Genotype x Environment Interaction and Grain Yield Stability Analysis of Rice (Oryza sativa L.)
Background: Upland rice has been introduced in to Ethiopia recently and widely produced in different parts of the country particularly after it was adopted as the "millennium crop" in 2000. However, limited availability of improved varieties hampers production of the crop.
Objective: To determine the nature and magnitude of genotype x environment interaction and to identify stable high yielding, blast, and brown spot diseases tolerant varieties for upland rice-growing environments.
Materials and Methods: The experiment was conducted at Gutin and Bako (2010−2011) and Boneya and Chewaka districts in the 2011 main cropping seasons. Eleven rice genotypes [WAB272-B-B-8-H1, YIN LU20, IRGA370-38-1-1-F-B1-1, CNAX3031-15-2-1-1, WAB502-8-5-1, WABC165(IAC165), WAB450-11-11P31-HB, WAB376-B-10-H3 and WAB368-B-1-H2-HB] including standard checks (IRAT 355 and SUPERICA 1) were laid out in a randomized complete block design with three replications. Grain yield data were collected and analyzed.
Results: The results showed significant variations among the genotypes in grain yield. The mean grain yield obtained over four environments ranged from 2.36 tons ha–1 (IRAT 355) to 4.23 tons ha–1 for Chewaka variety (YIN LU20) and SUPERICA-1 produced 2.54 tons ha–1. Regression analysis based on Eberhart and Russell Model showed that Chewaka variety and WABC165 (IAC165) had mean grain yield that were higher than the average for all genotypes. Regression coefficient (bi) did not differ significantly from unity and the squared deviations (s2di) approached zero. On the other hand, IRGA370-38-1-1-F-B1-1, WAB450-11-11P31-HB and WAB376-B-10-H3 had regression coefficient (bi) differ significantly from unity showing that these genotypes are sensitive to different environmental conditions and tend to give higher yield at favorable environments.
Conclusion: Among the tested genotypes, YIN LU20 and CNAX3031-15-2-1-1 were stable and high yielding and proposed as candidate varieties. In addition, genotype YIN LU20 was preferred by farmers for its stability, high seed yield and resistance to rice blast and brown spot diseases and released for cultivation in western Ethiopia and other areas in the country with similar agro-ecology, named as Chewaka variety.