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Recent trends and future demographic projections suggest that the need to produce more food and fibre will necessitate effective utilization of salt-affected land and saline water resources. Currently at least 20 per cent of the world's irrigated land is salt affected and/or irrigated with waters containing elevated levels of salts. Several major irrigation schemes have suffered from the problems of salinity and sodicity, reducing their agricultural productivity and sustainability. Productivity enhancement of salt-affected land and saline water resources through crop-based management has the potential to transform them from environmental burdens into economic opportunities. Research efforts have led to the identification of a number of field crops, forage grasses and shrubs, aromatic and medicinal species, bio-fuel crops, and fruit tree and agroforestry systems, which are profitable and suit a variety of salt-affected environments. Several of these species have agricultural significance in terms of their local utilization on the farm. Therefore, crop diversification systems based on salt-tolerant plant species are likely to be the key to future agricultural and economic growth in regions where salt-affected soils exist, saline drainage waters are generated, and/or saline aquifers are pumped for irrigation. However, such systems will need to consider three issues: improving the productivity per unit of salt-affected land and saline water resources, protecting the environment and involving farmers in the most suitable and sustainable crop diversifying systems to mitigate any perceived risks. This review covers different aspects of salt-affected land and saline water resources, synthesizes research knowledge on salinity/sodicity tolerances in different plant species, and highlights promising examples of crop diversification and management to improve and maximize benefits from these resources.

Suaeda salsa, a leaf succulent shrub in the family Chenopodiaceae, is one of the most important halophytes in China. Suaeda salsa produces dimorphic seeds (soft brown seeds and hard black seeds). Seeds of S. salsa were collected from the coastal salt flats near Huanghua City, China. Experiments were conducted to determine the salinity-alleviating effect of plant growth regulators, nitric oxide, nitrate, nitrite and light on the germination of dimorphic seeds of S. salsa. Brown seeds had a higher germination rate than black seeds in all experiments. Black seeds were more sensitive to salt in the absence of light in comparison to brown seeds. Brown seeds absorbed water more quickly in comparison to black seeds and were found to be more tolerant of salt stress. Our results showed that 1-aminocyclopropane-1-carboxylate (ACC, the immediate precursor of ethylene), nitrite, GA(4) and BA improved seed germination in the presence of salt. However, nitrate, GA(1), GA(3) failed to alleviate salt stress. ABA inhibited seed germination and seedling growth. Possible mechanisms involved in the alleviation of salt stress in S. salsa seeds and the ecological adaptation of the seeds to the environment are discussed.