influence of mineral - plant physiology · tially the entire root system of the plant. the middle...

THE INFLUENCE OF MINERAL DEFICIENCY ON VEGETATIVEGROWTH, FLOWER AND FRUIT PRODUCTION, AND MINERAL

COMPOSITION OF THE PEANUT PLANT'

ROGER W. BLEDSOE AND HENRY C. HARRIS2

(WITH FOUR FIGURES)

Received May 26, 1949

IntroductionThe peaniut plant, Arachis hypogaea L., is one of the few plants in which

the ovary of the aerial flower must be transferred by a gynophore to a sub-terranean position before maturation of the fruit will normally occur.The morphology and anatomy of the peanut plant as described by PETTIT(16), WALDRON (23), REED (17), and JACOBS (11) indicate that the gyno-phore has a stem-like anatomy and a root-like behaviour. Pettit (1895)

FIG. 1. Gynophore with root-hair-like epidermal outgrowths.

reported that the hypogeal portion of the gynophore forms root-hair-likeepidermal outgrowths and suggested that the organ was a part of the ab-sorptive system since few root hairs were found on the root of the plant.Waldron also assumed that the hairs on the gynophore might absorb waterand nutrients, while MOHAMMAD, et al., (15) and Reed considered absorp-tion by the hairs to be of little importance. The authors have observedthe epidermal outgrowths of the gynophore on field grown plants, and atvarious periods of the year when that organ developed in solution, sandand/or soil under greenhouse conditions, figure 1.

' Published with the approval of the Director, Florida Agricultural Experiment Sta-tion.

2 A part of this paper was presented before the American Society of Agronomy inColumbus, Ohio, 1946.

63

Copyright (c) 2020 American Society of Plant Biologists. All rights reserved.

PLANT PHYSIOLOGY

At the initiation of the present study the literature offered little in-formation on the nutrition of the peanut. VAN DER WOLK (21) observedthat water and darkness were essential to fructification, and that a soil ex-tract was beneficial. SHIBUYA (18) reported that only the first two factorsare necessary. BURKHART and COLLINS (6) demonstrated the uptake oflithium by the fruiting organs and reported that fruit quality was bene-fited by the presence of calcium in the fruiting medium.

BRADY, et at. (4), from studies initiated concurrent with and since thepresent investigation, reported a significant increase in fruit filling whena single calcium salt was added to the fruiting medium. Subsequent workby HARRIS (10) showed fructification to be negligible when a minus cal-cium nutrient solution was applied to the fruiting medium. Results ofMEHLICH, et al., (14) also indicate that fruit filling is related to the avail-able external calcium supply. THORNTON and BROADBENT (20) demon-strated the uptake and movement of isotopic nitrogen from the fruitingorgans to the vegetative portions of the plant. Recent work with radio-active calcium by BLEDSOE, et al. (3) indicates that the need of an-externalsupply of calcium by the developing fruit might be the result of poor trans-location of that ion from the plant to the fruit.

This report detls with the results of a study conducted in 1945 relativeto the necessity of an external supply of nutrients to the fruiting organ fornormal fructification and to an evaluation of salt movement from the fruit-ing organs to the vegetative tissue when differential nutrient treatmentswere applied to the root medium of the peanut plant.

ExperimentalPeanut seeds of the'Dixie Runner variety were placed in moist chain-

bers to germinate on Apxil 11, 1945. After five days the most vigorouslygerminating seeds were selected and single'seedlings were transferred toone-gallon jugs filled with acid-water-washed sand which had been inocu-lated with Nitragen E Culture.' When the plants were about 5 cm. high,selected containers with the more uniform individuals were placed in boxesof sand. The method of isolating the rooting and fruiting media, the basicand supplementary nutrient solutions used, and their method of applica-tion -have already been described (2). The pH of all solutions was ad-justed to approximately 5.5.

The complete nutrient solution was added to the fruiting medium of 24plants throughout the experiment, while differential nutrient treatmentswere started on the roots of the plants after they had received the com-plete solution for 80 days. At that time a mean of 43 gynophores per planthad penetrated the sand of the fruiting medium. The plants were thendivided into eight groups of three replicates of single plants and the fol-lowing nutrient treatments, with concentrations modified as reported pre-viously (2), were begun on the rooting media: complete, minus phosphorus,

64


BLEDSOE AND HARRIS: MINERAL DEFICIENCY IN PEANUT

minus potassium, minus calciunli, minus magniesium, minus sulphur, minusmicro-nutrients, and distilled water. Plants which received the coinpletesolution in root and fruiting media throughout the experiment are referredto hereafter as control plants.

Each of three boxes of sand held eight glass jugs with single plants.The eight nutrient treatments on the rooting media were randomized andeach treatment occurred once to a single plant in each box. A fourth boxcontained the ninth group of three jugs of single plants which receivedthe complete nutrient solution oln the roots, and distilled water on the fruit-ing medium throughout the experiment.

The glass jugs, which held the roots of the plants, were originally filledwith sand to within 1 inch of the tops. To allow for root growth, portionsof the sand were removed April 24 and June 8 by carefully washing itthrough the drain holes of the jugs. Sinee the plants made satisfactorygrowth after each removal of sand it is assumed that the roots were littleaffected by the operation. The top of each glass jug was placed 1i to 2inches above the surface of the sand in the boxes and drainage holes in thebottom of the latter permitted the escape of any excess rain water. Thus,the possibility of nutrients from the fruiting iiiedium contaminating thesolutions applied to the roots of the plant within the glass jugs was elimi-nated. A string mesh across the tops of the boxes prevented the branchesand foliage from touching the fruiting medium.

During the course of the experiment, flowers of all plants were counteddaily. Since the peanut flower is ephemeral and wilts after a few hours,an accurate record of flower production is obtained easily.

When the plants were 130 days old and had received the deficient solu-tions on the roots for 50 days, they were harvested; the entire plant andportions thereof were immediately weighed anid subsequently dried at 700C. Harvesting of plants was accomplished by first carefully flushing thesand from the roots and fruits through the drain holes of their respectivecontainers. The glass jugs were then broken anid the roots were washedfree of sald. This permitted a complete recovery- of all fruit anid essen-tially the entire root system of the plant.

The middle leaves of lateral branches and the following stages of fruitdevelopment were selected from each plant for mineral analysis: (1) gyno-phores prior to entering the sanid of the fruiting medium, (2) gynophoresin samid with slight basal enlargeimienit, anid (3) shells of mature fruit.Samples for mineral analysis (phosphorus, potassium, magniesium and cal-cium) were ashed for four hours in an electric iiuffle at 5000( C. Totalnitrogen was determined oni separate samlples. Nitrogen, phosphorus andcalcium were determined by the Official Method of Analysis (1), whilemagnesium was determined by the method of DROSDOFF aInd 'NEARPASS (8),and p)otassiulm by the sodiummi-cobaltinitrite miiethod of BROWN, ROBINSONanid BROWNING (5).

65


PLANT PHYSIOLOGY

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BLEDSOE AND HARRIS: MINERAL DEFICIENCY IN PEANUT 67

TABLE IIMEAN NUMBER AND MEAN PER CENT. PER PEANUT PLANT OF FLOWERS, GYNOPHORES, AND

FRUITS AS AFFECTED BY NUTRIENT TREATMENT. ROOTS OF PLANTS GROWN INCOMPLETE SOLUTIONS TO JULY 1 (80 DAYS) AND DEFICIENT

SOLUTIONS TO AUGUST 20 (50 DAYS)

NUTRIENT GYNo- GYNo-

TREATMENT MEAN FLOWERS FLOWERS PHORES FRUITINGMEAN MEAN iSOUND PRODUC- PRODUC- ENTERING MEDIUMNFLOW- GYNO- ING GYNO- MDU

MATURE ING FRUIT FRUITING PRODUCINGROOT FRUIT ERS PHORES FRUIT PHORES % MEDIUM FRUITZONE ZONE % %

ct ct 644 378 59.3 58.7 9.2 64.3 24.4C* O** 758 495 1.5 65.3 0.2 44.2 0.7O C 250 74 3.7 29.6 1.5 78.4 6.4- K C 481 229 41.5 47.6 8.6 76.8 23.6- P C 475 243 29.7 51.2 6.3 72.8 16.8- Ca C 392 179 21.0 45.7 5.4 69.8 16.8- Mg C. 583 312 13.7 53.5 2.3 52.9 8.3- S C 423 236 37.7 55.8 8.9 66.9 23.9- Micro-Nutrienits C 324 122 1.7 37.7 0.5 53.3 2.6

L.S.D. 5% 164 130L.S.D. 1% 225 179

* = Complete nutrienit solution.** = Distilled water.t = Referred to in text as control treatment.

FIG. 2. Peanut plailt wlhieli r2ceived a comiplete solutioin in the rooting mediumll aiiddistilled wvater in the fluitinig liiediulii.


PLANT PHYSIOLOGY

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BLEDSOE AND HARRIS: MINERAL DEFICIENCY IN PEANUT 69

Results

The necessity of aii externial suiplyp of nuiitrienits in both the rooting andfruiting media of the peanuit plant for optimum growth and fruit produc-tion is shown in tables 1, II, and IIT. Without exception it was foundthat plants supplied with the complete solution in the rooting medium,irrespective of the nature of the fruiting medium, notably surpassed theplants of all other cultures not only in the total amount of vegetativegrowth, flower and gynophore production, but also in the character ofgrowth and general appearance of the plants. However, the absence ofan external supply of nutrients in the fruiting medium resulted in ahighly significallt decrease in fructification. Fruit development was neg-lig,ible when distilled water only was used in the fruiting medium (fig. 2)in contrast to the number of fruit produced by the control plants (fig. 3).

..__a _~~~~~~~~~~~~~~~~~~~~~~~~~0_a.&_N

FIG. 3. Peanut plant which received a complete nutrient solution in the rooting anidfruiting media.

The former plants had a favorable appearance and exceeded the conitrolplants in vegetative vigor and in the niumiber of gynophores produced. Amean number of 219 gynophores per plant had entered the fruiting medium,but there was limited hypogeal development beyonid the iniitial stagre of en-

largement after penetrating the sand. This indicates the niecessity of somenutrients in the fruiting medium of the peanut planit for favorable fruc-tification.

The necessity of a nutrient balance in the rootingo medium is clearlyindicated by the results from the deficient cultures. Vegetative growth

69


PLANT PHYSIOLOGY

and mineral comnposition of planits were obviously affected by the withhold-ing of any ion or ions from the-external supply of the roots when the fruit-ilog organis were supplied the complete solution. Withholding all nutrientsfrom the roots after July 1, resulted in the smallest, plants in the experi-ment. Icighly significanit differences are demonstrable betweeni data of thelatter and control plants in all characters used as criteria for vegetativevigor and fruitfulness. -When -only distilled water was applied to the roots,flowering practically ceased after four days and slight vegetative growthwas mlade thereafter. The extreme retarded growth of previously vigor-ously growing plants in such a short period after all nutrients were with-drawn from the roots and the limited anmounit of growth thereafter when therewere many gynophores and some fruits developing in the mediumn supplied

FIGe. 4. Peanut plant which had micronutrients withheld from the roots after 80da-ys while the fruiting medium received a comiplete solutioni throughiout the experimenit.

time complete nutrienit solution leads to the conclusioni that there was a lim-ited movement of minerals from the fruiting organs to the vegetative tissue,of the plants unlder conditions of this experiment. Likewise, the rapid de-velopinneiit of foliar deficiency symptoms for mineral elements which re-sulted from the deletion of the external supply to the roots when the fruit-inig media were supplied the complete solution further supports that con-

clusion.Plants were grown under conditions coniducive to fruitfulness and dur-

ingf the period when peamiuts are usually grown in the field. The deficientsolutions were applied to the roots of the planlts durimigc the most activeperiod of flowering. Many gynophores produced in Aug-ust by plants

~~~~z 1

70


BLEDSOE AND HARRIS: 'MINERAL DEFICIENCY IN PEANITT7

grown on the complete solutioni were from stems which extended over thesides of the culture boxes. The yields reported for the control plants in-dicate that the rooting and fruiting media of the cultures had a favorablesupplying power for nutrients. All plants were harvested approximately20 days short of the usual growth period because of the severe nutrient de-ficient condition of some plants. As a result, the control plants had manyimmature fruits which resulted in less difference between yields of controland deficient cultures than would have occurred had plants been harvestedat a later date.

Summarization of data from tables I and II shows that when the com-plete solution was supplied to the fruiting media continuously and to theroots of plants for an 80-day period followed by a 50-day treatment to theroots with nutrient deficient solutions, it resulted in a statistically signifi-cant decrease between data of the latter and that of the control plants inthe following characters: (1) the mean green weight of all cultures, (2)the mean number of flowers of all except the minus potassium and minusmagnesium cultures, (3) the mean number of gynophores of all except theminus magnesium cultures, and (4) the mean number of fruits for all exceptthe minus potassium cultures.

Figures of mineral compositioni (table III) represent the mean of dupli-cate analyses of each of three plants. The mineral composition of middleleaves from lateral branches is assumed to be representative of the nutri-tional status of the vegetative portion of the plants. Likewise, the mineralcontent of gynophores before and after they entered the sand of the fruit-ing zone, and shells of mature fruit indicate the influenee of nutrient treat-ment on the mineral composition of those organs.

The withholdingf of all nutrients from the roots of the plant in generalresulted in a much lower percentage mineral content of plant parts ana-lyzed than did the omission of nutrients from the fruiting zone of the plant.Withholding an element from the roots resulted in a decreased percentageof that element in the leaves and all fruiting organs. However, there wasa tendency for the calcium and especially the potassium concentrations inthe gynophores to inerease after entering the fruiting zone supplied withthe complete nutrient solution. This occurred when the complete solutionwas applied to both rooting and fruiting media and when the minus potas-sium, minus calcium, and minus sulphur solutions were applied to the rootsof the plants. There was a slight decrease in the concentration of allminerals in the gynophores after entering sand to which only distilled waterhad been applied. When all nutrients were withheld from the roots of theplant after 80 days, it is questionable if the data of mineral content of thegynophores are comparable because thereafter very few gynophores enteredthe sand of the fruiting medium.

When the roots of the plants received the minus phosphorus or minusmagnesium solution, the phosphorus and magnesium coneentrations, re-

71


PLANT PHYSIOLOGY

spectively, of the gynophores did not inierease after those organs entered the-zone supplied the complete solution. The shells of mature fruit likewisehad a very low concentration of those ions. Thus, the data suggest thatafter the gynophore enters the fruiting medium, it has a greater absorptiveintensity for potassium and calcium than for phosphorus or magnesium,which might indicate a greater uptake of potassium and calcium from theexternal supply in that zone.

Mineral deficiency symptomsReports of symptoms of mineral nutrient deficiencies other than for the

young peanut plant do not occur in the literature (6). For that reason, adescription of nutrient deficiency symptoms of older plants as they oc-curred in this investigation will be recorded briefly with appropriate com-ments.

The early stages of leaf symptoms under conditions of phosphorus defi-ciency became evident within two weeks after phosphorus was withheldfrom the roots (6). Top growth was greatly restricted and in the laterstages there was premature defoliation of the yellow basal leaves, but stem.discoloration did not occur (6).

Three weeks after the potassium deficient solution was applied to theroots of the plant the foliage became a darker green in color. In laterstages there was some abscission of lower leaves, but marginal necrosis ofleaflets was very limited. After 40 days the terminal portion of stems andadjacent petioles became distinctly red, then brown, which was followed bydeath of the tissue. Fructification of the potassium deficient plants wassignificantly greater than plants of the other deficient cultures.

Magnesium deficiency as previously reported by BLEDSOE, et al., (2) didnot show the orange coloration of leaflet margins reported by BURKHARTand COLLINS (6). It is interesting that while flower and gynophore produc-tion of the minus magnesium cultures was not significantly less than thatof the control plants, fructification was significantly decreased. Data intable II and results reported by SOMMER and BAXTER (19) indicate the im-portance of magnesium in nut production.

Within two weeks after treatments were started, symptoms of calciumdeficiency became apparent by restricted growth and the appearance ofsmall interveinal brown pitted areas accompanied by marginal chlorosis onthe upper surface of fully developed leaflets proximal to the growing tips.At 27 days the leaflets at the tips were very small, chlorotic, crinkled anddistorted. Pitted areas were then present on both leaf surfaces and hadcoalesced to form numerous larger necrotic spots which resulted in a bronzeleaf color. Basal stem cracks and die-back of the affected shoots occurred inthe later stages. Roots of plants were stunted and decomposing when har-vested. Blossoming had decreased sharply within 10 days and was entirelysuppressed prior to termination of the experiment. Gynophore and fruitproduction was also significantly less than that of the control plants. Re-

72


BLEDSOE AND HARRIS: MINERAL DEFICIENCY IN PEANUI'T

stilts inidicate the necessity of an ample supply of calcimitii in the rootinlgmedium of the peanuiit planit irrespective of the natuire of the fruiitingmedium.

External deficiency symptoms for siilphur were not recogniizable. Shootand root growth was significantly deereased and niodulation was less thanthat of the control plants. Flower produlction remained rather constantthroughout the period that the planits received the sulphur deficient solu-tion on the roots.

The omission of the miero-nutrienits (Cu, AMn, Zn, B anid AMo) fromthe roots of the plants after 80 days resulted in a highly sigfnificant de-crease in all characters used as criteria for vegetative vigor and fruitful-niess, figure 4. Flowers were pale yellow in color and a high percentagefailed to produce gynophores. Interveiiial chlorosis of the terminal leafletsappeared at 27 days and all new growth of lateral branches was affected asage advanced. The failure of the gynophores to supply micro-nutrients tothe plants shoots in quantities sufficient for growth indicates that the absorp-tion by those organs was of a low order under conditions of this experinient.

The withholdingf of all nutrients fromii the roots of the plaint at 80 davsgreatly restricted top growth and blossoniing within a 10-day period. Thatwas followed bv earlv maturation, defoliationi of sonie basal leaves, and theappearaniee of cracks in the basal portioin of stems. Necrotic spots appearedon the terminal leaflets, aiid the meristematic region was affected in a simi-lar manner to the plants grown on the minus calcium solution. Chloroticeffects occurred oni the voumig growth and had spread progressively towardthe older leaves wheii the experimnenit was terminiated.

DiscussionIn this investigation, those plants supplied with a deficient soluition to

the root medium and a complete solution to the fruit medium were con-sidered as deficient cultures. The reserve of the deficient ion in the foliage,absorbed during the preliminary period wheni the plants were growmn on thecomplete solution, anid the redistribution of the reserve withimi the plantafter the external supplv of the ion had becomie (leficiemit to the root systemprobably in part accounts for the differenees in quantity of fruit producedby plants growmi on a given deficient solution.

Results indicate that the root is the primarv absorbinig organ of thepeaniut plant and an inadequate supply of niutrients in that region will havea deleterious effect on both vegetative growth aiid fructification. The rapiddevelopinemit of foliar deficieiney symptoms after the deficiemit solutions wereapplied to the roots of the plants, when the fruiting mediuin was suppliedthe complete solution, indicates that if elements were absorbed by the fruitingorgans from the external supply in the fruiting zone, then there was asmall amount translocated to the plant shoot. In some instances it appearedas if the developinmi fruit drew on the reserves of the leaves, thus accelerat-ing breakdown of the vegetative tissue. This is consistent with the gemieral

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PLANT PHYSIOLOGY

view that the mineral requirements of the fruit are satisfied at the expenseof the vegetative tissue if the external supply falls short of supplying theneeds of both. However, it has been demonstrated by HAMNER (9), LOEH-WING (12), and WADLEIGH (22) that the lack of balance may accentuatea given deficiency or be more detrimental to growth than generally realized.

It is assumed that absorption of some elements would occur by an organhaving the hypogeal structure of the gynophore (fig. 1). BURKHART andCOLLINS (6) demonstrated the uptake of lithium by the fruiting organ andits distribution within the plant. The nutritional status of the plant mighthave an influence on the absorption by the gynophores as shown by thework of THOR1TTON and BROADBENT (20), where the absorption of N'5 wasnegligible when an ample supply of nitrogen was available to the roots, butit was considerably increased when the roots were given a low nitrogen sup-ply. However, in all cases the amount of N"5 absorbed by the gynophoresrepresented only a small part of the total nitrogen of the plant. HARRIS(10) reported the uptake of radioactive phosphorus and cobalt by the fruit-ing organs to be insignificant when compared with that absorbed by theroots of the plants. The fruiting organs received a much greater amount ofthose ions when applied to the root medium of the plant than when thefruiting organs were in direct contact with the radioactive substances.

There are no data available on the ratio of surface of roots to hypogealportion of gynophores. In all probability the absorptive area of the latterwould represent only a small portion of the former and consequently thetotal amount of absorption by the fruiting organs would be expected to berelatively small as compared to the root system. Furthermore, some investi-gators assume that absorption by the fruiting organs occurs primarily dur-ing the early stages of fruit development, which, if true, would furtherlimit the absorption period of those organs.

Obviously, the results of this investigation give no indication of the ionicrequirements for fructification. This, of necessity, follows from the natureof the experimental set-up, which does not permit a measurement or even anapproximation of the external ions needed, the amounts or the stage of fruitdevelopment when such are essential. However, data of mineral composi-tion (table III) suggest that the fruiting organs had a greater absorptionintensity for potassium and possibly calcium from the external supply inthe fruiting medium than for phosphorus or magnesium. These results alsoshow that the nutrient deficient solutions had a greater effect on the potas-sium content of fruiting organs than that of other elements determined.Results by BURKHART and COLLINS (6) and BRADY, et al., (4) indicate thatthe known antagonism between potassium and calcium may come into playwhen the fruiting medium has a low available calcium supply. It is prob-able that an excessive potassium absorption by the roots of the plant or bythe developing fruit may influence the transport of calcium from the vege-tative organs to the fruit or the direct intake of calcium by the fruit.

74



The importance of an available calcium supply in the fruiting mediumfor favorable fructification has been emphasized by a number of investiga-tors (4, 6, 10, 14). BLEDSOE, et al., (3) recently reported that when radio-active calcium was administered to the fruiting medium there was a veryactive absorption of Ca45 by gynophores, shells and seed of fruit as com-pared with the small amount of absorption by those organs when Ca45 wassupplied to the root of the plant. In the latter case, the young gynophorehad a relatively high concentration of Ca45 but the concentration per unitof dry weight decreased as that organ developed and the shells of fully devel-oped green fruit contained only a small concentration of labeled calciumwhile never more than a trace could be detected in the seed. Thus, it appearsthat the transport of calcium from the plant to the rapidly growing gyno-phore is sufficient for its elongation but probably inadequate for conditions ofprotoplasm, wall formation, etc., required in fruit growth and development.The relative immobility of calcium and some other ions as reported byMASON and PHILLIS (13) will be recalled in this connection.

The available calcium supply in the fruiting medium has been demon-strated to have a greater influence on fruit filling than the availability ofany other known element. However, from data of table II, those reportedby other investigators (4, 7, 10,) and unpublished results by the authors, itappears obvious that factors other than the available calcium supply in thefruiting medium are important in fructification. The number of well de-veloped fruit even with the best known nutrient treatments represents asmall per cent. of the gynophores which enter the fruiting medium.Whether that failure of development is related to organic or inorganic sup-ply is as yet undetermined. Whatever the role of the external supply ofcalcium in fruit development may be, it would appear that its role would bealso other than that of merely adding calcium to the seed.

SummaryPeanut plants of the Dixie Runner variety were grown in sand culture

with a complete nutrient solution applied to the isolated fruiting media,while the roots of the plants received various deficient nutrient solutionsfollowing 80 days of growth on a complete solution. Nutrient deficiencysymptoms which developed under the above conditions are described. Vege-tative growth, fruit production, and mineral composition of plant parts wereadversely affected when any macro-element was withheld from the roots ofplants after 80 days. Fruit production was negligible when the roots re-ceived the complete solution, and distilled water was added to the fruitingzone of the plant. Mineral composition of gynophores before and after en-tering that zone supplied with the complete solution suggests that thoseorgans have a greater absorptive intensity for potassium and calcium fromthe external supply in the fruiting medium than for phosphorus or magne-sium. Results show that the root is the primary absorbing organ of the

75


PLANT PHYSIOLOGY

peanut plant and the necessity of a nutrient balance in the root zone foroptimum growth and fruit production is emphasized. ln no case was theabsorption of an element by the gynophores sufficient to offset the appear-ance of nutrient deficiency symptoms of that element when it was omittedfrom the roots of the plants.

UNIVERSITY OF FLORIDAAGRICULTURAL EXPERIMENT STATION

GAINESVILLE, FLORIDA

LITERATURE CITED1. ASSOCIATION OF OFFICIAL AGRICULTURAL CHEMISTS. Official and tenta-

tive methods of analysis. Ed. 6. Washington, D. C. 1945.2. BLEDSOE, R. W., HARRIS, H. C., and TISDALE, W. B. Leafspot of peanut

associated with magnesium deficiency. Plant Physiol. 21: 237-240.1946.

3. BLEDSOE, R. W., COMAR, C. L., and HARRIS, H. C. Absorption of radio-active calcium by the peanut fruit. Science 109: 329-330. 1949.

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influence of mineral - plant physiology · tially the entire root system of the plant. the middle...

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