Effects of Nitrogen Application and Number of Leaves Retained on the Yield and Quality of Yellow Sun-cured Tobacco

【Objective】The purpose was to study the effects of nitrogen application and leaves retention on the yield and quality of yellow sun-cured tobacco.【Method】Using the yellow sun-cured tobacco variety 'Cunsanpi' as the material, a split-area experimental design was adopted, and the two-factor experiments of nitrogen application of 82.5, 97.5, 112.5 and 127.5 kg/hm2 and the number of leaves retained of 16, 19 and 22 leaves/plant (Total 12 treatments) were conducted to studyits effects on the agronomic traits, yield, average price, yield value and appearance quality of yellow sun-cured tobacco.【Result】The results showed that increased nitrogen fertilization could promote the growth of tobacco plant and increase nitrogen metabolism, and at the same time, it was conducive to the improvement of agronomic traits such as stem girth, pitch, leaf length and width, and leaf area. Within a certain range of nitrogen application, tobacco yield increased with the increase in the number of leaves retained. Within a certain range of the number of leaves, the tobacco yield varied with the nitrogen application. When the number of leaves was 16 leaves/plant and 22 leaves/plant, the tobacco yield showed an upward trend with the increase of nitrogen application. When the number of retained leaves was 19 leaves/plant and the applied nitrogen ranged from 82.5 kg/hm2 to 112.5 kg/hm2, the tobacco yield increased with the increase of applied nitrogen. From the same level of nitrogen application of different number of leaves of tobacco leaf yield changes, when the nitrogen application of 127.5 kg/hm2, the tobacco yield with the increase in the number of leaves of tobacco leaf is a downward trend. When the nitrogen application was 112.5 kg/hm2 and the number of retained leaves was 19 leaves/plant, the tobacco leaf yield value was the highest, which was 54 567.00 yuan/hm2. When the nitrogen applications were 82.5 kg/hm2 and 97.5 kg/hm2, the tobacco leaf yield value increased with the increase of the number of retained leaves. From the point of view of the average price of tobacco with different number of leaves of the same nitrogen application, when the nitrogen application was 82.5 kg/hm2 and 127.5 kg/hm2, the average price of tobacco showed a decreasing trend with the increase of the number of leaves of the same application. When the N application was 97.5 kg/hm2, the average price of tobacco leaf increased with the increase of the number of retained leaves. When the nitrogen application was 112.5 kg/hm2, the average price of tobacco leaf increased and then decreased with the number of leaves retained, and was higher in the treatment with 19 leaves/plant. The appearance quality of tobacco leaf was better in three treatments: 82.5 kg/hm2 of nitrogen application, 16 leaves/plant; 97.5 kg/hm2 of nitrogen application, 22 leaves/plant and 127.5 kg/hm2 of nitrogen application, 19 leaves/plant.【Conclusion】Under the conventional cultivation condition of ensuring density of 15 150 plants/hm2, applying nitrogen at 112.5 kg/hm2 and retaining leaves at 19 leaves/plant, the yellow sun-cured tobacco variety 'Cunsanpi' could obtain better economic benefits in Fuquan, Guizhou.