Genotype-by-environment interaction analysis is key for selection and cultivar release, and to identify suitable production and test environments. The objective of this study was to determine the magnitude of genotype-by-environment interaction (GEI) for storage root yield, yield-related traits and sweet potato virus disease (SPVD) resistance among candidate sweet potato genotypes in Tanzania. Twenty-three newly bred clones and three check varieties were evaluated across six diverse environments using a randomized complete block design with three replications. The Additive Main Effect and Multiplicative Interaction (AMMI) and genotype and genotype-by-environment (GGE) biplot analyses were used to determine GEI of genotypes. Genotype, environment and GEI effects were highly significant ( P ≤ 0.01) for the assessed traits. Further, AMMI analysis of variance revealed highly significant ( P ≤ 0.001) differences among genotypes, environments and G × E interaction effects for all the studied traits. Both AMMI and GGE biplot analyses identified the following promising genotypes: G2 (Resisto × Ukerewe), G3 (Ukerewe × Ex-Msimbu-1), G4 (03-03 x SPKBH008), G12 (Ukerewe × SPKBH008) and G18 (Resisto × Simama) with high yields, high dry matter content and SPVD resistance across all test environments. The candidate genotypes are recommended for further stability tests and release in Tanzania or similar environments.

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Plant growth and productivity is adversely affected by environmental abiotic and biotic stresses. Drought is one of abiotic stresses that cause serious damage to plants. Therefore, understanding the extent of drought stress and assessing the mechanisms of drought tolerance in plants is very crucial to devise different coping mechanisms with the stresses. Brief discussions have been given on some of the terminologies such as drought tolerance vs. resistance; potential yield vs. yield potential, and water use efficiency. Mechanisms of adaptation to drought stress, inheritance of drought tolerance and the contribution of biotechnology to develop methods of coping up with the problems have been discussed. Finally, methods of screening for drought tolerance have been outlined. The integration of both agricultural practices and conventional and contemporary breeding strategies are necessary in developing crop varieties that are tolerant to abiotic stresses including drought.