杂交小麦同化物输配规律及机理的研究

【作者】 龚月桦；

【导师】 高俊凤；

【作者基本信息】 西北农林科技大学 ， 植物学， 2000， 博士

【摘要】 近年来作物源库流关系的研究表明：无论源强度、流的能力、还是库本身的特性都会对光合产物的输配产生影响，从而最终影响经济学产量。本文针对K型杂交小麦901叶片功能期长、同化能力强和生育后期青枝绿叶的特点，以杂交小麦901及其父本恢复系R205，母本不育系K3314A，常规小麦陕229、小偃22为试材，通过1997-2000年三年多的田间实验及盆栽实验，研究了小麦开花后源、流、库的特性，目的在于阐明同化物输配规律并探讨901生育后期同化物滞留源端的原因。 对小麦花后旗叶净光合速率、叶面积、叶绿素含量、旗叶蒸腾速率、旗叶干重、叶片碳水化合物含量等指标进行了动态分析测定。结果表明，杂交小麦901开花后早期光合速率较低，但中后期光合速率高于对照，表现出优势。而且901叶面积大，叶绿素含量下降缓慢，叶片功能期长。因此，在灌浆中后期901的源叶能提供充足的同化物。但是，901后期叶片淀粉含量升高，滞留的可用性碳水化合物较多，叶片物质输出率低，说明还有较多的光合同化物滞留源端。这与其亲本恢复系的特性密切相关。 用常规石蜡切片法和显微观测技术，对开花后28天的901、恢复系、不育系和陕229四个小麦品系的旗叶、叶鞘、节、节间、穗轴和籽粒腹沟区维管束进行显微观测。结果表明：杂交小麦901及其恢复系的旗叶、叶鞘、节、节间、穗轴的维管束数目和面积均比陕229的高，这些可能是其穗大、小穗数多、颖花较多的结构基础；而不育系的维管束数目少，面积小，则与其不育特性有关。但901的籽粒腹沟区维管束面积最小，则可能是其后期灌浆慢的原因之一。对源端装载区域和库端卸出区域的超微结构观察以及对装载部位进行ATP酶的细胞化学定位研究结果则表明，四品系间均未有明显的差异。 对籽粒体积、含水量、干物质累积、可溶性糖、蔗糖、淀粉含量等指标进行了动态分析测定。结果表明：杂交小麦901籽粒形成期扩张生长快，体积增大快，灌浆中后期灌浆速率缓慢，灌浆时间延长。可溶性糖和蔗糖作为淀粉形成的底物，它们的含量变化与淀粉累积、灌浆速率的动态变化密切相关。对蔗糖降解的几种酶活性变化进行分析测定表明，转化酶主要在籽粒形成期起作用。而蔗糖合成酶在淀粉开始迅速累积时活性最高，说明它在蔗糖向淀粉的转化中对蔗糖的降解起主导作用。901籽粒灌浆中 －杂交小麦同化物输配规律及机理的研究－第5页共96页一后期蔗糖合成酶活性低，是其生育后期灌浆慢的内在生理原因之一。 利用’‘CO。饲喂标记和同位素测定技术，对盆栽小麦灌浆后期旗叶‘Y－同化物的源端装载和库端卸出规律进行进一步研究得出，常规小麦陕229’℃－同化物源端装载快、输出快，标记后第二无输出极少，转运周期为 1天。而杂交小麦 901及其恢复系‘℃－同化物则在源端装载慢，输出慢，标记后第2 天仍有较多输出，运转周期拉长。并且旗叶中滞留的‘℃－可溶性同化物和‘℃－蔗糖较多，也表明其’℃－蔗糖的输出慢。常规小麦库端卸出快，标记后第 2天卸出很少；而 901及其亲本’℃－同化物库端卸出慢，第 2天仍有较多卸出，周期延长。 总之，杂交小麦90库处理源供应的‘℃－同化物能力低，需要时间长，分解蔗糖能。力较差，淀粉合成速率慢，即库活性弱，而源端物质输出率低，是杂交小麦 90 生育后期同化物滞留源端的主要原因。更多还原

【Abstract】 Title: Transport and partitioning mechanism of assimilates in hybrid wheat.Supervisor: Professor Gaojunfen Ph.D Candidate: Gong yuehuaThe approaches on the sink-source relationship of crops in recent years provioded that either source strength, flow availability or the characteristics of sink itself would affect the transportation and the partitioning of photo assimilates, and thus the final yield. K-type hybid wheat 901 has the the following characteristics: long functionate duration of leaves, strong assimilatibility,green leaves and shoot in the end of growth stage.Accordingly, the present paper used hybrid wheat 901,the father plant R205 and the mother plant K3314A,the general plant Shan229 and Xiaoyan22 as experimetal materials,to study the characteristics of the sink,flow and source after anthesis using pot and field experiments from 1997 to 2000.The purposes for this study were to reveal the transport and partitioning of assimilates,and the mechanism of assimilates left in the source area in hybrid wheat 901 during the end of growth stage.After anthesis,the net photosynthesis speed(Pn),the transpiration speed and the size of flag leaves, and the content of chlorophll and carbohydrates in flag leave were determined.The results showed that the Pn of the hybrid wheat was lower just after anthesis,but higher than that of the controlled plant during the mid- and end of the filling stage,having priority in this aspect. Also, the leaves of 901 had a larger size,its chlorophyll content lowered slowly,and the functionate duration of leaves was longer. As a result,in the middle and the end of filling stage, the source leaves could provided enough assimilates for utility.However, in the end of filling stage,the content of starch in the leaves of the hrbrid wheat was high,and much available carbohydrates reserved were left in the leaves while the matter in the leaves were exported slowly.All these showed that much photoassimilates were not export and left in the souruce leaves.This was closely related to the characteristics of the father plant.Wax slicing technique and micro-structure determination methods were adopted to study the vascular bundle structure in flag leaves,sheath,internodes,the 1st node below the ear,rachis of hybrid wheat 901,the father and mother plant,and Shan229.The results showed that the numbers and the area of vascular bundle in the above tissues of hybrid wheat 901 and its father plant were larger than Shan229.These might be the structure basis for 901 yeilding larger ears,many spikelets and many glumiflorous.However, the vascular bundle area in kernel crease tissues of 901 was the smallest,and thiswould be one of clues why the kernels of 901 were slowly filled in the end of filling stage. The ultrastructure research in source loading area and sink unloading area and the histochemical research of ATPase activity in source loading area both revealed that no apparent difference occurred in four experiment materials.The sizes, water content.the accumulation speed of dry matter weight of kernels, and the content of total soluble carbohydrates(TSC), sucrose and starch in the wheat kernels were determined.The results indicated that, during the formation stage of kernels,hybrid wheat 901 grew more quickly in cell expansion of kernels, and the size increased faster,but during the middle and the end of the filling stage the filling speed became slower with the filling time lasting longer. While TSC and sucrose being the substrates for starch formation.the changes of their content in kernels were strongly related with that of the starch accumulation speed and the filling speed. The changes of enzyme activities which dissoluted the sucrose showed that the invertase activities mainly played a role during the kernel formation stage, and the sucrose synthase activities were the highest during the time when starch began to accumulate quickly.This proved that the sucrose synthase had a key role in sucrose degradation during the transformation of sucrose to starch.The lower更多还原