Changes of Carbohydrate Content in Flue-cured Tobacco Leaves with Different Levels of Nitrogen Applied during Growth Phase

In this paper changes of carbohydrate content in two tobacco cultivars leaves (K326 and HD) with three different levels of nitrogen applied was studied during field growth phase. Total soluble sugar increased gradually in two cultivars leaves with different nitrogen levels and different stalk positions after tobacco seeds being transplanted. It reached a maximal content on the 72nd, and then decreased rapidly. There was a stable stage from the 82nd to the mature. Changes of reducing sugar content in two cultivar's leaves are the same with total soluble sugar content. The maximal starch content in two cultivars appears in middle and upper leaf on the 42nd, but on the 32nd in the lower leaf after being transplanted, which decreased a little on the 60th, then increased rapidly. There is a slow increasing after the 72nd day. The starch reached the maximal content in two cultivars' leaves on the 82nd, and then decreased with the leaf dextral maturity. There are no significance effects on the contents of total soluble sugar, reducing sugar and starch with different levels of nitrogen applied.