Genotype and the production of α-amylase in barley grains germinated in the presence and absence of gibberellic acid

Abstract

Decorticated barley grains of different genotypes were germinated with and without optimum amounts of gibberellic acid and potassium sulphate. For comparative trials, a standard germination time was chosen such that α-amylase formation was continuing, but substantial destruction of the enzyme had not begun. The influences of grain size, nitrogen content and threshing damage on α-amylase levels were assessed. In the presence of gibberellic acid, enzyme yield was regarded as a measure of the maximum enzyme-forming capacity of the grain tissues. The “α-amylase ratio”, the ratio of α-amylase formed in the presence of added gibberellic acid to that formed in its absence probably reflects the quantities of endogenous gibberellins formed in the germinating grain. When grains of 93 varieties were investigated, a wide range of enzyme levels occurred in the samples of adequate viability grown with gibberellic acid. This study has identified genotypes with unusually high and low α-amylase-forming capacities that are available for breeding purposes. Also a range of “α-amylase ratios” was encountered, suggesting that a spread of genetically regulated, gibberellin-forming capacities was present.