Effects of Different Nitrogen Application Rates and the Methods of Remaining Branch Tobacco on the Quality of Flue-cured Tobacco Leaves at Different Leaf Positions

In order to explore the effects of different nitrogen application rates and the methods of remaining branch tobacco on the quality of flue-cured tobacco leaves, the nitrogen application rate was set as 150 kg·hm^-2 (the conventional nitrogen application) and 127.5 kg·hm^-2 (the reduced nitrogen application), while the methods of remaining branch tobacco was 14 pieces per plant (no remaining branch tobacco as the control group), and 16 pieces per plant (remaining two pieces of branch tobacco at the top). The plot experiment of two factors and two levels with four treatments was carried out to study the effects of different nitrogen application rates and the methods of remaining branch tobacco on the physical properties, main chemical components, aroma components, sensory quality and economic traits of flue-cured tobacco leaves. The results showed that: (1) Under the conventional nitrogen application with the remained branch tobacco, the leaf length and single-leaf weight of the upper leaves of flue-cured tobacco were increased, the contents of total sugar and starch were increased, the contents of nicotine, total nitrogen and neutral aroma components were decreased, and the sensory quality was improved, while the leaf length, single-leaf weight, total sugar content and sensory quality of the middle and lower leaves of flue-cured tobacco were decreased. (2) When reducing the nitrogen application with the remained branch tobacco, the leaf length and single-leaf weight of tobacco leaves decreased, the total sugar and starch content decreased, the total nitrogen content increased, and the sensory quality of tobacco leaves decreased. (3) The output value of tobacco leaves was the highest under the conventional nitrogen application without remaining branch tobacco. (4) The average price and sensory quality of tobacco leaves were the highest when reducing the nitrogen application without remaining branch tobacco. In the experiment, the yield of tobacco leaves in the remained branch tobacco increased, while the output value and average price of tobacco leaves decreased. Under the conditions of this experiment, although the method of remaining two pieces of branch tobacco could increase the yield, it couldn't increase the economic benefit and improve the quality of tobacco leaves. Therefore, when the flue-cured tobacco had a slight early flowering phenomenon, it was not necessary to urge the tobacco farmers to reserve the remained branch tobacco.