覆膜对小麦14C-储备物在灌浆期转运分配的影响

【目的】阐明覆膜对西北旱地小麦花前同化的14C-储备物在灌浆期转运分配的影响。【方法】在小麦花前大约1周进行14CO2饲喂，在扬花和灌浆期对植株各部位的14C进行放射性测定。【结果】花前同化的14C在开花时约90％已储存在茎鞘和穗轴中，10%存留在叶片中；开花后两者都向籽粒转运。成熟时叶片的14C几乎都外运了，茎鞘和穗轴中还有大约65%的14C，籽粒中的14C分配率占30%～35％。覆膜小麦的14C向籽粒的转运比对照慢。另外，覆膜小麦的叶面积大，叶片衰老慢，同化能力强，干物质多，籽粒产量高。【结论】覆膜使小麦增产的原因在于使小麦中前期生长加快，后期衰老延缓，因而绿叶面积大，同化能力增强，最终使得同化的干物质总量大大增加，所以产量增加；但并不促进同化物向籽粒的转运分配。

Effect of Film-Mulching on the Remobilization and Distribution of 14C-Reserves in Wheat Grain-Filling Stage

The effects of the film mulching on the transportation and distribution of the pre-stored carbon 14C-reserves in the grain filling stage was studied with the techniques of feeding labelled 14CO2 to flag leaves and isotope tracing. The results showed that about 90 percent of the assimilated 14C-reserves before anthesis had been stored in the stem, sheath and rachis, and about 10 percent remained in the leaves at anthesis. Both of them will be transported to the kernels. When maturation, 14C-reserves in the leaves were almost exported entirely, about 65% 14C-reserves remained in the stem, sheath and rachis, and about 30-35% stored in the kernels. For the wheat with the film mulching treatment the 14C-reserves were transported in a slower speed than that in the control. The investigation also revealed that under the film mulching conditions, the wheat had a larger leaf area with a slower senescence speed and a stronger assimilatory power, accumulated more dry matter and high yield. It was concluded that the main cause of the kernel production increase under the film mulching were the faster growth in the early stage and the slower senescence in the later stage, hence with a larger green leaf area and a stronger assimilatory power leading to the total assimilated dry matter content increased greatly and the production increased similarly, Whereas this didn’t result from the increase of assimilates translocation and distribution to the kernels .