从解剖学角度着手,对杂种鹅掌楸〔Liriodendron chinense (Hemsl.) Sarg.×L. tulipifera L.〕扦插过程中不定根的发生发育进行了研究。结果表明:杂种鹅掌楸插穗内未发现潜伏根原基。扦插后,不定根原基起源于维管形成层区,属于诱导生根类型。维管形成层恢复活动后,在不定根发生的部位附近形成1个明显的多薄壁细胞区域,在此区域不定根较容易发生。愈伤组织内没有发现根原基,愈伤组织在发育的过程中,内部细胞部分分化,并形成不规则的输导组织。大量的愈伤组织对不定根的发生有较强的抑制作用。杂种鹅掌楸插穗上不定根的发生可分为4个阶段:(1)维管形成层恢复活动,分裂出多层薄壁细胞;(2)维管形成层及附近的薄壁细胞脱分化,形成不定根原基发端细胞;(3)根原基发端细胞不断分裂成具有方向性的根原基,根原基穿过韧皮射线和皮层,向皮孔或下切口方向发展;(4)不定根从皮孔或下切口伸出,其内部的维管系统开始发育。

The anatomical observation on cuttings of Liriodendron chinense ( Hemsl. )Sarg.×L . tulipifera L. was carried out by means of paraffin section method. It is significantly clear that incubate root primordium has not been found in cuttings. The induced root primordium of cuttings initialed from the vascular cambium cells near the pith ray. There are much more parenchyma cells near the vascular cambium, where the root primordium is formed , than those in other positions. No root primodium has been found in the callus, and too much callusis disadvantageous to formation of adventitious roots. Processes of adventitious roots in cuttings can be fallen into four stages:( 1)proliferation of vascular cambium cells at the base of the cuttings;( 2) dedifferentiation of the vascular cambium cells and formation of a root initial;( 3)growth and development of the root primordium; ( 4)emergence of adventitious roots from the lentice or the callus of the cuttings.