GGE Biplot Analysis of Forage Yield Performance and Stability Assessment of Tall Fescue Experimental Populations Selected Under Grazing Pressure in a Stress Environment
Integrating the yield and stability of genotypes selected under grazing pressure is an important objective in breeding forage crops. Genotype × environment (G x E) interaction is a major source of inconsistency in crop performance across locations. As a result, a genotype is considered stable if it has a low contribution to the G x E interaction. This study explores the effects of G x E interaction on yield and stability of 10 tall fescue experimental populations selected for persistence under grazing pressure outside the area of adaptation of the species (stress environment). Six standard checks were included. The populations were tested in a randomized complete block design with 5 replications in 9 environments. The pooled analysis of variance (ANOVA) revealed highly significant (p \u3c 0.01) variations between populations, locations, years, and G × E interaction. The first two principal components generated by the GGE biplot accounted for 46.78% and 28.45% variation in GGE for yield. The locations (Athens and Blairsville) were found to be the most significant causes of yield variation. The GGE biplot revealed three winning populations GALA1301 (ga1), GALA1302 (ga2), and GALA1306 (ga6) in terms of yield across environments. These populations performed better than all the checks. GALA1502T (g2t) was the most stable and GALA1502A(g2a), GALA1301(ga1), and GALA1303(ga3) are both comparatively stable and high yield performers. Comparison of the two populations g2t and g2a that were selected from the same base population but in different environments (g2t selected for persistence at Tifton under grazing pressure and g2a selected for yield without grazing in Athens) showed that g2t was the most stable across environments but lower in yield than g2a. Our results suggest that selection under grazing pressure in stress environments could result in improved stability across environments while yield performance will still depend on the genetic background of the germplasm
