GENETIC DIVERSITY IN ACCESSIONS OF Stylosanthes spp. USING MORPHOAGRONOMIC DESCRIPTORS

ABSTRACT: The great diversity of plants in the Brazilian Semiarid environment represents a vital natural resource for the human populations of these areas. Many of these plants have been subject to extractivism and among these, the species of the genus Stylosanthes, which have occurrence in this region, show great potential, however, studies on this topic are limited, and little is known about the existing variability among these plants. Therefore, further study is necessary, to facilitate the development of cultivars. This might reduce the scarcity of fodder supply in this region, but to commence a plant breeding programme, it is essential to identify genetic variability. Therefore, this study evaluated 25 accessions of Stylosanthes spp., to identify the most suitable candidates to be parents in a plant breeding programme for the semiarid region of the state of Bahia. Two experiments were carried out in different sites in an experimental design of randomized blocks with four replicates, with a spacing of 3.0 × 8.0 m. A large amount of genetic diversity was observed among accessions and the genotypes BGF 08-007, BGF 08-016, BGF 08-015 and BGF 08-021 were the most divergent in the overall evaluation. For the structuring of segregating populations, it is recommended to combine the genotypes BGF 08-016, BGF 08-015, BGF 08-007 and BGF 08-006, and for the interspecific crosses, a hybrid from the accession BGF-024 with the accessions BGF 08-016 or BGF 08-015. This might generate superior individuals for mass descriptors, which are the most important for animal forage breeding.

摘要：巴西半干旱环境中丰富的植物多样性，是该区域人类社群赖以生存的关键自然资源。其中多数植物已被开展采掘式开发利用，而分布于此的柱花草属（Stylosanthes）物种虽展现出极高的开发潜力，但目前相关研究较为匮乏，对该属植物现存遗传变异的认知亦十分有限。因此，为推动栽培品种的培育，亟需开展进一步研究——此举或可缓解该地区饲料供给短缺的问题，但要启动植物育种项目，首先必须明确其遗传变异基础。为此，本研究对25份柱花草属（Stylosanthes spp.）种质资源开展评价，旨在为巴西巴伊亚州半干旱地区的植物育种项目筛选适宜的杂交亲本。研究在两处不同试验地点开展，采用随机区组试验设计，设置4次重复，种植间距为3.0×8.0米。结果显示，各供试种质间存在丰富的遗传多样性；综合评价来看，BGF 08-007、BGF 08-016、BGF 08-015与BGF 08-021这4个基因型的遗传分化程度最高。若构建分离群体，推荐选用BGF 08-016、BGF 08-015、BGF 08-007与BGF 08-006进行组配；若开展种间杂交，则建议以BGF-024种质分别与BGF 08-016或BGF 08-015进行杂交。此类组合有望选育出针对饲料作物育种核心性状的优良单株。