Kuruppu P U, Schneider R W, Russin J S
Parks Library, Iowa State University, Ames 50011.
Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge 70803.
Plant Dis. 2004 Jun;88(6):620-624. doi: 10.1094/PDIS.2004.88.6.620.
Field soil artificially infested with laboratory-produced microsclerotia of Calonectria ilicicola was incubated for 1, 2, 3, or 6 weeks at 20, 25, 30, 35, and 40°C. These temperatures approximate soil temperatures that were measured in soybean fields during the growing season in south Louisiana. Germinable microsclerotia were enumerated after incubation at different temperatures, and soybean seeds were planted in these soils. After 8 weeks, percent root colonization was determined as a measure of infectivity of microsclerotia. Results showed that soil temperature is a critical factor in survival of microsclerotia. The optimal soil temperature range for survival of microsclerotia was 20 to 30°C, and the maximum soil temperature limit was 35°C, above which microsclerotia did not survive. Effects of temperature on soybean root colonization were examined in growth chambers by growing soybean plants in soil infested with laboratory-grown microsclerotia for 4 weeks after seed germination. Maximum infection of young soybean roots by C. ilicicola occurred between 25 and 30°C but decreased with increasing temperatures and was negligible at 40°C. According to these results, soil temperature is a critical environmental factor controlling the development of red crown rot in soybeans in Louisiana. These findings suggest that, if red crown rot is a threat, soybean planting time should be based on soil temperature rather than calendar dates.
将实验室培养的冬青拟盘多毛孢微菌核人工接种到田间土壤中，在20、25、30、35和40°C下分别培养1、2、3或6周。这些温度接近路易斯安那州南部大豆生长季节在大豆田测得的土壤温度。在不同温度下培养后，对可萌发的微菌核进行计数，并将大豆种子种植在这些土壤中。8周后，测定根定殖率，作为微菌核侵染力的指标。结果表明，土壤温度是微菌核存活的关键因素。微菌核存活的最佳土壤温度范围为20至30°C，土壤温度上限为35°C，高于此温度微菌核无法存活。在生长室中，通过在种子萌发后用实验室培养的微菌核侵染的土壤中种植大豆植株4周，研究温度对大豆根定殖的影响。冬青拟盘多毛孢对大豆幼根的最大侵染发生在25至30°C之间，但随着温度升高而降低，在40°C时可忽略不计。根据这些结果，土壤温度是控制路易斯安那州大豆红冠腐病发生发展的关键环境因素。这些发现表明，如果红冠腐病构成威胁，大豆种植时间应基于土壤温度而非日历日期。
