南瓜幼苗亚适温弱光耐受性指标筛选及综合评价

Index Screening and Tolerance Evaluation of Sub-optimal Temperature and Low Light Density in Seedling Stage of Pumpkins

为建立南瓜亚适温弱光耐受性综合评价体系,选育适宜我国冬春季设施栽培的南瓜品种,本试验以30个南瓜种质为材料(包括15个印度南瓜种质和15个中国南瓜种质),采用自然低温结合人工遮光处理方法,测定生长和生理指标的胁迫耐受系数,利用主成分分析、隶属函数、系统聚类和回归分析等方法,对胁迫耐受指标进行综合评价。结果表明,亚适温弱光胁迫处理后,30个南瓜种质各指标的胁迫耐受系数存在显著差异;主成分分析将各指标综合成4个独立指标,聚类分析将30个种质按弱光耐受性聚为4支,隶属函数分析筛选根部干重、根部鲜重、EC值、叶绿素含量等指标作为亚适温弱光耐受性鉴定指标,通过回归分析建立南瓜幼苗亚适温弱光耐受性预测方程(R^2=0.965,平均估算精度95%);利用该体系对30份南瓜种质进行综合评价,共获得4份亚适温弱光耐受性较强种质,分别为印度南瓜贝栗-2012D14、日南-99A17、中国南瓜黄皮小南瓜-2013D02-3和柿饼南瓜-5Bb040。本研究为南瓜亚适温弱光耐受性品种选育提供了理论依据。

The present study aimed to establish a system for evaluating sub-optimal temperature and low light density stress tolerance in pumpkin and select the stress tolerance pumpkin germplasms suitable for protected cultivation in winter and spring. 30 pumpkin germplasms were used as experimental materials（ containing 15 germplasms in Cucurbita maxima and 15 germplasms in Cucurbita moschata） and their stress tolerance coefficients of growth and physiological indices were measured in natural sub-optimal temperature combined with artificial shading conditions. A comprehensive evaluation method including principal component, membership functions, system clustering and regression analysis was applied to analyze the stress tolerance coefficients and evaluate the pumpkin germplasms. The results showed the stress tolerance coefficients of growth and physiological indices displayed a significant variation among the pumpkins germplasms. According to principal component analysis,the primary indices were changed in to 4 separate comprehensive indices. By system clustering analysis,30 pumpkin germplasms were divided into 4 groups. In membership function analysis,root dry weight,root fresh weight,EC value,chlorophyll content and other indices were selected as parameters to evaluate the potential tolerance of pumpkin germplasms. The comprehensive evaluation value（ D value） of all the pumpkin germplasms was obtained according to the membership function values. Stepwise regression analysis was used to establish a prediction equation（ R^2= 0. 965; average forecast accuracy was 95%） for evaluating the stress tolerance of all the pumpkin germplasms. Finally,4 germplasms were selected by the prediction equation due to their desirable tolerances under sub-optimal temperature and low light density stress. Their germplasms names are ＇Bei Li-2012 D14＇ and ＇Ri Nan-99 A17 ＇ in Cucurbita maxima and ＇Huang Pi Xiao Nan Gua-2013 D02-3 ＇and ＇Shi Bing Nan Gua-5 Bb040＇ in Cucurbita moschata. This study will help to provide a theoretical basis for screening sub-optimal temperature and low light density stress tolerance germplasms in pumpkin cultivar breeding.