Mechanism of dwarfing caused by dwarfing rootstock in peach.

为阐明矮化砧木造成桃树矮化的机理，比较了桃树和毛白李砧木的生长发育、光合作用和蒸腾速率、干物质分配、嫁接愈合的显微观察和多酚类物质的细胞化学和化学分析。毛白杨上的桃表现出较低的光合速率，这可能是由于叶片的气孔密度较低所致。虽然桃树砧木和毛白杨砧木的蒸腾速率差异不大，但矮化砧树的叶水势较低，日波动较大。在矮化砧木上，干物质更多地分配到树根中，而在健壮砧木上，叶片总数更多。嫁接结合的观察表明，在桃-桃组合中，…的形成过程愈伤组织中有更多的n个愈伤组织成功地发育到血管连接完成，在移植后6个月，几乎所有的坏死细胞都消失了。桃树-毛白桃组合的愈伤组织未被染色，但嫁接完成后，树皮细胞染成蓝色，表明桃树中含有较多的多酚类物质。而在桃树-绒毛组合中，愈合处的愈伤组织细胞被蓝色染色的细胞包围，在那里也观察到坏死细胞，这似乎阻碍了移植物的完全愈合。对嫁接体的丙酮提取物进行高效液相色谱分析，检测到4种保留时间超过15分钟的未知多酚。这些多酚类物质在桃-桃组合中的含量较高，尤其是在砧木部位，而在绒毛砧木中则不存在。这些结果表明，在桃-绒毛组合中，多酚物质可能在接穗处从桃的接穗转移到绒毛砧木中，从而对绒毛细胞产生不利影响，导致嫁接不完全。较少

To elucidate the mechanism of dwarfing caused by dwarfing rootstock, peach trees on peach and on Prunus tomentosa (dwarf) rootstocks were compared for tree growth, photosynthesis and transpiration rates, distribution of dry matter as well as microscopic observation of graft unions and cytochemical and chemical analysis of polyphenols.Trees on P.tomentosa grew slower and was about half the height of the trees on peach rootstock at 3 years after planting. Peaches on P.tomentosa showed a lower photosynthetic rate probably because of the lower stomata density of the leaves. Although transpiration rate was not different between the trees on peach stock and on P.tomentosa, the trees on dwarf stock showed lower leaf water potential which fluctuated more in a day. Dry matter distributed more into roots in the trees on dwarfstocks while total number of leaves was more on the trees on vigorous stocks.Observation of the graft union revealed that in peach-peach combination, the process of formatio … More n of callus to the completion of the connection of vasculars developed successfully, and at six month after grafting almost all necrotic cells had been vanished. On the contrary, considerable amount of the necrotic tissues remained in peach-tomentosa combination.Callus at the union was not stained, in the peach-peach combination but after the graft completion bark cells stained blue indicating that peach contains more polyphenols. While, in peach-tomentosa combinations callus cells at the union was surrounded by the blue-stained cells where necrotic cells were also observed which seemed to prevent the complete union of the graft. HPLC analysis of acetone extracts of the graft union detected 4 unidentified polyphenols of which retention times were more than 15 minutes. These polyphenols were present more in the peach-peach combinations, in particular, at the rootstock portion, but not present at tomentosa rootstocks.From these results, it is suggested that in the peach-tomentosa combination polyphenol substance may translocate from peach scion to tomentosa stock at the union and exert adverse effect on the cells of tomentosa resulting in incomplete grafting. Less