The nitrate reductase enzyme (EC 1.6.6.1) is the main responsible enzyme for the assimilation of nitrogen by plants and its activity is strongly affected by the soil water availability. This feature allows the use of this enzyme to evaluate plants in different environmental conditions. The objective of this study was to standardize the methodology to evaluate in vivo the nitrate reductase activity in leaves and roots of nine months and one year old peach palms (Bactris gasipaes). The plants were cultivated in a nursery and the essays were conducted according to the classical method of in vivo analyses. The experimental design was entirely randomized with six repetitions. The results showed that maximum nitrate reductase activity for leaves was obtained with an incubation time of 60 minutes, pH 7, temperatures from 35 to 37°C and, nitrate concentrations between 28 and 30mmol L-1. The nitrate reductase enzyme activity was higher in nine months than in one year old palms. The peach palm leaves showed higher enzyme activity than roots. The nitrate reductase activity varied during the day, with maximum activity at 10:00 hs, indicating an influenceby light and leaf water potential.
Bactris gasipaes; nitrate reductase enzyme; light; temperature; nitrate concentration
