[Effects of forms and application rate of nitrogen fertilizer on yield and qualities of tobacco in southeast Tibet].

Field experiments in southeast Tibet were conducted to study the effect of nitrogenous fertilizer supply and its forms on tobacco. The result indicated that the yield, production value, and the contents of nicotine, potassium oxide and total nitrogen of the cured leaves were positively correlated to the amount of N application, and significantly and negatively correlated to the percentage of superior-medium class leaves of tobacco and contents of deoxidize sugar. The highest yield and best quality of tobacco were obtained by applying 75 kg N per hectare. Inorganic nitrogenous fertilizer could significantly improve the yield and quality of tobacco, compared with organic nitrogenous fertilizer. Although there was no significant difference among ammonium N, nitrate N and nitrate-ammonium N application, the effects of ammonium N, nitrate N, and nitrate-ammoniun N application were significantly higher than that of urea application. The effect of ammoniun N application on tobacco yield and quality was better than that of nitrate N application, and the important reason was the great difference in the process of absorption and assimilation of ammoniun N and nitrate N.