Effects Of High Temperature Stress After Anthesis On Physiological And Biochemical Characters Of Different Wheat Varieties

High temperature stress after flowering can damage the Photosynthesis of leaves, accelerate the aging of leaves and plants, and thus affect the growth and development of wheat, as well as grain yield and quality. Three different wheat varieties were chosen for the experiment, Huaimai 30 (weak spring), Zhengmai 9023 (spring), and Yannong 19 (semi-winter), in which to investigate the effects of high temperature stress on photosynthesis, chlorophyll fluorescence characteristics, and endogenous protective enzymes in flag leaves at 7 and 15 days after flowering. The main results were as follows:1. Effects of high temperature stress on photosynthetic performance and chlorophyll fluorescence characteristics of the three wheat varietiesThe results showed that after high temperature treatment of 34℃/24℃ (day/night) at 7 days and 36℃/26℃ (day/night) at 15 days after flowering, the net photosynthetic rate (Pn), stomatal conductance (Gs), maximum photochemical efficiency of PSII (Fv/Fm), photochemical quenching coefficient (qp), non-photochemical quenching coefficient (qn), and the acyclic photosynthetic electron transfer rate of PSII (ETR) in Yannong 19 were significantly higher than in Huaimai 30 and Zhengmai 9023. The Pn and intercellular CO2 concentration (Ci) of Zhengmai 9023 were significantly higher than in Huaimai 30; after high temperature treatment of 36℃/26℃ (day/night) at 15 days after flowering, the Fv/Fm, qr, and ETR of Zhengmai 9023 were significantly higher than in Huaimai 30, and Yannong 19 has the minimum effect by the high temperature treatment, Zhengmai9023 has the maximum effect by the high temperature treatment.2. Effects of high temperature stress on the endogenous protective enzyme system in flag leaf of the three wheat varietiesThere is no significant differences in SOD activity for the three wheat varieties in the control group; for POD activity, Zhengmai 9023>Huaimai 30>Yannong 19, with significant differences between the varieties; CAT activity in Zhengmai 9023 and Yannong 19 was significantly higher than in Huaimai 30. In the high temperature treatment group at 7 days after flowering, SOD activity in Yannong 19 was significantly higher than in both Zhengmai 9023 and Huaimai 30, but there was no significant difference between Zhengmai 9023 and Huaimai 30; for POD activity, Zhengmai 9023>Huaimai 30>Yannong 19, with significant differences between the varieties; for CAT activity, Yannong 19>Zhengmai 9023>Huaimai 30, with significant differences between the varieties.3. Effects of high temperature stress on the endogenous protective enzyme system in seeds of the three wheat varietiesThe results showed that after high temperature treatment of 34℃/24℃ (day/night) at 7 days and 36℃/26℃ (day/night) at 15 days after flowering, SOD、POD and CAT activity in three wheat cultivars for grain showed significant differences. In the control group at 7 days after flowering, SOD、POD and CAT activity of Zhengmai 9023 increased; SOD、POD and CAT activity of Yannong 19, MDA content of Yannong 19 also increased, SOD activity of Huaimai 30 decreased, POD and CAT activity of Huaimai 30 increased, and SOD activity of Yannong 19 rised higher than Zhengmai 9023, In the control group at 7 days after flowering, SOD and POD activity of three varieties were all increased, CAT activity of Zhengmai 9023 was decreased,but Huaimai 30 and Yannong 19 increased, and SOD and POD activity of Yannong 19 rised higher than Zhengmai 9023.4. Effects of high temperature stress on the yield of the three wheat varietiesThe results showed that after high temperature treatment of 34℃/24℃ (day/night) at 7 days and 36℃/26℃ (day/night) at 15 days after flowering, the grain number per spike and 1000 grain weight of three wheat varieties showed significant differences, grain number per spike showed:without heat treatment, heat treatment, In the control group at 7 days and 15 days after flowering, and farmers is minimal decreased 19, Zhengmai 9023 the sharpest decline; varieties also showed significant difference, spend 7 days after high temperature treatment, performance of Zhengmai 9023 was significantly higher than that in Huaimai 30 and Yannong 19; In the control group at 15 days after flowering, the 1000-grain weight of Yannong 19 was significantly higher than Huaimai 30. In the same species, In the control group at 7 days and 15 days after flowering, the 1000-grain weight showed significant difference:not high temperature> In the control group at 7 days> In the control group at 15 days, the 1000-grain weight of Zhengmai 9023 decresed most, Yannong 19 decresed the less.