Effect of Zn application methods on wheat grain yield and Zn utilization in Zn-deficient soils of dryland

Soil Zn deficiency and drought are serious stress factors limiting the Zn nutrition of crops in northwest China. Field experiments were conducted to study the effects of soil application, foliar application and soil+foliar application of Zn on yield, Zn contents and accumulation in grain, and Zn use efficiency of winter wheat grown under two N rates at two locations in the middle part of Loess Plateau. Results show that Zn application does not increase the grain yield of winter wheat, but can increase the grain Zn contents. The increases are varied with the Zn application methods, the grain Zn contents are increased by about 40%, up to 40 mg/kg for foliar application and soil+foliar application, not significant with soil application, although the soil DTPA-Zn is triply increased. Zinc use efficiency of the foliar applied Zn is higher than those of the soil and soil+foliar applied Zn. Each one kg/ha foliar applied Zn is observed to be able to increase the grain Zn content by 6.70-13.04 mg/kg. The grain Zn utilization and total Zn utilization efficiency are respectively 6.02%-9.40% and 19.78%-30.91% for the foliar applied Zn, which are correspondingly 80 and 132-221 times more than those for the soil applied Zn. Nitrogen rates have no effect on the yield and Zn utilization. Therefore, the foliar application of Zn is more costeffective and environmental friendly than the soil application, and is one of the important practices to improve grain Zn concentration on Zn-deficient soils in dryland areas of northwestern China.