旱地覆膜对冬小麦花后~(14)C-同化物转运分配的影响

利用14CO2示踪研究了覆膜对旱地冬小麦花后14C-同化物在灌浆期转运分配的影响。结果表明,花后同化的14C在标记后24h约78%已储存在茎鞘和穗轴中,11%已转运至籽粒,11%还滞留在叶片中;成熟时叶片的14C-同化物几乎都外运了,茎鞘和穗轴中还滞留约28%,70%已转运分配到籽粒中。覆膜小麦的14C-同化物向籽粒的转运比对照慢。另外,研究还表明覆膜小麦花后叶片的叶绿素含量比对照高,MDA含量比对照低,叶片衰老延缓,同化能力强,干物质多,籽粒产量高。因此,覆膜使小麦增产的原因在于小麦中前期生长加快,后期衰老延缓,同化能力增强,最终使得同化的干物质总量大大增加;但并不促进同化物向籽粒的转运分配。

THE EFFECTS OF FILM-MULCHING ON THE TRANSLOCATION AND DISTRIBUTION IN ~(14)C-ASSIMILATES AFTER ANTHESIS IN WINTER WHEAT (Triticum aestivum L.) ON DRYLAND

The effects of film-mulching on transportation and distribution of ~(14)C-assimilates after anthesis of winter wheat on dryland were investigated using ~(14)C-radiolabelling technique.The results showed that about 78% of ~(14)C-assimilates was stored in the stem and sheath after 24 hours,11% was transported into the kernels,and about 11% remained in leaves.At maturity,~(14)C-assimilatess were almost entirely transported from the leaves,about 28% ~(14)C was found in the stem and sheath,and about 70% was in the kernels.The ~(14)C-assimilates in wheat with film-mulching were transported slower than that in the control.The results also suggested that under the film-mulching conditions,the leaves had higher chlorophyll contents,lower MDA contents,slower speed in the senescence and a stronger assimilability,while the wheat had much more dry matter and higher kernel yield.It was concluded that the reasons of the yield increase under the film-mulching were mainly on the faster growth during the early stage,the slower senescence in the later stage,and a stronger assimilation,leading to a great increase of the dry matter.However,this may not enhance the assimilate translocation and distribution to the kernels.