Abstract:

Rice bakanae disease, caused by the seed-borne fungus Fusarium fujikuroi, is a fungal disease primarily characterized by symptoms such as excessive elongation of seedlings, which can lead to plant death in severe cases. Currently, chemical control remains the primary method for managing this disease. The evaluation of bakanae disease standards for resistance in rice germplasm resources remains diverse and lacks unifies standards. The seedling stage is a critical period determining the occurrence of bakanae disease. To address this, a comprehensive resistance index was developed based on the elongation rate and seedling death rate at the seedling stage, using 99 rice germplasm resources (including 45 early indica rice, 30 late japonica rice, and 24 three-line sterile lines) to evaluate their resistance. The results revealed that only two out of the 99 germplasms exhibited resistance. Among them, the early indica rice line ‘Zhongfanzao E67’ had a comprehensive index of 1.8, rated as “resistant”, while the late japonica rice variety ‘Zhegeng 98’ had an index of 3.8, rated as “moderately resistant”. Among the remaining 97 susceptible materials, moderately susceptible, susceptible, and highly susceptible germplasms accounted for 22.22%, 16.16%, and 59.60% of the total, respectively. Additionally, japonica rice materials overall demonstrated a higher level of resistance compared to indica rice. The comprehensive index established in this study effectively reflects the resistance level of rice germplasms to bakanae disease at the seedling stage and has successfully identified two resistant germplasECEChese findings provide valuable insights for resistance identification and disease resistance breeding targeting rice bakanae disease.

Key words: rice, seedling stage, bakanae disease, elongation rate, seedling death rate, resistance identification

摘要：

水稻恶苗病是一种由藤仓镰孢菌（Fusarium fujikuroi）引起的种传真菌病害，其主要症状是植株徒长，严重时可导致死苗。目前，该病害的防治主要依赖化学农药。而关于水稻种质资源恶苗病抗病性的评价仍存在多样化、无统一标准的问题。。苗期是决定恶苗病发生与否的关键阶段。为此，本研究以99份水稻种质资源（包括早籼稻45份、晚粳稻30份及三系不育系24份）为材料，通过测定苗期的徒长率和死苗率，并转换成恶苗病抗性综合指数，用以系统评价这些种质在苗期的抗病性。结果表明，在99份种质中，仅2份表现为抗病。其中，早籼稻品系中凡早E67的综合指数为1.8，评价为“抗病”；晚粳稻品种浙粳98的综合指数为3.8，评价为“中抗”。其余97份感病材料中，中感、感病和高感种质分别占总数的22.22%、16.16%和59.60%。此外，粳稻材料的整体抗性水平高于籼稻。本研究建立的综合指数能够较全面反映水稻种质在苗期对恶苗病的抗性水平，并成功筛选出中凡早E67和浙粳98这两份抗病种质。本研究结果可为水稻恶苗病的抗性鉴定与抗性育种提供参考。

关键词: 水稻, 苗期, 恶苗病, 徒长率, 死苗率, 抗性鉴定