In vivo Nitrate Reductase Activity and Nitrite Reductase Activity in Response to Treatment of PGRs (IAA, GA₃ and KIN) in a Pulse Crop (Vigna radiata (L.) Wilczek.); Certain Studies on Kinetics of NR

Effects of foliar application of different concentrations of IAA, GA and kinetin onin vivoactivities of nitrate reductase (NR) and nitrite reductase (NiR) were studied in the leaves ofVigna radiata. The results showed significant increase in the NR and NiR activities. The in vivo NR activity was maximum on 7 days after treatment for IAA and KIN and 14 days for GA. The in vivo NiR activity was maximum on day 14th after spray for IAA and day 7th after spray for GA and kinetin. The optimum concentration was found 1 to be 10.0 mg/l for each plant growth regulator. Thein vivo kinetics of leaf NR was also studied with the foliar application of the optimum concentration of PGRs. The Km value for leaf NR using KNO as substrates was 5.0 mM for control and as well as for those sprayed with optimum concentration of each PGR. The optimum pH was also found to be same (pH 7.4) for control as well as for those sprayed with optimum concentration of each PGR.