南充市水稻稻瘟病区划和发生流行规律研究

为提高南充市水稻稻瘟病监测预警和综合防控水平,切实减轻稻瘟病危害,采用GPS和GIS定位、系统监测和普查、品种抗稻瘟性鉴定、稻瘟病菌生理小种监测和气象资料分析等方法,开展了南充市水稻稻瘟病发生流行区划、精准勘界和发生流行规律研究。首次明确了南充市稻瘟病的流行区划和精准勘界,探明了水稻稻瘟病菌越冬后的初始侵染源(即始见期)地点、发生特点、流行趋势和特点,明确了南充市水稻稻瘟病在田间存在4个流行高峰期,其中第1个流行高峰期发生面积对当年病害流行起着决定作用,5月底的累计发生面积与年发生面积成正相关,相关系数为0.8172;建立了孕穗末期病田率和蜡熟期病株率同年发生面积预测数学模型。对其成因探讨发现,导致南充市近年水稻稻瘟病重发及流行的内因是水稻品种抗稻瘟能力的降低或丧失、稻瘟病菌致病力强的生理小种增加与更强致病力的小种出现;温度适宜和阴雨寡照偏多是造成稻瘟病在南充市流行的外因。2001—2015年,全市水稻稻瘟病短期预报准确率达100%,中、长期预报准确率分别达到98%和95%以上,比1997年以前提高5~15个百分点,促进稻瘟病防效提高15%~30%。

Regionalization and Epidemic Regularity of Rice Blast in Nanchong City

In order to improve the level of monitoring, early warning and comprehensive control of rice blast in Nanchong City, and reduce the harm of rice blast, the methods of GPS and GIS location, systematical monitoring and survey, rice blast resistance variety identification, physiologic variety monitoring and weather data analysis were adopted to study the regionalization, accurate boundary settlement and occurrence and epidemic regularity of the disease. In this study, regionalization and boundary settlement were analyzed for the first time, the primary infection location, occurrence characteristics, trends and characteristics of the disease were verified. There were four epidemic peak periods and the damage areas of the first peak period played a decisive role, the accumulated occurrence area at the end of May was positively correlated with the year occurrence area, and the correlation coefficient was 0.8172. A prediction model of occurrence area based on the disease field rate at the end of boot stage and the disease plant rate at dough stage was established. Through investigation of the causes of blast disease in Nanchong in recent years, the authors found that the internal causes were the decrease or lose of rice blast resistance, the increase of high pathogenicity physiological race and the appearing of stronger pathogenicity physiological race, the external causes were suitable temperature and more overcast and rain and less sunlight. During 2010 to 2015, the short-term forecast accuracy for rice blast in Nanchong was up to 100%, medium-term and long-term forecast accuracy were also up to 98% and 95%, respectively, which increased by 5-15 percentage points compared with that before 1997, thus increased the control effect of rice blast in Nanchong by15%-30%.