Effects Of Nitrogen Fertilizer And Nitrogen/Potassium Ratio On Chemical Quality Of Different Varieties Flue-cured Tobacco In ZhuZhou

The test was conducted in Huotian, Yaobei and Jieshou of Chaling county, using "Yunyan97","Yunyan87" and "K326" as material. By measuring the content of nitrogen, potassium, nicotine, reducing sugar, starch and total sugar in those flue-cured tobaccos with C3F level, calculating their sugar/nicotine ratio, nitrogen/nicotine ratio, potassium/chlorine ratio and the gap between total sugar and reducing sugar, The tobaccos chemical compositions and chemical harmony were analyzed and compared in different nitrogen fertilizer levels (150,165,180, and195kg·hm-2) as well as different N/K ratios (1:1.5,1:2.0,1:2.5and1:3.0), which to provide theoretical basis and technical guidance for optimizing formulated fertilization and improving the quality of flue-cured tobacco. The results were as follows:(1)The treatments of different nitrogen levels had significant influence on three flue-cured tobaccos chemical compositions and chemical harmony. The content of N, K, nicotine and starch and potassium/chlorine ratio, the gap between total sugar and reducing sugar in Yunyan97leaves at195kg·hm-2of nitrogen level were significantly higher than other levels. The content of reducing sugar and total sugar at the165kg-hm-2of N level were significantly higher and the sugar-nicotine ratio, nitrogen-nicotine ratio under the150kg·hm-2of N level were significantly higher than other treatments. Under195kg·hm-2of nitrogen level, the content of N, nicotine and starch in Yunyan87leaves were significantly higher than other levels. The content of K, total sugar and the gap between total sugar and reducing sugar at the165kg·hm-2of N level were highest and the content of reducing sugar, the sugar/nicotine ratio, nitrogen/nicotine ratio and potassium/chlorine ratio at the150kg·hm-2of N level were significantly higher than other treatments. The influence of N level on the chemical compositions and harmony of K326was little.(2) The chemical composition and harmony of the three flue-cured tobaccos were influenced differently by N/K ratios. The results showed that the different N/K ratios had significant influence on the content of nicotine, sugar-nicotine ratio and nitrogen-nicotine ratio for Yunyan97, as well as the content of N, K, reducing sugar, starch and K/Cl, while it had little influence on the content of total sugar, the gap between total sugars and reducing sugar. For Yunyan87, the N/K had little influence on the content of starch in tobacco leaf. It influenced the content of K and K/Cl, nitrogen-nicotine ratio, the gap between total sugar and reducing sugar significantly, but merely to a smaller degree. The N/K ratio had larger influence on the content of N, nicotine, reducing sugar, total sugar and the sugar-nicotine ratio. For K326, the N/K had little influence on the content of K, reducing sugar, nicotine and sugar-nicotine ratio, the gap between total sugar and reducing sugar.(3) With the increase of N level, the comprehensive quality of Yunyan97was increasing significantly. The quality of K326also showed a increasing trend with the increase of the N level. Under the lower N level, the quality of Yunyan87was higher, it showed a decreasing trend with the increase of N level, but the trend did not reach the level of significant difference. Besides, we found that the quality of Yunyan97was significantly increasing, with the increase of N/K, the quality of Yunyan87changed a lot with the increase of N/K. For K326, there was no significant difference under different N/K treatments.In conclusion, under the high nitrogen level (180and195kg·hm-2of the nitrogen application rate) and high N/K ratio (1:(2.5-3)), the comprehensive quality of tobacco was best.