Abstract
Environments in sub-Saharan Africa fluctuate considerably across sites and seasons. This suggests the importance of assessing genotype x environment interaction (GEI) in cultivar development. The objective of this study was to estimate the magnitude of GEI for rice grain yield and identify high yielding and stable rice genotypes. Fifty six genotypes including 45 F3 rice populations, their 10 parents and one check were evaluated in 7 x 8 alpha lattice design with two replications under three no drought and one random managed drought stress condition at reproductive growth stage at three sites in coast region of Kenya. The additive main effects and multiplicative interaction (AMMI) analysis and genotype plus genotype x environment interaction (GGE) biplot analysis were used to measure grain yield stability of the 45 F3 populations and their 10 parents. Ranking of the genotypes changed in each environment and three mega environments were identified revealing a crossover type of GEI. The genotypes G39 (Luyin 46 x IR74371-54-1-1) and G40 (NERICA-L-25 x IR55423-01) were the most stable high yielding genotypes. These were identified as candidates with general adaption for advancement to homozygozity simultaneously selecting within each population good performing pure lines for release in the region. Key words: Additive main effects and multiplicative interaction (AMMI), genotype x environment interactions, genotype plus genotype x environment interaction (GGE) biplot, rice, yield stability.
Highlights
Genotype x environment interaction (GEI) is the differential genotypic response to environmental changes (Fox et al, 1997)
The parents included five O. sativa L. and five interspecific rice pure lines drawn from the African Rice Centre (ARC), the International Centre for Tropical Agriculture (CIAT) and the International Rice Research Institute (IRRI)
The AMMI analysis of variance showed that grain yield of 55 genotypes at four environments was significantly (P
Summary
Genotype x environment interaction (GEI) is the differential genotypic response to environmental changes (Fox et al, 1997). With significant GEI, differences between genotypes vary widely among environments. A significant GEI is manifested either as changes in the absolute differences between genotypes without affecting the rank order (non-crossover) or as rank order changes of the genotypes between environments (crossover GEI) (Crossa et al, 1995; Yan and Hunt, 2001). It reduces the association between phenotypic and genotypic values, complicating selection of superior cultivars and best testing sites for identifying superior and stable genotypes (Flores et al, 1998). Progress in providing farmers with high yielding cultivars is slowed down (Ceccarelli et al, 1994)
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