Abstract:

There are some problems in Yongzhou cigar production area, such as unclear suitable planting density and lack of quality control technology of tobacco leaves. To screen the suitable planting density and improve the quality and industrial availability of cigar tobacco in Yongzhou, using the variety ‘Xiangxue-1’ as the material, the effects of planting density on the growth and development of cigar tobacco plants and the quality of tobacco leaves were investigated. Three treatments were set up in the experimental field in Wulipai Town, Shuangpai County, Hunan Province: 23805 plants/hm² (T1), 20835 plants/hm² (T2), and 18525 plants/hm² (T3). A field plot experiment was conducted to study the agronomic traits of the tobacco plants in each treatment and the appearance quality, physical properties, conventional chemical components, sensory quality, and neutral aroma substances of the tobacco leaves after fermentation. The results showed that the plant in treatment T2 had the greatest height, and the appearance quality of the tobacco leaves in this treatment was the best, characterized by strong color intensity, uniform color, fine and flat veins, and the least green and impurities; the effect of planting density on the physical properties of cigar tobacco leaves was mainly manifested as an increase in leaf weight and equilibrium moisture content with the decrease in planting density; the potassium-chlorine ratio, sugar-alkaloid ratio, two-sugar ratio, and nitrogen-alkaloid ratio of the tobacco leaves after fermentation in each treatment increased first and then decreased with the decrease in planting density; treatment T2 had the best sensory quality, with good sweetness and burning properties, less impurities, and grayish-white color; in addition, the total amount of neutral aroma substances in the tobacco leaves increased first and then decreased with the decrease in planting density, and the content of neutral aroma substances in the tobacco leaves of treatment T2 was the highest. In conclusion, 20835 plants/hm² is the suitable planting density for cigar tobacco in Wulipai Town, Shuangpai County, Yongzhou City. Under this density, the tobacco plants grow robustly, the internal and external quality of tobacco leaves is coordinated, and the aroma substances are abundant. The research results can provide technical basis for standardized cultivation of cigar in Yongzhou, and the matching optimization of density, fertilization and topping can be carried out in the future.

Key words: planting density, cigar tobacco, growth and development of tobacco plants, quality of tobacco leaves, agronomic traits, chemical constituents, neutral aroma substances, Yongzhou