Abstract:

To optimize the fertilization practice of flue-cured tobacco under flood irrigation condition, increase the planting benefit and improve the quality, different amount of water-soluble humic acid was added in the form of basal fertilizer to study the effects on yield, conventional chemical composition, aromatic substances and sensory evaluation of flue-cured tobacco. Compared with conventional fertilization, the yield, output value and net benefit were increased by 12.35%, 17.16% and 9.31% respectively when the adding amount of humic acid was 900 kg/hm². The adding amount of humic acid was in accordance with quadratic correlation on yield, output value and net benefit, the optimal amount corresponding to the maximum yield, output value and net benefit was 924.56, 935.94 and 706.46 kg/hm², respectively. The addition of humic acid increased the nicotine content of flue-cured tobacco by 21.53%-43.06%, and reduced the chloride content by 24.80%-55.20%, and significantly improved the harmony of chemical compositions, increased the content of ketone, alcohol, acid, ester (lactone) and total amount of aromatic substances, and reduced the ratio of neophytadiene to other aromatic substances in tobacco leaves to different degrees. The adding of humic acid was beneficial to increase the aroma volume of unblended cigarette, adding burnt-sweet or hay-sweet flavor, but the adding amount higher than 900 kg/hm² could lead to lower sensory quality. Adding 706-900 kg/hm² water-soluble humic acid could increase the planting benefit and improve the quality of flue-cured tobacco under flood irrigation condition, which has a good value for promotion in flue-cured tobacco cultivation practice.

Key words: humic acid, flood irrigation, flue-cured tobacco, economic benefit, quality