An efficient in vitro shoot propagation of cranberry (Vaccinium macrocarpon Ait.) by axillary bud proliferation

Cultures of two cranberry (Vaccinium. macrocarpon Ait.) cultivars, 'Ben Lea r' and 'Pilgrim', and three cranberry clones from natural stands in Newfoun dland were established in a nutrient medium containing N-6 [2-isopentenylla denine (2iP) from nodal and/or shoot-tip explants obtained under aseptic co nditions. The cultivars differed in shoot regeneration in terms of shoot nu mber per explant with various concentrations of 2iP over two culture period s. Best total shoot production was obtained when nodal segments were cultur ed in the medium supplemented with 2.5-5.0 mg 2iP l(-1) (12.3-24.6 muM). Wi th higher 2iP levels, shoots did not expand and had a high mortality rate. Nodal explants of the three clones cultured in the same nutrient medium sup plemented with 2.5 mg 2iP l(-1) (12.3 muM) produced three to five healthy a xillary shoots per explant. In another experiment, nodal explants were more productive than shoot tips. In all experiments with subculture, there was an increase in shoot multiplication rate for all genotypes. Shoots were roo ted in vitro in the same media used for shoot proliferation, but without an y growth regulators. After their transfer to potting medium, almost all of the rooted plants survived. Cranberry genotypes can be efficiently propagat ed and maintained through nodal culture in a nutrient medium without auxin that contains 2.5-5 mg 2iP l(-1) (12-25 muM).