中国南瓜幼苗低氮耐受性指标筛选及综合评价

Index screening and tolerance evaluation of low nitrogen stress in seedling stage of Cucurbita moschata

氮肥过量施用是导致土壤退化及环境污染的重要原因之一,选育低氮耐受性较强的品种对中国南瓜的减肥增效生产具有重要意义。以8个中国南瓜种质为试验材料,采用水培法并设置适氮(7.0 mmol·L^(-1))和低氮(0.7 mmol·L^(-1))2个处理,测定苗期18个性状的低氮耐受系数,采用主成分、隶属函数和回归分析等方法建立中国南瓜低氮耐受性综合评价体系。结果表明,不同种质各指标的低氮耐受系数存在显著差异;主成分分析表明,一些表征植株生物量和叶片光合作用能力的指标与低氮耐受能力密切相关,其中根部干质量、根部鲜质量、根体积、壮苗指数等4个指标可作为低氮耐受性鉴定指标。利用回归分析建立中国南瓜幼苗低氮耐受性预测方程D’=0.9509-0.1212X1-0.2077X2+0.1341X3-0.0782X4(平均估算精度96.5%,R2=0.957),筛选获得1份苗期低氮耐受性较强的种质Cmo19(柿饼南瓜),初步实现中国南瓜幼苗期低氮耐受性种质资源的快速筛选鉴定,为中国南瓜氮高效利用品种选育及相关机制研究提供了依据。

Excessive application of nitrogen fertilizer is one of the major causes of soil degradation and environmental pollution.The selection of high-yielding varieties with strong low-nitrogen tolerance is of great significance for the efficient production in Cucurbita moschata.In this study,eight germplasm were used as experimental materials,and two treatments of suitable nitrogen(7.0 mmol·L^(-1))and low nitrogen(0.7 mmol·L^(-1))were set up in hydroponics to determine the low nitrogen tolerance coefficients of 18 traits in the seedling stage.The comprehensive evaluation system was established by using the methods of principal component,subordinate function and regression analysis.The results showed that the low nitrogen tolerance coefficients of different germplasm indicators differed significantly.The principal component analysis showed that the index characterizing plant biomass and photosynthesis were closely related to the low nitrogen tolerance ability,and that the four index,including root dry mass,root fresh mass,root volume and seedling index,could be used as index of the tolerance identification.Regression analysis was used to establish a predictive equation for low nitrogen tolerance in seedlings D’=0.9509-0.1212X1-0.2077X2+0.1341X3-0.0782X4(R2=0.957,average estimation accuracy 96.5%).One germplasm with strong low-nitrogen tolerance were finally obtained,namely Cmo19(Shibing Nangua).This study initially realized the high-throughput screening and identification of low nitrogen tolerance germplasm resources in Cucurbita moschata during the seedling stage,which provided a theoretical basis for the selection and breeding of nitrogen-efficient varieties of Cucurbita moschata and the study related mechanisms.