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为了构建甜瓜(Cucumis melo)种质耐冷性的评价体系并筛选耐冷种质,以19份遗传背景差异明显的甜瓜种质为实验材料,测定低温胁迫下幼苗的9个形态指标和8个生理指标,利用主成分分析、聚类分析及回归分析等多元统计方法对各指标的耐冷系数(α值)进行综合评价。结果表明,低温胁迫下甜瓜幼苗的形态和生理指标发生了明显的变化,其α值的变异系数均大于10%,生理指标的α值变化更为明显。利用主成分分析将原有的17个指标转换为7个独立的综合指标,其累计贡献率达84.64%,以此计算各种质的隶属函数值,并以主成分的贡献率进行加权,最终获得所有种质耐冷性的综合评价值(D值)。基于D值的聚类分析将所有种质按耐冷性强弱划分为3类,其中Oujin为耐冷性最强的种质,Xujin1等11份种质具有中等耐冷性,Qiuxiang等7份种质耐冷性较弱。通过逐步回归分析建立了甜瓜幼苗耐冷性评价的数学模型:D=0.048+0.048POD–0.119SOD+0.097PRO+0.042CRI+0.084RDW+0.206OFW。模型的预测精度大于93.0%。该耐冷性评价体系可广泛用于不同甜瓜种质耐冷性的快速鉴定和预测。
In order to construct the evaluation system of cold tolerance of Cucumis melo germplasm and to screen the cold-tolerant germplasm, nine kinds of morphological indexes and eight physiological indexes of seedlings under low temperature stress were selected from 19 melon germplasm with obvious difference in genetic background , Comprehensive evaluation was made on the coefficient of cold tolerance (α value) of each index by using the methods of principal component analysis, cluster analysis and regression analysis. The results showed that under low temperature stress, the morphological and physiological indices of muskmelon seedlings changed obviously. The coefficient of variation of α value was more than 10%, and the change of α value of physiological index was more obvious. Using the principal component analysis, the original 17 indicators are converted into seven independent comprehensive indicators, the cumulative contribution rate of 84.64%, in order to calculate the membership function values of various quality, and the main component of the contribution rate of the weighted, and ultimately The comprehensive evaluation of cold tolerance of all germplasm (D value) was obtained. Based on the D value of cluster analysis, all the germplasms were divided into three groups according to the degree of cold tolerance, among which, Oujin was the strongest cold tolerance germplasm, Xujin1 and other 11 germplasms had moderate cold tolerance, Qiuxiang et al. Weak sex. The mathematic model of melon seedling cold tolerance was established by stepwise regression analysis: D = 0.048 + 0.048POD-0.119SOD + 0.097PRO + 0.042CRI + 0.084RDW + 0.206OFW. The prediction accuracy of the model is greater than 93.0%. The cold tolerance evaluation system can be widely used for rapid identification and prediction of cold tolerance of different melon germplasms.