Abstract: High temperature stress at grainfilling stage often leads to reduced wheat grain yield and worsened grain quality. In order to find out effective measures to mitigate these adverse effects, a field trial with wheat variety Jimai 20 was conducted. High temperature stress at late grainfilling stage was created by plastic tunnel, and nitrogen and sulfur fertilizers were applied as basal and topdressing. The results showed that under high temperature stress, the grain yield and 1000-grain mass decreased significantly (from 19.7% to 28.3%), protein content increased, insoluble glutenin decreased while soluble glutenin increased, and the time for dough development and stabilization shortened. In the control (without high temperature stress), increasing nitrogen topdressing rate from 50% to 70% led to no significant change in grain yield but higher content of insoluble glutenin, higher polymerization index of glutenin (ratio of insoluble glutenin to soluble glutenin) and longer time for dough development and stabilization; while under high temperature stress, higher nitrogen topdressing rate resulted in a 2.07%-3.58% increase of grain yield and 1000-grain mass, and a shortened dough development and stabilization time. Compared with topdressing S, basal application of S increased the grain yield and glutenin polymerization index, and prolonged the dough development and stabilization time, whether high temperature stress existed or not. It was suggested that to mitigate the adverse effects of high temperature stress at late grain-filling stage on wheat grain yield and its quality, an appropriate fertilization mode could be a basal application of S fertilizer plus half basal applying and half topdressing N fertilizer.

Key words: AM fungus, Na-phytate, ALP, Extraradical hyphae