GGE Biplot Exploration of Resistance to Sheath Blight Disease in Doubled-Haploid Lines of Rice

Development of cultivars resistant to sheath blight (SB)disease caused by Rhizoctonia solani Kuhn is an important breeding objective for the southern U.S. rice (Oryza sativa L.)industry. The aim of this research was to explore performance, genotype (G)and genotype × environment (GE)interactions, and stability for SB resistance of 322 doubled-haploid (DH)lines of the SB2 mapping population produced by the RiceCAP project. Analysis was performed by heritability-adjusted genotype plus genotype × environment interaction (HA-GGE)biplot analysis, Hühn's nonparametric stability statistics, median polish, and additive main effects and multiplicative interaction (AMMI). Genetic material was evaluated in replicated plots for 2 yr (2006 and 2007)in Louisiana and Arkansas. A single mega-environment was identifi ed consisting of the four year-location combinations. Heritability-adjusted genotype plus genotype × environment interaction biplot analyses identifi ed 11 DH lines with high and stable levels of resistance at both locations. Five susceptible DH lines were also identifi ed with greater stability than the susceptible parent used to develop the SB2 population. Results from Hühn's nonparametric approach and median polish complemented those of HA-GGE biplot analysis. Material identifi ed in this study represents a potential source of high and stable SB resistance for cultivar development that warrants additional fi eld-plot evaluation.