Selection index based on phenotypic and genotypic values predicted by REML/BLUP in Papaya

Abstract Selection of superior genotypes based on the simultaneous responses to different characteristics is a fundamental strategy in plant breeding. This study aimed to compare the efficiency of four selection index constructed using phenotypic and genotypic values in a segregating population of the cultivar Rubi Incaper 511. Eight morpho-agronomic variates and the severity of black-spot and phoma-spot were evaluated under field conditions. The classical selection index were calculated based on non-standardized phenotypic means (NSM), standardized means (SM), and genotypic values predicted by REML/BLUP (GVP), using predetermined economic weights. Additionally, the rank sum (RS) was obtained on the basis of the classification of individuals in these three selection index. For ten characteristics, the selected individuals showed a higher mean than did the original population. The best selection differential values were obtained by SM, however, the highest degree of coincidence among the selected individuals was obtained between GVP and RS (80%). The index used were efficient at selecting individuals with higher soluble solids and lower diseases severity evaluated. Therefore, for the papaya breeding programs, different selection index need to be evaluated to maximize genetic gain.

摘要 基于多性状同步响应开展优良基因型选择是植物育种的核心策略之一。本研究旨在比较四种选择指数的应用效率，这四种指数分别利用表型值与基因型值构建，用于鲁比因卡佩尔511（Rubi Incaper 511）品种的分离群体。在田间条件下，本研究对8个形态农艺性状以及黑星病、茎点霉病的病情严重度进行了评价。经典选择指数分别基于非标准化表型均值（NSM）、标准化均值（SM），以及通过限制性极大似然估计（REML）与最佳线性无偏预测（BLUP）得到的基因型值（GVP）构建，并均采用预设的经济权重。此外，本研究还基于上述三种选择指数对个体进行分类，进而得到秩和指数（RS）。针对10个性状，入选个体的平均表现均优于原始群体。其中标准化均值（SM）获得了最优的选择差分值，但基因型值（GVP）与秩和指数（RS）对应的入选个体重合度最高，达80%。本研究采用的各类选择指数均能有效筛选出可溶性固形物含量更高、所评价病害严重度更低的木瓜个体。因此，在木瓜育种项目中，需对不同选择指数进行评估以最大化遗传增益。