以烤烟品种K326为材料,设置D1(16 529株/hm2)、D2(18 182株/hm2)、D3(20 202株/hm2)3个种植密度处理,于圆顶期对各处理烟株上、中、下3个部位叶片进行13C同位素标记,研究了烤烟不同部位叶片的碳同化能力差异和同化产物的分配特点,并探讨了种植密度对烤烟叶片碳同化能力差异和同化产物分配的调节效应。结果表明,烤烟不同部位叶片的13C同化能力表现为中部叶>上部叶>下部叶;同一叶片不同区段13C同化能力大小依次为叶中部>叶基部>叶尖部。上部叶的13C同化产物平均有19.71%运往根系,42.22%运往茎秆,38.07%留在叶片且大部分留在被标记的上部叶;中部叶的13C同化产物有33.42%运往根系,26.00%运往茎秆,40.58%留在叶片且大部分留在被标记的中部叶;下部叶的13C同化产物有33.67%运往根系,23.72%运往茎秆,42.61%留在叶片且大部分留在被标记的下部叶。上部叶的13C同化产物向茎秆的中部供应较多,中部叶和下部叶的13C同化产物向茎秆基部分配较多。随着种植密度增大,叶片的碳同化能力降低,向根、茎分配的同化产物量减少,尤其是在较高的种植密度(D3)下,各部位叶片的碳同化能力显著降低。综上,烟叶产量和品质形成的物质基础主要来源于烟叶生长期间自身的同化作用,种植密度对烤烟叶片的13C同化能力具有显著影响,在设置试验条件下,18 182株/hm2左右的种植密度有利于提高烤烟叶片碳同化能力和协调同化产物的运输分配。 The flue-cured tobacco variety K326 was used to set the planting density of D1 (16 529 plants / hm2), D2 (18 182 plants / hm2) and D3 (20220 plants / hm2) , Middle and lower parts of the leaves were 13C isotope labeled leaves of different parts of flue-cured carbon assimilation differences in ability and assimilation characteristics of assimilation, and to discuss the planting density on carbon assimilation ability of flue-cured tobacco leaves and the regulation of assimilate distribution . The results showed that the 13C assimilation ability of different parts of flue-cured tobacco showed the middle leaf> the upper leaf> the lower leaf. The 13C assimilation ability of different leaf segments of the same leaf followed the leaf middle> leaf base> leaf tip. The average 13C assimilates in the upper leaves reached 19.71% of the roots, 42.22% of the leaves in the roots, 38.07% remained in the leaves and most of the leaves remained in the labeled upper leaves. The 13C assimilates in the middle leaves had 33.42% of the 13C assimilates transported to the roots and 26.00% Stalks, 40.58% remained on leaves and mostly remained on marked middle leaves; 33.67% of 13C assimilates of lower leaves were transported to roots, 23.72% were transported to stalks, 42.61% remained on leaves and mostly remained on labeled Lower leaves. 13C assimilation products of the upper leaves supplied more to the middle of the stalk, while 13C assimilation products of the middle leaves and lower leaves were more distributed to the base of the stalk. With the increase of planting density, the carbon assimilation ability of leaves decreased, and the amount of assimilation products distributed to roots and stems decreased. Especially at higher planting density (D3), the carbon assimilation ability of all leaves was significantly reduced. In summary, the material basis for the formation of tobacco leaf yield and quality mainly comes from the assimilation of tobacco during its growth. The planting density has a significant effect on the 13C assimilation ability of tobacco leaves. Under the set experimental conditions, the planting density of 18 182 plants per hectare It is beneficial to improve the carbon assimilation ability of flue-cured tobacco leaves and to coordinate the distribution of assimilation products.