Effect of flooding on activities of soil dehydrogenases and alcohol dehydrogenase in rice (Oryza SativaL.) Roots

Abstract

Dehydrogenase activity and redox potential were monitored over a period of 100 days in flooded and drained soils in which rice was grown. The activity of the enzyme alcohol dehydrogenase (ADH) was measured in the roots of the rice plants. The immediate decrease in soil redox potential and rapid increase in soil dehydrogenase activity upon flooding indicated a shift of microflora from aerobic to predominantly anaerobic microorganisms. Soil dehydrogenase activity remained elevated as long as the soil continued to be flooded, but was negligible in soils allowed free drainage. The rice roots only initially experienced anaerobiosis during flooding. Root ADH activity was stimulated upon flooding but declined by day 47 to levels similar to those measured in plants grown in a drained soil. The development of aerenchyma (air-space) tissue in the continuously flooded plants may have provided a pathway for oxygen movement to the roots which allowed aerobic metabolism to proceed in spite of the reduced amount of subs...