| Chilling is a global natural disaster and one of the main adverse environmental factors that limit rice production in many countries.With the economic development,the rice production goal shifts from pursuing production to reducing costs and improving eco nomic efficiency.Due to its low production cost and easy operation,the area of direct seeding rice has rapidly increased,and it has become one of the important cultivation techniq ues in many rice areas in China.However,low temperature chilling seriously affects the direct seeding rice,causing seed germination and low seed set rate,resulting in severe yield reduction.The long-term traditional planting mode based on seedling transplanting has led to a large loss of low-temperature germination genes in rice varieties.Many high-yield and high-quality rice varieties cannot be used as direct seeding rice due to poor low-temperature germination ability,which limits the production of direct seeding rice.In view of the above problems,the germination rate,average number of germination days and germination coefficient of 44 rice cultivars from different sources in cold regions were analyzed at 12 °C,15 °C,18 °C,21 °C and 28 °C in this study.The evaluation method of low temperature germination ability of rice was established.The screening criteria for low temperature germination resources were proposed and using the established evaluation method and screenin criteria to screen 133 materials of the research group.The main results of this study are as follows:1.By comparing the germination rate,average germination days and germination coefficient of 44 materials at 12 °C,15 °C,18 °C,21 °C and 28 °C,the optimal identification temperature and identification time of three evaluation indicators of rice low temperature germination ability was determined.The evaluation method of low temperature germination was established,which were rate at 15 °C on the 8th day,average germination days at 15 °C,and low temperature germination coefficient at 15 °C on the 9th day.According to the results of the significant difference test of 44 materials under three evaluation indicators,the germination rate of the low temperature treatment on 8th day of 15 °C is more than 80%,and the average germination day of the low temperature treatment of 15 °C is less than 7 d and the germination coefficient of low temperature treatmen on 9th day of 15 °C was greater than 12 were proposed as a screening criterion for low temperature germination resources.2.Using the established evaluation method of low temperature germination ability of rice and the screening criteria for low temperature germination resources,17 low temperature germination materials were selected from 133 materials of the research group.Among them,8 varieties were from Liaoning Province,including Liaojing 294,Tielu 4,Liaoxing 10,Shendao 18,Liaojing 287,Liaojing 263,Tielu 14 and Yanqi 456.Their germination rates were between 93.28-100%,their average germination days were between 6.06-6.83,and their germination coefficients were between 14.61-16.50.One material(Tonghe 857)was from Jilin Province,and its germination rate was 91.67%.The average number of germination days was 6.27,and the germination coefficient was 15.17.Seven varieties were from Heilongjiang Province,including Longdao 23,Longdao 13,Longjing 20,Longdao 20,Yulong 8,Dongnong 428 and Dongnong 415.Their germination rates were between 84.52-98.28%,their average germination days were between 5.99-6.98,and their germination coefficients were between 13.21-16.40.Another cultivar "Zhongzao 39" came from Zhejiang Province,with a germination rate of 89.81%,an average germination day of 6.92,and a germination coefficient of 14.21.These varieties not only provide improved parents for subsequent direct seed ing rice breeding,but also provide basic materials for genetic basis research of low temperature germination. |
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