| Wheat is the most important crop and staple food of north people in our country, and it is main distributing in calcareous soil area where often Zn deficiency. People get Zn only from meal because it can not be synthesize by ourselves. However, the zinc bioavailability in grain of wheat often be reduced by some factors, and the phytic acid is main one. On the other hand, phytic acid is the main form of phosphorus in grain of wheat, the phytic acid may be influenced as the phosphorus fertilizer adding. So, a field and two culture solution experient were conducted to investigate the the effects of supplying Zn and P on Zn bioavailability in grain of different wheat genotypes. The main results are as follows:(1) An experiment with chelator-buffer nutrient solution was conducted to investigate the growth and Cu, Mn, Fe, P nutrition of three winter wheat genotypes (Mianyang 19, Han 6172 and Xinmai 13) under zinc deficiency. Four indices were chosen to characterize the tolerance of wheat plants to Zn deficiency: a) Zn efficiency, namely, relative shoot weight at low compared to high Zn supply; b) relative shoot/root ratio, namely, the ratio of shoot/root ratio at low zinc to high Zn supply; c) total shoot uptake of Zn under Zn deficient conditions; and d) shoot dry weight under deficient conditions. The results indicated that the shoot growth of wheat plants was decreased obviously, but the root growth can still keep well under zinc deficient conditions. Three wheat genotypes exhibited different tolerance to zinc deficiency, and the Han 6172 was consistently more tolerant than other two wheat genotypes by assessed using all four indices. The Cu, Mn, Fe concentration and the ratios of Cu/Zn, Mn/Zn, Fe/Zn were increased in shoot parts of all three wheat genotypes under zinc deficiency, and there was very significant negative correlations between Cu, Mn, Fe concentration and zinc concentration in shoot of wheat, suggested that it will stimulate Cu, Mn, Fe accumulation under zinc deficiency. On the contrary, the P concentration and uptake in wheat roots and shoots were decreased under zinc deficiency, and the concentrations of P in shoot tissue were positively correlated with Zn concentration, but the translocation ratio to shoots of P was increased under zinc deficiency, this was similar to Cu, Mn and Fe. In addition, the Han 6172 which had more tolerance to zinc deficiency accumulated more Cu, Mn, Fe and less P under zinc deficiency. It is postulated that there existed relation between the tolerance to zinc deficiency of wheat and the increased of Cu, Mn, Fe concentration, as well as decreased of P in shoots under Zn deficiency. (2) An experiment using chelator-buffer nutrient solution was conducted to investigate the interrelationship of P and Zn nutrition of wheat plants. The zinc rates was supplied at two levels of deficient (0μmol/L) and normal (3μmol/L), and there had three P adding levels, namely, 0 (insufficiency), 0.6 (normal), 3(excess) mmol/L. The obtained 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 root to shoot under normal P was larger at Zn supply than that of any other treatments in which zinc and phosphorus was 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 growth medium; however, the effect of Zn on P nutrition of wheat was mainly inhibition 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 was different, and it only occurred under zinc and phosphorus was in the status of deficiency or excessive supply.(3) A field experiment using 4 genotypes wheat (Zhongyu6, Xianyan22, Xiza1, Zhengmai9023) which have different zinc efficiency was conducted to investigate the interaction of P-Zn of wheat plants under different Zn and P supply levels. Zinc rates were supplied at two levels of deficient (0 kg Zn/ha) and normal (7 kg Zn/ha), and P was designed in five rates, namely, 0 (insufficiency), 50 (little), 100 (normal), 150 (more), 200(excess) kg P2O5/ha. The obtained results showed that P supply to soil led to shoot zinc concentration decreased of wheat plants, and it was more obviously at wheat growth prophase (seedling time, drawn bural times and tassel times) than growth anaphase. The phosphorus concentration of the shoot apparatus of wheat plants was decreased under zinc supply at seedling time, drawn bural times and mature times respectively, however, the phosphorus concentration increased at drawn burel and grouting times of wheat plants. It was said that the time of zinc and phosphorous antagonism was main at wheat growth prophase (seedling time, drawn bural times) and anaphase (mature times). At the different growth stages of wheat, the shoot zinc concentration decreased degree of wheat under phosphorus supply was different as different apparatus, the order of decreased degreed of zinc concentration was: stem>fringe (include wheat grain and glume) >leaves, and the main time of interaction time of phosphorus and zinc was wheat growth prophase at stem, and the grain was the main place at wheat growth anaphase. The shoot zinc concentration of wheat was decreased under phosphorus supply obviously, and the decreased more and more with the increased of phosphorus supply; on the other side, no matter what the phosphorus concentration increased or decreased under zinc supply, it only had little difference, most was not reach prominence levels, so 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 the place and degree of P-Zn antagonism of wheat was different at different growth stages.(4) A study was done by determine the phytic acid concentration in wheat grain of field experiment to inverstigate the interaction of P, Zn and phytic acid of wheat plants, and the effects of supplying Zn and P on Zn bioavailability in grain of different wheat genotypes. Results showed that Zn application to soil increased obviously the content of soil available Zn, even after a complete wheat growth season, the soil available Zn content under Zn application condition still was higher than that of no Zn application, in the meantime, the P concentration, P/Zn ratio, phytic acid concentration and [phytic acid]/[Zn2+] molecular ratio in wheat grain had slightly decreased, the zinc bioavailability was increased to a slight extent because of Zn fertilizer application. Whereas, the phytic acid concentration and [phytic acid]/[Zn2+] molecular ratio increased more obviously when applying P fertilizer: Firstly, P application led to the increase of phytic acid concentration and [phytic acid]/[Zn2+] molecular ratio, and decreased the zinc bioavailability in wheat grain; Secondly, phytic acid concentration and [phytic acid]/[Zn2+] molecular ratio in wheat grain increased at low rate of P fertilizer, and decreased with the increase of P fertilization rates, and excessive P fertilization to soil led to the decrease of phytic acid concentration of grain; Thirdly, the P/Zn ratio and [phytic acid]/[Zn2+] molecular ratio in grain was slightly lower under appropriate P supply (100 kg/ha) than low (50 kg/ha) or high (150 kg/ha) P supply, therefore, appropriate P application was a better measure for zinc nutrition of grain. It is concluded that the zinc bioavailability in grain may be increased under appropriate combination of Zn and P application, and P application is more important than Zn.
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