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晚播小麦灌浆期叶片光合同化量最高、约占60%以上,穗的光合同化量约占15%,叶鞘及茎的光合同化量均在11%左右。群体调节对植株上部器官(穗、旗叶)、茎和叶鞘的光合同化影响较小,而主要影响倒二叶及以下叶片的光合同化。增加密度使植株中、下部叶片的光合速率及光合同化量显著降低。灌浆期籽粒是植株光合物质的主要输入部位。光合物质向茎的分配取决于种植密度。在较低密度条件下,茎是光合物质的输入部位,而在高密度条件下则是光合物质的输出部位。在较低密度下植株光合物质向根系分配比例增多。研究初步认为,种植密度高易使晚播小麦植株中下部器官较早地降低或丧失功能,加快衰老进程,影响结实、灌浆和籽粒产量。适当较低的种植密度利于延长中下部器官的功能期,延缓衰老,增加籽粒灌浆物质来源,提高籽粒产量。
The photosynthetic assimilation of late-sowing wheat was the highest at grain filling stage, accounting for more than 60%, the photosynthetic assimilation of ear was about 15%, and the photosynthetic assimilation of leaf sheath and stem was about 11%. Population regulation had little effect on the photosynthetic assimilation of upper organs (ear, flag leaf), stem and leaf sheath, but mainly affected the photosynthesis of upside down leaf and below leaf. Increasing the density reduced the photosynthetic rate and photosynthesis of middle and lower leaves of plants significantly. Grain filling stage is the main input site of plant photosynthetic material. The distribution of photosynthetic substances to the stem depends on the planting density. At lower densities, stems are the input sites for photosynthetic matter, whereas at high densities they are the photosynthetic output sites. At lower densities, photosynthetic rate of plants increased to the root distribution ratio. Preliminary studies suggest that the high planting density easily lower plants in late-sowing lower organs or lower function of the wheat to speed up the aging process, affecting the fruiting, filling and grain yield. Properly lower planting density is conducive to prolonging the functional period of middle and lower organs, delaying aging, increasing the sources of grain filling material and increasing the grain yield.