Effects Of Nitrogen And Phosphorus Fettilization On Grain Zinc Of Winter Wheat And Its Regulation By Foliar Zinc Application On Dryland

Wheat is the staple food crop in northwestern China, so the grain zinc concentrationdirectly affects the zinc nutritional status of residents in this area, therefore improving wheatgrain zinc concentration is of great significance for human health. Based on a long-term fieldexperiment (2004-2013), a two-year study was conducted during2011-2013to investigate theeffects of long-term different N and P fertilization rates on Zn concentration of winter wheatgrain, the relationship of grain zinc, nitrogen and phosphorus as to their concentration andabsorption. Meanwhile, the foliar applied zinc requirement to reach the target of zincconcentration (40-60mg/kg) under different nitrogen and phosphorus fertilizer applicationrates, and the effects of nitrogen and phosphorus rates on zinc use efficiency of winter wheatwere also examined. The objective of this research is to lay a theoretical foundation for theeffective regulation of grain zinc nutritional quality of winter wheat and solving human healthproblems caused by zinc deficiency, and to propose practical measures for optimizingnitrogen, phosphorus and zinc fertilizer management in winter wheat production. Obtainedresults are as follows:1. By the field experiment of winter wheat grown at five nitrogen fertilizer rates (0,80,160,240,320kg N/ha), it was found that the grain Zn concentration and Zn uptake in theaerial plant part were all positively correlated with the N application rate (p<0.01), when itwas less than320kg/ha. By adding each100kg N/ha, the grain Zn concentration wasincreased by4.0mg/kg. They were also found positively correlated (p<0.01) with grin Ncocentration and N uptake in the aerial plant part, with each1g/kg N concentration increaseof grain leading to its Zn concentration increased by2.0mg/kg.2. From the field experiment of winter wheat growing at five phosphorus fertilizer rates(0,50,100,150,200kg P2O5/ha), it was observed that when the P application rate was lessthan200kg/ha, the grain Zn concentration was negatively (p<0.01) correlated with the Papplication rate and the grain P concentration, with each100kg P2O5/ha application increase,the grain Zn concentration was found decreased by9.2mg/kg, and with each1g/kg grain Pconcentration increase, it was decreased by24mg/kg. 3. Field experiment results of foliar zinc application under different N application ratesshowed that foliar zinc has no significant effect on grain yield. However, the grain zincconcentration, total zinc utilization efficiency, grain zinc utilization efficiency, and grain zincincrease index were enhanced significantly by the increase of foliar zinc application rate.Compared with no zinc application, the grain zinc concentration was increased from27.0mg/kg to32.1,38.0,47.8mg/kg by spraying0.85,1.70,2.54kg Zn/ha. By spraying0.85,1.70,2.54kg Zn/ha, the total zinc utilization efficiency were8.5%,12.0%,18.6%, and grain zincutilization efficiency were2.4%,3.2%,3.8%, and grain zinc increase index were6.1,6.5,8.2(mg/kg)/(kg/ha), respectively.4. Field experiment of foliar zinc application under different P application rates indicatedthat the effect of foliar zinc application on grain yield was also not significant. However, thegrain zinc concentration, total zinc utilization efficiency, grain zinc utilization efficiency andgrain zinc increase index of winter wheat were significantly increased with the increase offoliar zinc application rate. Compared with no foliar applied zinc, the grain zinc concentrationwas increased from28.6mg/kg to33.1,39.7,49.2mg/kg by spraying0.85,1.70,2.54kgZn/ha, with the total zinc utilization efficiency averaged to be8.4%,11.0%,19.2%, grain zincutilization efficiency2.8%,3.0%,3.7%, and grain zinc increase index5.3,6.6,8.1(mg/kg)/(kg/ha), respectively.