Abstract
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.
Highlights
Sweet potato (Ipomoea batatas [L.] Lam., 2n 1⁄4 6x 1⁄4 90) is an important storage root crop grown for diverse uses such as for food, feed and industrial raw material
The candidate genotypes are recommended for further stability tests and release in Tanzania or similar environments
The AMMI analysis of variance in the current study revealed great contribution of environments (64%) and GE interactions (25%) for variation in storage root yield compared with the main effect of genotypes (11%)
Summary
Sweet potato (Ipomoea batatas [L.] Lam., 2n 1⁄4 6x 1⁄4 90) is an important storage root crop grown for diverse uses such as for food, feed and industrial raw material. It is a rich source of carbohydrates, vitamins A and C, fiber and minerals (Woolf, 1992; Teow et al, 2007). The crop has inherently low requirement of production inputs. It provides reasonable yields under marginal growing conditions making it the crop of choice widely cultivated in sub-Saharan Africa (SSA) (Karyeija et al, 1998). The yield levels in the region are relatively low ranging between 4.0e10.0 tons/ha, compared with average yield of 21.5 tons/ ha reported elsewhere (FAOSTAT, 2014)
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