Comparison of Two Approaches for Estimation of Genetic Variation for Two Economic Traits in Faba Bean Genotypes Grown under Waterlogged Verisols
AbstractThere is little experimental evidence about whether component of variance calculated from separate analysis of variance in waterlogged conditions is effective in estimating the extent of heritable variation and the effectiveness of selection. Seven faba bean variety trials consisting of 17-25 different genotypes each were conducted at four locations in lattice or RCB designs with 2 or 3 replications on drained (using broad bed and furrow, BBF) and undrained (flatbeds) Vertisols between 1996 and 1999. Records on 1000 seed weight and grain yield were subjected to statistical analyses using SAS computer software. Grain yield was more sensitive to waterlogging stress than 1000 seed weight. Heritability and expected genetic gains calculated from separate analysis were higher than those calculated from pooled analysis of variance for both grain yield and 1000 seed weight. The relative precision improvement of pooled analysis of variance over separate analysis ranged from 57-83% for grain yield and 7-25% for thousand seed weight. Thousand seed weight was more heritable than grain yield. There was weak association between heritability and expected genetic gains calculated from separate and pooled analyses of variance for grain yield and strong positive association for 1000 seed weight, indicating that genetic variation and effectiveness of selection for thousand seed weight could, more accurately, be calculated from separate analysis of variance than grain yield. Thus, studies on genetic variability and effectiveness of selection for grain yield based on separate analysis of variance could be misleading under both drained and waterlogged Vertisols because of the potential danger of wrong conclusions that could be drawn from the confounding effects of genotype by environmental interaction.
Authors agree to retain copyright and grant the journal right of first publication with the work simultaneously that allows others to share with an acknowledgement of the work's authorship and initial publication in this journal.