A 2,4-D-Free Combined Direct Organogenesis-Indirect Somatic Embryogenesis Protocol for Mass Propagation of Date Palm (Phoenix dactylifera L.) cv.Barhi

A 2,4-D-free protocol for indirect asexual embryogenesis from root explants of date palm cv. Barhi has been established. Different mixtures and concentrations of plant hormones were applied for direct root induction from juvenile leaf explants of the apical meristem in the offshoot shoot terminal. The highest percentage of induced roots was obtained on the Murashige and Skoog (MS) medium complemented with NAA (1 mg L-1), NOA (3 mg L-1), IBA (1 mg L-1), and 2ip (0.1 mg L-1). The highest percentage of induced callus, both embryogenic and non-embryogenic callus, was achieved from in vitro-induced roots cultured on the Murashige and Skoog medium complemented with BAP (2 mg L-1) and NAA (0.1 mg L-1). The highest number of somatic embryos was acquired on the Murashige and Skoog medium complemented with BAP (2 mg L-1) and NAA (0.1 mg L-1). Successful rooting of date palm plantlets achieved on the PGR-free ½ MS medium following three weeks. The endurance value of rooted plantlets obtained from indirect somatic embryogenesis pathway, was 70.32%. The developed protocol would be applicable for rapid and efficient mass propagation of elite cultivars of date palm with less risk of generating genetic instability.