VARIATION FOR GRAIN FILL CHARACTERISTICS IN NORTHERN-ADAPTED SPRING BARLEY CULTIVARS

Rate and duration of grain fill determine maturity and grain yield in barley (Hordeum vulgare L.) cultivars. We assessed grain fill characte ristics and agronomic performance of northern-adapted spring barley cu ltivars for two years at Palmer and Fairbanks, Alaska. Rapid grain fil l rate was associated with high kernel weight, but not with grain fill duration. Cultivars with longer grain fill duration had higher kernel weights. Selection for shorter grain fill duration would not be effec tive in reducing GDD to ripe maturity. Environmental conditions that i ncreased grain fill rate also decreased grain fill duration. The super ior performance of newly developed, improved cultivars, relative to 'O lli', was due to both faster grain fill rate and shorter grain fill du ration. We recommend selection for both early ripe maturity and delaye d time to heading to develop early-maturing, high-yielding barley cult ivars.