重茬烤烟的烟碱积累和分配规律研究

烟叶生产中普遍存在重茬现象, 连续重茬对烟株发育和烟叶品质带来不良影响。为了给烟叶生产中合理选择种植方式提供理论依据, 并为今后深入研究烤烟重茬的障碍机理和合理解决烤烟重茬问题奠定基础,本试验在黑龙江省烤烟重茬较普遍的肇州县永胜乡, 采用田间小区试验, 研究了自然肥力和常规施肥条件下不同重茬年限烤烟的烟碱含量、积累与分配的关系。结果表明, 重茬烤烟移栽后3~11 周为烟碱缓慢积累期,11~17 周为快速积累期, 比新茬两个积累期晚2 周。收获时新茬烟碱积累量达到87.56 kg·hm^-2(自然肥力)和128.31 kg·hm^-2(常规施肥), 相同肥力下重茬烤烟积累量随重茬年限增加而显著降低。重茬烤烟根茎内烟碱分配比例随重茬年限增加而降低, 叶片中分配比例增加, 中下部烘烤烟叶烟碱含量升高, 上部叶烟碱含量降低;重茬烤烟烟碱的变化规律不因土壤肥力改变而发生变化。烤烟重茬栽培5 年后, 所有部位烟叶均未达到卷烟厂规定的优质烟叶烟碱含量标准。综合分析认为, 烤烟重茬栽培后, 烟碱积累、分配及烘烤烟叶中烟碱含量均会发生显著变化, 使烤烟烟叶质量降低, 重茬栽培不宜超过5 年。

Nicotine accumulation and distribution in tobacco under continuous cropping

Continuous cropping of tobacco affects the growth and quality of flue-cured tobacco. This study investigated the effect of continuous tobacco cultivation on the accumulation and distribution of nicotine with aim of developing suitable cultivation methods. The study also discussed the theories and obstacles of continuous tobacco production. For that purpose, experiments were conducted in natural and fertilized soils with different periods (0, 3 and 5 years) of continuous cultivation in Yongsheng Town, Zhaozhou County, and the relationships among nicotine content, accumulation and distribution in flue-cured tobacco were analyzed. The results showed that nicotine gradually accumulated during the first 3~11 weeks after transplanting with the 3-year and 5-year continuous cropping under the natural fertility. After 11~17 weeks of transplanting, nicotine accumulated very rapidly in the 3-year and 5-year continuous cropping under the natural fertility. Nicotine accumulation for 0-year continuous cropped tobacco under the natural fertility was two weeks earlier, compared with that for the 3-year and 5-year continuous cropped tobacco. Nicotine accumulation was respectively 87.56 kg·hm^-2, 64.79 kg·hm^-2, 38.35 kg·hm^-2 under natural fertility, and 128.31 kg·hm^-2, 90.09 kg·hm^-2, 53.71 kg·hm^-2 under fertilization in the 0-year, 3-year and 5-year continuous cropped tobaccos at leaf harvest, approximately 17 weeks after transplanting. Continuous cultivation decreased nicotine adsorption and accumulation in both fertilized and natural soils. While nicotine distribution in roots and stems decreased with increasing period of continuous cropping, it increased in leaves with increasing period of continuous cropping in both natural and fertilized fields. The contents of nicotine in the continuous cropping systems were: 3-year > 5-year > 0-year, 3-year > 0-year > 5-year and 0-year > 3-year > 5-year in the lower, middle and upper leaves of tobacco, respectively. The nicotine content of leaves in different positions of plant of tobacco continuously cropped for 5 years was not up to the scratch of high quality tobacco. Continuous tobacco cultivation severely affected nicotine accumulation and distribution, and also the quality of flue-cured tobacco.