Evaluation of Fresh and Dry Forage Yield Stability of Forage Sorghum Varieties (Sorghum bicolo L. moench) in Different Conditions

This study was conducted to estimate stability of yield in forage sorghum varieties for identifying varieties with combine stability and high yield potential across two cropping conditions. Thus, seven forage sorghum varieties were evaluated for three years under two cropping conditions including spring (E1) and summer (E2) cropping, using a randomized complete block design with four replications. Combined analysis of variance showed that environments, genotypes and genotype-by-environment (GE) interaction effects were highly significant, suggesting that the studied varieties differently responded to changes happened in environment. Genotype and genotype-by-environment (GGE) biplot analysis explained 94.8% and 76.5% of the fresh and dry forage yield variation due to GGE, respectively. The GGE biplot analysis ranked varieties for stability of performance as NECTAR≈CHOPPER≈KFS2>KFS3>KFS1 for fresh forage yield and PACIFICBMR>KFS1>KFS2 for dry forage yield, whereas NECTAR and KFS3 varieties and NECTAR and SPEEDFEED varieties had the highest fresh and dry forage yield, respectively. Based on genotype and genotype × environment interaction variation, variety NECTAR in both spring and summer cropping conditions for fresh forage yield, while for dry forage yield, variety SPEEDFEED in spring cropping condition and NECTAR in summer cropping condition showed as superior varieties with high specific adaptation. Based on a hypothetical ideal genotype, varieties NECTAR was better than other varieties across environments for yield and stability with wide adaptation.