Influence Of Nitrogen-Dressing Amount On Carbohydrate And Nitrogen Metabo Lism, Leaf Yield And Quailty At Later Growth Stage Of Flue-Cured Tobacco

Pot and field experiments conducted to study the influence of nitrogen-dressing amount on physiologic characteristic and secondary metabolism of lower-leaf and upper-leaf at later growth stage of flue-cured tobacco (NC89) from 2002-2004 in China Tobacco Training Center for Professional Technicians and Que-Shan county. The following results were obtained through analysising (or measurring) the carbohydrate and nitrogen accumulation , changes of C/N ratio in different position leaves after topping, yield and quality of tobacco leaf after harvested in this paper. 1. Nitrogen-dressing amount had a great effect on physiological process of lower-leaf after topping whether top-dressed once or twice. Under once, compared with no topdressing, with the increasing of topdressing amount, the nitrate reductase activity and free amino acid and ammonium nitrogen content of lower-leaf decreased, till ripened harvest, There was a positive proportion respectively between NR activity and ammonium nitrogen to topdressing amount. Before topdressing amount reached percent 30, along with the increasing of topdressing amount, the invertase activity and the chlorophyll content augmented, in excess of percent 30, both were on the contrary, at the same nitrogen-dressing amount, compared twice with once, the ammonium nitrogen and nitrate reductase activity was lower, and the effect of dressing on the nitrate reductase only could keep one week after topping. The free amino acid reached peak when nitrogen-dressing amount occupy percent 30 of total nitrogen amount.The influence of nitrogen-dressing amount on physiological process of upper-leaf was complicated. Dressed once, the nitrate reductase activity was the lowest under percent 30 nitrogen-dressing amount, when top nitrogen amount occupy percent 30 of total nitrogen amount, it was a bit higher than no topdressing treatment. Free amino acid content was the highest before 94th days after transplanting under percent 30 nitrogen-dressing amount. After that, it increased with the increase of dressing amount,in addition, the period of peak under percent 45 dressing amount postponed about five days than other treatment, ammonium nitrogen and dressing amount had a positive proportion relationships before 94th days after transplanting, since that, only percent 45 dressing amount was a little more than no dressing. The chlorophyll content had evident distinction between different nitrogen-dressing amount. Percent 45 dressing amount was the highest all along. At the same nitrogen-dressing amount, compared twice with once, the difference was that the nitrate reductase activity increase was more disciplinarian.2. Secondary metabolism took on a tendency increased in lower-leaf and a tendency decreased in upper-leaf with the increasing of nitrogen-dressing amount. Phenylalanine ammonia-lyase activity and Flavonoids content of lower-leaf were 45%<30%<0< 15% in a week after topping, subsequently, they were 45%<0<15%<30%, the total hydroxybenzene of lower-leaf was 45%<0<15%<30% at all times, compared twice with once, the three were lower at the same time. From 84th to 94th day after transplanting, phenylalanine ammonia-lyase activity of upper-leaf was 45%%<0<15%< 30% under once dressing and 45%<0<15%<30% under twice dressing, later, they were both 0<45%<15%<30%, the flavonoids content of upper-leaf was 45%<0<15%<30% all along, the total hydroxybenzene reduced with the increasing of nitrogen-dressing amount, but it was higher than no dressing when top nitrogen amount occupy percent 30 of the total N fertilizer after 94th day of transplanting.3. Nitrogen-dressing could improve total nitrogen and nitrogen accumulation of different positional leaves in different period. Once topdressing, with the increasing of nitrogen-dressing amount, the total nitrogen of low-lying 12 laminas increased, 12th-16th lamina of percent 30 dressing amount and upper 4 laminas of no topdressing were the highest at topping. At the same dressing amount, on the whole the effect of once topdressing on different positional laminas was no difference, the effect of twice topdressing on upper-leaf was more distinct. Nitrogen-dressing could shrink the fluctuate of nitrogen accumulation in 20 days after topping, compared with no dressing, the increased nitrogen accumulation of different positional laminas under percent 30 dressing amount was equal, and the increased nitrogen accumulation of low-lying laminas was less, and upper laminas was much under percent 45 dressing amount, there was a great difference between low-lying laminas and upper laminas, increased nitrogen accumulation low-lying laminas was lower twice topdressing than once topdressing. These results indicated that percent 30 dressing amount and once topdressing was the best appropriate. Nitrogen-dressing could improved C accumula- tion, but couldn't alter total C. with the increasing of dressing amount, C accumulation improved, C accumulation of ripened leaves had linear relationship, Nitrogen-dressing had different effect on different laminas. Once topdressing, the increased nitrogen accumulation of low-lying laminas was much, raised 19%, 25.8% respectively than no dressing, twice topdressing, the increased nitrogen accumulation of upper laminas was much, raised 29.2%, 30.7% respectively than no dressing, and low-lying laminas was less, indeed reduced.4. From topping to ripened harvest, C/N was influenced greatly by nitrogen-dressing...