水稻品种灌浆期耐热性的综合评判

建立了一种对水稻品种的灌浆期耐热性进行综合评判的方法.选取籽粒充实度、秕粒率、饱粒密度、垩白米率、垩白度等5个与水稻灌浆期耐热性强弱密切相关的性状,以参评品种这5个性状的耐热系数为指标,应用主成分分析法将5个彼此相关的单项指标转化为2个累计贡献率达到85%以上的相互独立的综合指标,根据每一品种的5个单项性状的耐热系数和综合指标的标准化特征向量求出每一品种2个综合指标的得分.计算每一品种2个综合指标得分的隶属函数值,并以综合指标的贡献率来确定2个综合指标的权重,在此基础上进行加权求和,从而得到每一品种灌浆期耐热性的综合评判值（D值）.采用系统聚类分析方法对各品种的综合评判值（D值）进行数量分类,同时结合生产实际的要求,可把每一品种划归为不同的耐性等级.外部独立样本组的统计检验以及实践验证的结果表明,所建立的综合评判方法具有理想的效果,可以对不同品种灌浆期综合耐热性能的强弱作出客观、准确的评判.

Comprehensive evaluated on heat tolerance at grain filling stage of different rice varieties

The characters of plants behave variously when stressed by adversity,and the range of variation of some certain character of different varieties under the stressed conditions is not completely identical.Consequently it is necessary to apply more than one index to give a comprehensive evaluation on stress resistant.In this article,taking the heat tolerance of different rice species at grain filling stage as an example,a comprehensive evaluation method that combines subordinative function method with principle component analysis and uses hierachical cluster analysis to do an quantitative classification has been set up to study the plants' stress resistant. Principal component analysis can transfer many correlating indexes into several independent comprehensive indexes with little original information lost.Based on the test results which show that significance of difference is above the significant point,five correlated characters which have very close relationship with the effect of rice's heat tolerance at its filling stage are chosen.They are grain plumpness,imperfect grains percentage,density of full-filled grains, chalky grains percentage,and degree of chalkiness.By taking the heat tolerance coefficients of the five characters of evaluated varieties as the target and using principal component analysis,the five correlated single indexes are transferred into two independent comprehensive indexes with contribution ratio of accumulative total of more than 85%.Then according to heat tolerance coefficients and standardization eigenvector of five respective characters of each variety,two comprehensive indexes' scores of every evaluated variety can be calculated accurately.The D value,comprehensive evaluation value of each variety's heat tolerance at its filling stage,can be deduced after calculating the subordinative function values of the two comprehensive indexes scores and using the contribution ratio of the comprehensive indexes to deduce the weight coefficient and then to weight sum.As the D value is a pure number between 0 to 1,the intensity difference of the stress resistant in different species and stress resistant grades of different species can be distinguished by using hierachical cluster analysis to do a quantitative classification and combining the produce requirement in reality.The statistical test of the group of external independent sample and the result proved by practice show that the comprehensive evaluation method set up by this study has an ideal effect.It can give an objective and precise evaluation on the comprehensive heat tolerance at the grain filling stage of different varieties.