Comprehensive evaluation of low temperature and waterlogging stress of direct-seeding rice at bud stage and seedling stage using membership function method

[Objective] Under the double stress of low temperature and waterlogging stress, some rice varieties area were evaluated, evaluation of the ability of early rice varieties to withstand low temperature and waterlogging stress during bud stage and seedling stage in double cropping rice area of Guangxi was conducted, and screened out the rice varieties suitable for early rice direct seeding, so as to provide reference for suitable early rice varieties of direct seeding in Guangxi. [Method] Based on the artificial simulated low temperature environment, the germination seeds of 25 tested rice varieties were treated with low temperature and waterlogging [daily average temperature 5 °C (12 h light +12 h darkness), water depth of germination box was 5 cm] and control [daily average temperature 5 °C (12 h light+12 h darkness), water depth of germination box was 3 mm]. The seeds of tested varieties after accelerating germination were cultured for 10 d. After this treatment, the seeds were restored to 28 T and continued to grow for 10 d. The seedling rate, root length, root numbers, seedling height, fresh weight per plant, above-ground fresh weight and root fresh weight were measured, and their low temperature and waterlogging tolerance abilities were comprehensively evaluated by membership function analysis and correlation analysis. [Result] Seedling rate stress coefficient of 25 rice varieties was different, the variation was 0-1.00, the average stress coefficient was 0.935. Through the correlation analysis of stress coefficient, there was significant positive correlation between seedling rate and above-ground fresh weight per plant under stress ( P<0.05, the same below), and positive correlation with other traits, but the correlation did not reach significant level ( P>0.05, the same below). Seedling height was extremely positively correlated with root length, above-ground fresh weight and root fresh weight ( P< 0.01, the same below), and significantly positively correlated with root number and plant fresh weight. According to the average results of membership function, the tested varieties were divided into three types: strong, medium and weak tolerance. There were nine varieties with strong tolerance, they were: Guiyu 12, Wushansimiao, High quality farm seed 2, Guiyu 9, Jinsimiao, Xiangzhou fragrant rice, Hexifengzhan, Y liangyou 1, Guiyu 11. Compared with the medium tolerancetypes and weak tolerance types, the rice varieties with strong tolerance hadimprovement in root length, root number, root fresh weight and seedling height. Compared with the control, under the condition of low temperature and waterlogging stress (LT+W), all measurements of plant traits were decreased, and the root length decreased the most, reaching 19.0%, followed by root fresh weight and root number, which decreased by 18.2% and 16.3% respectively. [Conclusion] The key indexes of tolerance to low temperature and waterlogging stress of direct seeding early rice are seedling rate, root indexes (root length, root number and root fresh weight) and seedling height. Nine varieties such as Guiyu 12 can be directly used in the production of direct seeding rice in Guangxi, and can also provide materials for the study of the mechanism of rice tolerance to low temperature and waterlogging and the cultivation of suitable direct seeding rice varieties. 摘要: 【目的】 对广西双季稻区早稻品种芽期和幼苗期耐低温淹水能力进行评价, 为广西稻区直播早稻品种选择 供参考。 【方法】 以25个水稻品种为试验材料, 基于人工模拟低温环境, 设低温淹水[日均温5 °C:(12 h光照+ 12 h黑 暗), 发芽盒水层深度5 cm]和对照[日均温5 °C:(12 h光照+12 h黑暗), 发芽盒水层深度3 mm]2个处理, 对供试品种已 催芽的种子培养处理10 d,处理结束后, 恢复到28 t条件下继续培养10 d,使种子恢复生长。测定成苗率、根长、根 数、苗高、单株鲜重、地上部鲜重和根鲜重, 通过隶属函数值分析和相关分析, 对其耐低温淹水能力进行综合评价和筛 选。 【结果】 25个水稻品种的成苗率胁迫系数存在明显差异, 变幅为0~1.00,平均胁迫系数为0.935。各指标胁迫系数 的相关分析结果表明, 成苗率与单株地上部鲜重呈显著正相关( P<0.05, 下同), 与其他性状也呈正相关, 但相关性未 达显著水平( P>0.05)。苗高与根长、地上部分鲜重和根鲜重呈极显著正相关( P<0.01), 与根数和株鲜重呈显著正相 关。根据隶属函数值将供试品种的耐低温淹水胁迫能力分为强、中、弱3种类型, 其中耐性强的品种有9个, 分别为桂 育12号、五山丝苗、优质农家种2号、桂育9号、金丝苗、象州香米、河西丰占、Y两优1号和桂育11号; 与耐性弱和耐性中 的水稻品种比较, 耐性强的水稻品种在根长、根数、根鲜重和苗高上有明显优势。与对照相比, 低温淹水胁迫下, 幼苗 的根长、根数、苗高、单株鲜重、地上部鲜重和根鲜重均有所降低, 其中根长降幅最大, 达19.0%, 其次是根鲜重和根 数, 降幅分别为18.2%和16.3%。 【结论】 成苗率、根系指标(根长、根数和根鲜重)和苗高可作为直播早稻耐低温淹水逆 境胁迫的关键筛选指标。桂育12号等9个品种可直接用于广西直播稻生产上, 也可为水稻耐低温淹水机理研究及培 育适合机直播的水稻品种提供材料。