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 for winter wheat in the Huang-Huai-Hai Plain of China, and both the occurrence and the severity of such events are likely to increase with global climate change. To investigate the recovery of physiological function and yield formation using a non-commercial new chemical regulator (NCR) following dry-hot wind stress, we conducted a three-year field experiment (2018-2021), and sprayed tap water (control), monopotassium phosphate (CKP), NCR at both the jointing and flowering stage (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 investigated. Among the single spraying treatments, the FSJ treatment was beneficial to accumulation of dry matter before anthesis, and to a larger increase of maximum grain-filling rate and mean grain-filling rate. The FSF treatment performed better in maintaining a high relative chlorophyll content as SPAD value, and low rate of excised leaf water loss in flag leaves, promoting dry matter accumulation and contribution to grain after anthesis, prolonging the duration of grain filling, and inducing the period until maximum grain-filling rate to be reached earlier. The CFS treatment was better than any other treatments in relieving 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 CKP treatment only increased grain yield by 6.69% in 2020–2021. The CFS treatment had the greatest mitigating effect on loss of yield under dry-hot wind stress, following by the FSF and FSJ treatments, and the CKP treatment 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 high incidence of dry-hot wind. This can effectively regulate green retention and water status of leaves, promote dry matter accumulation and efficient translocation, improve grain-filling process, and ultimately reduce yield losses.