Vegetos

Abstract

Leaf Nitrate Reductase activity was studied in Hyptis suaveolens (L.) Poit. at different phenological stages in relation to leaf position. Variability in nitrate reductase activity at different stages of growth coincident with seasonal changes was recorded. Least amount of nitrate reductase activity was observed in young vegetative stage during summer. This was followed by maximum nitrate reductase activity (4.90 ± 1.47μmole NO₂ g⁻¹f.wt.h⁻¹) in mature vegetative stage during rainy season and subsequent decline at flowering stage. Increased activity of nitrate reductase was also observed during post flowering stage of fruit setting in winter. Irrespective of phenological stages, apical leaves exhibited moderately high NRA. High nitrate reductase activity in mature vegetative stage of H. suaveolens characterizes an enhanced potential for nitrate assimilation ascribing to invasive nature of the weed. Present finding highlights a possible impact of morphophysiological status of the plant coinciding with seasonal changes on leaf nitrate reductase activity.