Harnessing genotype-by-environment interaction to determine adaptability of advanced cowpea lines to multiple environments in Uganda

Abstract

This study was conducted to determine the yield stability of advanced cowpea lines in diverse agroecological zones of Uganda in order to facilitate documentation requirements for national performance trials (NPT). Thirty cowpea genotypes were evaluated against six checks in three localities, over three growing seasons, making a total of 9 unique environments. The trials were laid in a 6x6 alpha lattice design with three replications and grain yield was the principal trait measured. Single-site and multilocation data were summarized using analysis of variance. Further analysis of stability was visualized using the genotype and genotype by environment interaction (GGE) biplot and the additive main effect and multiplicative interaction (AMMI) models. ANOVA depicted highly significant differences among the genotypes, locations, seasons and GEI for grain yield. Based on AMMI analysis, environmental effect accounted for the most variation (84.7%) in the phenotype followed by GE (9.45%) and genotypes (4.45%), alluding to the complex inheritance of grain yield in cowpea. The polygon view and the average environment coordination view of the GGE biplot revealed Ayiyi as the wining genotype in the major mega environment and the most stable and high yielding across environments respectively. The genotypes Ayiyi, WC64 and ALEGIxACC2 yielded higher than the checks and were very stable. The other genotypes G36 (WC 36), G3 (ACC12xSECOW3B), G32 (WC16), and G14 (MU9) did not outperform the checks but displayed high yield stability and the mean yields were above the overall average. These genotypes were considered desirable for advancement to National Performance Trial for potential release as new improved cowpea cultivars.

Recommendation of cowpea genotypes based on adaptability, stability and grain darkening

“…This shows that the genotypes had diff erent behaviours for grain yield, and that this variable was also infl uenced by the growth environments, in addition to there being an interaction between these factors. Similar results were obtained when evaluating the yield of cowpea genotypes in diff erent environments in Brazil and in other areas of production (Abiriga et al, 2020;Araméndis-Tatis;Cardona-Ayala;Espitia-Camacho, 2021;Cruz et al, 2020;Melo et al, 2020;Sousa et al, 2017;Tomaz et al, 2022).…”

“…The signifi cant G x E interaction explains the evaluations of adaptability and stability (Araméndiz-Tatis; Cardona-Ayala; Espitia-Camacho, 2021), especially when it comes to a complex trait such as grain yield (Abiriga et al, 2020). Furthermore, the predominance of the complex part of the G x E interaction confi rms that the behaviour of the strains varied greatly in the environments under evaluation.…”

“…Cowpea cultivation includes various methods, ranging from rainfed subsistence, practised by farmers with little access to technologies such as additives and improved seeds, to highly technological systems (Herniter;Muñoz-Amatriaín;Close, 2020;Kebede;Bekeko, 2020). As a result, the average crop yield is well below potential in the major growing areas (Abiriga et al, 2020;Araméndis-Tatis;Cardona-Ayala;Espitia-Camacho, 2021). In Brazil, the species is mainly grown in the north-east of the country, which, due to the large planted area, is the largest producer, despite the yields being low (EMBRAPA, 2020).…”

“…To safely recommend new genotypes, it is essential to understand the interaction between the genotype and the environment, for which it is necessary to evaluate the genetic materials in diff erent locations and/or at diff erent planting times (Abiriga et al, 2020;Abreu et al, 2019;Araméndis-Tatis;Cardona-Ayala;Espitia-Camacho, 2021). Furthermore, the type of cultivation system adopted, i.e.…”

Cowpea Constraints and Breeding in Europe

“…Identification of high-seed-yielding genotypes with broad adaptability and therefore yield stability [ 301 ] is considered one of the primary improvement goals [ 302 ] in Europe as in the rest of the world. However, cowpea yield is a complex trait, and it is difficult to directly breed for it, as it presents low heritability and pleiotropic effects [ 303 ].…”