Rice Growth as Influenced by Zn:P Ratio of the Growth Medium

Salt tolerance is a complex phenomenon and external Zn:P ratio seems to be related to the salinity tolerance of rice. A study on two rice lines with varying salinity tolerance was conducted in solution culture with different enternal Zn:P ratios in the presence (70 mol m-3 NaCl) and absence of NaCl salinity. A high Zn concentration under saline conditions as compared to in the normal Yoshida nutrient solution was required for better yield. Better growth of rice under different external Zn:P ratios was apparently related to the ionic composition of the leaf sap: there was an inverse relationship with moderately high Zn concentration (Zn:P ratio of 2.1000) in the external medium and the concentration of Na+ and Cl, P and Ca2+, and a positive relationship with K+ and Zn concentrations. It also improved the K+:Na+ ratios in the leaf.