| In order to investigate the effects of different degrees and frequencies of drought exercise on physiological indexes, yield and water use efficiency of winter wheat, and to screen out a reasonable drought exercise mode, the experiment used Xiaoyan 22 as the experimental material, and set up two levels of drought stress (mild drought stress W1: 50%~60% FC; moderate drought stress W2: 40%~50% FC, where FC is the field capacity) and two drought exercise modes (single drought exercise and repeated drought exercise). Seven treatments at healing stage W1 (ND-1), healing stage W2 (ND-2), tillering stage W1 + healing stage W1 (D1), tillering stage W2 + healing stage W2 (D2), tasseling stage W1 repeated drought exercise + healing stage W1 (DRD-1), and tasseling stage W2 repeated drought exercise + healing stage W2 (DRD-2), using the full water supply (CK, 70%~80% FC) during the whole life span as the control treatment. The effects of drought exercise on photosynthesis-related indexes, antioxidant protection, osmoregulatory substances, yield and water use efficiency were investigated and analyzed through a barrel cultivation experiment. The results showed that ND-1 and ND-2 significantly reduced winter wheat yield by 13.9%-21.2% and water use efficiency by 5.9% compared with CK; D-1 and DRD-1 increased the net photosynthetic rate, stomatal conductance, and transpiration rate of winter wheat by 13.7%-14.9%, 31.4%-36.1% and 34.7%-27.1%, and drought-resistant photosynthetic activity and heat dissipation capacity of winter wheat by 1.4%-2.3% and 5%-5.1%, and chlorophyll a and chlorophyll b contents by 2.7%-12% and 4.7%-13%. Compared with ND-1, D-1 and DRD-1 significantly accelerated the reaction rate of superoxide dismutase and proline19.7%-24% and 68.3%-76%, significantly increased the rate of soluble sugar production by 31.8-34.3 percentage points, and significantly reduced the peroxidase activity 8.3%-10.3%, and drought again at the heading stage did not significantly affect the net photosynthetic rate, light energy conversion efficiency, photochemical quenching coefficient and photosynthetic pigment content of winter wheat. Therefore, superoxide dismutase activity and proline can be used to evaluate the drought tolerance of winter wheat, and that the mild drought exercise improved the drought tolerance of winter wheat. The effect of drought exercise on winter wheat yield increase was as follows: mild drought exercise>moderate drought exercise, repeated drought exercise>single drought exercise>no drought exercise, in which mild single and repeated drought exercise at the tillering stage significantly increased the yield of winter wheat by 5.7% and 11.4%, and water utilization efficiency by 8.7% and 10.8%, respectively. Taken together, it was concluded that mild repeated drought exercise at tillering stage was a reasonable deficit regulation irrigation measure to improve drought tolerance, yield and water use efficiency of winter wheat. |
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