Adams, D.

Baker, F. E.

McLean, E. O.

UARK (University of Arkansas )

Journal of the Arkansas Academy of Science Volume 8 Article 7 1955 Cationic Activities and the Exchange Phenomena of Plant Roots: Relationship to Practical Problems of Nutrient Uptake E. O. McLean University of Arkansas, Fayetteville D. Adams University of Arkansas, Fayetteville F. E. Baker University of Arkansas, Fayetteville Follow this and additional works at: https://scholarworks.uark.edu/jaas  Part of the Agronomy and Crop Sciences Commons, and the Plant Biology Commons Recommended Citation McLean, E. O.; Adams, D.; and Baker, F. E. (1955) "Cationic Activities and the Exchange Phenomena of Plant Roots: Relationship to Practical Problems of Nutrient Uptake," Journal of the Arkansas Academy of Science: Vol. 8 , Article 7. Available at: https://scholarworks.uark.edu/jaas/vol8/iss1/7 This article is available for use under the Creative Commons license: Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0). Users are able to read, download, copy, print, distribute, search, link to the full texts of these articles, or use them for any other lawful purpose, without asking prior permission from the publisher or the author. This Article is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Journal of the Arkansas Academy of Science by an authorized editor of ScholarWorks@UARK. For more information, please contact scholar@uark.edu. 134CATIONIC ACTIVITIES AND THE EXCHANGE PHENOMENAOF PLANT ROOTSRELATIONSHIP TO PRACTICAL PROBLEMS OF NUTRIENT UPTAKE1E. O. McLEAN, D. ADAMS and F. E. BAKER 2University of ArkansasThe feasibility of measuring cationic activities in systems of plant rootswas indicated in a preliminary report on this general subject (4). The energywith which a cation is bonded to the exchange seats of the root surface can thenbe computed from the cationic activities. The present study has been conductedin an attempt to find whether these mean that free-bonding energies have anysignificance in practical problems involving nutrient uptake.Some plants utilize Na as a partial replacement for K needs. Such plantsaccumulate large amounts of Na. Other plants do not absorb Na to any appreciableextent. Itseemed worthwhile to determine whether the ability to accumulate Naby a plant would be reflected in the relative bonding energies of plant rootsfor Na.The maintenance of grass/legume pastures and meadows has become a diffi-cult task because of diversity of nutrient requirements by the grass as comparedto the legume. Some work has indicated that the relative cationic exchange capac-ities of the roots of the different species was important in this problem (1),hence it seemed likely that the mean free-bonding energies of the cations to theroots might be important also.The diverse ability of different plants to utilize phosphorus from insol-uble sources such as rock phosphate has long perplexed agronomists. Could it bethat the plants' ability to break up the tricalcium phosphate molecule in rockphosphate is related to the ability of the roots to bond calcium?EXPERIMENTALSince the previous report in this series, the determination of cationic ac-tivities and mean free-bonding energies for various cations has been extendedfrom soybean and alfalfa roots to those of Reed canary grass, red top, lespedeza,corn, oats, and another variety of alfalfa. The plants were grown in level cul-tures of 1/5 Hoagland's solution as has been described (4) (5). The plants weregrown for various lengths of time as follows: Cereals, 15 days; legumes, 30 days;and grasses, 50 days. The procedure for determination of cation activities wasexactly as previously described. The uptake of Na by several plants is being de-termined by replacing with NaO, 1/4, 1/2 and 3/4 of the K in the 1/5 Hoaglandsolution and growing the plants in quadruplicate in No.2 tin cans of gravelbathed with these solutions.In other studies reported elsewhere (6), the uptake of phosphorus from soiltreated with various phosphates by several of these same plant species was de-termined.DISCUSSION OF RESULTSAs these studies are still in progress, the results reported in tables 1, 2and 3 are in some cases incomplete. However, it is believed that sufficient pro-gress has been attained to justify inclusion here. It appears from the data ofTable 1 that some relationship does exist between the tendency to take up Na andthe bonding energy of Na to the plant root; however, there is need forcompletionof two key determinations before definite conclusions can be drawn.1Research paper No. 0000 Journal Series, University of Arkansas, Fayetteville, Arkansas. Pub-lished with permission of the Director of the Ark. Agr. Exp. Sta. A major part of this workhas been and is being submitted by the junior author as partial fulfillment of the requirementsfor the M. S. Degree in the Graduate School, University of Arkansas. This investigation waslargely supported by a grant from the Mathieson Chemical Corporation, and this support IIgratefully acknowledged.Associate Professor, Graduate Assistant and former Graduate Assistant, respectively.134Journal of the Arkansas Academy of Science, Vol. 8 [1955], Art. 7Published by Arkansas Academy of Science, 1955CATIONIC ACTIVITIES AND THE EXCHANGE PHENOMENA 135Table I.Mean Free-Bonding Energies of Plant Roots for Na in relation to NaUptake by These Different Plants.Plant Tendency to takeFNa up Sod ium*( Calor ies/mol e )Corn 0 nilReed canary grass 55 fOats 559 ModerateAlfalfa 599 ModerateCelery f Excessive• As recently reported in Soil Sci., 76:1 (1953)f- Values being determined but not yet available.Table 2. Mean Free-Bonding Energies of Legume and Grass Roots for Ca and Kin Relation to Their Relative Competition for These Cations.Plant AF (Calories/equivalent) £F ra Cation for whichCalcium Potassium Competition is KeenestLegumes:Alfalfa (K.C. ) 775 6.72 1.16 CalciumAlfalfa (B. ) 590 642 0.92 CalciumSoybean 827 711 1.16 CalciumLespedeza 815 705 1.16 CalciumGrasses:Red Top 509 861 0.59 PotassiumReed Canary Grass 329 648 0.51 PotassiumThe data of Table 2 appear to give excellent support to the work of Gray,et al (3). They showed that certain grasses are so competitive with clovers grownwith them that itis near impossible to maintain sufficient K in the soil to meetthe needs of the clover. The relatively high values of the Fpg/Fj/ ratio for thelegumes and the relatively low values for the grasses would"seem to offer someexplanation as to why legumes tend to accumulate Ca while the grasses tend toaccumulate K even to the detriment of the legumes.Evidently there is a definite relationship between the ability of a plantto utilize phosphorus from rock phosphate and the relatively high mean free-bonding energy of the roots for Ca (Table 3). Graham (2) showed that the freeenergy change in the exchange of Ca for H on various colloids correlated withthe abilities of the acid colloids to weather rock phosphate and render phos-phorus available to a test crop. This might suggest that the ability of buckwheatand similar crops to utilize phosphates of low solubility may be related to thisrelatively high mean free-bonding energy for Ca. Perhaps the latter is a formid-able weathering force in attacking rock phosphate much in excess of that of cer-tain other types of plant roots. Truog (7) indicated many years ago that plants'abilities to take phosphorus from low solubility materials was related to theircalcium content in the tissues.Table 3. The Mean Free Bonding Energy Ratios as Indices for Determiningthe Abilityof a Plant to Utilize Rock Phosphate.Plant FCa Ability to Utilize RockAFy P hosphate*Buckwheat 1.67 HighAlfalfa 1.16 ModerateSoybean 1.16 ModerateLespedeza 1.16 ModerateRed Top 0.59 LowReed Canary Grass 0.51 LowIn part based on studies reported (6) and in part based on general knowledger i | • . • |• « ,TI_ I L 135Journal of the Arkansas Academy of Science, Vol. 8 [1955], Art. 7https://scholarworks.uark.edu/jaas/vol8/iss1/7136 ARKANSAS ACADEMY OF SCIENCE1234567REFERENCESDrake, M., Vengris, J. , and Colby, W. J. Cation-exchange capacity of plantroots. Soil Sci. 72, pp. 139-147 (1951).Graham, E. R. Availability of natural phosphates according to energy changes.Soil Sci. Soc. Amer. Proc. (In Press) (1954).Gray, B. ,Drake, M., Colby, W. G. Potassium competition ingrass- legume asso-ciations as a function of root cation exchange capacity. Soil Sci. Soc. AmerProc. 17, pp. 235-239 ( 1953).McLean, E. 0. and Baker, F. E. Cationic activities and the exchange phenom-ena of plant roots. I. A preliminary report. Ark. Acad. of Sci. V, pp. 23-26(195 2).McLean, E. 0. and Hoelscher, J. E. Factors affecting yields and uptake ofphosphorus by different crops. Soil Sci. (Manuscript prepared) (1954).McLean, E. 0. and Baker, F. E. Cationic activi ties in systems of plant roots.Soil Sci. Soc. Amer. Proc. 17. pp. 100-102 (1953).Truog, E. The Utilization of phosphates by agricultural crops, including anew theory regarding the feeding power of plants. Wise. Agr. Exp. Sta. Res.Bui. 41 (1916).136Journal of the Arkansas Academy of Science, Vol. 8 [1955], Art. 7Published by Arkansas Academy of Science, 1955

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Cationic Activities and the Exchange Phenomena of Plant Roots: Relationship to Practical Problems of Nutrient Uptake

ScholarWorks@UARK

Journal of the Arkansas Academy of ScienceVolume 8 Article 71955Cationic Activities and the Exchange Phenomenaof Plant Roots: Relationship to Practical Problemsof Nutrient UptakeE. O. McLeanUniversity of Arkansas, FayettevilleD. AdamsUniversity of Arkansas, FayettevilleF. E. BakerUniversity of Arkansas, FayettevilleFollow this and additional works at: http://scholarworks.uark.edu/jaasPart of the Agronomy and Crop Sciences Commons, and the Plant Biology CommonsThis article is available for use under the Creative Commons license: Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0). Users are able toread, download, copy, print, distribute, search, link to the full texts of these articles, or use them for any other lawful purpose, without asking priorpermission from the publisher or the author.This Article is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Journal of the Arkansas Academyof Science by an authorized editor of ScholarWorks@UARK. For more information, please contact scholar@uark.edu.Recommended CitationMcLean, E. O.; Adams, D.; and Baker, F. E. (1955) "Cationic Activities and the Exchange Phenomena of Plant Roots: Relationship toPractical Problems of Nutrient Uptake," Journal of the Arkansas Academy of Science: Vol. 8 , Article 7.Available at: http://scholarworks.uark.edu/jaas/vol8/iss1/7134CATIONIC ACTIVITIES AND THE EXCHANGE PHENOMENAOF PLANT ROOTSRELATIONSHIP TO PRACTICAL PROBLEMS OF NUTRIENT UPTAKE1E. O. McLEAN, D. ADAMS and F. E. BAKER 2University of ArkansasThe feasibility of measuring cationic activities in systems of plant rootswas indicated in a preliminary report on this general subject (4). The energywith which a cation is bonded to the exchange seats of the root surface can thenbe computed from the cationic activities. The present study has been conductedin an attempt to find whether these mean that free-bonding energies have anysignificance in practical problems involving nutrient uptake.Some plants utilize Na as a partial replacement for K needs. Such plantsaccumulate large amounts of Na. Other plants do not absorb Na to any appreciableextent. Itseemed worthwhile to determine whether the ability to accumulate Naby a plant would be reflected in the relative bonding energies of plant rootsfor Na.The maintenance of grass/legume pastures and meadows has become a diffi-cult task because of diversity of nutrient requirements by the grass as comparedto the legume. Some work has indicated that the relative cationic exchange capac-ities of the roots of the different species was important in this problem (1),hence it seemed likely that the mean free-bonding energies of the cations to theroots might be important also.The diverse ability of different plants to utilize phosphorus from insol-uble sources such as rock phosphate has long perplexed agronomists. Could it bethat the plants' ability to break up the tricalcium phosphate molecule in rockphosphate is related to the ability of the roots to bond calcium?EXPERIMENTALSince the previous report in this series, the determination of cationic ac-tivities and mean free-bonding energies for various cations has been extendedfrom soybean and alfalfa roots to those of Reed canary grass, red top, lespedeza,corn, oats, and another variety of alfalfa. The plants were grown in level cul-tures of 1/5 Hoagland's solution as has been described (4) (5). The plants weregrown for various lengths of time as follows: Cereals, 15 days; legumes, 30 days;and grasses, 50 days. The procedure for determination of cation activities wasexactly as previously described. The uptake of Na by several plants is being de-termined by replacing with NaO, 1/4, 1/2 and 3/4 of the K in the 1/5 Hoaglandsolution and growing the plants in quadruplicate in No.2 tin cans of gravelbathed with these solutions.In other studies reported elsewhere (6), the uptake of phosphorus from soiltreated with various phosphates by several of these same plant species was de-termined.DISCUSSION OF RESULTSAs these studies are still in progress, the results reported in tables 1, 2and 3 are in some cases incomplete. However, it is believed that sufficient pro-gress has been attained to justify inclusion here. It appears from the data ofTable 1 that some relationship does exist between the tendency to take up Na andthe bonding energy of Na to the plant root; however, there is need forcompletionof two key determinations before definite conclusions can be drawn.1Research paper No. 0000 Journal Series, University of Arkansas, Fayetteville, Arkansas. Pub-lished with permission of the Director of the Ark. Agr. Exp. Sta. A major part of this workhas been and is being submitted by the junior author as partial fulfillment of the requirementsfor the M. S. Degree in the Graduate School, University of Arkansas. This investigation waslargely supported by a grant from the Mathieson Chemical Corporation, and this support IIgratefully acknowledged.Associate Professor, Graduate Assistant and former Graduate Assistant, respectively.134Journal of the Arkansas Academy of Science, Vol. 8 [1955], Art. 7Published by Arkansas Academy of Science, 1955CATIONIC ACTIVITIES AND THE EXCHANGE PHENOMENA 135Table I.Mean Free-Bonding Energies of Plant Roots for Na in relation to NaUptake by These Different Plants.Plant Tendency to takeFNa up Sod ium*( Calor ies/mol e )Corn 0 nilReed canary grass 55 fOats 559 ModerateAlfalfa 599 ModerateCelery f Excessive• As recently reported in Soil Sci., 76:1 (1953)f- Values being determined but not yet available.Table 2. Mean Free-Bonding Energies of Legume and Grass Roots for Ca and Kin Relation to Their Relative Competition for These Cations.Plant AF (Calories/equivalent) £F ra Cation for whichCalcium Potassium Competition is KeenestLegumes:Alfalfa (K.C. ) 775 6.72 1.16 CalciumAlfalfa (B. ) 590 642 0.92 CalciumSoybean 827 711 1.16 CalciumLespedeza 815 705 1.16 CalciumGrasses:Red Top 509 861 0.59 PotassiumReed Canary Grass 329 648 0.51 PotassiumThe data of Table 2 appear to give excellent support to the work of Gray,et al (3). They showed that certain grasses are so competitive with clovers grownwith them that itis near impossible to maintain sufficient K in the soil to meetthe needs of the clover. The relatively high values of the Fpg/Fj/ ratio for thelegumes and the relatively low values for the grasses would"seem to offer someexplanation as to why legumes tend to accumulate Ca while the grasses tend toaccumulate K even to the detriment of the legumes.Evidently there is a definite relationship between the ability of a plantto utilize phosphorus from rock phosphate and the relatively high mean free-bonding energy of the roots for Ca (Table 3). Graham (2) showed that the freeenergy change in the exchange of Ca for H on various colloids correlated withthe abilities of the acid colloids to weather rock phosphate and render phos-phorus available to a test crop. This might suggest that the ability of buckwheatand similar crops to utilize phosphates of low solubility may be related to thisrelatively high mean free-bonding energy for Ca. Perhaps the latter is a formid-able weathering force in attacking rock phosphate much in excess of that of cer-tain other types of plant roots. Truog (7) indicated many years ago that plants'abilities to take phosphorus from low solubility materials was related to theircalcium content in the tissues.Table 3. The Mean Free Bonding Energy Ratios as Indices for Determiningthe Abilityof a Plant to Utilize Rock Phosphate.Plant FCa Ability to Utilize RockAFy P hosphate*Buckwheat 1.67 HighAlfalfa 1.16 ModerateSoybean 1.16 ModerateLespedeza 1.16 ModerateRed Top 0.59 LowReed Canary Grass 0.51 LowIn part based on studies reported (6) and in part based on general knowledger i | • . • |• « ,TI_ I L 135Journal of the Arkansas Academy of Science, Vol. 8 [1955], Art. 7http://scholarworks.uark.edu/jaas/vol8/iss1/7136 ARKANSAS ACADEMY OF SCIENCE1234567REFERENCESDrake, M., Vengris, J. , and Colby, W. J. Cation-exchange capacity of plantroots. Soil Sci. 72, pp. 139-147 (1951).Graham, E. R. Availability of natural phosphates according to energy changes.Soil Sci. Soc. Amer. Proc. (In Press) (1954).Gray, B. ,Drake, M., Colby, W. G. Potassium competition ingrass- legume asso-ciations as a function of root cation exchange capacity. Soil Sci. Soc. AmerProc. 17, pp. 235-239 ( 1953).McLean, E. 0. and Baker, F. E. Cationic activities and the exchange phenom-ena of plant roots. I. A preliminary report. Ark. Acad. of Sci. V, pp. 23-26(195 2).McLean, E. 0. and Hoelscher, J. E. Factors affecting yields and uptake ofphosphorus by different crops. Soil Sci. (Manuscript prepared) (1954).McLean, E. 0. and Baker, F. E. Cationic activi ties in systems of plant roots.Soil Sci. Soc. Amer. Proc. 17. pp. 100-102 (1953).Truog, E. The Utilization of phosphates by agricultural crops, including anew theory regarding the feeding power of plants. Wise. Agr. Exp. Sta. Res.Bui. 41 (1916).136Journal of the Arkansas Academy of Science, Vol. 8 [1955], Art. 7Published by Arkansas Academy of Science, 1955

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Cationic Activities and the Exchange Phenomena of Plant Roots: Relationship to Practical Problems of Nutrient Uptake

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