PHENOTYPIC GRAIN YIELD STABILITY OF SEVERAL SOYBEAN OS-CULTIVARS

Objective of this study was to evaluate the level and stability of grain yield as well as adaptability level of several domestic soybean cultivars. The trials were conducted on three locations in the region of the eastern Croatia (Osijek, Brijest, Donji Miholjac) in the period from 1998-2002 and involved 14 soybean cultivars. Tested cultivars were created in soybean breeding programme at the Agricultural Institute Osijek. They belong to maturity groups 0, 0-I and I according to vegetation period length. Two parameters are used in the analysis of yield stability and cultivar adaptability: portion of variance of genotype x environment interaction of each genotype to total variance of genotype x environment interaction (S2GxE) and regression coefficient (bi). Obtained results indicated significant differences in level and stability of grain yield as well as level of cultivar adaptability. Six of the 14 tested cultivars: Ika, Podravka 95, Smiljana, Kuna, Anica and Tisa had high and stable grain yield and wide-general adaptability. Other tested cultivars had unstable grain yield and narrow (specific) adaptability.