Objective The aim of this study is to clarify the impact of one-time harvesting of middle and upper tobacco leaves on the quality and industrial usability of upper flue-cured tobacco leaves.

Method With 'Guangdong Tobacco 212' as the experimental material, a completely randomized block experiment was carried out in Nanxiong City, Guangdong Province, focusing on three factors: the presence or absence of stems, maturity, and the number of leaves harvested at once. The appearance quality, chemical composition, physical properties, and sensory quality of the flue-cured tobacco leaves were identified, evaluated, and statistically analyzed.

Result Different harvesting methods had a significant impact on the appearance quality, physical properties, and chemical composition of upper tobacco leaves. The harvesting method with stems had high comprehensive evaluation scores for maturity, identity, and appearance quality of flue-cured tobacco leaves, with maturity, identity, and appearance quality scores increasing by 8.33%, 6.25%, and 2.64%, respectively. There was a significant difference in the equilibrium moisture content of tobacco leaves harvested with stems, with an decrease of 6.13%; The total alkaloid and total nitrogen contents in the upper leaves harvested with stems were significantly lower than those harvested without stems, with reductions of 11.98% and 14.42%, respectively. Starch content was significantly higher than that harvested without stems. The chemical composition score of tobacco leaves harvested with stems was significantly higher than that harvested without stems, increasing by 3.61%, and the chemical composition coordination improved. The quality data of flue-cured tobacco leaves under different harvesting maturity treatments showed that the color score and total score of tobacco leaves harvested when 100% maturity level were higher than those harvested when 80% maturity level, with an increase of 1.41% and 2.23%, respectively; The comprehensive evaluation score of the chemical composition of tobacco leaves harvested when 80% maturity level was higher than that of harvested when 100% maturity level. The quality data of flue-cured tobacco leaves with different treatments of one-time harvesting leaves showed that the comprehensive evaluation score of chemical composition of tobacco leaves with 10 pieces of one-time harvesting leaves was the highest, which was 3.21% higher than that of 6 upper leaves. Quality data one-time harvesting of flue-cured tobacco leaves under different treatments showed that the comprehensive evaluation score of the chemical composition of tobacco leaves treated with 10 leaves collected at once was the highest, which was 3.21% higher than that of 6 upper tobacco leaves with stems.

Conclusion Therefore, the harvesting method of "harvesting 10 upper tobacco leaves with stems at one time when 80% maturity level" yields the highest comprehensive evaluation score for the quality of the upper roasted tobacco leaves, which was the best harvesting mode in the local tobacco area.