Invertase and amylase activities in ryegrass and white clover plants and their relationships with activities in soils under pasture

Abstract

Invertase and amylase activities were determined in the herbage and roots of ryegrass and white clover grown under aseptic and field conditions, and in the herbage, litter, roots, and soil of three grass-legume pastures. These activities were appreciably greater in all plant materials than in soil, on either a dry weight or an organic C basis. Invertase-amylase activity ratios in plant materials and in soil were not directly related at the three pasture sites. The activities of aseptically grown plants were not consistently influenced by harvest conditions under light or darkness. They did differ in different tissues and plant species, with amylase activity greatest in white clover. Plant roots did not appear to excrete enzymes with these activities. Chromatographic data suggest that β-amylases contributed most to the amylase activity of herbage and roots, whereas α-amylases and possibly other hydrolytic enzymes, were most important in litter and soil. Other evidence suggests that β-amylases, as well as α-amylases, would also have been active in the soils. Under field conditions, the invertase and amylase activities of the herbage and roots appear to be due mainly to plant-derived enzymes, rather than to associated micro-organisms. In the soils, microorganisms and plants appear to contribute to these activities.