Micropropagation of elite date palm (Phoenix dactylifera L.) cultivars Samany and Bertamoda through immature inflorescence explants

Abstract

A detailed study was conducted on micropropagation of two elite date palm cvs. Samany and Bertamoda using immature spikelet explants. Initially the callus cultures were established using spikelet explants of immature spathes (avg. 15 cm). Initiation medium containing 0.5 mg L^-1 2,4-dichlorophenoxyacetic acid (2,4-D), 3.0 mg L^-1 2-isopentenyl adenine (2iP) induced significantly highest callus in cv. Samany (95%) followed by cv. Bertamoda (81%). Medium containing micro and macronutrients of MS, vitamins of MS, 30 g L^-1 sucrose, 100 mg L^-1 myo-inositol, 200 mg L^-1 L-Glutamine_, 0.05 mg L^-1 2,4-D, 3.0 mg L^-1 2iP, 3 g L^-1 Activated Charcoal (AC) induced white friable embryogenic callus in cv. Samany (84%) and in cv. Bertamoda (69%). Significantly highest multiplication of somatic embryos was obtained in cv. Samany (85%) and in cv. Bertamoda (76%) on the medium containing 0.1 mg L^-1 naphthalene acetic acid (NAA), 0.1 mg L^-1 Kinetin (Kin) under light. Leaf number, leaf length, root number and root length as significantly highest values were obtained on the medium containing 0.1 mg L^-1 BA, 0.1 mg L^-1 NAA. Root trimming of primary single root resulted in production of multiple roots in each plantlet. The in vitro hardening supported to select healthy plantlets to be able to grow vigorously in greenhouse. Soil mixture based on peatmoss, river sand, hill sand (4:1:1 v/v) resulted in significantly highest survival (91%) of plantlets in greenhouse during acclimatization. Micropropagated plants (45 cm in height) with 3-4 compound leaves grown in the greenhouse were transferred in the open field for tree and fruit evaluation. Results showed that cvs. Samany and Bertamoda produced true-to-type fruits after three years of plantations in open field. Fruits of cv. Samany were harvested at late khalal stage and utilized to make Chhuhara (boiled/ dried dates) which showed excellent quality. Micropropagation of elite date cultivars is need of the time which will boost varietal structure in the area.