Study on the different responses of different winter wheat cultivars to dry hot wind.

Dry hot wind (DHW) is one of the main agro-meteorological disasters that occur during the grain filling stage of winter wheat in northern China. In this study, three major winter wheat cultivars planted at the Mazhuang experimental station, Xinji city, Hebei Province, including Henong 6119 (HN6119), Gaoyou 5218 (GY5218), and Jimai 325 (JM325), were analyzed. Through natural DHW and artificially simulated DHW experiments, we investigated how the physiological parameters of the three cultivars were affected on the day with DHW and the day before and after DHW occurred. Comparative analysis of the different responses among the physiological parameters of the three cultivars demonstrated that HN6119 experienced less leaf water loss by reducing its stomata conductance and transpiration rate under natural DHW conditions, while GY5218 and JM325 experienced more leaf water loss by increasing their stomata conductance and transpiration rates under natural DHW conditions. The net photosynthetic rate, transpiration rate, and stomata conductance of HN6119 recovered after the DHW conditions, while those of GY5218 and JM325 showed a continuously decreasing trend. The leaf photosynthetic water use efficiency decreased on DHW days because the net photosynthesis rate was reduced for HN6119, but the transpiration rate increased for GY5218 and JM325. HN6119 showed a significant positive correlation between physiological parameters, while GY5218 and JM325 showed a poor correlation after being affected by DHW conditions. The effect of artificial simulation under mild and severe DHW stress on the thousand kernel weight (TKW) of HN6119, GY5218 and JM325 was 0.01%, 3.51%, 3.57% and 0.36%, 8.12%, 8.84%, respectively. HN6119 showed better resistance to DHW, followed by GY5218, and JM325 showed the weakest resistance.