Nitrate Reductase Activity in Corn Seedlings as Affected by Light and Nitrate Content of Nutrient Media

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Abstract
Young corn plants placed in complete darkness for 48 hours lost 90% of their nitrate reductase activity1. The activity was restored when the plants were returned to the light. Two other enzymes were not affected by the same treatment. Decreasing incident light intensity decreased, in rough proportion, the nitrate reductase activity of corn plants. It was shown that both light and nitrate must be supplied to corn seedlings before they could synthesize normal amounts of nitrate reductase. Greenhouse experiments in which nitrate content of the media was varied demonstrated that the level of nitrate reductase activity was dependent in part upon the substrate concentration. There was a positive correlation between nitrate reductase and growth and protein content. Shoots and leaves of corn hybrid Hy2 x Oh7 have a higher level of nitrate reductase activity and protein content than hybrid WF9 x C103, presumably due to genetic differences.