水稻多元有害生物为害特征及产量损失量化

收集了云南粳稻主产区沾益、寻甸两县106块稻田水稻有害生物为害和产量等信息,并用两种方法对其分析。第一种方法应用聚类分析和对应分析描述水稻有害生物为害类型和产量水平之间的关系,第二种方法应用主成分分析和多元逐步回归估计各为害的产量损失。聚类分析确定了7种有害生物为害类型,其中IN1、IN2和IN3为害水平较低,而IN5、IN6和IN7为害水平较高。有害生物为害类型和水稻产量水平之间的对应分析,在前两个轴构成的因子空间内绘出了各为害类型和产量水平的位置,并给出了一条与为害类型紧密联系的产量水平增加路线。该分析暗示与位于该因子平面右边的有害生物为害类型(IN1、IN2和IN3)相比,位于左边的为害类型(IN5、IN6和IN7)将引起水稻更大的产量损失。主成分多元回归分析评估了水稻各种病、虫、草害所造成的减产量及其相对重要性。分析结果表明,高于水稻冠层杂草、蛀茎害虫(白穗)、稻纵卷叶螟、白叶枯病、粘虫、叶瘟病和稻飞虱是该稻作区对水稻产量影响较大的为害因子。

A characterization of rice multiple-pest injuries and quantification of yield losses

A total of 106 individual farmers'' fields were surveyed in Zhanyi and Xundian counties (the main japonica-rice-producing areas of the Yunnan plateau) of Yunnan province. The data pertaining to pest injuries and yields was collected and analyzed using two analytical approaches. The first approach was intended to characterize relationships between injury profiles and yield levels using cluster and correspondence analyses, while the second approach was aimed at generating yield loss estimates using combinations of principal components and step-wise multiple regressions. Seven pest injury profiles (abbreviated as IN) were determined using cluster analysis; IN1, IN2, and IN3 were lower injury levels of pest combinations in seven profiles, while IN5, IN6, and IN7 were higher injury levels. Clusters of injury profiles (IN1-IN7) and yield levels (Y1-Y5) are plotted on the two first axes of correspondence analysis between patterns of injury profiles (IN) and yield levels (Y). The correspondence analysis yielded a path of increasing yield levels (Y1 to Y5) associated with varying combinations of injuries in the plane defined by axes 1 and 2. This would suggest that injury profiles (IN5, IN6 and IN7) located on the left in the factorial plane may cause more considerable damage than others (IN1, IN2 and IN3) located on the right. The principal component analysis with multiple regressions generated estimates of yield reductions due to rice diseases, insects and weeds. The results showed that injuries caused by weeds above rice canopy, stem borers (white heads), leaf folder, bacterial leaf blight, army worms, leaf blast and plant hoppers were the most damaging factors in this region. Results of this study will provide some foundations for developing pest management strategies and improving rice production level at the regional scale.