Guinea grass (Megathyrsus maximus Jacq.) is an important forage species in vast rangelands/grasslands of India and several tropical countries owing to its high biomass yield, good nutritional quality and wide adaptation. Evaluation of the existing natural variation and selection of desirable genotypes is the most plausible breeding method for this apomictic and polyploid grass. Developing a core sub-set to narrow down the number of germplasm required for future genetic studies is also pertinent. The present study involved characterization of 152 diverse M. maximus germplasm representing collections from different agro-ecological zones of India as well as those procured from Africa and Brazil; and development of a core sub-set. Nineteen metric, seven non-metric and nine nutritive traits together established the presence of wide variability among the genotypes. Clustering of the genotypes resulted in eight distinct clusters. The largest cluster included genotypes from Ethiopia, north India, north-western India, south India and north-eastern hill region, thus represented the highest diversity. Eleven of the total 26 Ethiopian genotypes clustered together. Non-metric morphological traits effectively differentiated the genotypes, and were associated with nutritional quality also. Genotypes which flowered once in a year showed slightly better crude protein and digestibility. The clusters were further sub-clustered and representatives were selected to develop the core sub-set of 23 genotypes comprising 20 indigenous and three exotic accessions. Comparison of the range of diversity and mean value for traits as obtained in the core sub-set and that in the total germplasm indicated successful capturing of maximum diversity in the core sub-set.

中文翻译：

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几内亚草（Megathyrsus maximus Jacq.）（Poales：禾本科）基因型的多样性研究和核心种质集的开发

几内亚草 (大鲵Jacq.) 因其高生物量产量、良好的营养品质和广泛的适应性而成为印度和几个热带国家广阔牧场/草原的重要牧草物种。评估现有的自然变异和选择理想的基因型是这种无融合性和多倍体草最合理的育种方法。开发一个核心子集以缩小未来遗传研究所需的种质数量也是相关的。本研究涉及 152 种不同的M. maximus代表来自印度不同农业生态区以及从非洲和巴西采购的种质；和核心子集的开发。19 个度量、7 个非度量和 9 个营养性状共同确定了基因型之间存在广泛的变异性。基因型的聚类产生了八个不同的聚类。最大的集群包括来自埃塞俄比亚、印度北部、印度西北部、印度南部和东北部山区的基因型，因此代表了最高的多样性。总共 26 个埃塞俄比亚基因型中有 11 个聚集在一起。非度量形态性状有效区分基因型，并与营养质量相关。一年开花一次的基因型显示出稍好的粗蛋白和消化率。这些集群被进一步细分，并选择代表来开发 23 个基因型的核心子集，包括 20 个本地和 3 个外来种质。比较在核心子集中获得的性状多样性范围和平均值与在总种质中获得的性状表明成功捕获了核心子集中的最大多样性。