YIELD STABILITY AND ADAPTATION OF NORDIC BARLEYS

Grain yield was studied in a collection of 220 Nordic barley lines at diverse locations in the Nordic countries. Two-row (2r) and six-row (6 r) lines differed very significantly in reaction to the growing condit ions within and between the two locations, Svalov (in southern Sweden) and Hojbakkegard (in Denmark). This difference was also highly signif icant at Viikki (in Finland), but not at As (in Norway) or between Vii kki and As. Genotype x location (GL) and genotype x year(GY) variance components were used to estimate phenotypic yield stability by Shukla' s stability variance (sigma(i)(2)). Only 7 lines did not contribute si gnificantly to GL- and GY-interactions, and their yield levels were 7- 27% lower than that of the highest yielding line (5057 kg/ha). Estimat es of GL- and GY-stability parameters were not significantly correlate d. Neither responsiveness, measured by the regression coefficient (b(i )), nor phenotypic yield stability, measured by the deviations from re gression (Tai's lambda(i)) were correlated with yield. Pedigree studie s showed that both b(i) and sigma(i)(2) can be changed by recombinatio n and/or induced mutations. Mixing of near isogenic lines with differe nt resistance genes, and selection within a landrace, also resulted in changes in responsiveness. Recently released 2r-cultivars were more u nstable than older 2r-cultivars revealed by positive correlation betwe en the year of release and lambda(i). Cultivars originating from south ern Scandinavia were higher yielding than cultivars originating from t he central or the northern regions of Scandinavia.