Detection of seed-borne and field performance of bakanae disease in 36 rice varieties
36个水稻品种带恶苗病菌检测和田间病害表现

摘要

目的 检测36个水稻品种种子带恶苗病菌率，明确水稻苗期恶苗病发病率和拔节初期恶苗病发生量，为水稻种业生产和恶苗病防控提供科学依据。方法 采取平皿培养鉴定法、谷粒保湿镜检法检测水稻种子带菌率；叠盘育秧25d后调查苗期发病率；田间小区直播观察拔节初期发病率。结果 常规晚粳稻种子带菌率和发病率显著高于杂交稻。常规晚粳稻（12个品种）保湿镜检带菌率3.33%~34.67%（平均21.83%），平皿培养法3.33%~12.00%（平均8.50%）；杂交稻（24个品种）保湿镜检带菌率0~12.67%（平均4.47%），平皿培养法0~4.67%（平均1.42%）。常规晚粳稻苗期发病率1.80%~5.27%（平均3.27%），拔节初期30m²小区病株数4~43株（平均18.08株）；杂交稻苗期发病率0~1.40%（平均0.36%），拔节初期病株数0~11株（平均2.04株）。结论 水稻品种间种子带菌率存在显著差异，带菌率与苗期、拔节初期发病率呈极显著正相关（r＞0.9153，P=0.0000）。平皿培养法检测带菌率≤3%时，田间发病风险较低。建议繁种基地加强后期防控，降低种子带菌率，减轻生产中恶苗病防控压力。

Abstract

Objective This study aimed to determine the seed-borne rate of bakanae disease in 36 rice varieties, and to clarify the incidence of bakanae disease at the seedling stage and its occurrence at the early jointing stage, so as to provide a scientific basis for rice seed production and bakanae disease control.
Methods The seed-borne rate was detected using the plate culture method and the moist chamber incubation method. The incidence of bakanae disease at the seedling stage was investigated after 25 days of tray-overlapping seedling raising. The occurrence of bakanae disease at the early jointing stage was observed in direct-seeded field plots.
Results The seed-borne rate and disease incidence of conventional late japonica rice were significantly higher than those of hybrid rice. For the 12 conventional late japonica rice varieties, the seed-borne rate detected by the moist chamber incubation method ranged from 3.33% to 34.67% (average 21.83%), and by the plate culture method ranged from 3.33% to 12.00% (average 8.50%). For the 24 hybrid rice varieties, the seed-borne rate detected by the moist chamber incubation method ranged from 0 to 12.67% (average 4.47%), and by the plate culture method ranged from 0 to 4.67% (average 1.42%). The incidence of bakanae disease at the seedling stage in conventional late japonica rice ranged from 1.80% to 5.27% (average 3.27%), and the number of diseased plants per 30m² plot at the early jointing stage ranged from 4 to 43 (average 18.08). In hybrid rice, the incidence at the seedling stage ranged from 0 to 1.40% (average 0.36%), and the number of diseased plants per 30 m² plot at the early jointing stage ranged from 0 to 11 (average 2.04).
Conclusion   There were significant differences in the seed-borne pathogen rate among different rice varieties, and this rate showed an extremely significant positive correlation with the disease incidence at the seedling stage and early jointing stage (r > 0.9153, P = 0.0000). When the seed-borne rate detected by the plate culture method was ≤ 3%, the risk of bakanae disease occurrence in the field was relatively low. Therefore, it is advisable that disease control be strengthened during the late growth stage of rice in the seed multiplication process to reduce the seed-borne rate and alleviate the pressure of bakanae disease management in rice production.