Local citrus genetic resources of the Maltese Islands

Abstract

The Maltese Islands are enriched with a diversity of citrus genetic resources, most of them in the form of old-aged trees. Citriculture in the Islands have been practiced for more than a thousand years, in areas protected from winds and with fresh water sources available all year round in valley heads and walled gardens. In the past Maltese citrus fruits were very much renowned in European countries for their taste and quality and fetch high prices. But the importance of citriculture lowered due to the cultivation of vines and other fruit trees. At present only 0.9% of the total utilisable agricultural land is cultivated with citrus, with equal areas in Malta and Gozo. The diversity of local citrus genetic resources has been described by Dr. John Borg in 1922. More recently clonal and sanitary selection has been carried out in order to identify old local varieties for their propagation and conservation, to increase production fruits from local varieties and to decrease the chance of introducing the Citrus Tristeza Virus. In the Sub-sector studies for key sectors, suggestions have been given in order to propagate from local citrus genetic resources and to control major citrus diseases, namely the CTV and its main vector Toxoptera citricida. The importance of conserving local citrus genetic resources has been evidenced in the Rural Development Programme for Malta 2007-13, especially the old aged citrus trees. For this reason a register has been set-up in order to record these old citrus trees. Local citrus genetic resources is facing a number of threats that slowly are causing its loss, factors like the lack of local nurseries that propagate them, lack of characterisation and identification, water scarcity and climatic conditions, diseases like the CTV, lack of sanitary assessment and other economic factors. The conservation of local citrus genetic resources requires particular attention. Strategies for its conservation include the establishment of a responsible institution, inventorying, characterisation of local varieties, collection and conservation in-situ and ex-situ, and projects for the propagation and utilisation of local varieties.