Salinity and Water Stress

Abstract

Seven percent of the land's surface and fi ve percent of cultivated lands are affected by salinity. There are often not suffi cient reservoirs of freshwater available and most of the agronomically used irrigation systems are leading to a permanent increase in the soil-salinity and step by step to growth conditions in-acceptable for most of the conventional crops. Signifi cant areas are becoming unusable each year. Although it is a world-wide problem, most acute is in Australasia, the Near East and Africa, North and Latin America and to an increasing degree also in Europe. This large extent of salinity problem reduces crop productivity. In contrast to crop plants, there exist specialists that thrive in the saline environments along the sea shore, in estuaries and saline deserts. These plants, called halo-phytes, have distinct physiological and anatomical adaptations to counter the dual hazards of water defi cit and ion toxicity. The sustainable use of halophytic plants is a promising approach to valorize strongly salinised zones unsuitable for conventional agriculture and mediocre waters. There are already many halophytic species used for economic interests (human food fodder) or ecological reasons (soil desalinisation, dune fi xation, CO 2 -sequestration). However, the wide span of halophyte utilisation is not jet explored even to a small degree. For economic utilisation of potential halophytes ecological studies should be complemented with comparative physiological studies about salinity tolerance in halophytes are essential.