Phosphorus translocation in salt-stressed cotton

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 m M NaCl) on phosphorus translocation in cotton plants ( Gossypium hirsutum L. cv. Acala SJ-2) grown in nutrient solutions containing 10 μ M Pi]. The effect of additional Ca to a concentration of 10 μ M 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