Salt stress

Abstract

Saline water occupies 71% of the Earth area. It is thought that even a quarter of the whole pedosphere is affected by salts (Glenn and O'Leary, 1985), amounting to 950 x 106 ha (Flowers and Yeo, 1995), while 23 % of the 1.5 x 109 ha cultivated land is considered as saline (Rhoades and Loveday, 1990). Furthermore, about a half of all the existing irrigation systems of the world (3 x 108 ha) are under the influence of secondary salinization, alkalization and waterlogging, and about 10 x 106 ha of irrigated land are abandoned each year because of the unfavorable effects of secondary salinization and alkalization (Szabolcs, 1987). Such unfavorable soils of low fertility are generally unsuitable for agricultural production, causing unacceptable yield reduction, and in some cases, being far from any reasonable utilization. Because of the increased need for food production and increasing distribution of soils affected by salinity, research on plant responses to salinity has rapidly expanded in recent decades.