Identification And Screening Of High-temperature-tolerance Characteristics Of Core Chinese Japonica Rice Germplasm Resources

With the acceleration of industrial processes,the global greenhouse effect is becoming increasingly serious.High temperatures will have a great impact on crop growth and development,yield and quality.As a result,the assessment and screening of high temperature resistant germplasm resources has become one of the key methods.In this experiment,2000 germplasm resources of japonica rice from different countries and regions were taken as the research object.By adjusting the sowing date of each variety(line)and using natural high temperature,each variety(line)was subjected to a considerable degree of high temperature stress treatment.The total number of grains,the number of real grains,the thousand-grain weight,the seed setting rate,the number of effective ears,and the ear length of various varieties(lines)of rice were measured in order to screen out germplasm materials with better comprehensive agronomic traits and strong heat resistance It is used for rice breeding;in addition,through pot experiments to find scientific and reasonable screening methods for high temperature resistant germplasm.The main test results are as follows:1. In the field test,39 varieties(strains)with good yield-related factors and high temperature tolerance were selected,including 26 strong high-temperature-tolerant japonica rice varieties(strains):Huajing No.2,Yunjing No.42,Chujing No.38,Yunjing No.24,Nongke 843,Huluxiangdao,W1202,W1210,Suzi No.26,Jiaodonghandao-1,Kenyu 59,Liaojing No.10,Jianjing No.6,Fengdao No.9,Zhonghua No.15,Chujing No.3,Xindao No.48,Ji 85-21,Huangnianjingzi,Lindao No.16,Yingfeng No.1,Daopin No.55,Wen’anxiaohongmang I,Xindao No.45,Daopin 31,Zhenghan No.9;and 13high-temperature-tolerant japonica varieties(strains):W1306,Liaojing 244,Daopin 43,Daopin 76,Hexi No.27,Liaojing 326,Zhengdao CB29,Aoyu 392,Jindao 105,Xinfeng No.2,Dianchao 601,Xiangdao,Lige;2. A total of 246 varieties(strains)were selected in the two trials in 2017 and 2018 (including 5 control varieties),when subjected to high temperature stress before and after heading and flowering period,the average total grain number of 246 varieties(lines)decreased by 21.17%.The number of grains decreased significantly in different varieties(strains)after high temperature stress,the number of grains per ear did not change significantly.The total grain number of 39 high-quality and high-temperature-resistant varieties(strains)decreased by only 16.48%,indicating that high temperature stress before and after heading and flowering period would adversely affect the grain number of rice,but the impact was small;The average 10~3-grain weight of 246 varieties(lines)decreased by 16.78%,and the average 10~3-grain weight of 39 high-quality and high-temperature-tolerant varieties(strains)decreased by 8.58%.In addition,the rice experienced high temperature before and after heading and flowering,the change in panicle length was not obvious;3. The results of the high temperature tolerance classification of the 15 varieties in the pot test are as follows:Aoyu 392,Lindao No.16,Longjing No.25,Mudanjiang 17are strong high-temperature-tolerant varieties;W1202,Hexi 27,Kenyu 16,Liaojing 326,Qinghandao,Shenlong 2100,Wannian,and Yongshandao are high-temperature-resistant varieties;Qianzhonglang,Fengyou 100 and Yuanziniandao are Intermediate varieties;and the high-temperature classification results of the pot test are almost the same as those of the field test;4. The total grain number of each variety in the pot test was 7.64%lower than that of the control,but the total grain number of each variety was not significantly different from the control;the 10~3-grain weight of each variety was different,and the 10~3-grain weight of 11 varieties was slightly different from the control.Increased,the 10~3-grain weight of 4 varieties was slightly lower than that of the control;5. The trend of the activity of antioxidant enzymes(SOD,POD,CAT)in the pot experiment is consistent with the results of evaluating the high temperature resistance characteristics with relative seeding rate.That is,the stronger the rice’s ability to withstand high temperatures,the greater the increase in the antioxidant enzyme activity of rice leaf leaves after high temperature stress.