Mechanism of dwarfing caused by dwarfing rootstock in peach.

点击翻译按钮获取中文摘要

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