[Effect of nitrate and cytokinin on nitrate reductase activity in isolated corncockle embryos]

The effects of cytokinin and nitrate on the activity of nitrate reductase (NR) in isolated embryos of Agrostemma githago L. were studied. It was shown that the effects of cytokinin and NO-3 on the induction of NR is additive during 8, 12 and 18 hrs of embryos incubation in the solutions of the two inducers. Anticytokinin decreased the cytokinin induced NR by 35--39% and had no effect on the NR induction by nitrate. The substrate and hormonal induction of NR differed in the duration of the lag period. This difference dependent on the physiological state of the embryos at the beginning of incubation. The data obtained are indicative of the independence of cytokinin and NO-3 effects on the NR synthesis in isolated embryos of Agrostemma githago L. Abscisic acid supressed cytokinin- and nitrate-induced NR and had practically no effect on total incorporation of the label into the protein. It is assumed that the induced synthesis of the protein is more sensitive to the action of abscisic acid that the total protein synthesis.