<i>In</i><i>vitro</i> regeneration of plantlets of Canary Island pine (<i>Pinus</i><i>canariensis</i>)

A protocol is described for plantlet formation in juvenile tissues of Pinuscanariensis Sweet ex K. Spreng. (Canary Island pine). Adventitious buds were induced on 3-day-old cotyledonary explants cultured on Bornman's MCM medium supplemented with cytokinin. The concentration of benzylaminopurine, the use of other cytokinins alone or in combination with benzylaminopurine, and the concentration of mineral salts strongly affected the bud forming capacity of the cotyledonary explants. Also, the age of the explants significantly influenced the frequency of adventitious bud formation. Bud development was enhanced by the elimination of phytohormones, a reduction of mineral salts and sucrose, and the inclusion of activated charcoal in the medium. The conditions used during the induction phase strongly affected the ability of the induced buds to develop into vigorous rootable shoots. Vitrification problems were eliminated by transferring the shoots to the elongation medium solidified with Gelrite, and shoot remultiplication was enhanced by removing the apical bud. Maximum rooting was obtained by pulsing shoots with a high concentration of indolebutyric acid and by using peat–vermiculite or peat–vermiculite–perlite as substrates. Roots developed within 6–8 weeks, and the regenerated plantlets were transferred to soil under nonsterile conditions, where further development occurred.