国内外栽培木薯(Manihot esculenta Crantz)种质资源表型多样性分析

Phenotypic Diversity Analysis of Cassava(Manihot esculenta Crantz)Germplasm from China and Abroad

以国内外不同地理来源的228份木薯资源为材料,通过评价植株15个茎和块根的描述型表型性状及7个与产量相关的数量性状,初步了解其表型遗传多样性,为种质资源创新利用、针对性地引种和育种亲本选配提供理论参考。结果表明,国内外不同地理来源木薯资源描述型性状频率分布较一致,多以张开型、三分叉、30°~45°分枝角度、主茎内皮浅绿色居多,块根性状以表皮粗糙、外皮淡褐色、内皮乳黄色、肉质白色资源居多;数量性状多样性指数为1.895~2.073,描述型性状多样性指数为0.435~1.889,表明228份木薯资源遗传多样性丰富,且数量性状存在较大程度变异(8.91%~44.60%),国内资源块根直径极显著高于国外资源,国外资源干物率极显著高于国内资源,说明国内外资源的块根直径和干物率具有明显的遗传差异,利用现有资源可能选育出产量高、品质好的品种。两步聚类分析将参试资源明显划分为两大类群,类群Ⅰ主要特征为株型张开、分枝角度中等偏大,群体不整齐,主茎较粗,薯块产量较高资源;类群Ⅱ为株型紧凑直立型、分枝角度小,群体整齐,主茎较细,薯块干物率较高资源。在今后的育种工作中,可选择同类资源中表型差异互补的种质为亲本,聚合优良性状,以达到育种期望目标。

A total of 228 accessions of cassava germplasm were collected from 19 regions of China and abroad. 22 morphological and agronomic characters including 15 descriptive morphological characters of stems and roots, as well as 7 quantitative characters related to yield, were evaluated. The aim of the study was to understand the genetic diversity of germplasm and provide a theoretical reference for germplasm innovation, as well as introduction and selection of parents for breeding. Results showed that the frequency and distribution of morphological characters of cassava resources from China and abroad were uniform. The majority were the types of open-branches with three bifurcation, 30 degrees to 45 degrees of branching angle, light-green endothelium, white fleshy roots with rough and brown epidermis, and yellow endothelium. Diversity indexes showed 1. 895-2. 073 and 0. 435-1. 889 for quantitative and morphological traits respectively. Broad range of variability from 8.91%-44.60% of quantitative characters was observed among the 228 accessions. Root diameter of China resources was significantly higher than that of foreign resources, while dry matter content of the foreign resources was significantly higher than that of China resources, indicated that the root diameter and the dry matter content of domestic and foreign resources had obvious genetic differences. It was possible to choose high yield and good quality varieties from these germplasms. Two step cluster analysis obviously divided the resources into two similatity groups Ⅰ and Ⅱ. Group Ⅰ was composed of open-branch types with medium to large branching angle, irregular population and thick stem, high tubers yield. Group Ⅱ was composed of compact and upright plant types with small branching angle, regular population, thin stem and high dry matter content in the tuber. Future breeding work should integrate phenotypie differences of the parents into progenies by combination of elite characters to achieve expected objectives in breed- ing programs.