关键词: 烤烟, 上部烟叶, 碳肥, 微生物菌剂, 耐熟性指数, 经济性状, 烟叶品质

Abstract: To improve the usability of upper tobacco leaves，a field experiment was conducted in Xiangxi Autonomous Prefecture，Hunan Province，using flue‑cured tobacco cultivar Yunyan 87 as the test material. Based on conventional fertilization（CK），three treatments were established：additional application of carbon fertilizer（60 kg/ha carbon‑enriched organic water‑soluble fertilizer，T1），combined application of carbon fertilizer and 30 kg/ha Tanmu microbial inoculant（T2），and combined application of carbon fertilizer and 30 kg/ha anti‑continuous cropping agent （T3）. The study investigated the effects of these treatments on the growth，ripening tolerance，economic traits，appearance quality，physical characteristics，chemical composition，and sensory quality of the top six leaves after topping.The results showed that the upper tobacco leaves continued to grow and accumulate dry matter after topping. The leaf length，leaf width，and dry weight increased with the descending leaf position（from top to bottom），whereas their overall acceleration rates as well as the leaf SPAD values exhibited a gradually declining trend. Compared with CK，the T1，T2，and T3 treatments significantly enhanced the length，width，and dry weight of the upper leaves. Specifically，the treatments increased the ripening resistance index of upper leaves by 21.44%，27.44%，and 48.95%；leaf yield by 4.43%，20.21%，and 15.08%；output value by 9.60%，21.22%，and 22.40%；appearance quality index（AQI） by 1.74%，6.03%，and 12.03%；chemical component usability index（CCUI）by 3.80%，1.86%，and 4.28%；smoking quality index（SQI）by 8.24%，6.27%，and 8.91%；and comprehensive quality index（CQI） by 6.05%，3.15%，and 6.15%，respectively. Among them，the T3 treatment demonstrated the most outstanding comprehensive performance in terms of appearance quality，physical properties，chemical composition，and sensory quality，remarkably optimizing the ripening resistance index，yield，output value，and overall leaf quality.In conclusion，under the ecological conditions of the low‑altitude mountainous tobacco‑planting areas in Western Hunan，the combined application of carbon‑enriched organic water‑soluble fertilizer at 60 kg/ha and anti‑continuous cropping agent at 30 kg/ha is an effective strategy to promote the usability of upper tobacco leaves.

Key words: Flue?cured tobacco, Upper tobacco leaves, Carbon fertilizer, Microbial agent, Ripening resistance index, Economic traits, Tobacco leaf quality