干旱区生态环境知识资源中心

Salinity is an important problem in arid and semi-arid regions. The estimated rate of increase in coastal salination in the Mediterranean Basin is about 0.1-0.2 dS/m, and the decline of water table is 0.1-0.5 m/year. The major commodity group threatened by salinity are horticultural crops. A project was initiated to select species that have high salt removing capacity and have commercial value. Various wild species adapted to coastal regions of the Mediterranean as well as some commercially grown varieties were screened for this attribute. A pot trial is set up with three salinity levels (0, 3.5 and 6.5 dS/m) and in the year 2000, purslane (Portulaca oleracea) and four accessions of Beta maritima collected from the Aegean coast were tested in perlite medium. In 2001, purslane was compared with New Zealand spinach (Tetragonia tetragonoides) and barley cv. Hassan (Hordeum vulgare) in sand culture. The fertigation is made with half strength Hoagland solution. A parallel trial where these plants are tested as intercrop with satsuma mandarins is still ongoing. The vegetative growth [fresh and dry plant weight (root and above ground parts)], stage of flowering, salt, water and nutrient uptake parameters are determined. The results showed that there is a significant difference in terms of salt uptake of the tested Beta maritima accessions. Due to its dense planting and method of harveting (marketed with the roots as a whole plant) purslane is accepted as a promising salt removing crop. Beta maritima is used as animal fodder and purslane and New Zealand spinach are used as leafy vegetables in various Mediterranean countries. High salt uptake and vigour of the tested species at salinity levels of 6.5 dS/m prove that they can be integrated into rotation programs or planted as intercrops for perennial plants in order to control salination.