Effects of foliar nitrogen application during the grain filling period on yield and quality of spring wheat

Objective To investigate the enhancement effect of foliar nitrogen application during the grain filling stage on the yield and quality of spring wheat with a view to providing scientific basis for optimizing cultivation management practices.

Methods The local spring wheat varieties, namely Gaoyuan 196, Gaoyuan 619, and Gaoyuan 202, were selected as experimental materials, in the Qinghai-Tibet Plateau region, a randomized block design was employed, and a 2% urea solution was sprayed on the leaves during the grain filling stage. Meanwhile, different treatment groups were set up, including a control (N0), one application at the early grain filling stage (N1), and three consecutive applications before, during, and after the grain filling stage (N3), with each application containing 10.35 kg/hm², to explore the effects of foliar nitrogen application on the yield and quality of spring wheat.

Results (1) Compared with the control, foliar nitrogen application during the filling stage significantly increased the yield of spring wheat. Among them, the N3 treatment showed better yield enhancement, with a yield increase of 13.5%, 9.0%, and 14.7% for Gaoyuan 196, Gaoyuan 619, and Gaoyuan 202, respectively. (2) Under the same nitrogen application rate, both of the treatments were able to increase the grain protein content of spring wheat, with a greater improvement observed in N3 treatment. The protein content of Gaoyuan 196, Gaoyuan 619, and Gaoyuan 202 increased by 6.7%, 9.3%, and 8.5% respectively. The treatments also contributed to the improvement of SDS sedimentation value and wet gluten content in wheat flour, with increases of 12.4%, 14.9%, 8.9% and 8.9%, 22.4%, 6.7% for SDS sedimentation value and wet gluten content of Gaoyuan 196, Gaoyuan 619, and Gaoyuan 202, respectively.

Conclusion During the grain filling stage, foliar nitrogen application at a rate of 10.35 kg/hm² has a significant positive effect on spring wheat yield and quality, with three applications showing a better enhancement effect on both yield and grain protein content.