Stability analysis of grain yield in barley (Hordeum vulgare) in the US mid-Atlantic region

Stability of grain yield performance is an important characteristic in the selection of new crop cultivars. Information from cultivar trials, however, is seldom fully analysed for genotype by environment interactions and, the refore, information on stability of current crop cultivars is lacking. The objectives of this study were to investigate the stability of agronomic tra its among genotypes of barley (Hordeum vulgare) across 17 environments (loc ation-years) in Maryland (USA) from 1994 through 1997 and to examine the ef fect of locations and years of testing on grain yield performance in this r egion. Significant differences were observed among barley cultivars and exp erimental lines for grain yield, plant height, and heading date. Grain yiel d was positively correlated with plant height and negatively correlated wit h heading date. Genotype x environment interactions measured through regres sion analysis were significant for grain yield, heading date and plant heig ht, with the environmental component having the largest effect. Most barley genotypes tested (90%) had regression slopes for grain yield that did not differ from 1.0, indicating good potential for yield response under improvi ng environmental conditions. The most widely grown cultivar in the mid-Atla ntic region, 'Nomini', had a regression slope that was higher than 1.0 for grain yield. This indicates that it tends to respond with increasingly high er yields under favorable conditions. In this study, the slope and the stan dard error of the slope were moderately correlated with grain yield, The ge notype's coefficient of variation was not a good indicator of stability for this region. Grain yields of genotype entries common to all years and loca tions were correlated with corresponding yields at each of the locations an d years to assess the relative performance of each location and year. Corre lation coefficients across locations were relatively high (r=0.64) within e ach year of testing. Correlations between years for the same and across loc ations were generally much lower. The data presented here supports a testin g program over more years rather than increased locations to fully characte rise the performance of new cultivars.