巴西橡胶树不同高度导管的结构特征及其对嫁接树导管结构的影响

用光学显微镜技术研究了巴西橡胶树（Ｈｅｖｅａ ｂｒａｓｉｌｉｅｎｓｉｓ Ｍｕｅｌｌ．Ａｒｇ）不同高度导管的结构特征和树皮嫁接的砧穗接合区导管。研究结果表明：橡胶树从枝条、树干、根茎过渡区到小侧根的新形成的木质部导管孔径变化曲线近似“ Ｍ”形，导管密度变化曲线则近似“Ｕ”形。在树干一定高度导管孔径值有一个高峰，在根茎交界区导管孔径值和密度值都处于低谷，在枝条和细根部分，导管孔径值和导管密度值表现为负相关。树皮嫁接接合区的接穗和砧木的导管结构具有显著差异，接穗导管大于砧木。造成差异的一个重要原因在于位置效应，即取材时接穗在原来亲本中的位置和嫁接接合处在砧木中的位置不同。提供了与发育阶段无关的位置效应在嫁接中具有作用的初步证据，提出了“位置信息记忆”的概念。

Vessel Structural Characters in Different Parts of the Rubber Tree Hevea brasiliensis and their Effect on the Vessel of Graft Union of Patch Graft

The vessel structural parameters in different parts of the rubber tree (Hevea brasiliensis) and their effect on the vessel of graft union of patch grafts were studied using optical microscope. The variable diameters of vessels in the newly--formed xylem appeared as a curve like M and the variable densities of the vessels like U from branch, trunk, stem--root transition region to lateral root Of the seedling trees and grafting trees. In the vessel diameter curve, a peak was found at a certain height of the trunk while a valley at the stem --root transition region where the vessel density also had the lowest value. Vessel diameter and density showed negative correlation in the branch and lateral root. Vessels in the scion were larger and more than those in the stock, which formed significant difference in the patch graft union. One of the factors that led to the difference was position effect, i.e the position in the scion parent where the scion was taken and the position in the rootstock where the grafting was made. Preliminary evidence was obtained to prove the action of the position effect which has no relation to developmental phase on the grafts. A concept of positional information memory was proposed.