Effect of light and temperature on nitrate uptake and nitrate reductase activity in rye and oat seedlings

Abstract

The effect of light and temperature on nitrate uptake and the activity of nitrate reductase was investigated in rye (Secale cereale L. cv. MSU Exp. 1) and oat (Avena sativa L. cv. Garry).Light enhanced nitrate uptake and led to the induction of more enzyme. However, in plants that received a 16-h dark period before both nitrate and dark treatment, no enzyme was induced, although considerable nitrate accumulated in the plants. Enzyme induction increased with light intensities up to 1500 ft-c during 12 hours exposure of light and during the subsequent dark period. Nitrate uptake in the dark was saturated at 300 ft-c of light pretreatment.Nitrate and nitrate reductase of oat seedlings, grown at 22 °C (day) and 17 °C (night) for 3.5 days, decreased with increasing light intensities.