Relationships between Rooting in Softwood Cuttings of Mume (Prunus mume Sieb. et Zucc.) and Sorbitol in Shoots.

We attempted to vegetatively propagate mume (Prunus mume Sieb.et Zucc.) by softwood cuttings and investigated the relationship between carbohydrates in shoots and root formation. With IBA treatment, rooting rate was more than 50% when cuttings were collected in early June to early August, whereas it decreased to no rooting in October. Without IBA treatment, cuttings did not root except in June. There is a relationship between rooting ability and bud dormancy in that rooting ability decreased as bud break rate became reduced. High rooting rate occurred when sorbitol content in the cuttings was high. The carbohydrates, sorbitol and total sugars content, in the basal part of cuttings increased in IBA-treated cuttings 14 days after planting, whereas in untreated cuttings, they increased 21 days after planting. Moreover, the maximum quantity of sorbitol in IBA-treated cuttings was more than that in untreated ones. When sorbitol, glucose, sucrose and fructose were tested in in-vitro rooting of microcuttings, the highest in vitro rooting rate and the largest number of roots per microcutting were obtained when the explants were imbedded in WP medium supplemented with sorbitol.