Abstract: In view of the disadvantages of the 3,5-dinitrosalicylic acid (DNS) method, we developed a rapid micro-volume procedure utilizing p-nitrophenyl-a-maltopentaoside (PNPG5) as a substrate for specific determination of b-amylase activity. The assay procedure was evaluated with seeds from 4 plant species, and the exact degree of interference by a-amylase was determined. This modified method could be applied to the selective measurement of b-amylase activity in different plant seeds.