Selection indexes in the simultaneous increment of yield components in topcross hybrids of green maize

Abstract: The objective of this work was to define the most suitable selective strategy for the simultaneous increment of yield components of green maize, by comparing three selection indexes weighted by economic weights and by the REML/BLUP method, in the assessment of predicted genetic gains for traits of interest. An experiment with 75 topcross hybrids from partially inbred S1 lines of green maize was carried out in Jataí, in the state of Goiás, Brazil, using a randomized complete block design, with four replicates. The following yield traits were evaluated: straw ears and commercial ears, grain mass, ear length, ear diameter, and number of ear rows. The selection indexes of Smith and Hazel, Williams, and Mulamba & Mock were applied and weighted for four economic weights (1, CVg, CVg/CVe, and h2). Among the tested selection indexes, those of Williams and Mulamba & Mock are the best-fit ones for the selection of topcross hybrids of green maize, as they provide positive and more balanced selection gains for all evaluated traits. The REML/BLUP method shows better predicted genetic gains than those achieved by the three selection indexes, besides being efficient for the selection of topcross hybrids of green maize.

摘要：本研究旨在明确最适用于同步提升青玉米产量构成因子的选择策略，通过比较3种基于经济权重加权的选择指数，并结合限制性最大似然/最佳线性无偏预测（REML/BLUP）方法，对目标性状的预测遗传增益进行评估。试验以75份来自部分自交S1代株系的青玉米顶交杂种为材料，于巴西戈亚斯州雅塔伊市开展，采用随机完全区组设计，设置4次重复。本试验评估的产量性状包括：秸秆果穗与商品果穗、粒重、穗长、穗粗以及穗行数。选用Smith与Hazel、Williams以及Mulamba & Mock这3种选择指数，并以4种经济权重（1、CVg、CVg/CVe及h²）进行加权。供试选择指数中，Williams指数与Mulamba & Mock指数最适用于青玉米顶交杂种的选择，二者可对所有被测性状实现正向且更均衡的选择增益。相较于上述3种选择指数，REML/BLUP方法可获得更优的预测遗传增益，同时可高效用于青玉米顶交杂种的选择。