Effects Of Drought-rewatering At Different Durations On Physiological Regulation Mechanism And Yield Of Summer Maize

Drought is one of the main factors restricting the development of agriculturalthe condition of limited water resources,the rational use of water resources is imminent.Therefore,studying the physiological regulation mechanism of crops is one of the focuses of current agricultural research.Maize is one of the three major food crops,with the characteristics of high yield and large water consumption.In arid and semi-arid areas,limited water resources are insufficient to meet the normal irrigation needs of maize.Therefore,studying the physiological regulation mechanism of summer maize under water deficit is of great significance for us to understand the crop physiological activities from the mechanism,and provide a theoretical basis for proper moisture regulation during the growth period.The experiment was conducted at the Farmland Water Conversion Test Field of China Arid Area Water-saving Agricultural Research Institute,Northwest A&F University.The experiment adopts the method of barrel planting,water stress treatment at the seedling stage?M?and jointing stage?B?of summer maize and setting three water stress treatment:normal treatment?CK?:75%?85%?_f??_f is expressed as field moisture capacity?,mild?W₁?:60%?70%?_f,moderate?W₂?:50%?60%?_f;and setting three stress durations,7 days?T₁?,10 days?T₂?,13 days?T₃?.This study aims at summer maize yield and IWUE,clarifies the response mechanism of osmotic adjustment substances and antioxidant enzyme system of summer maize in water stress-rewatering,and hopes to come up with an irrigation scheme suitable for summer maize itself growth and excellent yield.To provide a theoretical basis for efficient water use in agriculture.The main results of the study are as follows:?1?The proline osmotic adjustment ability of summer maize at jointing stage is greater than that at seedling stage,Pro tends to increase first and then decrease during stress period,and moderate water stress>mild water stress,all treatments at seedling stage peaked on the thirdthe T₁ and T₂ groups have a cumulative effect after rewatering.During joint stress,except for the inflection point of W₁T₃ and W₂T₃ treatment on the 10th day of stress,the proline content of other treatments increased to the end of stress,and the Pro content returned to CK control after rewatering.It can be seen that the 10-day stress duration is a critical value that affects the ability of osmotic adjustment when summer maize is subjected to drought stress.?2?The superoxide dismutase?SOD?,peroxidase?POD?,and catalase?CAT?of summer maize showed a tendency to increase first and then decrease during stress.At the seedling stage,the antioxidant enzyme activity was basically peaking on day 3 stress.The enzyme activity at the jointing stage was the highest on the 7th or 10th day,and the enzyme activity was greater than the enzyme activity at the seedling stage,indicating that the antioxidant enzyme system of summer maize at the jointing stage can remove oxygen free radicals at a higher level than the seedling stage.After the peak of the treatment for 13 days,the enzyme system was disordered and the enzyme activity decreased due to lack of water.After rehydration,the antioxidant enzyme activity of these treatments increased to varying degrees,producing a certain compensation effect.?3?When summer maize was subjected to water stress,the MDA content increased,and the MDA content of moderate water stress was higher than that of mild water stress,and the longer the stress duration,the higher the MDA content,and the MDA content returned to the CK control level after rewatering.And summer maize subjected to the same treatment,MDA content at jointing stage is generally higher than seedling stage.?4?The photosynthesis of summer maize during jointing period was generally higher than that during seedling period.Water stress will reduce the net photosynthetic rate,stomatal conductance and transpiration rate of summer maize,and the longer the stress duration,the greater the degree of stress,the smaller the photosynthetic index.By analyzing the leaf WUE of each treatment,it can be concluded that during stress,summer maize is mainly through reducing the opening of stomata and reducing the entry of CO₂,thereby reducing the transpiration rate and improving the efficiency of leaf water use;after rewatering,the compensation effect of summer corn photosynthesis appears,the net photosynthesis rate increases,and the leaf water use efficiency is improved.?5?The yield and water use efficiency of summer corn at jointing stage were higher than those at seedling stage,and the yield of mild water stress was higher than that of moderate water stress treatment.The effect of stress duration on yield index was not significant.Among them,the yield of BW₁T₃ treated at the jointing stage was the highest at 111.01 g.A comprehensive analysis of the relationship between summer maize yield and biochemical and photosynthetic indicators reveals that yield is very significantly negatively correlated with SOD,MDA and Pro,and extremely significantly positively correlated with photosynthetic index?P<0.01?.Under the condition of limited irrigation water,considering the combined effects of yield,water use efficiency and the physiological and photosynthetic indicators of summer maize stress-rehydration period,it is not recommended to carry out water deficit treatment at the seedling stage,and a mild water stress program for 7 days at the jointing stage?BW₁T₁?is more beneficial to the growth and development of the crop itself,and the yield of summer corn can also be guaranteed.