雪腐核盘菌菌核的萌发条件与致死温度

菌核是核盘菌Sclerotinia spp.在土壤中的主要存活形式和菌核病的主要初侵染源,在土壤中可存活8年以上,其数量和存活状况直接影响着菌核病的发生和危害程度。本研究以雪腐核盘菌Sclerotinia nivalis菌株SS-TB为材料,分析了菌核萌发的影响因素、致死温度以及土壤温度对菌核存活的影响。结果表明,未成熟菌核较成熟菌核更容易萌发;菌核萌发的最佳温度为20-25℃、pH为3.0-4.0、土壤含水量为20%-45%。菌核长时间浸泡水中对其存活不利,浸泡30d以后,存活率开始急剧下降,至47d时存活率为0。雪腐核盘菌菌核具有较强的耐高温特性,随着温度和处理时间的增加,菌核萌发率呈下降趋势。菌核在水浴中85℃ 5min、80℃ 10min、75℃ 10min、70℃ 30min、65℃ 120min、60℃ 180min时全部丧失活力。在土壤温度30℃和35℃处理5周、40℃和45℃处理4周时菌核全部失去活力。该研究结果为通过水旱轮作和土壤高温处理来防治西洋参菌核病提供了理论基础。

Germination condition and lethal temperature for sclerotia of Sclerotinia nivalis (Ascomycota,Helotiales)

The sclerotia of Sclerotinia nivalis are the main survival structure in the soil and primary inoculum for Sclerotinia rot, which remain viably for up to eight years. Therefore, the occurrence and severity of Sclerotinia rot are determined by the number and survival status of the sclerotia in the soil. The optimal germination condition, lethal temperature, and survival status affected by soil temperature for sclerotia of S. nivalis strain SS-TB were determined. Our results showed that the immature sclerotia germinated faster than mature sclerotia. The optimal temperature, pH, and soil moisture for sclerotial germination was 20-25°C, pH 3.0-4.0, and 20%-45%, respectively. Long-term soak in water was unfavorable to the survival of sclerotia. The survival rate of sclerotia significantly decreased since soaking in water for 30d, and the sclerotia completely lost vitality after soaking for 47d. The sclerotia have strong tolerance to high temperature. The germination rate of sclerotia decreased with the increase of treatment time under high temperatures. The sclerotia were completely dead under 85°C in 5min, 80°C in 10min, 75°C in 10min, 70°C in 30min, 65°C in 120min and 60°C in 180min. The sclerotia completely lost vitality under soil temperature treatments of 30-35°C for 5 weeks and 40-45°C for 4 weeks. These results provide reference for disease control and management of Sclerotinia rot of Panax quinquefolius through paddy-upland crop rotation and soil high temperature sterilization.