A number of super-high yielding rubber trees(budding trees) that yield 10～15 times higher than the local ordinary rubber trees are found in China. The structure of barks(opposite to the bark 10 cm above the cutting line) of the trunk and conducting roots of the very high yielding budding trees (unselected seedlings as rootstocks and PB86 as scions) were investigated in order to reveal the causes of their super-high yield. The results showed that the thickness of conducting phloem, the number of young latex vessel rings, the total number of latex vessel rings, the ratio of the number of young latex vessel rings to the total number of latex vessel rings, the diameter of latex vessels and sieve tubes in the tree trunk of the super-high yielding rubber trees were obviously higher than those in the ordinary rubber trees. Especially, the ratio of the number of latex vessel rings to the number of cell layers in the conducting phloem was higher in the super-high yielding rubber trees than in the ordinary rubber trees. Moreover, the thickness and number of layers of cortical parenchyma cells in the conducting roots were significantly lower in the super-high yielding rubber trees than in the ordinary rubber trees, but the diameter of vessels in the conducting root were higher. This suggests that the cambium was higher in latex vessel differentiation and water and nutrition transport in the super-high yielding rubber trees than in the ordinary rubber trees.%据数年来的观测表明,在生产实践中出现有少量的植株(称其为"超高产橡胶芽接树"),其单株产胶量约达当地普通橡胶芽接树平均单株产胶量的15～20倍.为了探索这些超高产芽接树高产的原因.对砧木为无选择种子砧木,接穗为PB86的树干割线上10 cm背面的树皮和输导根的结构进行了研究.结果表明,超高产橡胶芽接树树干有输导功能韧皮部的厚度、幼嫩乳管列数、总乳管列数、幼嫩乳管列占总乳管列比例、乳管口径和筛管口径均显著大于普通芽接树.特别是超高产芽接树有输导功能韧皮部乳管列数与有输导功能韧皮部细胞层数的比值显著大于普通芽接树;另外,超高产橡胶芽接树输导根的皮层薄壁细胞厚度和皮层薄壁细胞层数显著小于普通芽接树,而导管口径却显著地大于对照(普通芽接树),这表明超高产橡胶芽接树形成层分化为乳管的能力、营养物质和水分运输能力都强于对照株.
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