Biotechnology and Date Palm Development

Correspondent
Yaarub Al-Yahya
Wye College, University of London
EMail Y.Al-Yahya@wye.ac.uk


The date palm (Phoenix dactylifera L. 'Nakhla' in arabic) is the "tree of life" and is just one of many examples of a tree crop that can benefit immediately from applications of the recent biotechnologies of plant tissue culture and plant molecular biology. Slow growth, dioecy (separate male and female trees), the slow offshoot-based propagation system and the impossibilities of predicting adult characteristics of the seedlings have severely restricted improvement of this ancient tree crop.

Distributed throughout the Middle East, North Africa and South Sahel, areas of East and South Africa, SW USA, Central and South America and even in Southern Europe (Spain and Italy) - the total number of date palm trees is approximately 105 million covering an area of 800,000 ha - date palms have yet to be developed in other suitable areas of the globe which experience harsh climates and in which there is a desperate need to stabilise and also to create new sustainable environments. In addition to producing a valuable dessert fruit, valuable by-products such as building materials and versatile starting materials forhandicrafts can be derived from its leaves and trunks making it an important multiple purpose tree and a significant earner of foreign revenue for both small and large farmers. The date palm also makes a significant contribution towards the creation of equable microclimates within oasis ecosystems thus enabling agricultural development to be sustained in many drought- and saline-affected regions. The nutritional value of the relatively easy-to-store date fruit is high with sugars comprising up to 70% of the fruit ( in most varieties the sugar component consists of glucose and fructose). Dates are also good sources of iron, potassium, calcium, magnesium, sulphur, copper and phosphorus, along with various vitamins, including thiamine, riboflavin, biotin, folic and ascorbic acid. The rich fruit play an important role in the nutrition of human populations in the above regions. Its use also as a livestock feed supplement gives the tree much added value. The secondary products generated from fruits are syrups, jams, ice creams, baby foods, alcoholic beverages and soft drinks. Small- and intermediate-scale industries can therefore be supported over long term periods in both urban and rural situations. This is reflected in its widely acknowledged sustainability value in social, economical and ecological terms.

Date palm trees are essential integral components of farming systems in dry and semi-arid regions and can be produced equally well in small farm units or as larger scale commercial plantation units. The tremendous advantage of the tree is its resilience, its requirement for limited inputs, its long term productivity and its multiple purpose attributes.

For centuries, the propagation of date palms by offshoots was the only commercial method of vegetative propagation used in date palm growing regions of the world to multiply up the best varieties. These offshoots are produced from axillary buds situated on the base of the trunk during the juvenile life of the palm. Offshoots develop slowly and the numbers of these are limited and are produced only within a certain period in the mother palm's life. The low number of transplantable offshoots available in the life time of a selected tree varies from 10 to 30 depending on the cultivar and the cultivation practices used. No field-based methods are as yet available with which to increase the numbers of offshoots produced by each tree. Offshoots have to be large enough (i.e. 10 to 12 kg) to survive when transplanted in the field, a process of regeneration that can take up to 10 years.

Sexual propagation is the most convenient method by which to propagate date palm: seeds can be stored for years, they germinate easily and are available in large numbers. However, this method can not be used commercially for propagating the cultivars of interest in a true-to-type manner for several reasons. The most obvious is the heterozygous characteristics of seedlings which is related to the dioecious nature of the date palm: half of the progeny are generally male, which produce no fruits, and large variations in phenotype can occur in progeny. Furthermore, no method is known at the present for sexing date palm at an early stage of tree development. It is therefore not possible to eliminate non-productive male trees in the nursery before plantation on a field scale. Another important drawback of seed propagation is that the growth and maturation of seedlings is extremely slow. A date palm seedling may take 8 to 10 years or more before fruiting occurs. For all of these reasons, propagation by seed is not practised by farmers and this propagation method is used only in exceptional cases when supplies of offshoots are unavailable.

Date palm breeding is hampered by the long generation cycles of trees. It usually takes more than 30 years to complete three backcrosses and to obtain the first offshoots from an intervarietal cross. To produce sufficient offshoots for testing in the field, other generations are required and if the breeding target is yield or fruit quality even more time will be needed as a date palm does not reach full commercial production for 10 years. It is therefore not surprising that little date palm breeding has been achieved using traditional approaches. In order to speed up the progress of date palm breeding programmes, particularly in those cases where date palms are being threatened by devastating diseases like the Bayoud as is the case in the Magreb countries in North Africa, biotechnology tools of tissue culture and genetic engineering can now effectively speed up all of the above processes and in addition genetic fingerprinting can be used to generate quicker and more precise analyses of elite clones and varieties, thus taking years off the traditional methods. Biotechnology is not necessarily the solution but it is one newly available tool that can assist breeders and palm producers improve the qualities of date palm and allow its use in many types of socio-economic, horticultural and agricultural development situations in dry and semi-arid regions of the world.

The Unit for Advanced Propagation Systems based at Wye College, University of London, UK has a long record of scientific studies on palm tree crops including date palm. In view of its long experience and acquired know how in the area of date palm propagation in particular with its many training and research links with North Africa and the Middle East, the Unit has recently established a date palm consultative group called NAKHLATEC which offers a range of technical, scientific and academic services geared to transfering its acquired expertise in the cause of date palm development. Its main aim is to integrate the biotechnologies of micropropagation and molecular biology so as to generate appropriate solutions to date palm genetic improvement. Its highly qualified team of arab, french and english speaking scientists and technicians all with practical experiences of these date palm biotechnologies provides:

Based in the Unit for Advanced Propagation Systems, Wye College on a University of London campus, NAKHLATEC can organise and offer a wide range of academic and research support services including the training of technicians and research scientists in all of the laboratory and greenhouse techniques necessary to achieve integrated practical solutions to date palm improvement. Higher degrees at the Diploma, M.Sc, M.Phil and Ph.D levels can be arranged to facilitate the staffing of date palm propagation and genetic fingerprinting units.

For information of these services and terms of the technical support consultancies offered by NAKHLATEC please contact:
NAKHLATEC Date Palm Consultative Group,
c/o Yaarub Al-Yahya
EMail: Y.Al-Yahya@wye.ac.uk


This page was last updated on 8th December, 1995.