Abstract

Maize (Zea mays L.) possesses high productive potential, excellent chemical composition and nutritive value, is one of the most important cereals in the world. This work aimed to evaluate the biochemical changes in two cultivars of maize, BRS Planalto and BR5202 Pampa, exposed to different amounts of nitrate and glutamine. The seeds were sown in polyethylene pots acclimated in a greenhouse, where began treatments with nitrate and glutamine at different doses (0.00, 0.10, and 10.00 mM) in five plots a completely randomized statistical design with six replicates. At 30 days, a single collection of material was performed and evaluated: chlorophylls a, b and total, carotenoids, total soluble carbohydrates, starch, sugars reducers and non-reducers, soluble protein and activity of nitrate reductase in leaves and roots. The content of photosynthetic pigments showed differences only between the doses tested. In general, an increase in nitrate concentration and a decrease in starch content, total soluble sugars, reducers and non-reducers for both cultivars. Comparing the effects of different sources and levels of N, the cv. BRS Planalto presented the greatest levels of total soluble proteins in leaves compared to cv. BR5202 Pampa. There was a decline in the activity of RN in both genotypes in response to high doses of N. Overall, there was no significant difference between N sources used. Nitrate reductase activity is greater than the 0.1 mM of nitrogen source, and is greater in leaves in relation to the roots, and glutamine does not inhibit its activity.

Key words: Zea mays L., nitrate reductase, nitrogen fonts.