Parametric and non-parametric indexes applied in the selection of sour passion fruit progenies

Abstract Several traits must be observed in the selection of sour passion fruit progenies. For such, selection indices could be used for gradually increasing the frequency of favorable genotypes for the set of the traits of interest. This study aimed to compare parametric and non-parametric selection indices to be used in the selection of passion fruit progenies and identify the best economic weights. Thus, 118 full-sib families and three controls were assessed for days regarding flowering, productivity in kg ha-1 year, fruit mass in g, number of fruits, average length of fruits in mm, average fruit diameter in mm, fruit shape, average shell thickness in mm, pulp yield, pulp color, total soluble solids, titratable acidity and SS/ATT ratio. The non-parametric selection indexes used to obtain genetic gains were Mulamba and Mock, genotype-ideotype distance, multiplicative and Elston. Smith and Hazel, Williams and Pesek and Baker parametric indexes were used, with different economic weights attributed. The Mulamba and Mock, genotype-ideotype distance nonparametric selection indexes and the Williams parametric index showed satisfactory and balanced gains. The genetic variation coefficient, genetic standard deviation and random weight economic weights provided higher gains for non-parametric selection indexes. Similar gains were obtained for parametric indexes, regardless of assigned weight, except for Pesek and Baker, whose genetic standard deviation provided the highest gain.

摘要
酸百香果（sour passion fruit）杂交后代的选育过程中，需对多项性状进行考察。对此，可借助选择指数（selection index）逐步提升目标性状集合内优良基因型的频率。本研究旨在对比适用于百香果杂交后代选育的参数化选择指数（parametric selection index）与非参数化选择指数（non-parametric selection index），并筛选最优经济权重（economic weight）。
为此，本试验共评估了118个全同胞家系（full-sib family）与3个对照材料，调查性状涵盖：开花天数、产量（单位：kg·ha⁻¹·year⁻¹）、单果质量（单位：g）、果实数量、平均果实长度（单位：mm）、平均果实直径（单位：mm）、果实形状、平均果皮厚度（单位：mm）、出浆率、果肉颜色、总可溶性固形物、可滴定酸度以及SS/ATT比值。
本研究选用的非参数化选择指数包括用于获取遗传增益（genetic gain）的Mulamba与Mock指数、基因型-理想型距离指数、乘性指数与Elston指数；参数化选择指数则采用Smith与Hazel指数、Williams指数以及Pesek与Baker指数，并为各指数设置了不同的经济权重。
结果显示，Mulamba与Mock指数、基因型-理想型距离这两种非参数化选择指数，以及Williams参数化选择指数均表现出优异且均衡的遗传增益。对于非参数化选择指数而言，以遗传变异系数（genetic variation coefficient）、遗传标准差（genetic standard deviation）与随机权重作为经济权重时，可获得更高的遗传增益。参数化选择指数的遗传增益整体不受所分配权重的影响，仅Pesek与Baker指数除外：当其以遗传标准差作为经济权重时，可获得最高的遗传增益。