基于氮素效应的烤烟叶型垂直分布特征分析

为明确不同施氮水平对烤烟叶型特征的影响，以云烟87、豫烟12和秦烟96为供试材料，设3个施氮水平，分别为N1(30 kg/hm2)、N2(60 kg/hm2)、N3(90 kg/hm2)，测定了烤烟叶片长度和宽度、茎叶角度、叶面积指数、群体透光率等指标，并对其在烤烟冠层垂直分布特征的差异进行了分析。结果表明：①随着生育期推进，烤烟群体叶面积指数向中上层转移，分层叶面积指数随冠层高度增加呈先增大后减小的趋势，施氮水平对分层叶面积指数的调控因冠层高度和基因型而异。②茎叶夹角随冠层高度增加而增大，施氮会使茎叶夹角增大，但不同冠层高度和基因型的增幅有所不同；茎叶垂角在N1和N2水平下随冠层高度增加而减小，而在N3水平下随冠层高度增加表现为先下降而后升高的趋势；叶片弯曲度与茎叶垂角的变化趋势相同。③烤烟群体透光率随冠层高度增加而增大，随施氮水平的增加而减小，透光率随冠层高度变化符合二次多项式曲线，方程参数在施氮水平间差异显著，在基因型间不显著。④3个烤烟品种的透光率随累积叶面积指数增加而呈指数递减，不同累积叶面积指数下豫烟12的透光率最低，在累积叶面积指数小于1.2时秦烟96的透光率比云烟87小，而大于1.2时则相反。总之，N2(60 kg/hm2)水平下烤烟叶型的垂直分布特征较好，有利于烟叶的生长发育及品质的形成。

Analysis of Vertical Distribution Characteristics of Leaf-type in Flue-cured Tobacco Based on Nitrogen Effect

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.