Variation of Beta -Amylase Activity in Barley as Affected by Cultivar and Environment and its Relation to Protein Content and Grain Weight

The cultivar and environmental variation of beta -amylase activity was studied using two barley cultivars with contrasting growth properties. There was a significant difference in beta -amylase activity between the two cultivars used, 92-11 being significantly higher than Xiumai 3. A significant variation in beta -amylase activity was detected between grains at different positions within a spike. The two cultivars showed the same pattern, with top grains showing the highest and bottom ones the lowest activities. The relative difference within a spike varied between the cultivars, with 92-11 being larger than Xiumai 3. Both seeding rate and timing of N application dramatically affected the beta -amylase activity. With N application at the booting stage, beta -amylase activity increased, mainly due to the significantly increased beta-amylase activity in the topmost grains. The bottom grains showed a lower response to timing of N application. The variation in protein content and grain weight between cultivars and among the various treatments was also examined. The possible influence of these factors on beta -amylase activity are discussed.