The Role of Auxins and Phloroglucinol in Adventitious Root Formation inRubusandFragariaGrownin Vitro

Abstract

Auxin-phloroglucinol synergism has been observed to promote the rooting of the Rubus hybrid (R. ursinus Cham, and Schlectxß. idaeus L.) but not the perpetually fruiting strawberry cv Gento Hummell (a hybrid of Fragaria virginiana Duchesne xF. chiloensis Duchesne). In strawberry PG was successfully substituted for IBA but the presence of both IBA and PG reduced rooting compared with other treatments. In strawberry PG affected the organization of tissues and the pattern of root branching; no callus was formed and growth of second order laterals was enhanced. Promotive effects of PG on leaf development were observed in both species but their effects may be indirect since root development was enhanced in treatments that also stimulated leaf growth. In both Rubus and strawberry the non-indole auxin a α-naphthaleneacetic acid showed no synergistic effects with PG on leaf and root development. These results demonstrate that the growth promotive effects of PG are not specific to Malus species.