Influence of cytokinins and medium texture on organogenesis and plantlet regeneration in date palm (Phoenix dactylifera L.) cv. Najda

Abstract

Najda cv. is an important date palm cultivar due to its high fruit quality and resistance to bayoud, a disease that killed million plants of date palm. The in vitro propagation of cv. Najda through organogenesis is hampered by some physiological disorders, namely hyperhydricity, tissue browning and precocious rooting. In order to achieve efficient and large-scale propagation of true-to-type plantlets of cv. Najda, we evaluated the effect of different cytokinin types and concentrations (6-benzylaminopurine (BAP), 6-(dimethylallylamino) purine (2iP) and thidiazuron (TDZ), at 0.1, 0.2, 0.3, 0.4 or 0.5 mg/L), as well as that of medium texture (semi-solid and liquid) on adventitious shoot bud multiplication, hyperhydricity, tissue browning and precocious rooting. The optimal culture conditions for shoot bud proliferation and subsequent development were observed on semi-solid half-strength Murashige and Skoog (MS/2) medium supplemented with 0.5 mg/L 1-naphthaleneacetic acid (NAA) and 0.4 mg/L BAP, where an average of 23.8 shoot buds per explant, low rate of hyperhydricity (22.5%), moderate tissue browning (55.0%) and low percentage of precocious rooting (20.0%) were observed. Shoot elongation and rooting were performed on semi-solid and liquid plant growth regulator (PGR)-free MS/2 medium. Shoots were then transferred to the glasshouse, where the survival rate reached 95 %. The findings of the present study will be highly beneficial to rehabilitate the Moroccan palm groves infested by bayoud.

Keywords

• brunissement des tissus
• cytokinine
• enracinement précoce
• organogenèse
• palmier dattier
• vitrification