施氮水平对烤烟根冠平衡及氮素积累与分配的影响

在盆栽条件下，设不施氮（CK），每株施N 5.45g（N1）和8.18g（N2）3个施氮水平，运用15N示踪技术，研究了不同施氮量条件下烤烟根冠平衡及氮素在不同器官间的积累与分配。结果表明，移栽至打顶期烤烟地上部干物质累积量随施氮量增加而增加，根系干物质积累量以N1处理最高；打顶至成熟期地上部干物质累积量N1处理最高，根系干物质积累量随施氮量增加而增加。打顶期根冠比随施氮量增加而降低，成熟期根冠比随施氮量增加而提高。打顶至成熟期烟株氮素积累量以N1处理最高；期间N1处理各器官均有一定氮素积累，而 N2处理和CK下部叶及中部叶有一定量的氮素输出。打顶期氮素在根系中的分配比例随施氮量增加而降低。随施氮量增加，烤烟积累的氮素中来自肥料氮的比例增加；积累的肥料氮中来自基肥氮的量增加。在本试验条件下，施氮（N）5.45 g/plant可促进根冠平衡，使烟株稳健生长。

Effect of nitrogen rates on root-shoot balance and nitrogen accumulation and distribution in flue-cured tobacco

A pot-cultured experiment was conducted to study the ratio of root to shoot and nitrogen accumulation and distribution of tobacco under different nitrogen levels by using ¹⁵N tracer technique. Tobacco plants were applied N 0 (CK), 5.45 (N1) and 8.18 g (N2) per plant respectively. The results showed that above-ground dry matter accumulation amount increased with the increasing of nitrogen rate, root dry matter accumulation amount of treatment N1 was the most among the three treatments from planting to topping stage. From topping to maturity stage, the above-ground dry matter accumulation amount of treatment N1 was the most and the root dry matter accumulation amount increased with the increasing of nitrogen rate. The ratio of root to shoot decreased with the increasing of nitrogen application rate at topping stage while increased in maturity stage. The nitrogen accumulation amount of total plant of treatment N1 was the most among the three treatments from topping to maturity stage; nitrogen accumulation was observed in each plant organ of treatment N1, whereas in treatment CK and N2, the outputs of nitrogen were observed in lower and middle leaves. The distribution proportion of nitrogen in roots decreased with the increasing of nitrogen application rate at topping stage. With the increasing rate of nitrogen application, the proportion of nitrogen uptake from fertilizer increased while decreased from soil, and the proportion of nitrogen uptake from basal fertilizer increased while decreased from topdressing fertilizer. About this experiment, the treatment of 5.45 g nitrogen applied per plant could accelerate root-shoot balance, and plants grew naturally.