Studies On Physiological Character For High Nitrogen Efficient Utilization In Maize

In this study, 6 NUE (N utilization efficiency) and 6 NUIE (N utilization inefficiency) varieties of sweet maize, waxy maize, common maize were conducted to study their differences in N accumulation and dry matter accumulation. The enzyme differences of N metabolism of different maize varieties was indicated, and the effect of different N nutrition levels on key enzymes activities of nitrogen and the yield and quality of maize was revealed, contributing a lot to the improvement of quality and culture with higher yield and better quality of maize. The main results were as follows:1. N accumulation dynamics in different varieties was a S curve. There were no significant differences in N efficiency of different varieties of maize at the jointing stage. From jointing stage to silking stage, N accumulation in NE was significantly higher than that in NIE. With the jointing stage, leaf area index between NE and NIE had no significant differences, from 12th leaf stage to maturity stage. Leaf area index in NE was significantly higher than that in NIE. The tendency of common maize, sweet, waxy maize was similar. Different maize in leaf area index reached maximum at silking stage. Under the same split plot of N topdressing treatments, dry matter accumulation in NE was the highest in the whole growth period. Compared between different kinds of varieties, the accumulation of dry matter of common maize was highest, secondly it is waxy maize, the sweet maize was the lowest.2. NR, GS, GDH activity of all varieties throughout the whole period showed a single peak curve. With the increaseing split plot of N topdressing treatments, the key enzyme activity of N metabolism increased. Sweet maize, waxy maize reached a peak at the jointing stage, while common reached in 12th leaf stage. At the jointing stage under the same nitrogen level, the key enzyme activity of N metabolism in nitrogen efficient varieties was significantly higher than that of low nitrogen species. Common maize, sweet maize and waxy maize showed the same trend.3. At the filling stage, the key enzyme activity of N metabolism of all varieties in the leaf located near the ear fell presented the downward trend. In the performance of the total N for the jointing stage conditions, the NE varieties of GS activity was significantly higher than NIE species, under the same fertility condition. At grain filling stage, GS activity showed a single peak curve, the peak value periods appear after 28 days at the silking stage. Under different nitrogen treatments, with N nutrition increasing grain GS activity increased, while at the same nitrogen treatment, NIE varieties of grain GS activity were significantly higher than NIE varieties. The peak value periods of GDH activity appear after 40 days in the silking. Under the same N level, nitrogen to deal with significant differences between, and under the same N level, NE varieties at grain filling stage of GDH activity was significantly higher than that of NIE varieties.4. With the increase of nitrogen fertilizer application, while the grain of maize starch, protein content could be improved obviously, total soluble sugar increased a little and had no significant difference. The impact of nitrogen fertilizer on protein content of each component was different, on different gliadin and glutenin storage proteins belonged to an appropriate number of N, with the increase in nitrogen application rate of different genotypes of maize grain ethanol-soluble glutenin content of protein and a significant increased, while globulin and albumin had no significant effect.5. The analysis of different varieties of the key enzyme activity showed that NR activity, GS activity had highly significant positive correlation with leaf nitrogen content. At the filling stage, NE and fresh yield, NE and yield of mature and he key enzyme activity. GDH activity had a very significant positive correlation with leaf nitrogen content only in the jointing stage and the filling stage. GDH activity had a significant positive correlation with fresh yield at the jointing stage and the 12th leaf stage, but there was no significant correlation in the mature stage.