Phosphorus translocation in salt‐stressed cotton

Abstract

The effect of salinity on plants has usually been studied at high inorganic P concentration ([Pi]) in the nutrient solution, and salinity × Pi interactions have been examined at much higher [Pi] than found in soil solutions. Short‐term 32Pi experiments were carried out to study the effect of salinity (150 mM NaCl) on phosphorus translocation in cotton plants (Gossypium hirsutum L. cv. Acala SJ‐2) grown in nutrient solutions containing 10 μM [Pi]. The effect of additional Ca to a concentration of 10 μM was also tested. Salinity inhibited 32P translocation from root to shoot. This inhibition was more evident at higher [Pi] in the root medium. Increasing [Pi] 33‐fold in the solution resulted in a 4.3‐fold increase in [32P] in the root under saline conditions, but only in a 1,8‐fold increase in the shoot. In older shoot tissues total [P] was elevated in the salinized plants. In the young tissues, however, total P concentration was higher in control plants. Inhibition of 32P translocation by salinity was greater from root to young leaves than to mature shoot tissues. Salinity also decreased 32P recirculation from the cotyledons to the young leaf. Inhibition by salinity of both 32P translocation and recirculation to young leaves was fully reversed by increasing Ca supply from 1 to 10