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

Abstract

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.

Afrikaans: Hierdie studie is onderneem om genotipe x omgewingsinteraksie (gxe) en opbrengs stabiliteit te evalueer van agt bambara grondboon genotipes in drie lokaliteite met twee plantdatums; om stabiliteitsparameters te gebruik om stabiele opbrengste te bepaal; om korrelasies tussen opbrengs en opbrengskomponente te ondersoek; om die effek van plantdatum op opbrengs en opbrengskomponente te bepaal, en om vas te stel hoe die proteïeninhoud deur omgewing beïnvloed word. Veldproewe is by twee plantdatums geplant by drie lokaliteite. ‘n Gerandomiseerde blokontwerp is gebruik met drie herhalings. Data is ingesamel vir dae tot 50% blom, aantal peule per plant, opbrengs, 100 saadmassa en dae tot volwassenheid. Data is onderwerp aan eenvoudige ANOVA’s vir alle gemeette eienskappe. Betekenisvolle verskille is vir meeste eienskappe gevind. Gekombineerde variansie analise oor alle lokaliteit is gedoen vir alle eienskappe. Betekenisvolle verskille is gevind vir genotipe, omgewing en die interaksie tussen die twee. Die beste genotipe was SB4-4 oor die lokaliteite. Vier stabiliteits parameters naamlik die Eberhart and Russell regressie model, Lin en Binns se cultivar superioriteits meting (Pi), Wricke se ekovalensie (Wi) en die Additiewe Hoof Effekte en Veelvoudige Interaksie (AMMI) is gedoen om opbrengs stabiliteit te bepaal. SB16-5A was die mees stabiel volgens Eberhart en Russell, SB19-3 volgens Wricke se ekovalensie, SB7-1 deur die ASV en SB4-4 deur cultivar superioriteit en opbrengs rangorde. Die resultate het getoon dat SB19-3 die derde mees stabiele genotipe is volgens Eberhart en Russell en Lin en Binns se opbrengs rangordes; en eerste en tweede mees stabiel deur Wricke en die AMMI model. Daarom was SB19-3 die mees stabiele genotipe. ASV en Wricke se ekovalensie het SB4-4 en SB1-1 as die eerste en tweede mees stabiele genoptipes uitgewys vir 100 saadmassa, terwyl SB19-3 eerste en tweede was vir aantal peule per plant. Die AMMI model som die patrone en verwantskappe op vir gxe interaksies en help om goeie opbrengs voorpellings te maak. Die resultate vir die opbrengs stabiliteit is nie finaal nie, en meer as een seisoen se data sal ingesluit moet word om werklik sinvolle afleidings te maak. Korrelasies is eers bepaal vir afsonderlike lokaliteite, en daarna vir gekombineerde data oor lokaliteite. Honderdsaadmassa, biomassa, aantal peule per plant en wortelmassa was positief gekorreleer met opbrengs. Biomassa en 100 saadmassa het sterk positiewe korrelasie gehad met opbrengs. Plantdatum het geen betekenisvolle effek gehad op opbrengs nie. Proteïeninhoud is ook nie betekenisvole deur gxe interaksies beïnvloed nie.