Genotype by environment interaction and grain yield stability analysis for advanced triticale (X. Triticosecale Wittmack) genotypes in western Oromia, Ethiopia

Genotypes by environment (gxe) interactions are almost unanimously considered to be among the major factors limiting response to selection and, in general, the efficiency of breeding programs. Cognizant of this fact, 15 advanced triticale genotypes and one standard check, Dilfikir, were evaluated at Arjo, Gedo and Shambu localities in 2010 and 2011, and at Getema in 2011, to identify stable high yielding genotypes and the extent of gxe interaction. The analysis of variance using additive main effect and multiplicative interaction (ammi) model revealed highly significant (P≤0.01) variations among environments, gxe interaction and Interaction Principal Component Analysis (ipca-I) but insignificant variations among genotypes and the remaining ipcas. This implies that, the tested genotypes respond differently over environments as the test environments are highly variable. Only the first ipca-I was significant (p < 0.01) and contributed to 43.86% of the total genotype by environment interaction. It is found that genotypes tcl-70 and tcl-77 are high yielding next to tcl-76, have ipca value closer to zero, Genotype Selection Index (gsi) of 4 each and ammi stability value (asv) of 0.124 and 0.087, respectively. Analysis using Eberhart and Russell model showed that genotypes tcl-70 and tcl-77 have regression coefficients closer to unity (bi= 1.115 and 1.013) and nearly acceptable deviation from regression (s2di = 0.297 and 0.148), respectively. However, the regression coefficients were significantly different (P≤0.05) from unity for tcl-76, tcl-67, tcl-64, tcl-60, tcl-63 and Dilfikir. Therefore, both tcl-77 and tcl-70 genotypes are proposed for possible release and are recommended for wider adaptability; the uppermost yielding genotype tcl-76, is recommended for specific environme