Influence of nitrogen nutrition on growth, nitrate reductase and nitrite reductase of seedlings of maize (Zea mays L. cv LG12)

Abstract

The effects of three N levels on etiolated and green leaves of Zea mays were studied. It was found that the activity of both nitrate reductase (NR) and nitrite reductase (NiR) was affected, although differently, and the former showed higher sensitivity. NR activity rose with N increase, but different values in the three groups of seedlings appeared only after the second day in light/darkness; both nitrate and light were necessary to obtain a high level of activity. The interference of the N supply on NiR was observed only in seedlings grown in light. Seedling growth was also affected and the leaf weight appeared to correspond with the level of N supplied. In seedlings grown in darkness, the nitrate accumulated in the leaf increased with the decrease of the supplied N, whereas in light/darkness the opposite occurred. Different values of the leaf protein in the three seedling groups appeared only under light/dark and after the second day and by SDS‐PAGE they were found to be quantitative.