JOURNAL OF ACMIIM, RESEARCH 
Vol. IX Washington, D. C., April 16, 1917 No. 3 
ABSORPTION OF NUTRIENTS AS AFFECTED BY THE 
NUMBER OF ROOTS SUPPLIED WITH THE NUTRIENT 
By P, U. GilE, Chemist , and J. O. Carrero, Assistant Chemist , 
Porto Rico Agricultural Experiment Station 
INTRODUCTION 
In the course of several investigations on the mineral nutrition of rice 
(<Oryza sativa ) it became necessary to know whether the plant could 
absorb an optimum amount of the mineral element which was supplied 
to only part of the roots if all the other essential elements were supplied 
to all the roots. At first thought it would seem the plant could absorb 
sufficient of the element supplied to only part of its roots if sufficient 
selection could be exercised in the absorption of the different nutrients 
by individual roots. So far as known, no quantitative study has been 
made of this point; hence, the tests reported below were conducted. 
The selective absorption of mineral elements was early established by 
Saussure, 1 Gorup-Besanez, 1 and W. Wolf (12). 2 E. Wolff (13) showed that 
the selective absorption could be altered by changing the proportion of 
salts in the nutrient solution. Some recent studies on antagonism have 
also demonstrated that absorption or penetration of ions in plant roots 
is affected by the relative concentrations of ions in the solution. Most 
of such studies, however, have been made on unbalanced solutions of one 
or two salts only, and the object has been to ascertain the influence of 
different proportions of salts on root growth aside from nutritive effects. 
The results show that a nutrient solution, to be a proper medium for root 
growth, must contain the salts in certain proportions. These propor¬ 
tions may be varied considerably, especially in low concentrations of a 
variety of salts, without appreciably affecting growth (3, n). 
The present work does not deal with the effect of the medium on 
selective absorption by roots, but with the effect of localization of the 
supply. The results emphasize to what a great extent selective absorp¬ 
tion may be altered by limiting the supply of an element to a few roots, 
without changing the medium. Some work done previously is similar to 
this investigation, in that plants were grown with their roots divided 
between two unlike media. Quantitative data, however, were not 
secured on the point which is the subject of this work. 
1 Cited by Heiden (6, p. 280-286). 2 Reference is made by number to "Literature cited," p. 94-95. 
Journal of Agricultural Research, 
Washington, D. C. 
hu 
(73) 
Vol. IX, No. 3 
April 16, 1917 
Key No, B—13 
