不同供氮方式和施氮量对烤烟生长和氮素吸收的影响

Effects of rates and methods of N application on growth and N uptake of flue-cured tobacco

2005年5月至9月在云南玉溪采用田间试验和微区试验相结合的方法,研究了传统施肥和优化施肥2个施氮水平对烤烟生长和氮素积累的影响。结果表明,施N 120 kg/hm2的烟株在打顶以后以吸收土壤氮为主;施N52.5 kg/hm2的烟株在团棵期以后以吸收土壤氮为主,该施氮量能够保证烟株从移栽至打顶(即移栽后60 d)阶段的生长需要。但与施N 120 kg/hm2相比,植株氮素营养略有不足,烟株各部位及整株的干物重和氮素积累量略有降低;各时期干物重的分配比例没有区别。另外,打顶期和成熟期,两施氮处理植株所吸收的肥料氮绝对量差异达显著水平,施氮量越高,吸收量也越大。同时,施氮量越多,各个时期各部位和整株中肥料氮的比例越大,且均在团棵期达到最大值;之后呈下降趋势,施氮越多,下降幅度越小。两处理植株都呈现肥料氮比例随叶位上升而减少的规律,施氮量越高,部位间差异越小。

Our previous study showed that both changing N applying method and reducing N application rate to 52.5 kg/ha could meet the growth requirement of tobacco plant for N. A field experiment combining with a microplot in Yunnan province was carried out to further study the effects of N fertilization on the growth and N uptake of flue-cured tobacco. Two N application rates of 120 and 52.5 kg/ha were used. The results showed that tobacco supplied N 120 kg/ha mainly utilized soil N after topping, while soil N became the dominant N source after rosette for plants with N 52.5 kg/ha. Nitrogen application with 52.5 kg/ha could assure the growth of plants from the stage of transplanting to topping ; but their dry matter gain and N accumulation decreased slightly comparing with the treatment of N 120 kg/ha due to inadequate N supply after topping. Changing N application rates had no effect on dry matter distribution in tobacco plant. The higher the rate of fertilizer N supplied, the more fertilizer N was found in the plant, and the higher the ratio of fertilizer N to total N in different organs and whole plant was. The highest ratio of the fertilizer N to total N in plant was found in rosette stage, and then it declined slowly. In addition, the ratio of the fertilizer N to total N in upper leaves was smaller than that in lower leaves. And the difference of the ratio of fertilizer N to total N between the upper and lower leaves was smaller, when more N （120 kg/ha） was supplied.