Citation: Mwale, S.E.; Shimelis, H.; Nkhata, W.; Sefasi, A.; Fandika, I.; Mashilo, J. Genotype-by- Environment Interaction in Tepary Bean (Phaseolus acutifolius A. Gray) for Seed Yield. Agronomy 2023, 13, 12. https://doi.org/10.3390/ agronomy13010012 Academic Editor: Joseph Robins Received: 24 October 2022 Revised: 14 December 2022 Accepted: 16 December 2022 Published: 21 December 2022 Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). agronomy Article Genotype-by-Environment Interaction in Tepary Bean (Phaseolus acutifolius A. Gray) for Seed Yield Saul Eric Mwale 1,2,3, * , Hussein Shimelis 1,2 , Wilson Nkhata 2,4 , Abel Sefasi 5 , Isaac Fandika 6 and Jacob Mashilo 1,2 1 Crop Science Discipline, University of KwaZulu-Natal, Private Bag X01, Pietermaritzburg 3201, South Africa 2 African Centre for Crop Improvement (ACCI), University of KwaZulu-Natal, Private Bag X01, Pietermaritzburg 3201, South Africa 3 Biological Sciences Department, Mzuzu University, Private Bag 201, Mzuzu 105203, Malawi 4 Alliance of Bioversity International Institute of Tropical Agriculture (CIAT), Chitedze Agricultural Research Station, Lilongwe 206102, Malawi 5 Horticulture Department, Lilongwe University of Agriculture and Natural Resources, Lilongwe 201303, Malawi 6 Kasinthula Agricultural Research Station, Chikwawa 315105, Malawi * Correspondence: saul.mwale@gmail.com Abstract: Genotype-by-environment (GEI) analysis guides the recommendation of best-performing crop genotypes and production environments. The objective of this study was to determine the extent of GEI on seed yield in tepary bean for genotype recommendation and cultivation in drought- prone environments. Forty-five genetically diverse tepary bean genotypes were evaluated under non-stressed and drought-stressed conditions for two seasons using a 9 × 5 alpha lattice design with three replications in four testing environments. Data were collected on seed yield (SY) and days to physiological maturity (DTM) and computed using a combined analysis of variance, the additive main effect and multiplicative interaction (AMMI), the best linear unbiased predictors (BLUPs), the yield stability index (YSI), the weighted average of absolute scores (WAASB) index, the multi-trait stability index (MTSI), and a superiority measure. AMMI analysis revealed a significant (p < 0.001) GEI, accounting for 13.82% of the total variation. Genotype performance was variable across the test environments, allowing the selection of best-suited candidates for the target production environment. The environment accounted for a substantial yield variation of 52.62%. The first and second interaction principal component axes accounted for 94.8 and 4.7% of the total variation in the AMMI-2 model, respectively, of surmountable variation due to GEI. The AMMI 2 model family was sufficient to guide the selection of high-yielding and stable genotypes. Based on best linear unbiased predictors (BLUPs), yield stability index (YSI), superiority measure (Pi), and broad adaptation, the following tepary bean genotypes were identified as high-yielding and suited for drought-prone environments: G40138, G40148, G40140, G40135, and G40158. The selected tepary bean genotypes are recommended for cultivation and breeding in Malawi or other related agroecologies. Keywords: additive main effect and multiplicative interaction; best linear unbiased predictors; drought; tepary bean; yield stability; genotype-by-environment interaction 1. Introduction Recurrent drought remains an impediment to the attainment of the Sustainable Devel- opment Goals (SDGs) of the United Nations, notably SDG 2, which calls for zero hunger, achieving food security and improved nutrition, and SDG 13, which advocates for strength- ening resilience and adaptability to climate-related hazards [1]. Drought affects sustainable agricultural production and productivity, impacting food systems. The impact of drought in southern Africa is exacerbated by erratic rainfall, the cultivation of drought-sensitive cultivars, a lack of crop genetic diversity to extreme climatic events, and the poor resilience of smallholder farmers to drought shocks [2]. There is an increased interest in drought Agronomy 2023, 13, 12. https://doi.org/10.3390/agronomy13010012 https://www.mdpi.com/journal/agronomy