Effects Of Drought Stress And Re-watering On Active Oxygen Scavenging System Of Soybean

The soybean planting area is widely distributed,the whole growth stage is closely related to the rainfall,and the influence of the final yield on the rainfall is very obvious.Because the growth of crops has a certain growth pattern,the demand for water in different growth periods is not the same,and the effect of drought on crop growth will be different according to the different period,which will affect the yield and quality of soybean.The experiment was carried out in the glass rainproof shed of Northeast Agricultural University in 2016-2017 years.The test material was the HN44?the drought resistant type?and the HN65?sensitive type?.The soil moisture was monitored by EM-50,and the drought treatment at the beginning of the flowering period and the re-watering treatment at different time after the drought.Effects of drought stress and re-watering on the activity oxygen scavenging system and its yield and quality were studied systematically,including the degree of membrane lipid peroxidation,superoxide anion content,hydrogen peroxide content,osmotic regulator,protective enzyme activity,ascorbic acid caspin cycle and antioxidant capacity to drought stress.The response rule and the response after re-watering were also discussed.The aim is to reduce the injury degree of drought to soybean under drought conditions,and to provide theoretical basis and guidance for drought resistant cultivation and breeding of soybean.The main results are as follows:?1?Soil drought stress increased the content of MDA and superoxide anion in soybean leaves,and the content of H₂O₂ increased first and then decreased.When the soil water content was 15.5%,the relative increase rate increased obviously,and the sensitive cultivar HN65 was higher than that of the drought resistant cultivar HN44.The content of HN44 MDA was restored to the control level after re-watering,and the content of H₂O₂ was recovered.After 14 d of water,the water was recovered to the control level.?2?The content of proline,soluble sugar and soluble protein in soybean leaves increased with soil drought stress.When soil water content was 15.5%,the relative increase rate increased obviously.The osmotic adjustment ability of drought resistant cultivar HN44 was significantly higher than that of sensitive type HN65.After re-watering,the content of proline,soluble sugar and soluble protein still showed an upward trend.?3?Soil drought stress increased the activity of soybean leaf protective enzyme first and then decreased.When soil water content was 15.5%,the relative increase rate increased obviously.The activity of HN44 protection enzyme of drought tolerant cultivar was higher than that of sensitive type HN65.After re-watering,the activity of protective enzymes was reduced.?4?Soil drought stress increased the antioxidant content and antioxidant enzyme activity in the ASA-GSH cycle of soybean leaves obviously.When soil water content was 15.5%,the relative increase rate increased obviously.The antioxidant substance content and antioxidant enzyme activity of drought tolerant variety HN44 were significantly higher than that of sensitive cultivar HN65.After re-watering,the activities of ASA,DHA and GSH,APX,GR,MDHAR and DHAR showed an upward trend,and GSSG content decreased to below the control.?5?The total antioxidant capacity of soybean leaves increased with soil drought stress.When soil water content was 15.5%,the relative increase rate increased obviously.The total antioxidant capacity of drought resistant cultivar HN44 was significantly higher than that of the sensitive cultivar HN65.After re-watering,the total antioxidant capacity of two varieties increased.?6?The soil water content,the content of MDA,the content of superoxide anion,the content of osmotic substances,the content of antioxidants,and the activity of antioxidant enzymes were in the form of exponential equation,and the fitting effect of the equation was better.?7?With the increase of soil drought,the number of effective pods,per pod per pod,100 grain weight,grain weight of single plant decreased,and the quality of soybean decreased.When soil water content was 15.5%,the yield of soybean decreased significantly,and the decrease of drought resistant variety HN44 was significantly less than that of sensitive type HN65.?8?Under the condition of PEG simulated drought,the osmotic adjustment ability and protective enzyme activity of soybean leaves increased with the decrease of water potential and the prolongation of stress time,and the total antioxidant capacity increased,and the drought resistant cultivar HN44 was obviously higher than that of the sensitive type HN65.?9?Under the condition of black soil,soil water content 15.5%is the threshold of water in the flowering period of soybean.Under 15.5%,the physiological damage of soybean leaves and the system of active oxygen scavenging system are seriously damaged and must be irrigated in time.