Evaluation of bambara groundnut (Vigna subterranea) for yield stability and yield related characteristics

[摘要] English: This study was undertaken to evaluate genotype x environment interaction (gxe) and yield stability of eight bambara groundnut genotypes in three locations at two planting dates; to compare the stability parameters used in determining stable yields, to correlate yield and related characters of the crop, to determine the effect of planting date on yield and yield components; and to assess the effect of location and genotype on protein content. Field trials were planted with two different planting dates in three localities. A randomized complete block design with three replications was used. Data collected was days to 50% flower, number of pods per plant, grain yield, haulm yield, 100 seed weight, and maturity days. Data was subjected to simple ANOVA's for all measured characteristics. Significant differences were found for most of these characteristics. Combined analyses of variance were computed across locations to determine the performance of yield and related characteristic. Significant differences were found for genotype, environment and Gxe interactions. The best genotype was SB4-4 across locations. Four stability parameters namely Eberhart and Russell regression model, Lin and Binns' Cultivar Superiority Measure (Pi), Wricke ecovalence (Wi) and Additive Main Effects and Multiplicative Interaction (AMMI) were performed to determine yield stability. SB16-5A was regarded the most stable by Eberhart and Russell, SB19-3 by Wricke ecovalence, SB7-1 by ASV and SB4-4 by cultivar superiority and yield rankings The results showed that SB19-3 was the third most stable genotype according to Eberhart and Russell and Lin and Binns yield ranking; and the first and second most stable genotypes by the Wricke and AMMI model. Therefore SB19-3 proved to be the most stable genotype. ASV and Wricke ecovalence value ranked SB4-4 and SB1-1 to be the first and second most stable genotypes for 100 seed weight, while ranking SB19-3 first and second respectively for number of pods per plant. The AMMI model summarizes patterns and relationship between gxe interactions and helps to obtain a good yield estimates. The results for stability of yields are not conclusive since the data is for one season, therefore the trials must be repeated to validate the results. Correlation analyses were first computed for separate trials and then for combined trials across locations. Hundred seed weight, haulm yield, number of pods per plant and root weight were positively correlated with grain yield with haulm yield and 100 seed weight having strong positive correlations to grain yield. Planting date did not significantly affect yield and protein content was also not significantly affected by gxe interactions.

[发布机构] University of the Free State