EFFECT OF SOLUBLE SALTS ON PLANT RESPONSE TO AND ABSORPTION OF PHOSPHORUS

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Abstract
Fertilizer experiments indicated that much higher plant response to phosphorus occurred on moderately saline than on non-saline soil. Soil analyses showed that this difference could not be explained by the amount of sodium bicarbonate extractable phosphorus contained in these two soils.Greenhouse experiments with artificially salinized soil indicated that the uptake of phosphorus by barley plants was related to the salt concentration in the soil. Phosphorus absorption increased with increasing salt concentration, reached a maximum when the saturation soil extract measured approximately 6 millimhos, and then declined with further increases in salt concentration. This relationship was similar for fertilized and unfertilized plants. However, the increase in phosphorus absorption was much greater when phosphorus fertilizer was applied.The same relationship between salt concentration and phosphorus absorption was obtained with increasing NaCl concentration in liquid cultures. Maximum phosphorus absorption by barley occurred when the solution contained between 0.05 and 0.10 molar NaCl This relationship is attributed to the effect of salts on the physiology of the plant rather than the effect of salts on phosphorus solubility.