .90 .5 3 H ig h Ca:Low K 6 .1 3 2.10 1.5 6 .55 H igh C a :H ig h K 8 .6 2 1*.33 .8 1 .1*4 2 H oagland 8 . 3U 3.75 1 .0 2 .1*3 1*.63 2.77 .83 .1*7 1 H oagland L .S .D . L .S .D . .0 ? .01 NH^ N .S. •^Average d r y w e i g h t o f th ree .29 .75 •44 1.1 4 p la n ts in gram s. .13 .20 The g r o w t h o f tne tops showed r e l a t i v e l y cium and also potassiu m in d icated m ined i n the s n a p d r a g o n a s m e a s u r e d by d r y w e i g h t o f the th at p lan t req u irem en t of re la tiv e ly ra tio s the little in the n u t r i e n t potassium tissu e d ifferen ce and c a lc iu m w ere n e a r This co n ten ts d eter t h e maximum v a l u e s , snapdragon f o r p o tassiu m in the and and c a l c i u m was tops o f snapdragon p la n ts h i g h e s t m agnesium c o n t e n t o f The c o n t e n t o f m a g n e s i u m i n cant decrease when t h e any o f the p la n t the p l a n t s o l u t i o n was i n c r e a s e d . calcium in io n s the n u t r i e n t on th e m agnesium c o n t e n t o f Of a l l so lu tio n for s n a p d r a g o n p l a n t s w a s n e a r 1^. fell below root tissu e showed a s i g n i f i ­ The c r i t i c a l the p l a n t s effect by a d e c r e a s e the n u t r i e n t When t h e pH o f w ilted in the grow th of sn a p ­ affected pH o f ions to p s. stu d ied , the stu d ie The c o n c e n t r a t i o n o f th e p la n t d ra g o n p l a n t s was m o st s e r i o u s l y tio n sp ecies s o lu t i o n had l i t t l e the p l a n t s p e c ie s pH. tops had th e c o n c e n tr a tio n o f potassium the n u t r i e n t in so lu tio n the so lu ­ and a breakdow n o f the occurred. C hrysanthem um v a r i e t y W h ite M efo . an aly ses trien t so lu tio n s. low . The t i s s u e ical w ith w ide c a l ­ of so lu tio n s to p s o f com pared w i t h chrysanthem um p l a n t s in d icated am ounts o f P o ta s s iu m o f chem­ grown i n n u ­ t h a t chrysanthem um s a b s o rb l a r g e and m o d erate the o th e r The r e s u l t s p lan ts am ounts o f stu d ied (See c a l c i u m when T able 8). kS TABLE 8 THE GROWTH AS MEASURED BY DRY WEIGHT AND THE PERCENTAGE COMPOSITION OF CALCIUM, POTASSIUM, AND MAGNESIUM IN THE TOPS OF CHRYSANTHEMUM VARIETY VJHITE MEFO GROWN IN VARIOUS NUTRIENT SOLUTIONS (Into s o l u t i o n : D e c e m b e r 1 8 , 195>3j h a r v e s t e d : J a n u a r y 2 5 , 1951+) Ir..tment Dr, W.lghf ■ » * g |S I Low C a : L o w K 10.63 3.33 .51+ .1+9 Low C a : H i g h K 1 0.99 7.66 .1+1+ .l+o 1 H oagland 1 3 .8 9 5.1+7 .91+ •1+3 H ig h Ca:Low K 10 .6 1 3.01+ 1.3 1 H igh C a :H ig h K 12.1 1 7.13 .93 .37 3 H oagland 1 0 .0 1 ; 5.7 3 .31 .31+ 13.9 0 il-. 93 .9 6 .3 9 1 .7 6 2.1+5 1 .0 3 1.1+6 .18 .2 6 .06 .0 9 1 H oagland L .S .D . L .S .D . .05 .01 NH^ ^Average dry w e ig h t o f th ree p l a n t s i n grams. .1+1+ k(> Increased c o n c e n t r a t i o n s o f p o ta s s iu m io n s i n the n u t r i e n t s o l u t i o n s d e c r e a se d th e c a lciu m c o n te n t in the to p s o f c h r y sa n th em u m p l a n t s * The c o n c e n t r a t i o n o f c a l c i u m i n t h e n u t r i e n t s o l u t i o n had l i t t l e e f f e c t on t h e p o t a s s i u m c o n t e n t o f c h r y sa n th em u m t o p s . The g r o w t h o f ch rysa nthem um p l a n t s i n t h e d i f f e r e n t n u t r i e n t s o l u t i o n s a s m ea s u r ed by d r y w e i g h t o f t o p s i n d i c a ­ t e d t h a t c h r y s a n t h e m u m s had a h i g h r e q u i r e m e n t f o r b o t h p o t a s s i u m and c a l c i u m (2). The m agnesium c o n t e n t i n t h e t o p s o f chrysanthem um showed a r e v e r s e r e l a t i o n s h i p w i t h t h e c o n c e n t r a t i o n o f p o t a s s i u m and c a l c i u m i o n s i n t h e n u t r i e n t s o l u t i o n . In­ c r e a s i n g c o n c e n t r a t i o n s o f p o t a s s i u m and c a l c i u m i o n s i n t h e n u t r i e n t s o l u t i o n c a u s e d a d e c r e a s e i n t h e magnesium c o n te n t o f the p la n t t o p s . The c o n c e n t r a t i o n o f p o t a s s i u m i n t h e n u t r i e n t s o l u t i o n had a g r e a t e r d e p r e s s i v e e f f e c t o n m a gn e siu m a b s o r p t i o n by t h e r o o t s o f chrysanthemum p l a n t s than d id the c o n c e n t r a t io n o f calcium * Chrysanthemum was one o f t h e more t o l e r a n t s p e c i e s i n r e g a r d to t h e e f f e c t o f pH o f t h e n u t r i e n t s o l u t i o n on g r o w t h and c a t i o n a b s o r p t i o n . A slig h t, although not s i g ­ n i f i c a n t d e c r e a s e o f p o t a s s i u m and magnesium c o n t e n t i n the p lan t pH. t o p s c o u l d be a t t r i b u t e d to a d e c r e a s e in the s o l u t i o n U7 S tock v a r i e t i e s chem ical ent an aly ses so lu tio n s p ercen tag es when th e S h asta of* t h e in d icatea ent so lu tio n s sto ck th e p l a n t to p s th at The r e s u l t s of* s t o c k p l a n t s the p la n t tis s u e of* grown i n n u tri­ co n tain ed high o f b o t h c a l c i u m and p o t a s s i u m and e s p e c i a l l y co n cen tratio n s stu d ied , 8nd L a v e n d e r , (37). Compared co n tain ed tissu e of th ese (See io n s w ere h ig h i n to t h e o t h e r p l a n t a h ig h p e rc e n ta g e the n u t r i ­ species of calcium in T able 9 ) . A h ig h c o n c e n t r a t i o n o f p o ta s siu m io n s i n the n u t r i e n t solution d e c r e a s e d slig h tly , lev e l. tops o f sto c k compared t o p l a n t s grown a t a l o w e r p o t a s s i u m However, s o l u t i o n had l e s s p lan ts the c a lc iu m c o n t e n t of th e the potassium c o n c e n tr a tio n in the n u t r i e n t e f f e c t on t h e c a l c i u m c o n t e n t o f s t o c k than I t d id w i t h th e o t h e r p l a n t s p e c i e s a n a l y z e d . W it h t h e v a r i e t y S h a s t a , calciu m in an i n c r e a s e i n c o n c e n t r a t i o n o f the n u t r i e n t s o l u t i o n in c r e a se d c o n te n t o f the p la n t t o p s . an i n c r e a s e the p o ta ssiu m W ith t h e v a r i e t y L a v e n d e r , i n the c a lc iu m c o n c e n t r a t i o n i n the n u t r i e n t s o l u t io n caused a d ecrease of the t o p s . in the pota ssiu m c o n c e n t r a t io n Not enough d i f f e r e n t c o n c e n t r a t i o n s o f p o t a s ­ si u m and c a l c i u m w e r e a v a i l a b l e i n t h e n u t r i e n t s o l u t i o n s to o b s e r v e the f u l l o f calciu m in However, i t trend of the e f f e c t of c o n c e n tr a tio n t h e n u t r i e n t s o l u t i o n on p o t a s s i u m a b s o r p t i o n . appeared t h a t a t low c o n c e n t r a t i o n s o f calciu m in the n u t r i e n t s o l u t i o n an i n c r e a s e i n c a l c i u m c o n c e n t r a t i o n 1+8 T A B LE 9 THE GROWTH AS MEASURED BY DRY WEIGHT AND THE PERCENTAGE COMPOSITION OF CALCIUM, POTASSIUM, AND MAGNESIUM I N THE TOPS OF STOCK VARIETIES SHASTA AND LAVENDER GROWN IN VARIOUS NUTRIENT SOLUTIONS ( A, V a r i e t y S h a s t a ) s o l u t i o n : D e c e m b e r 1 8 , 1 9 5 3 ; h a r v e s t e d : J a n u a r y 2 9 , 1951+) E x p r e s s e d as % Dry W e ig h t Trea tment Dry W eight (Into km Low C a : L o w K u .7 3 2 .3 9 .1+8 • 33 Low C a : H i g h K 1+.51 5.56 .71 .1+3 1 Hoagland 3 .9 0 ij-.86 1.90 • 32 H i g h Ca:Low K U.85 2.36 2.08 .28 High Ca:High K 3.76 6.70 1.89 .27 3 Hoagland 3.U2 7.1+8 2.17 • 31 L.S.D . L .S.D , 1.36 1 .8 9 .35 . .1)9 .1+8 .. ,6.7. .06 .0 8 .05 *01 ....... (B. V a r i e t y L a v e n d e r ) s o l u t i o n : N o v e m b e r ll+, 1 9 5 3 ; h a r v e s t e d r D e c e m b e r E x p r e s s e d a s % Dry W eig h t Dry W eight * Treatm ent . %K $ Ca $Mg (Into Low C a : L o w K 5.05 2.61+ .68 .35 Low C a : H i g h K 5-19 7.32 *86 • U9 1 Hoagland 1+.88 5.32 2.01 .31+ H i g h Ca:Low K li-.Wt 2.96 2*35 .30 High CasHigh K 5.1U 6*10 1 .9 8 .29 3 Hoagland 3 .2 8 6.19 2.35 • 36 L.S.D . L.S.D . 1 .2 3 1 .7 0 .1+9 .69 • 15 .2 0 .01 .02 .05 .01 ^Average dry w eight of three plants in grams. 1+9 m ight s tim u la te concentrations the po tassiu m potassium ab so rp tio n , a further in c re a se m ight cause a b s o r p t i o n by s t o c k p l a n t s The c o n t e n t o f m a g n e s i u m i n was a f f e c t e d m o re by t h e nutrient solution High l e v e l s the while a t very high of t h a n by the calcium in of stock plants calcium in the co n cen tratio n of potassium . the n u t r i e n t so lu tio n decreased a b s o r p t i o n o f magnesium by s t o c k p l a n t s . where the tration concentration In so lu tio n s of c a l c i u m was l o w a n d of potassium high, in (35). the t i s s u e co n cen tratio n of a decrease the concen­ th e magnesium c o n t e n t o f t h e tops was i n c r e a s e d . The g r o w t h o f of the p la n t concentrations th at although stock calcium elem ents and p o t a s s i u m , is as m e a s u re d by d r y w e i g h t tops in n u tr ie n t s o lu tio n w ith d if f e r e n t and p o t a s s i u m cates stock p la n ts plants the n o t as g r e a t wa s q u i t e actual as i n of larkspur contained to calcium the (See tops of annual requirem ent fo r In o f l a r k s p u r was much more l i k e like stock. was The r e s u l t s of chemical larkspur plants this showed of potassium respect the that compared com position chrysanthemum th an i t the was s ta n d a r d Hoagland s o l u t i o n , the h ig h calcium :high potassium a balance s trate• these The g r e a t e s t a m o u n t o f d r y w e i g h t w a s p r o d u c e d when p l a n t s w ere g row n i n and indi­ chrysanthemum. a high percentage Table 1 0 ) . This co n tain high percentages of Larkspur v a rie ty Light B lue. analyses constant* calcium solutions where th e r e between calciu m and p o tassiu m ions in the sub- 50 TABLE 1 0 THE GROWTH AS MEASURED BY DHT WEIGHT AMD THE PERCENTAGE COMPOSITION OF CALCIUM, POTASSIUM AND MAGNESIUM I N THE TOPS QF LARKSPUR VARIETY LIGHT BLUE GROWN IN VARIOUS NUTRIENT SOLUTIONS (Into solution: Treatm ent J a n u a ry 6, 1954? Dry Weight'* h a r v e s t e d : March 9, 1954) Expressed foK % Dry W e i g h t ic a as Low C a : L o w K 6.86 2.82 .56 .34 Low C a : H i g h K U-^7 6.86 .1+5 .32 1 Hoagland 7.55 5.16 .71 .30 H ig h CaiLow K 5.72 3.37 1.19 .29 High Ca:High K 8.25 5.53 .56 .23 2 Hoagland 4.66 6.26 .86 .29 5.56 Ip *66 .82 .28 2.26 3.17 1.00 1 . 14-0 .55 .77 .18 .25 1 Hoagland L.S.D . L.S.D . *0^ .01 NH^ ^-Average d r y w e i g h t o f three plants i n grams* 51 W ith i n c r e a s i n g nutrient in the solutions, plant increasing tended to increase tops in the with failed to the p l a n t s solution the This i n d i c a t e d ions absorption in ions in the p o ta ssiu m the the of calcium of calcium fact, grown i n th e plants that substrate . An the n u t r i ­ c o n te n t of grown i n the the low c a l c i u m r lo w p o t a s s i u m t h e low c a l c i u m r l o w p o t a s s i u m present, did n o t, t h e p l ”a n t In in com position of calcium of potassium the ions p o ta s s iu m had a h i g h e r p o ta s s iu m c o n t e n t Since ammoni um i o n s potassium decrease. decrease of lark sp u r plants. solution. to concentration high calcium rlow that tended interfere of the p e rc e n ta g e concentrations ent solution tops concentrations the and the high difference calcium rlow potassium in potassium to p s m ig h t be a t t r i b u t e d s o l u t i o n had content in to an i n t e r f e r e n c e of ammoni um a n d h y d r o g e n i o n s w i t h a b s o r p t i o n o f p o t a s s i u m ions from th e n u t r i e n t s o l u t i o n by l a r k s p u r r o o t s . The m a g n e s i u m c o n t e n t o f t h e was a f f e c t e d by sium io n s the n u t r i e n t in and c a l c i u m i n the concentration tops of la r k s p u r of b o t h c a l c i u m and p o t a s ­ solution. the n u tr ie n t plants High l e v e l s so lu tio n decreased of potassium the content of magnesium i n the tops o f l a r k s p u r . The c o n c e n t r a t i o n o f calcium ions In the solution not significant e f f e c t on magnesium c o n t e n t o f l a r k s p u r did the had a s l i g h t l y c o n c e n tra tio n of potassium Ions, greater, although than DISCUSSION Th e R e l a t i o n s h i p B e t w e e n R e l a t i v e C a t i o n E x c h a n g e C a p a c i t y o f P l a n t R o o t s and P o t a s s i u m A b s o r p t i o n In order capacity of crops to show t h e r e l a t i o n s h i p the ro o t studied capacities creasing potassium ent solution and the system and p o ta s s iu m are l i s t e d exchange solutions was of potassium in The n u t r i ­ grown i n all content of potassium calcium rlow potassium expressed solutioh. solution, as m i l l i e q u i v a l e n t s other in p lan ts and the of potassium or gained. may c o n t a i n species ty root employed I n the nutrient the p l a n t tops The maxi mum a m o u n t o f p o t a s s i u m that the the o rd e r of i n ­ (See Table 1 1 ) . as a r e f e r e n c e of potassium the high in exchange the h i g h e s t c o n c e n tr a tio n of calcium was com pared w i t h t h e difference lost treatm ents concentrations containing absorption, the o r d e r o f in c r e a s in g and th e e x p e r i m e n t was s e l e c t e d grown i n in low est concentration The c o n t e n t between c a tio n Is (36). a plant to a b s o rb a ch aracteristic The p e r c e n t does c o n t a i n of that a plant species the p a r t i c u l a r p la n t o f t h e maxi mum p o t a s s i u m is content a measure of th e p l a n t ’s a b i l i ­ potassium under the environm ent in which the p i a n t was g ro w n . Although p la n ts w ith the such as c o r n ma y h a v e lower ro o t exchange contained la r g e r 52 capacities amounts o f p o ta s s iu m 53 than at plants with, h i g h e r lower p o tassiu m of potassium in ro o t exchange c a p a c itie s concentrations; the n u t r i e n t s o l u t i o n , root exchange capacities sium than p la n ts that in terms may t a k e m ulate a g re a te r percentage of a t low c o n c e n tr a tio n s tio n , than p la n ts w ith a high the p l a n t s T h is means the p l a n t s c a p a c i t y were a b le of potassium in r o o t exchange c a p a c ity , solution capacity, exchange such as to a c c u m u la t e compared to p l a n t s increased concentration accu­ ions con­ solu­ capacity. Plants s to c k and c h r y ­ relatively less the n u t r i ­ w i t h a low r o o t exchange th e most in p o ta s s iu m of potassium to the n u t r i e n t p o t a s s i u m from low c o n c e n t r a t i o n s o f p o ta s s iu m i n ent with t h e i r maxi mum p o t a s s i u m w ith a high c a tio n santhemum, w hich were a b l e with higher capacities. o f maxi mum p o t a s s i u m c o n t e n t , w ith a low c a tio n exchange concentrations up a s much o r more p o t a s ­ w ith low er exchange roots tent at higher accumulated in c o n t e n t when t h e the n u t r i e n t solution increased♦ As a p o s s i b l e absorption to consider solution. tion, by t h e Xn v e r y d i l u t e as c a l c u l a t e d (1?). it solutions necessary the e f f e c t i v e the theory of (17) > In d i l u t e ions in concentra­ of equal molar o f p o t a s s i u m and c a lc iu m s a l t s to is o f c a l c i u m and p o t a s s i u m from ion a c t i v i t i e s , According of Debye-Huckel the observed potassium d iffe re n t plan t species, the a c t i v i t y coneentrations equal explanation for are nearly interionic solutions attraction an i n c r e a s e in % m olar c o n c e n tra tio n vity a g r e a te r r e d u c tio n in the c o e ffic ie n t of d ivalent would a p p ly in affects the to the range o f nutrient solutions m olar c o n c e n tr a tio n s the n u t r i e n t This c o n c e n t r a t i o n s which were employed of the e x p e rim e n t. Thus, as o f p o t a s s i u m and c a l c i u m i n c r e a s e solution, concentrations than monovalent io n s . acti­ the in the d i s p a r i t y between the e f f e c t i v e of potassium and c a l c i u m ions increases in favor of potassium . From t h i s by p l a n t s is plant roots ions in P lants it appears related and relation to that the the a b s o rp tio n of potassium c a tio n exchange c a p a c ity the e f f e c t i v e c o n c e n tr a tio n to o t h e r ions in exchange sium io n s solution. in potassium co n ten t the n u t r i e n t capacities increases as the than p la n ts effective in resp ect the of potassium w ith h ig h e r r o o t exchange c a p a c itie s increases of solution. s how g r e a t e r w ith lower ro o t co ncentration of p o ta s­ to o t h e r ions in the n u t r i e n t TABLE 11 THE POTASS I UP. CONTENT OF THE T0P3 OF SOLE PLANT SPECIES WITH DIFFERENT ROOT CATION EXCHANGE CAPACITIES GROWN IN NUTRIENT SOLUTIONS WITH INCREA3CNG POTASSI UN CONCENTRATIONS ( A. C r o p s grown i n Corn and w i n t e r ) Solutions 2 1 Hoag­ High K 3 Hoag­ High K land H i g h Ca land Low Ca _____ 1 Low K Low K H i g h Ca Low Ca Crop^ fe ll 1015 -110 + 31+1 + 711 + i+lil + 766 Snapdragon 633 -2 5 1 + 621 + 826 + 61+6 + 790 Snapdragon 538 -69 + 359 + 572 +1+21+ + 700 Chrysanthemum 779 + 75 + 621+ + 101+9 + 690 + 1185 Stock, Shasta 605 +8 +6>l+l +1113 +1313 + 821 Stock, Lav. 589 + 88 + 775 4 975 + 999 + 1288 861+ -li+X +1+59 4551+ + 71+1 f 895 Larkspur (3, Crop ^ Corn Snapdragon China A s t e r Stock, Shasta Crops grown i n l/3 , Hoag--1 land 1 Hoag­ land spring a n d s u mme r ) Solutions 2 Hoag­ land 2 High K Low Ca 1333 + ^+57 + 85 -1+38 91+9 0 +13 + 21+3 1090 + 195 + 359 +1+28 + 1+61+ + 769 +1310 767 ^M illiequivalents of potassium /1000 2M i l l i e q u i v a l e n t s l o s t o r gained o f p o t a s s i u m / 1 0 0 0 grams d ry w e ig h t c o m p a r e d t o t h e h i g h Ca :Low K s o l u t i o n . 3plant species root cation grams d r y w e i g h t . are arran g ed in the o rd er of exchange c a p a c i t i e s . increasing 56 The R e l a t i o n s h i p B e t w e e n R e l a t i v e C a t i o n E x c h a n g e C a p a c i t y o f P l a n t R o o ts and C a lc iu m A b s o r p t i o n The r e l a t i o n s h i p plant less roots in calcium content w ith cium c o n c e n t r a t i o n s (See ing calcium plant 12). larkspur, but rath er in between the the external ion accum ulation th e m o st c a l c i u m from t h e i n t e r n a l to absorb Plants solution at is long term ex p erim en ts the i3 w ithin plant. calcium than and would an i n c r e a s e the n u t r i e n t s o lu tio n . cation in absorption, but rather r o o t exchange the This In th a t r o o t exchange w ith n u trie n t solutions effect of absorption the of external chrysanthemum, content c o n te n t with the h y p o th esis city employed, in which tended to e q u ilib riu m w ith the a lower calcium concentration a factor corn, the s o l u t i o n , would relatively less would r e a c h g ain in calcium n o wa y c o n t r a d i c t s then p la n ts such as which c o n ta in s t o c k and s n a p d r a g o n , calcium the o r d e r were a l i m i t i n g the m ost c a lc iu m from th e n u trien t solution. and l a r k s p u r , (1), solution remove show l e s s corn in calcium ions w ith in in external and content. those tend cal­ the o r d e r of d e c r e a s ­ factor also increasing This does n o t f o llo w capacities equilibrium and is the n u t r i e n t s o l u t i o n were r e g i s t e r e d chrysanthemum, Table of ro o t exchange If in snapdragon, that order crops t h a n w i t h p o t a s s i u m o r magnesium a b s o r p t i o n . increases by s t o c k , exchange c a p a c i t y of and c a l c i u m a b s o r p t i o n by d i f f e r e n t apparent G reatest between c a tio n capa­ th at in s u c h a s were c a p a c i t y on c a l c i u m o v e rsh a d o w e d by t h e u t i l i z a t i o n of calcium T A B LE 1 2 THE CALCIUM CONTENT OF THE TOPS OF SOME PLANT SPECIES WITH DIFFERENT HOOT CATION EXCHANGE CAPACITIES GROWN IN NUTRIENT SOLUTIONS WITH INCREASING CALCIUM CONCENTRATIONS (A* C r o p s grown f a l l a nd w i n t e r ) Solutions 1 2 Low Ca Low Ca 1 H o a g ­ H i g h Ca 3 H o a g ­ H i g h Ca H i g h K Low K land High K land Low K +100 +50 115 -5 +55 +115 Crop^ Corn Snapdragon 205 -Uo +3*4-5 +175 +360 +610 Snapdragon 235 -15 +215 + 1 70 +275 +5*4-5 Chrysanthemum 220 +5o +250 +2*4-5 +195 +*4*4-5 Stock, Shasta 355 -1 1 5 +595 +590 +730 +685 Stock, Lav. 1+30 -90 +575 +5 6 0 +7*i5 +71+5 225 +55 +130 +1 5 5 + 2 05 +3 7 0 Larkspur (B# C r o p s g r o w n i n s p r i n g Crop’ a n d s u mme r ) 2 Solutions '172 Low Ca H o a g ­ 1 H o a g - 2 H o a g ­ H i g h Ca Low K land land High K l a n d Corn 135 +W +10 +10 + 55 Snapdragon 130 + 280 +280 + 300 +580 35 + 2 30 +205 *235 +565 215 4200 +615 *710 +1090 China A s te r Stock •^Milli e q u i v a l e n t s of calcium /1000 grams o f d r y w eight# 2M i l l i e q u i v a l e n t s o f c a l c i u m / 1 0 0 0 g r a m s o f d r y w e i g h t l o s t o r g a i n e d compared to th e low C a : h i g h K s o l u t i o n # 3 p l a n t s p e c i e s a re a r r a n g e d i n the o r d e r of i n c r e a s i n g r o o t c a tio n exchange c a p a c itie s * S3 The r e s u l t s are in obtsined not n ec e ssa rily soil. It of soluble sible in soil, Also calcium soil is s ame a s is p o s s ib le tions plants. the this m nutrient would strongly than are monovalent ions ference t h o s e w’. vl c h w o u l d affect a s V . a d l e i g h a n d Bo we r h e l d more s o lu tio n s w ith calcium solutions to w a te r than i s pos­ c a l c i u m a b s o r p t i o n by (50) have p o i n t e d o u t , by t h e c l a y c o l l o i d s and t h i s introduces b e t w e e n c a l c i u m a b s o r p t i o n by p l a n t s compared be o b t a i n e d t o m a i n t a i n mu c h h i g h e r c o n c e n t r a ­ calcium and in n u trie n t in the the d i f ­ from s o i l as culture. The R e l a t i o n s h i p B e t w e e n R e l a t i v e C a t i o n E x c h a n g e C a p a c i t y o f P l a n t R oots and Magnesium A b s o r p t i o n The s ame c o n c e n t r a t i o n o f m a g n e s i u m i o n s w a s e m p l o y e d in all tion to nutrient solutions. o f m agnesium by th e the tions effects in solutions. in the o rd e r of in c r e a s in g of the roots and the g a in o r l o s s magnesium i n the plant tops s ta n d a rd Hoagland s o l u t i o n nutrient solution, relative cation of the plants c a n be a t t r i b u t e d The p l a n t s cation studied exchange c a p a c i t i e s compared to p l a n t s is g i v e n i n Table of grown i n 13. b o t h c a l c i u m and p o t a s s i u m i n tops are in m illiequivalents the o f p l a n t s whose r o o t s had h i g h exchange c a p a c itie s more m agnesium t h a n when t h e p l a n t s Hoagland s o l u t i o n . in absorp­ c a l c i u m and p o t a s s i u m c o n c e n t r a ­ listed At low l e v e l s the d iffe re n c e different of varying the n u t r i e n t Thus, tended to c o n t a i n were grown i n s t a n d a r d T h i s w o u l d be i n a g r e e m e n t w ith the hypothesis 59 th at plants w ith high ro o t the g r e a t e s t present ent in increase the highest solution. in exchange absorption effective capacity of the to show ion which is concentration in P l a n t s w i t h low r o o t exchange showed a d e c r e a s e tend the n u t r i ­ capacities i n m a g n e s i u m c o n t e n t o f t h e t o p s wh e n t h e c o n c e n t r a t i o n o f b o t h c a l c i u m a n d p o t a s s i u m was l o w e r in the standard solution Hoagland s o l u t i o n . was l o w , this Since t h e pH o f could have been a f a c t o r than this i n magnesium a b s o r p t i o n w i t h s n a p d ra g o n and c o r n . Corn, in Snapdragon, the p e rc e n ta g e and chrysanthemum p l a n t s of magnesium i n the p l a n t c o n c e n t r a t i o n o f p o t a s s i u m was i n c r e a s e d tio n of plants the calcium decreased grown i n tops of te n t under the the tops ;just o p p o s i t e tent, solution. f o r the when t h e corn, increased compared solution. compared to s a me s p e c i e s calcium snapdragon, the In co n trast, i n magnesium c o n ­ to p l a n t s grown i n The c o n t e n t o f m a g n e s i u m i n a p p e a r e d t o be a f f e c t e d c o n c e n t r a t i o n was i n c r e a s e d concentration a f f e c t e d when compared Hoagland and the c o n c e n t r a ­ solution decreased Stock and l a r k s p u r decreased while t o p s when t h e s ta n d a rd Hoagland s o l u t i o n . s a me c o n d i t i o n s and th e p o t a s s i u m solution. the s to c k and l a r k s p u r s ta n d a r d Hoagland the p l a n t in decreased in the n u t r i e n t i n magnesium co n ­ and chrysanthemum were l e s s to p l a n t s grown i n the s ta n d a rd 60 T A B LE 1 3 THE MAGNESIUM CONTENT OF THE TOPS OF SOME PLANT SPECIES WITH DIFFERENT ROOT CATION EXCHANGE CAPACITIES GROWN IN NUTRIENT SOLUTIONS WITH DIFFERENT CONCENTRATIONS OF CALCIUM AND POTASSIUM Crop^ 1 Hoag­ land Solutions 2 Low Ca High K Low K Low Ca H i g h Ca Low K Corn 275 -108 -50 0 Snapdragon 550 -216 -75 4 50 Snapdragon U-5S -66 -25 -1 6 Chrysanthemum 350 +50 -25 48 Stock, Shasta 266 48 491 -33 Stock, Lav. 283 48 +125 -8 2^0 433 +16 -8 Larkspur ^ M i l I I e q u i v a l e n t s o f m agnesiu m /1000 grams o f ^ M i l l i e q u i v a l e n t s o f m a g n e s i u m / 1 0 0 0 grams o f l o s t o r g a i n e d compared to t h e 1 Hoagla nd 3 p la n t sp e c ie s are arranged in the o rd er of r o o t c a t i o n exchange c a p a c i t i e s . dry w eight. dry w e i g h t solu tio n . increasing 61 It appears depress high the that fo r plants absorption r o o t exchange tain large depressed low r o o t tained plants m especially those the to p s* Potassium ions capacities and i n amounts o f p o ta ss iu m would s u g g e s t species calcium that the those p lan ts in the p la n t Excessive the a b s o rp tio n of sium c a u s e d a d e c r e a s e th a t con­ in p lan ts w ith c o n t e n t o f magnesium i n s t u d i e d was i n f l u e n c e d by (1^) . ions in p la n ts with a b s o r p t i o n o f magnesium io n s exchange large th© c a l c i u m of magnesium io n s capacities, amounts o f the studied, which c o n ­ tops* This the p la n t c atio n balance in either the calcium or p o ta s ­ i n magnesium c o n t e n t * D e te r m in a tio n o f the R e l a t i v e C ation Exchange C a p a c i t i e s o f P l a n t Roots Two t h e o r e t i c a l to the ties considerations determ ination of of p la n t roots* determ ination? capacities of the Roberts aceous outside (39) there of the l e a f Broyer (5) uous p ro to p lasm ic concentration of found concluded salts in the in the exchange of d iff e r e n t p lan t species? that in apple le a v e s p e c tin pathway r e a c h i n g from the to the w a lls pathways p ro b a b ly are paths in regard b ein g measured differences and e x t e n d i n g Sim ilar involved c a t i o n exchange c a p a c i ­ actually compounds form a c o n t i n u o u s extensions. roots* roots et al the r e l a t i v e What i s Why a r e are to in that present the v e in in plant i o n s mo v e d a l o n g c o n t i n ­ the xylem, the of external e s p e c i a l l y wh en t h e s o l u t i o n was h i g h . 62 Frey-W yssling perm eable (16) to a l l e n t ions* observed plasm olytic compounds cellular s p a c e s may e n t e r capacity of capacities the and cytoplasm in enters (28), however, this III) into cell the c e ll w alls and i n t r a ­ The c o m p a r i s o n o f of d ia liz e d indicated that by e l e c t r o d i a l y s i s . the cytoplasm of feels that the cell felt th a t with plasm olysis ization of c y t o p l a s m b r o u g h t a b o u t by d i a l y s i s , action species rooted This tend 38). influence to e n t e r to have h ig h e r species, does of The f a c t n o t mean t h a t into that in of c e l l s tissues as a r u le the and d i s o r g a n ­ all of exchange r e ­ c o a rse r rooted exchange c a p a c i t i e s by t h i s the chemical the r e s u l t i n g allows the measured than f i n e - assum ption. co m p o sitio n of the in d if f e r e n t p lan t the measured differences the r o o t w o u l d be e x p l a i n e d exchange m a te r ia ls the the cytoplasm . in perm eability (19, M attson w a l l I s more i m p o r t a n t is cells the p l a n t the m easured exchange r e a c t i o n . It cortical the exchange the p e r m e a b i l it y of had b een i n c r e a s e d that exchange and u n d i a l i z e d than the to n u t r i ­ the measured c a tio n curves are the c e l l w a lls respect increase w alls and t h e r e f o r e compounds i n into a possibility cells in titration the c e l l s also in plant roots. (See F i g u r e There i s agents Thus b o t h c e l l u l o s e and p e c t i n a c e o u s roots that cellulosic species does n o t exchange capacity. To a c c o u n t f o r exchange capacities of the r o o ts d iffe re n t plant species, It is assumed that there are of 63 differences in the a m o u n ts and c h e m i c a l c o llo id a l m aterial spaces, and roots. However, in the cell in cytoplasm of the r a t i o w alls, the the roots, of d i f f e r e n t w ith f in e r than rooted that as i f crops. exchange c a p a c itie s were h i g h e r felt tends to that solution ferent for can a f f e c t tissues in in interpretation and B aker sure of colloids the the p la n t in the r o o t From t h e the texture of r o o t exchange c a p a ­ should than behave those ratio of the r o o t in stock as i f their a c tu a lly measured. these crops t h i s way. com position of the n u t r i e n t the q u a n t i t i e s of the d i f ­ T h i s may a c c o u n t i n p a r t exchange c a p a c i t i e s w hich were the d i f f e r e n t n u t r i e n t tre a tm e n ts . O ther fa c to rs the shown t h a t in p lan t ro o ts. differences obtained they t h e y do b e h a v e (18) has of tissues the n u t r i e n t com position of show t h a t Hayward cells C o m p a r i n g s n a p d r a g o n and species, is intracellular a c t u a l l y m e a s u r e d when com par ed w ith co arser rooted It the the r e l a t i v e measured of d iffe re n t p la n ts. corn should behave c i t y were low er in cortical s h o u l d be k e p t i n mind i n e v a l u a t i n g exchange c a p a c ity com position of (31) besides point the bonding e n e r g ie s ion ab so rp tio n can a ls o o f r o o t exchange c a p a c ity d a ta . out t h a t exchange c a p a c ity bonding energy f o r w ith those mentioned a particular same e x c h a n g e for specific ratios. c a p a c i t y may h a v e cations and McLean is cation. affect no m e a ­ Plant different this w ill alter 6U P ractical Tli© i n t © r p r e t a t i o n o f values in cation needs besides terms of p ra c tic a l of p lan ts fertilizer ex te n t of the fluence root soil soil is of determ ine the a plant as the the root to logical Other f a c to r s the of therefore the p la n t stages absorb m ineral r o o t exchange c a p a c i t y . cation in in all of about the n u t r i e n t r e ­ the d i f f e r e n t p h y sio ­ fertilizer p r o g r a m f o r a c r o p can be d e r i v e d . absorb available specific A fertilizer alter soil the for tends to in m oisture, the cations the show t h e ability of (11, a A fter p la n t amount the p la n t 12, 26, of the ca tio n s in to the (L|5j 1+3). obtained e f f e c t of different to 36) • t h e n be a d o p t e d w h i c h a t t e m p t s growth data the seasonal before along w ith the can be c o n s i d e r e d ratios best plant and t e m p e r a t u r e known, soil, program can existing A lthough the m e ta b o lic A dditional of lig h t, already The d o e s n o t a p p e a r t o be r e l a t e d necessary are in­ cations o f d e v e l o p m e n t and u n d e r d i f f e r e n t requirem ents The of the r o o ts , conditions nutrient (3 2 ). soil exchange c a p a c ity of th e p l a n t . inform ation is quirem ents in the the amount of a texture requirem ent fo r a p a r tic u la r species for predicting difficult. elem ent needed as w e l l p r o c e s s e s ofa p l a n t to in r o o t exchange c a p a c ity applications s y s te m and the a b i l i t y the actual relative r o o t exchange c a p a c ity particular from A pplications root in the experim ent conducted, exchange c a p a c ity on i o n 65 absorption, responses m ents s ome i n t e r p r e t a t i o n s in of the the different crops ture the literature the cations r o o t systems of grown i n n u t r i e n t observations, 1+8), for solutions. interpretations reviewed needed in to r e q u i r e ­ determ ined. the tex­ the d i f f e r e n t p l a n t On t h e b a s i s of of n u tr ie n t requirem ents these , and ( 2 , 3 , 1 1 , 1 2 , llj., 2 6 , 3 2 , 3 6 , 3 7 , 1+6 , am a t t e m p t was made to p r e d i c t levels in regard o b s e r v a t i o n s w e r e a l s o made o f and e x t e n t o f species solutions studied Some g e n e r a l c a n b© mad© f r o m g r o w t h soil for the r e l a t i v e the p lan ts studied potassium ( S e e T a b l e 11+). E a c h s p e c i e s was g i v e n a n u m e r i c a l r a t i n g b e t w e e n one and th re e on the sidered. change basis of its For example, capacity so corn has that i t from low c o n c e n t r a t i o n s tive value of p o tassiu m need f o r one f o r a relatively tends of potassium . p o t a s s i u m need on th e b a s i s o f exchange a relative value of all plant characteristics determ ining the p la n t three for the listed in c a p a c i t y was g i v e n same i t e m . listed the p otassiu m need of species are the p l a n t in potassium in stock, larkspur, and s n a p d r a g o n (See that from than co rn , the soil the s o i l , the o rd e r of t h e i r available d o e s n o t mean Considering as of equal v alu e ing need f o r corn, low r o o t ex­ T t was g i v e n a r e l a ­ L a rk s p u r w ith a h ig h exchange in item con­ to a b s o r b p o t a s s i u m e a s i l y capacity. of th e the the soil! decreas­ chrysanthemum, T a b l e 1U) . T h i s c h r y s a n t h e m u m w o u l d r e m o v e mo r e p o t a s s i u m but rath er th a t in orderto obtain 66 the p otassium necessary for needs a higher soil than corn. level the of read ily b e s t growth, chrysanthemum a v a ila b le potassium in the 67 TABLE 11| A RELATIVE EVALUATION OF THE AVAILABLE POTASSIUM HEEDED IN SOI L BY THE PLANT SPECIES STUDIED ON THE BASIS OF SPECI ES CHARACTERISTICS Species Charac t e r i s t i c s Corn Snap­ dragon P la n t Species Chrysan­ S tock t hemum Larkspur C ation exchange c a p a c i ty 1 1 2 2 3 Po t a s s i u m requirem ent 3 1 3 2 1 Extent of ro o t s y s tem 1 2 2 3 2 Texture of 3 2 3 1 2 2 1 3.____ 10 7 S alt roots tolerance To t a l “ 13 '“' T h e h i g h e r t h e n u m b e r t h e h i g h e r able potassium needed. 1 11 the l e v e l 9 of a v a il­ SUMMARY The r e l a t i v e for the r o o ts ity of the cation of a number of f l o r i c u l t u r e species capacities exchange c a p a c i t i e s studied had r e l a t i v e had an exchange c a p a c i t y o f roots that to the cells the site magnesium, in d iffe re n t 9U m i l l i e q u i v a l e n t s closely the r o o t. of th e measured to the nutrient found to related p e r 100 to s how I t was n o t d e t e r m i n e d e x c h a n g e c a p a c i t y was I n ro o t exchange c a p a c ity , species. When p l a n t s the calcium , top p o r ti o n s snapdragon, of annual and c o r n grown s o l u t i o n s was d e t e r m i n e d on a f la m e be r e l a t e d in nutrient to t h e solution in the p la n t c o n c e n t r a t i o n of p o t a s ­ and t h e p a r t i c u l a r p l a n t were grown in s t a n d a r d Hoagland s o l u ­ the w in te r , m illiequivalents however, botanically The c o n t e n t o f p o t a s s i u m sium i o n s tio n during the per cytoplasm . chrysanthemum, spectrophotom eter. t o p s was Annual l a r k s p u r , and p o t a s s i u m c o n t e n t o f th e stock, of catio n s c a p a c i t y wa s p o s s i b l y a s s o c i a t e d w i t h or the addition larkspur, r o o t c a t i o n exchange E v i d e n c e wa s p r e s e n t e d cortex of c e ll w all In which were exchange The m a j o r ­ The c a t i o n e x c h a n g e c a p a c i t y o f t h e be s i m i l a r . of the w hether the dry w eight. of p la n ts tended crops. b e t w e e n 2 5 a n d 1|5 m i l l i e q u l v a l e n t s 100 grams d ry w e ig h t of r o o t s . grams o f were d e te rm in e d all species c o n t a i n e d n e a r 1200 p e r 1000 grams o f d r y 68 tissue. The d i f f e r e n t 69 species ^rown i n solution showed more v a r i a t i o n Table 11)* solutions than in s p r i n g a n d s umme r i n The g r o w t h of* p l a n t s indicated spring and summer. concentration of on t h e calcium by the tion in nutrient of the of the potassium grown. The the n u t r i e n t s o l u t i o n had l i t t l e of p o ta ss iu m in in t o p s was a f f e c t e d the p la n t the p la n t in the n u tr ie n t p lant species involved. tops. solu­ However, c o n c e n tra tio n of potassium ions tops. ions the calcium An i n c r e a s e in the n u trie n t content io n s had l e s s in in the the in the solution tops than w ith o th er The d i f f e r e n t crops. species plant S t o c k a l s o had studied species to d e c r e a s e Potassium land Snapdragon contained (5^0 m i l l i e q u i v a l e n t s contained of dry (See the h i g h e s t Table 1 2 ) . s t u d i e d had v a r y i n g amounts the p la n t 1000 grams tended of a l l p l a n t s . o f magnesium i n solution. con cen tratio n of e f f e c t u pon c a l c i u m a b s o r p t i o n by s t o c k , calcium c o n te n t of th e larkspur crops the s o l u t i o n had an e f f e c t upon the calciu m c o n t e n t the p la n t however, (see the d i f f e r e n t n u t r i e n t calcium ions the p a r t i c u l a r addition, in calcium concentration of and in content Corn and c h r y sa n th e m u m had concentration The c o n t e n t o f potassium a h igher potassium requirem ent in w inter h ig h e st potassium requirem ents effect in s ta n d a r d Hoagland t o p s when grown i n s t a n d a r d Hoag- th e m o s t magnesium p e r 1000 grams of dry t i s s u e ) , the l e a s t tissue). and (250 m i l l i e q u i v a l e n t s p e r 70 The a b s o r p t i o n tration in tration o f p o t a s s i u m and tion, the plant of magnesium as m easu red by the c o n c e n ­ tops wa s a f f e c t e d calcium The m a g n e s i u m c o n t e n t ions in the by b o t h t h e c o n c e n ­ in the n u t r i e n t tops of corn, solu­ snapdragon, and c h ry sa n th e m u m te n d e d to be d e c r e a s e d m o s t by i n c r e a s i n g potassium in concentrations the n u t r i e n t s o l u t i o n , the magnesium c o n t e n t of s to c k by i n c r e a s i n g tion# tended calcium c o n c e n tra tio n s Larkspur e ith e r potassium showed l i t t l e while to be d e c r e a s e d m o st in the n u t r i e n t difference o r calcium co n cen tratio n s o l u t i o n upon th e magnesium c o n t e n t of in the solu­ e f f e c t of in the n u tr ie n t the p l a n t to p s . 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