不同形态氮肥在稻田土壤中的变化规律及对烤烟生长和烟碱含量的影响

试验于2007年在湖南农业大学进行，以烤烟K326为试验材料，围绕稻烟复种土壤的特定条件。开展不同形态氮肥对烤烟生长及品质影响和氮肥在土壤中转化的研究。结果表明：在稻田土壤中硝态氮在整个烤烟大田生长期呈逐渐下降的趋势。施用100％.铵态氮肥的烤烟前中期的生长势较强，而硝态氮与铵态氮各50％的烤烟在收获时茎围、株高、叶面积最大，干物质积累量最大。单一施用硝态氮或铵态氮的烤烟，烟叶中烟碱含量较高，而硝态氮与铵态氮各为50％的烤烟烟叶中烟碱含量较低。采用硝态氮与铵态氮各占50％配比的烤烟对氮肥的利用率较高。

Transformation Law of Different Formal Nitrogen Fertilizer in Paddy Field and Its Effect on Growth and Nicotine Content of Flue-cured Tobacco

In tobacco-rice sequential cropping system, a field experiment on effect of different ratio of NO3ˉ-N to NH4^＋- N on growth and quality of flue-cured tobacco and transformation of nitrogen fertilizer in tobacoo growing season was conducted with K326 as material in Hunan Agricultural University in 2007. The results showed that the content of NO3ˉ- N in the 0-20 cm soil layer showed a decreased trend during the whole growth duration of tobacco. It was beneficial to growth of tobacco in early and middle growing period of flue-cured tobacco in 100% NH4^＋-N treatment. The stem circle, plant height, leaf area and dry matter accumulation of flue-cured tobacco were highest＇in treatment of NO3ˉ-N ： NH4^＋- N=50% ： 50%. The nicotine content in tobacco leaves was higher in treatments of 100% NO3ˉ-N or 100% NH4^＋ -N, while it was lower in treatment of NO3ˉ-N ： NH4^＋-N = 50% ： 50%. Nitrogen use efficiency was higher in treatment of NO3ˉ-N ： NH4^＋ -N=50% ： 50%. It means that the ratio of NO3ˉ-N to NH4^＋ -N was 50% to 50% is befitting to flue-cured tobacco production.