沙棘微扦插不定根发生的形态解剖学研究

利用石蜡切片法对沙棘微扦插不定根的发生进行形态解剖学研究。结果表明:沙棘属于诱导型生根，观察到其不定根原基起源于2个区域，一部分根原基起源于维管形成层细胞，另一部分起源于韧皮部薄壁细胞区域。沙棘不定根原基继续发育时，一部分沿射线向外生长，另一部分向外生长的同时会与茎段的髓连接起来，这种现象在其他树种中尚未发现。沙棘插穗不定根的发生整体上可分为4个阶段:1）维管形成层细胞和韧皮部薄壁细胞分裂出一些排列紧密、细胞质浓、具有分生组织特点的薄壁细胞团；2）新形成的薄壁细胞团不断分裂并且脱分化，形成具有很强分生能力的不定根原基发端细胞；3）根原基发端细胞继续分裂,沿着射线向远离轴心的方向伸展，从而形成根原基；4）根原基穿过韧皮射线和皮层，向外继续朝皮孔方向发展，最终从皮孔伸出形成不定根，不定根伸出皮孔前内部维管系统发育完善并与茎部维管系统相连接。 

Morphological and anatomical features during the formation of adventitious roots of sea buckthorn by micro-cuttage multiplication

Morphological and anatomical features were observed during the formation of adventitious roots of sea buckthorn by micro cuttage multiplication with paraffin method. The results showed that adventitious root primordium originated from two areas(one was cell of vascular cambium, and the other was cell from cortex parenchyma) was inductive root formation type. When the adventitious root of sea buckthorn continued to grow, this phenomenon that one of its part extended out in ray direction and the other part would connect with the marrow of stem while it was stretching out remained undiscovered in other species. In general, formation of adventitious root of sea buckthorn can be divided into four stages: 1)The cells of cortex parenchyma and vascular cambium divided into parenchyma cell groups which contained the characteristics of meristem, stood in a line and bore dense cytoplasm concentration.2)Newly formed parenchyma cell groups kept dividing and dedifferentiating, forming adventitious root primordium initial cells which showed strong mitogenetic ability. 3)Root primordium initial cells continued to divide and extended in ray direction which was far from axis. Then the root primordium formed. 4)What’s more, root primodium pierced through phloem ray and cortex and kept stretching out to the lenticel direction, then the adventitious root formed. Not until adventitious root inner vascular system well matured and connected with stem vascular system, would it stretch from lenticel.