海岛棉和陆地棉叶片光合特性、冠层结构及物质生产的差异

【目的】探讨海岛棉和陆地棉两个棉花栽培种群体物质生产存在差异的原因，揭示海岛棉和陆地棉产量形成的机理，为选育高光效棉花品种和高产高效栽培提供理论依据。【方法】在新疆气候生态条件下，选用能适应北疆棉区的海岛棉品种（系）（新海22号、H858）和陆地棉主栽品种（新陆早13号、新陆早33号）为试验材料，分别测定不同棉花品种（系）叶片的叶绿素含量、叶面积指数、冠层开度、叶片向日性运动、群体光合速率和生物量等指标，探讨海岛棉和陆地棉两个栽培种间群体冠层结构、叶片光合组分和光合生产特性等的差异。【结果】陆地棉品种冠层上部叶片数量多，叶面积指数大，冠层开度小，上部叶片光截获量占冠层光截获总量的比例大，冠层中下部光截获量少；海岛棉品种冠层上部叶片少，叶面积指数小，冠层开度大，截获的光占冠层光截获总量的比例小；海岛棉品种群体光合速率均比陆地棉高；两个棉花栽培种光合物质生产能力存在显著差异，海岛棉光合产物总量多，但生殖器官占总光合产物的比例显著低于陆地棉；海岛棉和陆地棉产量构成因子及皮棉产量差异显著，陆地棉单位面积总铃数约为1.30×10⁶个/hm²，皮棉产量为3 000-3 500 kg·hm^-2，海岛棉虽然单位面积铃数显著大于陆地棉，达到1.54×10⁶个/hm²左右，但单铃重远低于陆地棉，皮棉产量仅1 500 kg·hm^-2左右；在棉铃空间分布上，海岛棉棉铃主要分布在冠层中下部，而陆地棉棉铃在冠层中上部的分布比例大。【结论】与海岛棉相比，陆地棉总光合产物低，但经济系数高，籽棉产量高，通过改善陆地棉冠层结构，延长群体光合功能期，提高光合产物累积量，有利于陆地棉产量的进一步提高；与陆地棉相比，海岛棉冠层光能利用率高，群体光合速率高，光合物质生产潜力大，但单铃重低，总铃库较小，且铃库与光合源比例失衡，光合产物转运效率低，经济系数小，产量较低。选育大铃、早熟性好的海岛棉品种，并适当增大种植密度，可能是海岛棉增产的技术途径。

Study on Differences in Comparative Canopy Structure Characteristics and Photosynthetic Carbon Assimilation of Field-grown Pima Cotton(Gossypium barbadense) and Upland Cotton(G. hirsutum)

【Objective】The objective of this experiment is to study different characteristics of the canopy structure development, photosynthate accumulation and distribution between pima cotton and upland cotton, and to summarize the principle of yield formation which is of great significance to excavate yield potential and construct a high-yield cultivation technique system.【Method】Pima cotton cultivars Xinhai 22, and H 858 and upland cotton cultivars Xinluzao 13 and Xinluzao 33 were selected as experimental materials. Leaf area index, diffuse non-interceptance, canopy apparent photosynthetic rate, photosynthate accumulation and distribution were measured at different growing stages.【Result】Compared to pima cotton cultivar, the development of upland cotton canopy structure had a more dramatic change throughout the growth period, particularly at the early and late growing stages. Upland cotton cultivars had higher leaf area index, as well as the light absorption rate at the top of canopy. Upland cotton cultivars had lower canopy apparent photosynthetic rate and photosynthate accumulation. Pima cotton cultivar’s leaf area index was lower throughout the growth period, except for the late growth stage. The canopy apparent photosynthetic rate and photosynthate accumulation of pima cotton cultivar were higher than upland cotton cultivar at the full bolling stage and boll opening stage, respectively. However, the ratio of the weight of reproductive system to photosynthate accumulation was significant lower than upland cotton, which led to the significantly differences of economic coefficient and lint yield (upland cotton cultivar 3 000-3 500 kg·hm^-2, pima cotton cultivar 1500 kg·hm^-2).【Conclusion】The significant differences of photosynthate accumulation affected by canopy structure and photosynthetic capacity and photosynthate distribution were main factors causing the lint difference between upland cotton and pima cotton. Improving canopy structure and canopy apparent photosynthetic rate can further increase the production of upland cotton, while balancing the source-sink properties and promoting the conversion efficiency of photosynthate to boll-sink by increasing the plant population density and breeding early-maturing and big-boll varieties are of very important significance for improving the economic coefficient and excavating yield potential of pima cotton cultivar.