大赖草的交配系统及生殖对策

Mating System and Reproductive Strategy of Leymus racemosus

为了探讨禾本科赖草属植物大赖草的交配系统,对其的花设计、花展示、花粉活力、柱头可授期及交配方式进行了研究。结果表明:①单花的3个花丝不同步伸长,其中两个生长速度相对较快先弯曲,然后花药纵裂散出花粉,第三个花丝随后弯曲,花药纵裂散出花粉,3个花药的不同步散粉延长了单花的"花粉寿命"。②花药被送出内外稃完成散粉后,羽状柱头伸到内外稃外接受外来花粉,避免了单花内的雌雄干扰。③大赖草花序上小花阶段性批量开放(确保了同一时刻开放的小花是同步的),还可降低同株异花花粉对柱头的干扰。④大赖草属自花授粉不亲和型,同时同株异花授粉也不亲和,大赖草已进化出了特殊的花设计、花展示和短的花粉寿命等特征来促进异花授粉。这些特征是大赖草在适应极端的沙漠环境的过程中进化出的一种生殖对策。

The mating system of Leymus racemosus was studied from aspects of flower design,flower display,pollen viability,duration of stigma receptivity and mating mode.The results are as follows：The asynchronous dehiscing of three anthers in one floret can elongate the pollen viability.The feature that pinnate stigma is delivered out of lemma and palea to receive exotic pollens after three anthers having dispersed the pollens not only can avoid the sexual interference in one single floret,but also can decrease the interference caused by geitonogamous pollens on stigmas in combination with that florets in the same inflorescence open in the way of stage and mass.It is concluded that L.racemosus is not only incompatibility of self-pollination but also incompatibility of geitonogamous pollination.During the process of long adaptation to the desert environment,L.racemosus has evolved unique characteristics of flower design and flower display as well as short pollen longevity and so on to promote cross-pollination.