As halophytes grow vigorously in saline soils, they serve as extraordinary resources for the identification and development of new crop systems. Understanding the mechanisms of tolerance of halophytes to salinity in combination with other co-occurring constraints such as drought, flooding, heavy metals and nutrient deficiencies, would facilitate efforts to use halophytes for saline land revegetation, as well as provide new insights that might be considered in future breeding of plants for salt-affected agricultural lands. Recent results suggest that salinity may improve the response of halophytes to other stresses. Some physiological and biochemical mechanisms of tolerance to salinity are common to many halophytes when plants are subjected to salinity, whereas others are specifically amplified under a combination of stresses. Therefore, the response of halophytes to multiple stresses may not reflect an additive effect of these constraints, but rather, constitute specific response to a new situation where many constraints are operating simultaneously. Comparative studies between halophytes and glycophytes have shown that halophytes are better equipped with the mechanisms of cross-stress tolerance and are constitutively prepared for stress. Moreover, other data has shown that the pre-treatment of halophytes with salinity or other constraints in the early stages of development improves their subsequent response to salinity, which suggests the capacity of these plants to ‘memorise’ a previous stress allows them respond positively to subsequent stress.

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The use of saline water for the irrigation of forage crops to alleviate water scarcity has become necessary in semi-arid and arid regions and researchers have been seeking ways to offset the harmful results of soil salinity. Soil amendments with compost, manure and other organic material provide a valuable source of plant nutrients and appear to speed up soil recovery. The aim of this study was to compare the benefits of farmyard manure and a municipal solid waste (MSW) compost (40 mg ha−1) for raising alfalfa (Medicago sativa, cv. Gabès) under salt-water irrigation. Both compost and manure improved plant mineral uptake and growth of alfalfa cultivated in clay soil. Using compost in clay soil increased the content of copper (Cu), cadmium (Cd), and zinc (Zn) in plant tissues compared to manure, while the bio-accumulation factor (BAF) of Cu, Pb and Zn was higher in plants grown with manure compared to MSW compost with salt stress. Compost addition could enhance alfalfa growth under salt stress, which depends on salt doses and can greatly improve the recovery effects in a cost-effective way, although additional amendment type should receive special attention in order to be used as a tool for sustainable agriculture.