直播早籼稻品种芽期耐冷性鉴定研究

低温胁迫是水稻生产面临的重要非生物胁迫之一,鉴定水稻种质资源芽期耐冷性,筛选耐冷品种对水稻生产具有重要意义。以江西地区主推的33份早籼杂交稻品种和8份常规稻为试验材料,设置12个芽期低温胁迫处理,以死苗率为指标探讨了早籼稻芽期耐冷性的适宜鉴定方法。同时在8℃低温处理10d,恢复生长后调查其成苗率、苗高、根长、根数、地上部生物量、根系生物量和根冠比。运用主成分分析、模糊隶属函数法和聚类分析法来探讨直播早稻芽期的耐冷性评价方法及筛选耐冷品种。结果表明,8℃低温处理10d,直播早籼稻品种死苗率的方差和变异幅度大,能较好地鉴别品种间耐冷性差异,是直播早籼稻芽期耐冷性鉴定的最合理方式;杂交稻品种的耐冷性强于常规稻;低温胁迫后成苗率、苗高、根长、根数、地上部生物量、根系生物量和根冠比基本低于25℃对照处理;利用主成分分析将7个单项指标转化为3个独立的综合指标（CI₁、CI₂、CI₃）,主成分分析表明,根系生物量和地上部生物量最能代表直播早籼稻对低温胁迫后的响应情况,可作为芽期耐冷性鉴定的评价指标。通过聚类分析,将41份早籼稻品种划分为3类,筛选出陵两优7108、两优287、锦两优816等9份强耐冷品种,株两优1号、潭两优83、株两优22等15份中度耐冷品种,温229、中早33、五丰优157等17份冷敏感品种。这些品种可以进一步为耐冷育种和生产服务。

Identification of Cold Tolerance of Direct Seeded Early Rice Varieties at Bud Stage

Low temperature stress is one of the most important abiotic stresses in rice production. It is important to identify cold tolerance of rice germplasm resources at bud stage and screen cold tolerant varieties for rice production. In this study, 33 early indica hybrid rice varieties and 8 conventional rice varieties in Jiangxi Province were used as experimental materials, 12 low temperature stress treatments were set up at bud stage, and the suitable identification method of cold tolerance at bud stage of early indica rice was discussed with the dead seedling rate as an index. At the same time, the seedling rate, seedling height, root length, root number, aboveground biomass, root biomass and root-shoot ratio were investigated after 10 days of 8℃ low temperature treatment. Principal component analysis, fuzzy membership function and cluster analysis were used to explore the evaluation methods of cold tolerance at bud stage of direct seeding early rice and to screen cold tolerant varieties. The results showed that the variance and variation range of dead seedling rate of direct seeding early indica rice varieties were large under 8℃low temperature for 10 days, which could better identify the difference of cold tolerance among varieties, and it was the most reasonable way to identify cold tolerance of direct seeding early indica rice at bud stage; the cold tolerance of hybrid rice varieties was stronger than that of conventional rice; the seedling rate, seedling height, root length, root number, aboveground biomass, root biomass and root-shoot comparison after low temperature stress were decreased compared with 25℃ treatment, and seven indices were transformed into three independent comprehensive indices (CI₁, CI₂, CI₃) by principal component analysis. The principal component analysis showed that root biomass and aboveground biomass could best represent the response of direct seeding early indica rice to low temperature stress and could be used as an evaluation index for cold tolerance identification at bud stage. By cluster analysis, 41 early indica rice varieties were divided into three categories. Nine strong cold-tolerant varieties, such as Lingliangyou 7108, Liangyou 287 and Jinlingyou 816 were selected. Fifteen moderate cold-tolerant varieties, such as Zhuliangyou 1, Tanliangyou 83 and Zhuliangyou 22, and 17 cold-sensitive varieties, such as Wen 229, Zhongzao 33 and Wufengyou 157 were selected. These varieties can further serve for cold tolerance breeding and production.