Abstract:

Drought is one of the major abiotic stress factors limiting rice production. Clarifying the identification methods for drought tolerance at the seedling stage and screening drought-tolerant rice varieties are of vital importance for promoting rice production. In this study, 16 conventional late japonica rice varieties from Zhejiang Province were selected and cultivated in artificial climate chambers. Subsequently, drought stress was imposed using a 25% PEG-6000 solution, and various indicators were measured in detail, including survival rate, seedling length, root dry biomass, shoot dry biomass, root-to-shoot ratio, root diameter, total root length, and root surface area. The results showed that under drought stress, the average values of survival rate, seedling length, root dry biomass, shoot dry biomass, root diameter, total root length, and root surface area decreased by 29.08%, 16.51%, 14.72%, 26.89%, 10.39%, 7.86%, and 26.84%, respectively, while the root-to-shoot ratio increased by an average of 15.29%. Based on the coefficient of variation of the relative values of these eight traits, it was concluded that survival rate, root dry weight, total root length, and root surface area could serve as key indicators for evaluating drought tolerance at the seedling stage in conventional late japonica rice varieties from Zhejiang Province. To further verify the reliability of these indicators, fuzzy membership function analysis and principal component analysis were employed to assess the drought resistance of the varieties. The results showed a 100% overlap between the two methods, confirming the feasibility of the selected evaluation indices. Additionally, cluster analysis classified the 16 rice varieties into four groups. Group I exhibited high drought tolerance, Group Ⅳ showed high sensitivity, while Groups Ⅱ and Ⅲ were characterized as moderately drought-tolerant and moderately sensitive, respectively. Based on the comprehensive evaluation, Zhekegeng 121 and Zegeng 136 were identified as highly drought-tolerant varieties, whereas Zegeng 99 and Zegeng 122 were classified as highly sensitive. This study not only provides a scientific and effective method for assessing drought tolerance in conventional late japonica rice varieties in Zhejiang Province, but also offers valuable parental resources for future breeding programs.

Key words: conventional late japonica rice, drought stress, seedling stage, drought tolerance, comprehensive evaluation

摘要：

干旱是制约水稻生产的主要非生物胁迫因素之一。明确水稻苗期耐旱性的鉴定方法，并筛选出耐旱水稻品种，对于促进水稻生产具有至关重要的意义。本研究将选取的16个浙江常规晚粳稻品种置于人工气候箱中进行培养，随后利用浓度为25%的PEG-6000溶液对各品种进行干旱胁迫处理，详细测定了各品种的存活率、苗长、根干物质量、地上部干物质量、根冠比、根直径、总根长以及根表面积等指标。结果显示，在干旱胁迫条件下，各品种的存活率、苗长、根干物质量、地上部干物质量、根直径、总根长和根表面积平均分别下降29.08%、16.51%、14.72%、26.89%、10.39%、7.86%、26.84%；而根冠比平均增加15.29%。依据这8个性状指标相对值的变异系数进行分析，得出存活率、根干物质量、总根长和根表面积可作为鉴定浙江常规晚粳稻品种苗期耐旱性的关键指标。为进一步验证这些指标的可靠性，运用模糊隶属函数法和主成分分析法对参试品种的耐旱能力进行分析，发现两种方法得出的筛选结果重合率高达100%，进一步证实了所选鉴定指标的可行性。此外，通过聚类分析，将16个浙江常规晚粳稻品种划分为4类。其中，类群Ⅰ表现为高度耐旱型，类群Ⅳ表现为高度敏感型，类群Ⅱ和类群Ⅲ则分别为耐旱型和敏感型。根据综合评价结果，本研究筛选出浙科粳121和浙粳136为高度耐旱型品种，浙粳99和浙粳122为高度敏感型品种。本研究不仅为浙江省常规晚粳稻品种耐旱性研究提供了科学有效的方法，还为后续的育种工作提供了优质的亲本支撑。

关键词: 常规晚粳稻, 干旱胁迫, 苗期, 耐旱性, 综合评价