大葱花芽分化过程及形态特征变化

Morphological Characteristic Changes in Floral Bud Differentiation Process of Welsh Onion

为了明确大葱(Allium fistulosum L.var.giganteum Makino)花芽分化过程及形态特征变化,以易抽薹品种辽葱5号和耐抽薹品种天光一本为试验材料,苗期进行人工低温春化、抽薹开花处理,利用体式解剖镜观察大葱花芽分化过程及形态特征变化,并对花芽分化时期进行划分。结果表明:2个不同抽薹性大葱品种的花芽分化过程及形态特征变化基本一致,均可分为诱导感应期、花芽分化初期、花序原基和花原基分化期、花器官分化期4个时期。大葱茎尖营养生长锥转变为中央凸起的环状体时,植株从营养生长转变为生殖生长,可作为大葱花芽分化初始的标志;总苞原基闭合或即将闭合可作为花序原基和花原基分化期开始的标志;当花茎伸长至5~10 mm时,花序轴上部每个三角形的花原基顶点处形成1个扁圆形的外层花被片原基和被其包裹的球形外层雄蕊原基,标志着花器官分化开始启动,当总苞开裂后顶端30%小花开放时花器官分化进入末期。辽葱5号和天光一本在诱导感应期持续时间差异较大,分别为20 d和35 d,花芽分化初期、花序原基和花原基分化期、花器官分化期持续时间相近,分别为10、15 d和30 d。

In order to clarify morphological characteristic in the floral bud differentiation process of Welsh onion(Allium fistulosum L.var.giganteum Makino),this study took easy bolting variety‘Liaocong No.5’and tolerant bolting variety‘Tianguangyiben’as test material;conducted artificial low-temperature vernalization at seedling stage;observed the floral differentiation process and changes of morphological characteristic in green Welsh onion by anatomical lens;and divided the period of floral bud differentiation.The results showed that the floral bud differentiation process and changes in morphological characteristic of these 2 Welsh onion varieties with different bolting ways were basically the same.They could be classified into 4 phases including induction stage,initial stage of flower bud differentiation,inflorescence and flower primordium differentiation stage,flower organ differentiation stage.Plant transformed from nutrional growth to reproductive growth when vegetative growth cone turned into a central convex ring form,might being considered as the initial sign of the floral bud differentiation of Welsh onion.The closure or impending closure of the involucral bracts was considered as signs for beginning of the inflorescence and flower primordium differentiation stage.When the flower stem extended to 5-10 mm,an oblate outer peripheral primordium and a spherical outer stamen primordium formed at the apex of each triangle flower primordium on the upper part of the inflorescence axis,marking the initiation of flower organ differentiation.Floral organ differentiation entered into late stage when 30%top florets opened after involucral cracking.There were larger differences between the induction durations of‘Liaocong No.5’and‘Tianguangyiben’,by 20 days and 35 days,respectively.The duration of initial flower bud differentiation,inflorescence primordia and floral primordia differentiation,floral organ differentiation were similar,being 10 days,15 days,and 30 days,respectively.