Reda Meziani

Micropropagation of Date Palm: A Review

Somatic embryogenesis and organogenesis are the two pathways of choice for rapid and large-scale propagation of date palm. They have been successfully used for the micropropagation of elite genotypes and have proved their effectiveness for the commercial production of many cultivars. Nevertheless, regeneration through somatic embryogenesis or organogenesis in date palm is still difficult to achieve for recalcitrant genotypes and is often hampered by certain physiological disorders. In the present review, we report the results of a number of studies carried out on date palm micropropagation. It also describes different factors that influence each stage of somatic embryogenesis and organogenesis and the main problems encountered during these two micropropagation processes.

Effects of plant growth regulators and light intensity on the micropropagation of date palm (Phoenix dactylifera L.) cv. Mejhoul

The present study aimed to determine the best combination of plant growth regulators (PGRs) and light intensity in order to improve organogenesis of date palm (Phoenix dactylifera L.) cultivar Mejhoul. Organogenic cultures obtained from shoot tip explants were cultured on half-strength Murashige and Skoog (MS/2) medium supplemented with various combinations of two auxins: 2-naphthoxyacetic acid (NOAA) and indole-3-acetic acid (IAA) at 0, 0.2, or 0.4 mg L−1and two cytokinins: kinetin and 6-(dimethylallylamino) purine (2iP) at 0, 0.4, or 0.8 mg L−1 under different light intensities. Our results revealed that after 3 months of culture, the combination of 0.2 mg L−1 NOAA, 0.2 mg L−1 IAA, 0.4 mg L−1 2iP, and 0.4 mg L−1 kinetin was the optimal for shoot proliferation (12.8 shoot buds per explant), with low levels of hyperhydricity (20.0%), tissue browning (20.0%), and precocious rooting (30.0%). The present study showed also that darkness and low light intensity (500 lux) significantly increased the incidence of precocious rooting while high light intensities (2,000 – 3,000 lux) decreased shoot bud proliferation and stimulated shoot elongation and greening. The optimal light intensity during the multiplication phase was 1,000 lux (13.2 shoot buds per explant, 15.0% greening, 25.0% precocious rooting). Shoot elongation and rooting occurred on PGR-free MS/2 medium then the plantlets were transferred to a greenhouse where 88.0% survived after 3 months. Our results are beneficial for the efficient and large-scale propagation of the elite and endangered date palm cultivar Mejhoul.

Use of TDZ for Micropropagation of Some Mediterranean Crop Species

Plant tissue culture is now a widely used technology for many applications. Plant growth regulators (PGRs) play an important role in this technology. Auxins and cytokinins are by far the most commonly used PGR classes in plant tissue culture. N-Phenyl-N′-1,2,3-thiadiazol-5-ylurea, also known as thidiazuron or TDZ, is a synthetic PGR and a phenylurea derivative with a strong cytokinin-like activity. TDZ has been successfully used for the micropropagation of several plant species and sometimes was reported to be more effective than adenine-based cytokinins or to fulfil both the auxin and the cytokinin requirement for in vitro growth and differentiation. In this chapter, we will focus on the use of TDZ for the micropropagation of six Mediterranean crop species. Thus, we will report some findings from past and recent studies in which TDZ was employed for in vitro culture and regeneration of Olea europaea L., Citrus spp., Ceratonia siliqua L., Punica granatum L., Ficus carica L., and Prunus dulcis Mill. We will also highlight the specific action of TDZ depending on its concentration as well as the species, the genotype, the explant, and the concentration of the associated PGRs.

Effect of Cultural Practices on the Growth of Date Palm VitroPlants Planted in Errachidia (South East of Morocco)

In vitro multiplication of date palm is a very promising way for the rehabilitation of Moroccan palm devastated. The objective of this work was to study the development of vitroplants introduced into traditional and modern palm of the Errachidia region. The procedure followed is to make descriptive diagnoses in different sites where the palm was introduced and to evaluate the mortality of plants and cultural practices. The mortality rates varied from 78% to 19% in new plantation depending on the cultivation technique used. At the traditional palm, the rate of recovery of plantlets was zero. The mortality is higher in Nejda cultivar compared to Boufegouss. This variety also presented a better adaptation in terms of shoot height in comparison with the development of Nejda and Mejhoul varieties. The production of offshoots as well as inflorescences takes place three years after plantation. The importance of improving cultivation techniques in date palm for the development of this sector in Morocco is discussed.