## 1 Introduction  
Currently, the main agricultural challenge is to meet the rapidly growing and changing demand for food in an environmentally and socially sustainable way [1]. Whilst the increase in food production will have a decisive role in meeting this target, the Earth's finite resources will negatively affect the process, with food producers already experiencing greater competition for natural resources [2]. Under this scenario, the production of food using alternative natural resources, including salt-affected soils and saline waters, might represent a necessary tool to explore [3]. Plants can be arranged in two main groups with respect to their response to salinity: salt-sensitive (i.e., glycopythe) and salt-tolerant (i.e., halophyte) species [4]. Other classifications, such as for instance [PERSON]'s [5], correlate the crop yield to the electroconductivity in the soil identifying four groups of responses: sensitive, moderately sensitive, moderately tolerant and tolerant. Currently, the majority of agricultural crops are salt-sensitive. A possible explanation for this is that the domestication and selection of the requested productive traits have been made under nonsaline conditions, where a possible loss of salt-tolerance traits did not represent an actual constraint [6]. Despite these detailed classifications, most data on crop salt-tolerance, for instance those presented by the FAO, are actually based on a single variety of a specific crop species [5; 7]. However, it has been shown that different varieties are characterized by different tolerance to salinity [8]. Moreover, data on crop salinity tolerance are often obtained through screening made with NaCl solutions, which do not reflect the more complex salinity conditions of salt-affected soils. In fact, only a small number of studies on salinity consist of enough critical information to meet the requirements for a good salt-tolerance dataset [9]. In response to the increasing saline conditions in several world areas, a number of halophyte species have been recently investigated as potential new crops for these harsh environments [3; 10; 11; 12; 13; 14; 15; 16]. Anyhow, to the best of our knowledge, the role of different salt types on determining specific salinity stress conditions for the plant has rarely been investigated. A screening that would consider the more salt-tolerant varieties of commonly grown glycopre crops along with potential new edible halophyte crops, under different types of salinity conditions, would provide a better understanding of potential crops suitable for saline agriculture. Salt-affected soils occur in more than 100 countries, and their worldwide extent is estimated at about 1 billion ha [17] more than 34 Mha arable lands are salt affected [18]. These surfaces are currently not suitable for most agricultural crops either because they are coastal or because inappropriate irrigation practices have degraded the soil and depleted or salinized the groundwater [19]. The causes of soil salinization are numerous, including the use of saline irrigation water, the deposition of salts on the soil surface due to capillary rise from a shallow water table, drought, poor drainage, and seawater intrusion in coastal areas [20]. Although seawater is often detrimental to a plant's growth, it has been proven that its specific mineral composition may represent a balanced ionic environment for plants [21]. In fact, despite a very high sodium and chloride content (i.e., about 75% NaCl and 10% of MgCl\({}_{2}\)), seawater is rich in nutritive elements needed by plants [12], also including the necessary trace elements and living or dead micro-organisms [22; 23]. In addition, the detrimental effects of salinity on crop yield depend on co-occurring factors. For instance, a different response in crop yield to increasing soil salinity has been observed for sandy and clay soils, with the former being favorably tested in saline conditions [8; 13].