Genotype by environment interaction and stability analysis of cowpea [Vigna unguiculata (L.) Walp] genotypes for yield in Ethiopia

Abstract

Ethiopia is claimed to be a center of diversity for cowpea production. The crop is the most drought tolerant and could help the country overcome the recurrent drought problem; however, the yield is very low due to lack of effort to develop varieties. This research was conducted to evaluate the stability of cowpea genotypes and to estimate the magnitude of genotypes by environment interaction (GEI) effect on grain yield. Sixteen cowpea genotypes were tested at seven environments in an experiment laid out in a 4 × 4 triple lattice design during 2016/17 cropping season. The combined analysis of variance over environments showed significant differences among genotypes and environments, along with significant effect of GEI on grain yield, days to flowering, days to maturity, plant height and pods per plants. Analysis of variance for grain yield from AMMI model indicated the contribution of genotype and environment, with GEI accounting for about 63.3, 5.3 and 29.7% of the total sum of squares, respectively. The result indicated that environments contributed much to the observed variations suggesting the need to test cowpea genotypes in diverse environments. Considering all stability parmeters, viz; deviation from regression (S 2 di), coefficient of regression (bi) from ER's model, IPCA1, IPCA2 and AMMI stability value (ASV) from AMMI model, GGE biplot and variety TVU was identified as the most stable with mean yield above the mean grain yield of genotypes. Two genotypes: IT-99K-1060a (1398.8 kg/ha) and 86D-378 (1377.1 kg/ha) had first and second highest yield, identified as responsive to both environments but more to favorable environments suggesting the need to further test and develop as varieties. The other two genotypes: 95K-1095-4A and 93K-619-1, identified as unstable and highly responsive to environments suggested to consider the genotypes as candidate varieties where they performed best. Melkassa, Sekota and Jinka were identified as more descrimnating environments, whereas Arbaminch and Kobo were ideal for selecting superior genotypes; however, Babile and Meisso were non descrimnating environments. Key words:Additive main effects and multiplicative interaction (AMMI) stability value, Eberhart and Russell, deviation from regression and triple lattice.

Yield stability among cowpea genotypes evaluated in different environments in Uganda

“…In this study, three PCAs accounted for the observed variation in G × E since their F tests indicated strong significance (Table 3). Similar results were reported by Crossa (1990) and Tukamuhabwa et al (2012) for soybean genotypes as well as Tariku et al (2018) for cowpea genotypes. However, Sabaghnia et al (2008) reported a more complex interaction with up to seven PCAs.…”

“…This is because AMMI analysis is very efficient in identifying both high yielding and stable genotypes (Asio et al, 2005). AMMI analysis has been extensively used to determine stable cowpea genotypes (Asio et al, 2005;Ddamulira et al, 2015;Horn et al, 2018;Tariku et al, 2018;Kuruma et al, 2019;Abiriga et al, 2020;Haisirikul et al 2020). The AMMI method has also been used to assess the causes of G × E interactions in crops like rye grass (van Eeuwijk and Elgersma, 1993) and wheat (Mohammadi et al, 2017) but not cowpea.…”

The evaluation of a southern African cowpea germplasm collection for seed yield and yield components

“…However, seasonal effect and its interactions are confounded and unpredictable and are therefore not useful for guiding breeding and selection strategies. Simion et al (2018) reported the significant effect of genotype, environment, and GE interaction on cowpea seed yield and some other yield-related traits and suggested the importance of further stability analysis. The highly significant GLS effect for almost all the traits indicated larger influence of location-specific seasonal effects on these traits.…”

“…In Zimbabwe, Matova and Gasura (2018) reported significant GE interactions for cowpea grain yield across locations and years. Studies done by Gereziher et al (2018), Simion (2018), and Simion et al (2018) reported significant GE interaction for grain yield, days to flowering, days to maturity, plant height, and pods per plant in Ethiopia. In Brazil, da Silva et al (2016) and Sousa et al (2018) reported significant GE interactions for protein content and grain yield, respectively.…”

“…Genotype × environment interactions for cowpea [Vigna unguiculata (L.) Walp. ] have been reported in Egypt (El-Shaieny, Abdel-Ati, El-Damarany, & Rashwan, 2015), Brazil (da Silva, Santos, & Boiteux, 2016;Sousa, Damasceno-Silva, Rocha, Júnior, & Lemos Lima, 2018), Ethiopia (Gereziher, Diriba, & Molla, 2018;Simion, 2018;Simion, Mohammed, & Amsalu, 2018), Zimbabwe (Matova & Gasura, 2018), and South Africa (Gerrano et al, 2020;Horna, Shimelis, Sarsuc, Mwadzingenia, & Lainga, 2017). El-Shaieny et al (2015) reported significant GE interaction for the number of pods per plant, number of seeds per pod, average weight per plant, and total dry seed yield in Egypt.…”