关键词: 烤烟, 施氮水平, 叶型, 垂直分布, 株型

Abstract: In order to clarify the effect of different nitrogen application on the characteristics of leaf-type flue-cured tobacco, this experiment took 3 flue-cured tobacco Qinyan96, Yuyan12 and Yunyan87 as test materials; designed 3 nitrogen application levels N1 (30 kg/hm2), N2 (60 kg/hm2), N3 (90 kg/hm2); and determined the indexes of leaf length & width, angle between stem & leaf, leaf area, community light penetrating rate, etc.; and analyzed the differences in the characteristics of leaf canopy vertical distribution. The results showed that: ① Group leaf area index(LAI) transferred to middle & upper layer with the advance of growth stage, LAI was first increased and then decreased with canopy height increasing, the regulating effects of nitrogen levels on LAI varied with canopy height and different genotype. ② The angle between stem and leaf increased with the increase of canopy height and nitrogen application rate, but the increase range of canopy height and genotype was different; the vertical angle of stem and leaf decreased with the increase of canopy height at N1 and N2 levels, but decreased first then increased afterwards with the increase of canopy height at N3 level; the change tendency of leaf curvature and stem leaf angle was the same. ③ The transmittance of group flue-cured tobacco increased with canopy height, and decreased with the increase of nitrogen application rate; the light transmittance rate was in accordance with the changes in 2-order polynomial curve, the equation parameters were significantly different between nitrogen application levels, but there was no significant difference among genotypes. ④ The transmittance of 3 varieties decreased exponentially with the increase of cumulative leaf area index. The light transmittance of Yuyan12 was the lowest under different cumulative leaf area index. The transmittance of Qinyan96 was smaller than that of Yunyan87, when the accumulated leaf area index was less than 1.2. While, when it was over 1.2, the result was just the opposite. In a word, the vertical distribution characteristics of tobacco leaf-type were better at N2(60 kg/hm2) level, which was in favor of tobacco leaf growth and development, and the formation of quality.

Key words: flue-cured tobacco, nitrogen application level, leaf-type, vertical distribution, plant type