桤木插穗不定根发生与发育的解剖学观察

采用常规石蜡切片法对桤木插穗进行解剖观察,研究茎的次生结构及不定根的起源和发生发育过程,探讨影响不定根发生的因素。结果表明:桤木茎的次生构造从外至内由周皮、皮层和次生维管组织3部分组成。皮孔有2种类型。不定根的发育过程可分为4个阶段:(1)维管形成层与髓射线交叉处的细胞活动,产生具有典型分生组织特点的薄壁细胞团;(2)薄壁细胞不断分裂,形成不定根原基发端细胞;(3)分裂分化形成的不定根沿着韧皮射线向皮层延伸;(4)随着不定根内部的维管系统的发育,不定根从皮孔或下切口伸出。

The Origin and Development of Adventitious Roots in Alder Cuttings

By means of paraffin section and microscopic observation of alder cuttings,the secondary structure of stems and the process of adventitious root development was dealt with in this paper,in order to understand the factors affecting adventitious root events.The results show that the secondary structure of alder stems were composed of three parts from periphery to center on the cross section,e.g.periderm,cortex,and secondary vascular tissue.Two types of lentical co-exist on the periderm on hypo-structrue of cuttings and the process and development of adventitious roots of alder were treated by paraffin section,to probe into the factors of the adventitious roots development.The ontogeny proess of adventitious roots can be divided into following four stages:(1)A group of parencheyma cells of meritem cell feature proliferates at the cross of vascular cambium cells and vascular rays;(2)Continually proliferating vascular cambium cells form a root initial;(3)The adventitious roots develop via the pith ray into the cortex;(4)With the development of the vascular systems in the adventitious roots,the roots extrude from the lenticel or the cutting callus.