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[Objective] The present paper aimed to investigate the effects of varying light intensities on the photosynthetic, antioxidant and qualitative aspects of cigar leaves. [Method] In the field experiment, 5 treatments were set up using Chuanxue No. 1 as the experimental material( CK: 100% natural light intensity; Tl: 85% natural light intensity; T2: 70% natural light intensity; T3: 55% natural light intensity; T4: 40% natural light intensity). [Result]Under different light intensities, the contents of chlorophyll and carotenoid in cigar leaves increased initially and then decreased; The contents of MDA and H202 in cigar leaves increased slowly; The activities of SOD and POD increased initially and then decreased; And the activity of CAT in cigar leaves increased initially and then decreased. Cigar leaves' photosynthetic pigment content, intercellular CO2 concentration, water use efficiency, and antioxidant enzyme activity increased as light intensity decreased, while MDA content, H202 content, net photosynthetic rate, stomata! conductance, and transpiration rate decreased. However, a low-light-intensity environment did not promote the enhancement of cigar leaves' photosynthetic and antioxidant characteristics. The levels of total sugar, total nitrogen, and nicotine in cigar leaves increased at first and subsequently fell as light intensity increased; Chlorine and potassium increased, and reducing sugar, the sugar-alkali ratio, the nitrogen-alkali ratio, and the two-sugar ratio decreased. With insufficient light intensity, the coordination of chemical components in cigar leaves was weak, which was detrimental to cigar leaf quality. [ Conclusion] Moderate low light ( 55 % - 70% natural light intensity) was found to be beneficial in increasing the content of photosynthetic pigment, promoting light energy absorption, maintaining stable photosynthetic characteristics, benefiting cigar leaf growth and development, and increasing the activity of antioxidant enzymes all at the same time. Cigar leaf membrane lipid peroxidation damage was minimized, antioxidant properties were strengthened, and the chemical composition of cigar leaves was well coordinated, all of which aided in the production of cigar quality. [ABSTRACT FROM AUTHOR]

In order to screen new varieties of flue-cured tobacco suitable for the ecological environment of Xunyi tobacco area, and to provide a basis for the production and utilization of high-quality tobacco leaves, we used Qinyan 99 as the control in 2022, which was the main cultivar in Xunyi tobacco growing area. The differences in field growth period, botanical properties, agronomic properties, field natural incidence rate, economic properties, conventional chemical composition content, appearance quality and sensory quality of flue-cured tobacco were compared among Qinyan 99, Qinyan 96, Qinyan 201, Zhongyan 100, Yuyan 13 and Y2001. Results showed that there was little difference in the growth period among different tobacco varieties, ranging from 142 to 155 days; Qinyan 96 and Y2001 had strong growth potential in the field, strong disease resistance, high yield, output value and the proportion of medium to high grade tobacco. They had excellent appearance and sensory quality, and good coordination of chemical components, which could be used as reserve varieties for promotion and planting in Xunyi tobacco area. [ABSTRACT FROM AUTHOR]