Genetic erosion of traditional varieties of vegetable crops in Europe: tomato cultivation in Valencia (Spain) as a case Study

Ever since the arrival of the tomato to Spain in the 16th century, great diversification of the crop has taken place, giving rise to a rich collection of varietal types. The ‘Comunidad Valenciana’, with its deep-rooted agricultural tradition, is one of the Spanish regions with the greatest diversity in traditional tomato varieties, characterised by their local adaptation and high fruit quality. Nevertheless, traditional varieties of tomato have been progressively abandoned over recent decades. A survey was carried out in the ‘Huerta de Valencia’ area of the ‘Comunidad Valenciana’ in order to evaluate the factors involved in the genetic erosion of traditional tomato varieties, as a model of the process affecting vegetable crops in Europe. The growth of urban areas that absorb horticultural land, the change in agricultural techniques, the low profitability of farms and their small size, the advanced age of farmers, the conversion of vegetable gardens to other crops and the incidence of viral diseases, have been identified as the major factors affecting genetic erosion in this analysis. The development of resistant traditional varieties through a formal plant breeding programme, and the consolidation of the specialised markets that efficiently exploit the organoleptic quality of these varieties, would help to assure the profitability of these varieties, and hence their active conservation on an on-farm basis. Consequently, the loss of these materials that make up gene combinations of an outstanding value could be prevented, and farmers would obtain a profitable alternative in a highly competitive agriculture.