Effects of Chemical Fertilizer Reduction Combined with Biochars on Yield, Quality and Main Chemical Components of Flue-cured Tobacco

【Objective】The effects of combined application of chemical fertilizer and biochar on the yield, quality, and main chemical components of flue-cured tobacco were discussed to provide a theoretical basis for the chemical fertilizer reduction application.【Method】Tobacco variety Yunyan 85 was taken as the test material, five treatments of chemical fertilizer and biochar were set up, CK (control): conventional fertilizer; T1: conventional fertilizer+180 kg/hm2 biochars; T2: conventional fertilizer+360 kg/hm2 biochars; T3: 80% base chemical fertilizer+180 kg/hm2 biochars; T3: 80% base chemical fertilizer+360 kg/hm2 biochars. Three repeated randomized block experiments were used in the field. Representative tobacco plants were selected to measure their agronomic traits and SPAD value after transplanting 63 d (topping stage). After curing, the yield and output value of flue-cured tobacco in each treatment were investigated, the main chemical components and sensory quality evaluation were analyzed.【Result】Application biochar promoted the growth and development of flue-cured tobacco, and significantly increased the plant height, maximum leaf area, and stem girth. Chemical fertilizer reduction combined with biochar were not significantly reduced the plant height, maximum leaf area, and stem girth, but the SPAD values in the middle leaves were significantly lower. The yield and output value of treatments were T2>T4>T3>T1>CK. The exorbitant value of soil C/N ratio was beneficial for improving the yield and output value of flue-cured tobacco.The content of total sugar and reducing sugar in tobacco leaves under all treatments with over 26% and 22%, respectively, exceeded the standard of high quality tobacco leaf, and the content of total nitrogen, nicotine, potassium, nitrogen-nicotine ratio and potassium-chloride ratio were all within the appropriate range, respectively. Tabcco leaves under the T1 and CK treatments had more harmonious chemical components. With increasing soil C/N ratio value, contents of total sugar, reducing sugar and potassium of flue-cured tobacco were increased, but decreased the contents of total nitrogen and nicotine. A suitable amount of application biochar resulted in coordination of tabacco leaf chemical components. However, excessive application biochar reduced quality of tobacco leaves. The sensory quality scores in T1 treatment were the higher (66.10), then in CK and T3 treatments (61.11), and the lowest in T2 treatment (59.86).【Conclusion】T