Effect of chemical regulators on the recovery of leaf physiology, dry matter accumulation and translocation, and yield-related characteristics in winter wheat following dry-hot wind

Dry-hot wind stress causes losses in wheat productivity in major growing regions worldwide, especially winter wheat in the Huang-Huai-Hai Plain of China, and both the occurrence and severity of such events are likely to increase with global climate change. To investigate the recovery of physiological functions and yield formation using a new noncommercial chemical regulator (NCR) following dry-hot wind stress, we conducted a three-year field experiment (2018-2021) with sprayed treatments of tap water (control), monopotassium phosphate (CKP), NCR at both the jointing and flowering stages (CFS), and NCR only at the jointing stage (FSJ) or flowering stage (FSF). The leaf physiology, biomass accumulation and translocation, grain-filling process, and yield components in winter wheat were assessed. Among the single spraying treatments, the FSJ treatment was beneficial for the accumulation of dry matter before anthesis, as well as larger increases in the maximum grain-filling rate and mean grain-filling rate. The FSF treatment performed better in maintaining a high relative chlorophyll content as indicated by the SPAD value, and a low rate of excised leaf water loss in flag leaves, promoting dry matter accumulation and the contribution to grain after anthesis, prolonging the duration of grain filling, and causing the period until the maximum grain-filling rate reached earlier. The CFS treatment was better than any other treatments in relieving the effects of dry-hot wind. The exogenous NCR treatments significantly increased grain yields by 12.45-18.20% in 2018-2019, 8.89-13.82% in 2019-2020, and 8.10- 9.00% in 2020-2021. The conventional measure of the CKP treatment only increased grain yield by 6.69% in 2020- 2021. The CFS treatment had the greatest mitigating effect on yield loss under dry-hot wind stress, followed by the FSF and FSJ treatments, and the CKP treatment only had a minimal effect. In summary, the CFS treatment could be used as the main chemical control measure for wheat stress resistance and yield stability in areas with a high incidence of dry -hot wind. This treatment can effectively regulate green retention and the water status of leaves, promote dry matter accumulation and efficient translocation, improve the grain -filling process, and ultimately reduce yield losses.