Nitrogen Metabolism and Fresh Weight Production of Crambe under Different Nitrate Doses and Ph Values in Nutrient Solution

摘要

The aim of this work was to evaluate the effects of variation in nitrate (NO3 -N) supply and different - pH levels in nutrient solution on several aspects of nitrogen metabolism and the fresh weight production of crambe (Crambe abyssinica Hochst. ex. R.E. Fries). In the first experiment, crambe plants were submitted to crescent NO3 -N doses (0.2; 2.0; and 4.0 mM) in hydroponic system located in a greenhouse. The second - experiment was conducted with crambe plants cultivated under different pH values (5.0; 5.5; 6.0; and 6.5) also in nutrient solution at the same conditions. In both experiments the harvest was performed at the end of vegetative stage. Plants under pH 5.5 showed a high flux of NO3 -N reduction and assimilation. The results - obtained also indicate a key role of stem in NO3 -N storage in crambe, probably as part of vacuolar pool. - A significant increase in fresh weight of stem and leaves was obtained in plants submitted to 2 mM NO3 -N and - under pH 6.5. These results indicates a possible way to reduce the utilization of high NO3 -N doses for crambe - production and the necessity of soil adjustment, aiming the use of the culture for ruminant feed.