小麦穗部维管束联络关系分析

ANALYSIS ON THE CONNECTION OF VASCULARBUNDLES OF SPIKES IN WHEAT

采用石蜡连续切片法，对小麦２个春性品种、３个半冬性品种的穗部维管束进行了连续观察。结果表明：（１）小麦穗部大维管束数随小穗位上升而递减，每上升１个穗轴节片，大维管束数减少１个，该大维管束进入同一穗轴节片节上着生的小穗中。顶小穗一般有３～５条大维管束，可认为顶小穗是由３～５个未能完全分化的小穗联合构成。（２）小穗上各位小花维管束数目随小花位上升而递减。第１，２朵小花一般有５～７条分支维管束进入，它们与小穗轴直接相连；第３，４朵小花有３～５条维管束分支，其中１条是下位花维管束的分支；第５朵小花以上各位花均只有３条维管束，且自上而下依次相连于邻花的维管束。

Observations on the vascular bundles at different position of spikes in five wheat cultivars(Triticum aestivum L.)were conducted. The results are as follows:(1) The number of macro-vascular bun-dles of rachis from base to top decrease with the change of the position. One macro-vascular bundles reducewith one rachis increasing,this macro-vascular bundles enter the spikelet adhering to the same rachis node.There are usually three to five macro-vascular bundles in the top spikelet.It might be true that top spikeletwas composed of three to five uncompletely differentiated spikelets.(2)The number of vascular bundles ofeach floret in spikelet decrease with the rising of floret position.There are generally five to seven vascularbundles in the first and second florets,the vascular bundles directly connected with vascular bundles of rachis.There are three to five vascular bundles in the third andbrth florets,one of which stemed from the branchesof lower florets,there were only three vascular bundles in the fifth floret and the others,these vascular bun-dles jointed successively with ones of neighbeur floret from up to low.