Effect of Basal Medium, Explants Size and Density on the In Vitro Proliferation and Growth of Date Palm (Phoenix dactylifera L.) Cultivar '16-bis'

The effect of basal medium, explant size and density on shoot multiplication, growth, rooting and acclimatization of date palm cv. ‘16-bis’ was evaluated. Bud clusters of different sizes (2, 3, 4 and 5 buds per cluster) were cultured at density of 1, 2, 3 and 4 clusters on Murashige and Skoog medium (MS), woody plant medium (WPM) and Nitsch medium (NM) supplemented with 0.5 mg/L 2-naphthoxyacetic acid and 0.5 mg/L kinetin for three months (multiplication phase). Separated shoots of different sizes (<3 cm; 3 to 4.5 cm and 4.5 to 6 cm) were cultured at density of 1, 2, 3 and 4 shoots on hormone free MS medium, WPM or NM for three months (Elongation-rooting phase). The proliferation and development of shoots were affected by the basal medium, explant size and density. The optimal shoot proliferation (18.1) was observed when 4 buds clusters were cultured at the density of 2 clusters per jar in MS medium. Separated shoots of 4.5 to 6 cm length exhibited the optimal in vitro development in terms of leaf length and greening, and root number and length when cultured on MS medium. In addition, these shoots reached the highest acclimation frequency with 80%. Our results would be utilized for an efficient propagation of plantlets of cv. ‘16-bis’, a selected date palm cultivar resistant to the bayoud disease.