Experiment Station Record, Volume 92, January-June, 1945 Page: 186
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186 EXPERIMENT STATION RECORD [Vol. 92
influenced by polyvalent cations was made with excised roots capable of accumulating
large amounts of K and Br in a short time. Contrary to the concept of antagonism
deduced from experiments conducted usually with high salt concentrations on
material incapable of active aerobic metabolism, these studies indicated that a
variety of polyvalent cations accelerate K and Br absorption, Ca being most effective.
A ratio greater than 30 Ca ions to 1 K ion in the solution was necessary
before K absorption could be depressed below absorption from pure KBr. Ca, Mg,
Sr, Ba, and Al were effective in increasing K and Br absorption, but no regular
series of efficiencies could be determined. Mixtures of CaSO4 and MgSO4 produced
increases in absorption of the same magnitude as did these salts used alone
with KBr, indicating that the polyvalent cations are performing the same common
function with different degrees of efficiency. The influence of Ca on ion absorption
in its relationship to the increased respiration and sugar loss is discussed,
and the difficulty of separating primary and secondary effects is noted. Roots
grown with different Ca supplies responded similarly to the presence of Ca in the
KBr 'solution during subsequent ion absorption. Absorption of K and Br from
relatively high concentrations of KBr could not be accelerated by Ca when the roots
were deprived of 02 or treated with KCN. The effect of Ca on K and Br absorption
was apparent over a wide temperature range. Two interpretations of the data
are considered, and the difficulties of separating metabolism from permeability in
discussions of ion accumulation are reemphasized.
Some effects of boron supply on the chemical composition of tomato leaflets,
R. Q. PARKS, C. B. LYON, and S. L. HooD. (U. S. D. A.). (Plant Physiol., 19
(1944), No. 3, pp. 404-419, illus. 3).-A brief review of the literature (55 references)
indicated striking disagreement as to the effects of B supply on the mineral
content of plants. This investigation, run under carefully controlled conditions,
was undertaken in an effort to elucidate this relationship. In the two experiments
reported upon, using tomato plants grown in sand culture, the concentrations of K,
Ca, Mg, S, Na, P, N, Mo, Cu, Mn, Zn, Fe, Co, and B were employed as criteria of
chemical concentration. As the B supply was increased, its concentration in leaflet
material became significantly increased. There were also large differences
among treatments with respect to the concentration of most of the other elements
examined as the B supply was increased, the concentration of some elements being
altered as much as several hundred percent. The results offered a possible explanation
for the confusion existing in the literature. For instance, reports of
trends involving increased Mg, Ca, or K concentrations, or decreased Mg, Ca, or K
concentrations associated with increased B supply could all be supported by these
data if different initial levels of B supply were assumed. It was evident that
the B supply had specific effects with respect to different elements, since the trends
shown in plant composition for varying B supplies were completely dissimilar for
different elements. Differences among trends shown for various elements could
not be correlated with type of ion (cation or anion), valence of ions, or total
growth of plants. The possible importance of these effects with respect to plant
nutrition and to the nutritive value of food crops is discussed.
The translocation of potassium among peach roots, 0. W. DAVIDSON. (N. J.
Expt. Stas.). (Soil Sci., 58 (1944), No. 1, pp. 51-59, illus. 6).-By use of special
double-chambered sand cultures which enabled the separation of peach roots into
two distinct horizontal layers, it became possible to apply K to one layer of roots
without contaminating the others. Results via this method indicated that K may
be absorbed by one layer of roots and translocated vertically up or down through
the root system rapidly and in considerable amounts to other roots receiving no
external supply of this element.
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U.S. Department of Agriculture. Agricultural Research Administration. Office of Experiment Stations. Experiment Station Record, Volume 92, January-June, 1945, book, 1947; Washington D.C.. (digital.library.unt.edu/ark:/67531/metadc5064/m1/199/: accessed August 19, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.