Studies on dwarfing mechanisms of dwarf rootstocks

在苗期准确评价砧木的矮化能力，可以加快矮化砧木育种的进展。本研究的目的是确定是否从矮化砧木的愈伤组织限制生长的另一种愈伤组织从接穗品种在体外将预期从现场性能。以桃和李的茎段为外植体，诱导愈伤组织。这些愈伤组织生长在接穗砧木位置，在它们之间放置滤纸。处于储备位置（即与培养基接触生长）的桃愈伤组织在日本梧桐愈伤组织下生长时的重量比在桃愈伤组织下生长时的重量轻。在桃愈伤组织上，接穗部位的愈伤组织重量较大。在接穗位置的桃愈伤组织在桃或P.japonica愈伤组织上同样生长良好。在另一个实验中，将桃愈伤组织转移到预先将日本桃愈伤组织孵育一周的培养基中，然后除去。桃愈伤组织重量较轻的培养基上先前与P.japonica。桃愈伤组织的预培养不影响愈伤组织的生长。当桃和枇杷愈伤组织相邻而不接触时，一种愈伤组织对相邻愈伤组织的生长没有影响，枇杷愈伤组织中酚类物质含量比桃高，但桃愈伤组织的生长与枇杷本身和枇杷愈伤组织中酚类物质含量无关。结果表明，砧木的矮化能力可以用组织培养技术来评价，矮化作用是由日本松释放的某些化合物引起的。

Accurate evaluation of the dwarfing ability of rootstocks at the seedling stage permits faster progress in breeding programs for the dwarf rootstocks. The objective of this study was to determine whether callus from a dwarfing rootstock restricted growth of another callus from a scion cultivar in vitro as would be expected from a field performance. Calli were derived from shoots of peach and Prunus japonica Thunb. These calli were grown in scion-stock position, placing filter paper between them. Peach callus in the stock position, i.e. grown in contact with the media, weighed less when grown under P.japonica callus than when grown under peach callus. P.japonica callus in the scion position weighed more when grown on peach callus. Peach callus in the scion position grew equally well on either peach or P.japonica callus. In another experiment, peach callus was transferred into the media where P.japonica callus was previously incubated for one week and then removed. Peach callus weighed less on the media previously incubated with P.japonica. Preincubation of peach callus did not affect growth of P.japanica callus. When peach and P.japonica calli were placed in the adjacent position without contact, one kind of callus did not affect growth of callus adjacent to it.P.japonica contained nore phenols than peach, but growth of peach callus was independent of phenol contents of P.japonica and itself. The results suggest that dwarfing ability of rootstocks couldbe evaluated by tissue culture techniques and that dwarfing is caused by some compounds released from P.japonica.