Effect Of Nitrogen On Growth, Nutrient Uptake And Distribution, And Quality Of Flue-cured Tobacco Plants

Pot experiment was carried out to study the effect of different nutrient levels and nitrogen forms on the growth, nutrient uptake, partitioning, and potassium flow within flue-cured tobacco plants. The accumulation and partitioning of dry matter and nutrients within flue-cured tobacco plants and relationship between values of nitrate test and contents of nicotin and total nitrogen of leaves were also studied in field conditions in Yunnan Province.Under quartz culture condition, ammonium inhibited the growth of plants and uptake of K+, Ca 2+, Mg2+and H2PO4-, decreased transpiration while increased the content of 8 13C in the leave tissue, and had divergent effects on the plant water-use efficiency at the two nutrient levels. As ratio of NH/ increased in the solutions at both nutrient levels, the amount of K+ transported to shoot via xylem kept stable while that of recycled via phloem ascended within plants.Under field conditions in Yunnan province, flue-cured tobacco accumulated dry matter mainly during the period between the 5th and 9th weeks after transplanting, and about 14.5 gram per plant per day was obtained at this period. The accumulation of nitrogen and potassium mainly took place at the stage between the 5th and 7th weeks after transplanting and the increment of nitrogen and potassium was 0.5 and 0.7 g plant-1 per day-1, respectively. There was obvious export of nitrogen and poatassium in the middle and lower leaves in the later stages, but had divergent direction. The two harvest ways had no obvious effects on the accumulation of dry matter and partitioning of nitrogen and potassium among different plant parts.The midrib base of the first extended leave might be suitable for nitrate test. The values of such test at the time about one week before decapitation had good correlation with contents of nicotin and total nitrogen in tobacco leaves after curing. So values of nitrate test at that time could be a suitable index to predict the quality of later tobacco leaves.