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Potassium and the absorption of calcium and magnesium by potato plants from soil
Author(s) -
Addiscott Thomas M.
Publication year - 1974
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740250914
Subject(s) - xylem , distilled water , potassium , phloem , chemistry , magnesium , calcium , botany , soil water , nutrient , absorption of water , horticulture , agronomy , biology , chromatography , ecology , organic chemistry
Potato plants were grown in soil in pots with various additions of K 2 SO 4 . Before and after the tubers formed, plants were taken and detopped just above the soil. The xylem sap exuded from the stump was collected; the stems and petioles were macerated under distilled water and the diluted “whole stem sap” (representative of all stem cells) retained. The soil was extracted with distilled water. The K 2 SO 4 increased the Ca and Mg concentrations in the soil extract, but consistently decreased the Ca concentration in the exuded xylem sap. Before the tubers formed, the Mg concentration in the exuded sap decreased with the smaller K additions but increased again with the larger; after the tubers formed, K had little effect on it. Giving K 2 SO 4 sharply decreased the concentrations of both Ca and Mg in the “whole stem sap”. Explanations for these observations are offered in terms of the possible influence of K nutrition on the potential difference between the xylem sap and the soil solution and on the phloem translocation of Mg into the roots from the tops.