西瓜种质资源若干数量性状的评价指标探讨

Evaluating criteria of some quantitative characteristics of watermelon genetic resources

通过对国家西瓜、甜瓜种质资源中期库内的西瓜（Citrullus Lanatus（Thunb）Matsum＆Nakai）种质资源果实质量、果实长度、蔓节间长度、种子千粒质量等9项数量性状数据进行统计分析。结果表明,变异系数最大的是种子千粒质量为50.5%,变异系数最小的是果实宽度为15.5%,各数量性状数据均为偏正态分布,偏态度最大的性状是果皮硬度,偏态度大小为6.31,偏态度最小的性状是果实宽度,偏态度大小为0.63;使用等距法绘制各数量性状数据频率分布图,参照国际植物新品种保护联盟（UPOV）标准,结合我国西瓜种质资源描述评价工作,对果实质量、果实长度和宽度、果形指数（l/w）、果皮硬度、果皮厚度按1~3级分级,2级为中级,分布频率大于50%;对节间长度,含糖量,种子千粒质量按1~5级分级,3级为中级,分布频率大于40%;每个性状的各等级选取2个参照品种：1个国外品种、1个国内品种,极端性状除外。

The data of nine quantitative characteristics of watermelon genetic resources in National Mid-term Genebank for Watermelon Melon were analyzed.The result showed that the coefficient of variation of 1000-Seed-weight was the biggest with 50.5%;the coefficient of variation of fruit width was the least with 15.5%.All quantitative characteristic data were skewed normal distribution.The maximum skewness was found in fruit rind hardness（6.31） and the minimum was found in fruit width（0.63）.The classification of eight quantitative characteristics of watermelon fruit was researched,which referred to the criteria of International Union for the Protection of New Varieties Of Plants（UPOV）.Five quantitative characteristics including fruit weight,fruit length,fruit width,Fruit shape ratio（l/w）,fruit rind thickness and fruit rind hardness were graded according to 1 to 3 levels of graduation.Grade 2 was intermediate level and the distribution frequency was more than 50%.Internode length,1000-seed-weight and soluble solids content in center flesh were graded according to 1~5 levels of graduation.Grade 3 was intermediate level and the distribution frequency was more than 40%.Two reference cultivars were selected for single characteristic of each grade,one was a foreign cultivar,the other a Chinese cultivar,except extreme characteristics.