The effects of times and method of urea fertilizer application on grain protein content and nitrogen remobilization under supplementary irrigation in dryland wheat

Nitrogen plays an important role in increasing the quantitative and qualitative yield of wheat in dryland regions. To evaluate the effect of nitrogen (urea) by different foliar application treatments and top dressing fertilizer on grain protein and nitrogen remobilization of wheat, a strip split-plot design based on RCBD with three replicates was conducted under dryland and supplemental irrigation conditions during two growing seasons (2016-17 and 2017-18). Experimental treatments were: A: control (without application of N), foliar application of urea during booting, booting + grain filling and grain filling stages as the main plot, B: wheat cultivars as sub-plots, C: top dressing fertilizer including application and non-application (control) in strip factor were considered. The results of combined analysis of variance and mean comparisons showed that foliar application of urea fertilizer in all three growth stages significantly increased grain yield, nitrogen content, percentage and yield of grain protein and grain nitrogen remobilization of shoots. The application of top dressing fertilizer in both dryland and supplementary irrigation conditions was significant on grain protein yield. The highest grain protein yield in both dryland and supplementary irrigation conditions were 393 and 492 kg/ha, respectively. Foliar application at the grain filling stage had the largest role in the nitrogen remobilization to the grain and the control. Foliar application at the grain filling stage had the highest and control (without foliar application) had the lowest share of nitrogen remobilization to the grain.