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enotype by environment interaction (GxE) complicates the process of selecting genotypes suitable for quanti tative traits like seed yield in beans, hence slows down the development and release of varieties by breeding
programs. GxE study on seed yield in beans enables identification of stable genotypes across sites and best site(s)
for discriminating the tested genotypes in terms of seed yield. The purpose of this study was to evaluate the
influence of the environment, genotype, and genotype by environment interaction on seed yield stability and
adaptability of common bean landraces, lines, and improved varieties across three different agro-ecologies in
Tanzania. The 99 common bean genotypes (Landraces, lines, and improved varieties) were planted following
alpha lattice design in three replications each contained five blocks with 20 plots. Soil properties from the
experimental sites, days to 75% flowering, Seed yield, 100 seed weight, number of seeds/pod, and number of
pods/plant were recorded. Data on seed yield and its components were analyzed using Additive main effect and
multiplicative interaction (AMMI), genotype main effects plus genotype environment interaction (GGE), and
yield stability index (YSI). The AMMI revealed very highly significant (P 0.001) effects of genotypes, envi ronmental, and genotype environment interaction on all the traits. AMMI analysis revealed that genotype main
effects accounted for 39.3% of the total sum square of seed yield, whereas the environment and genotype
environmental interaction accounted for 31.4% and 26.8 % respectively. Genotype main effects largely influenced
the variation in days to 75% flowering (55.5%), number of pods/plant (49.2%), number of seeds/pod (73.3%),
and 100 seed weight (71.2%). Among soil properties recorded, available soil phosphorus, soil pH, soil
exchangeable K, Ca, and Na had a strong positive association with common bean seed yield, while soil organic
carbon and total nitrogen exhibited a strong negative association with seed yield. GGE revealed that E1 (TARI Selian) was the most discriminative and representative site for common bean genotypes seed yield. Based on the
yield stability index, the most stable and high seed yielding genotypes were ACC 714, Selian 14, Selian 9, Katuku,
and Msolini. The identified high seed yielding and stable genotypes can be further tested in participatory variety
selection involving farmers and later on released as varieties and can also be used for different breeding purposes
in different agro-ecologies of Tanzania. |
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