黄河流域棉花落叶型黄萎病发生消长与气象因子的关系

2001—2005年,在山西省农业科学院棉花研究所棉花落叶型黄萎病地(致病菌系为落叶型SXMV4I型),对晋棉13号感病品种6月初至8月下旬进行了棉花黄萎病的系统调查,并结合当地的气温、相对湿度等气象因子对黄萎病的发生消长关系进行了系统分析。结果表明,当每年6—8月月平均气温在24～26℃之间,雨日在12 d以上,降雨量在100 mm以上,大气相对湿度在70%～80%之间,均最适宜黄萎病的发生;黄萎病病情指数的增加与相对湿度的相关性很密切,与雨日和降雨量相关性较差,与气温的相关性最差,但偏相关中相对湿度与雨日相关性极强;合并5 a的资料,通过多因子和偏相关系数的筛选,得出平均5 d内病指(y)与相对湿度(x1)和雨日(x2)的二元回归方程为y=1.981 7x1+12.230 5x2-120.54。

Analysis on the Relationship between Defoliating Type of Verticillium Wilt of Cotton and Meteorological Factors in the Yellow River Valley

The experiment was conducted at the seriously infected cotton fields of Verticillium wilt SXMV 4 I in Institute of Cotton,Shanxi Academy of Agricultural Sciences,in Yuncheng Shanxi,at the middle and lower reaches of Yellow River during 2001-2005.The disease incidence of susceptible cotton cultivar Jianmian 13 in the same field was investigated in early June to late August for 5 years successively.At the meantime,the correspondent weather factors such as temperature,relative humidity, etc.were acquired to analyze the relationship between the disease incidence and weather factors.The result showed that the average temperature was at 24-26 ℃ in June,July and August,raining days were over 12 days,precipitation was over 100 mm, and relative humidity was 70%-80%,which were the most favorable to the disease development.The increase of the disease incidence index was closely related to the relative humidity,less related to the raining days and precipitation,lest related to the temperature,but in the patial correlation,the relative humidity was extremely related to raining days.By multi-factors and partial correlation coefficient selection,the equitation,y=1.981 7x 1 +12.230 5x 2-120.54 was inferred to describe the relationship among the disease index with 5 days(y),relative humidity(x 1) and raining days(x 2) based on 5-year data.