Propagation of Alnus maritima from softwood cuttings

Alnus maritima (Marsh,) Nutt. (seaside alder) is a rare, woody-plant specie s with potential for use in managed landscapes. Information on the propagat ion and production of this species is not available. Our objective was to e valuate the use of softwood cuttings to propagate A. maritima, with emphasi s on how indole-3-butyric acid (IBA), plant provenance, and time of collect ion affect cutting survival, rooting percentage, the number of roots produc ed, and their length. Propagation trials were conducted with cuttings from seven trees on the Delmarva Peninsula (Eastern Shore of Maryland and southe rn Delaware) and seven trees in Oklahoma. Cuttings from mature plants in bo th provenances were collected on 14 June and 23 Aug. 1998; wounded; treated with IBA at 0, 1, or 8 g.kg(-1); and placed under intermittent mist in a g reenhouse for 9 weeks. Use of IBA at 8 g.kg(-1) caused a greater rooting pe rcentage (68%), root count (7.2), and root length (39.2 mm) than did the ot her IBA rates when applied to cuttings from Oklahoma in June, but IBA had l ittle effect on cuttings from the Delmarva Peninsula. Across IBA treatments , rooting of cuttings from Oklahoma (55% in June and 12% in August) was gre ater than the rooting of cuttings from Delmarva (27% in June and 3% in Augu st). Cuttings from Oklahoma had greater survival, callus development, root length, and root count than did cuttings from the Delmarva Peninsula during June and August trials. Averaged over IBA treatments and provenances, cutt ings collected on 14 June rooted more frequently (41%) than did cuttings co llected 23 Aug. (8%). We conclude that softwood cuttings from mature plants are an effective way to multiply clones of A. maritima, particularly when cuttings are collected early in the season and treated with IBA at 8 g.kg(- 1).