Zinc deficiency in rice

Abstract

Solution culture studies revealed no marked difference in the ability of the resistant variety IR8 or the susceptible variety IR 184-67 to absorb zinc from low external concentrations comparable with those occurring in the soil solutions of deficient soils. However IR8 appeared to have a slightly lower tissue requirement for zinc than IR 18467 (critical values 0.23 and 0.27 jxg atoms /g respectively) and IR8 was significantly less susceptible to bicarbonate concentrations (< 1 m M). Despite these differences, the two varieties appeared equally susceptible to zinc deficiency during the first four weeks of growth under field conditions. In the field, both varieties underwent a spontaneous recovery from zinc deficiency after four to eight weeks' growth, but the recovery of IR8 was more rapid and more complete in terms of both shoot growth and final grain yield than that of IR 184-67. The superior ability of IR8 to recover from an initial set-back due to zinc deficiency was further demonstrated in a solution culture experiment. It is concluded that differences in the field performance of the two varieties under conditions of zinc deficiency are largely due to differences in ability to recover when zinc again becomes available to the plant.