Effect Of Nitrogen And Mineralization Of Soil Nitrogen On Growth And Quality Of Flue-Cured Tobacco

Higher nicotine content of upper leaf results lower usability of tobacco leaf in industry, for this problem, we designed field experiments of different nitrogen fertilizer levels, mineralization experiment of organic nitrogen, isotope label experiments and investigated agricultural practice of peasants. Through these experiments, we studied dynamic change of inorganic nitrogen and mineralization rule of organic nitrogen in soil, analyzed accumulation and distribution of nitrogen from different origin in plant by isotope label experiments, and studied the influence of nitrogen supply on nicotine content of upper leaf of flue-cured tobacco, researched agricultural practice of peasants. The main research results as follows:1.The application of inorganic nitrogen fertilizer could raise the content of inorganic nitrogen in the soil depth of 0-20cm and 20-40cm layer only last a short time; the content of inorganic nitrogen in the soil depth of 20-40cm layer was affected slightly by nitrogen fertilizer and was lower than that in the soil depth of 0-20cm layer at the same period; the content of inorganic nitrogen in the soil depth of 0-40cm layer at Fenggang field was higher than those of Jinsha at latter growth stage.2.The nitrogen mineralized in the field of Fenggang was obviously higher than that of Jinsha at growth period, the nitrogen mineralized was very little in the field of Jinsha in 4 weeks after transplanting and revealed the trend of descent, then it increased since 4th week after transplanting, but it was still obviously less than that of Fenggang. The seemingly nitrogen mineralized was 4.9kg/hm2 after topping at Jinsha, 39.9kg/hm2 at Fenggang, it was about 8 times of that of Jinsha. At the ripe stage of upper leaf, the seemingly nitrogen mineralized was above 10kg/hm2in the field of Fenggang, but it was below Okg/hm2 in the field of Jinsha.3.The accumulation and distribution of nitrogen from different origin in plantwas obviously affected by the content of organic matter in soil. The nitrogen accumulated in tobacco plant was mainly from soil nitrogen at the whole growth period at Fenggang, and fertilizer nitrogen accumulated was little, the nitrogen accumulated in plant and leaves of different position was mainly from soil nitrogen at latter stage at Fenggang; and the soil nitrogen accumulated in plant and leaves of different position was increased with the progress of growth, but the fertilizer nitrogen accumulated was little all time; the influence of soil mtrogen on leaves of different position was upper leaf > middle leaf> lower leaf, for fertilizer nitrogen, it was lower leaf > middle leaf> upper leaf; the soil nitrogen accumulated in leaves was increased with the enhance of leaf position, but it was contrary for fertilizer nitrogen. The nitrogen accumulated in tobacco plant was mainly from fertilizer nitrogen at Jinsha; the fertilizer nitrogen accumulated in plant and leaves of different position at latter stage was more than soil nitrogen at Jinsha, the influence of soil nitrogen on leaves of different position was upper leaf > middle leaf > lower leaf, for fertilizer nitrogen, it was lower leaf> middle leaf > upper leaf.4.The area of leaves, stem perimeter, plant height of flue-cured tobacco was enhanced with the increase of nitrogen fertilizer, but it was not obvious for the treatments of high nitrogen fertilizer. The accumulation of dry matter and nitrogen was mainly completed at period of rapid growth; the distribution of dry matter in every organ was affected slightly by nitrogen fertilizer levels, and the final proportion of dry matter of root, stem, leaves in tobacco plant was 12-21%, 23-26% and 54-65%; the distribution of nitrogen in every organ was affected slightly by nitrogen fertilizer levels, and the final proportion of nitrogen accumulated in root, stem, and leaves was 12-19%, 20-26% and 58-67%.5.the area of upper leaf of every nitrogen fertilizer level at Jinsha was higher than those of Fenggang, but it was contrary for the treatment of no nitrogen fertilizer; the mt...