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小麦的穗领在系统演化和个体发育中形成过程的初步探讨

RESEARCHES ON THE FORMATIVE COURSES OF THE SPIKE COLLAR OF WHEAT IN SYSTEMATIC EVOLUTION AND INDIVIDUAL DEVELOPMENT

  • 摘要: 小麦的穗领有三种类型:领腹完全敞开的U形穗领、领腹完全闭合的O形穗领和领腹呈V型交叉的V形穗领。穗领是系统演化中顶生叶叶鞘减化后的遗迹,也是个体发育中穗轴基部第一侧生小穗下苞叶原始体的痕迹。在一定条件下,从穗领可以长出叶鞘和叶片,穗轴基部节间可以变为茎节间,穗领腋内的小穗可以变为腋芽、带柄分枝穗或分枝花序。其余侧生小穗下都有一个领腹完全敞开的U形小穗领,其形态与U形穗领相似。它们是系统演化中二次轴分枝花序的苞叶叶鞘减化后的遗迹,也是个体发育中苞原始体的痕迹。一定条件下,从小穗领也可以长出叶鞘和叶片。穗轴基部节间变茎的同时,基部几个小穗若发生向圆锥花序的部分返祖变异,随着变异程度加深,从穗领和小穗领逐渐形成叶鞘和叶片。说明在系统演化中。顶生叶和苞叶先减化叶片,后减化叶鞘,最后形成穗领和小穗领。小麦祖先的花序与茎叶之间没有明显的界限。

     

    Abstract: 1. The spike collars fall roughly into three categories:Ushape, O-shape, V-shape.2. The spike collar represents the vestige of an abortive terminal leaf sheath in systematic evolution, And a mark of the primordium of a leaf under the first lateral spikelet in individual development. Under given conditions, the spike colhr can be returned to leaf, the internodes of rachis can be turned into internodes of stem, the lateral spikelet can be transformed into a bud, a branch spike or a branch inflorescense.3. There is a U-shape spikelet colhr under the rest each lateral spikelet, it represents the vestige of an abortive bracteal leaf sheath in systematic evolution, and a mark of the primordium of a leaf in individual development. Under given conditions, the spikelet collar can be returned to braeteal leaf.4. When the lateral spikelets occur atavistic variation, the spike collar and the spikelet collar progressively return to leaf sheath, leaf blade, ligule and auricles.5.The lateral spikelet are all metamorphosed buds, the internodes of rachis are all metamorphosed internodes of stem. So the place where the inflorescence and stem meet of wheat remote Ancestor has nota clear boundary line.

     

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