Study on P-Zn interaction of wheat using chelator-buffer
solution culture technique

An experiment using chelator-buffer nutrient solution was conducted to investigate the interaction of P and Zn nutrition of wheat plants. Zinc rates were supplied at two levels of deficient (0 mol/L) and normal (3 mol/L), and P was designed in three rates, namely, 0 (insufficiency), 0.6 (normal), 3(excess) mmol/L. Results showed that excessive P supply to nutrient solution led to zinc deficiency of wheat seedling, and typical Zn-deficiency symptoms occurred: interveinal chlorosis developed between the mid-vein and leaf margin of little leaves; while the tip, base and margins remained green. The wheat plants showed slight P toxicity under high P and no zinc addition: developed yellow chlorotic and necrosis of the tip and margins of old leaves. It is said that high P concentration induces zinc deficiency, but not P toxication. The growth of wheat was increased under normal P supply, but there would be depressed if excess P addition to culture solution, and it was more severe under Zn addition. The zinc, phosphorus uptake by wheat plants and translocation from roots to shoots under normal P was larger at Zn supply than that of any other treatments in which zinc and phosphorus were in the status of deficiency or excessive supply. Moreover, the interaction between P and Zn for each other was different: firstly, as far as the ways of P-Zn reaction, the effect of P on Zn nutrition of wheat was done through decreasing uptake of Zn from the growth medium; however, the effect of Zn on P nutrition of wheat was mainly inhibited of P translocation from roots to shoots. Secondly, the degree of P-Zn antagonism was different: The effect of P to Zn was more obvious than Zn to P, maybe it was because plant needs more P than Zn. It is concluded that the way and degree of P-Zn antagonism were different, and it only occurred under zinc and phosphorus were in the status of deficiency or excessive supply.