Effects Of Different Amount And Methods Of Nitrogen On The Growth And Quality Of Yellow Sun-Cured Tobacco

Field experiments were conducted during 2004-2005 to study the effects of different amount and methods of nitrogen on nutrents change in the soil, biological characteristic, accumulation of the dry matter, nitrogen, phosphorus and potassium, physiological characteristic, carbon and nitrogen metabolite of cutters and upper-leaf, yield and quality of the yellow sun-cured tobacco of Ningxiang. The results were as follows:1. During the whole growing period, the content of available N went lower without nitrogen, but with nitrogen fertilizer it goes higher and then lower again. After fertilizing phosphorus and potassium fertilizer, the contents of available P and available K reached the highest points on the 30th day after planting. During the 30th to 45th days the contents dropped quickly, but later slowly. As the amount of nitrogen went higher, the content of available N went higher too, but the contents of available P and available K decreased. At the same level of nitrogen, as the rates of nitrogen dressing increased, while the contents of available P and available K decreased. In certain scale, as the rates of nitrogen dressing increased, the utilization rate of nitrogen fertilizer was higher. And when the amount of nitrogen exceeded 180kg/hm~2, the utilization rate began to fall. With the increased of N dressing rates, the utilization rate of nitrogen fertilizer went up obviously.2. The height, stem girth and available leaves of the plant increased with the increased of the amount of nitrogen. And so did the squares of cutters and upper-leaves, inside the scale of 0～180kg/hm~2. The height, stem girth and internode length rose gradually with the increased of N dressing rates. So did the amount of available leaves and the squares of cutters and upper-leaves.3. During the whole growing period, the dry matter of yellow sun-cured tobacco presented a slow-fast-slow increased trend. But the accumulative velocity of the dry matter was different in different period. The accumulation and accumulative velocity of the dry matter increased with the raise of N application and dressing rates. But the accumulation dropped little in later stage when the amount of nitrogen exceeded 180kg/hm~2. The accumulation of N, P, K increased quickly in early...