Keywords

11.1 Introduction

According to Hasanuzzaman et al. (2014), the total area of salt-affected soils is reported to lie around 831 million hectares in the world including 397 million hectares of saline and 434 million hectares of saline or sodic soils. The pollution, degrading environmental conditions, increasing natural calamities, and global climate change are reported to be the main cause for the decrease in agricultural lands (Hasanuzzaman et al. 2013a, b, 2014). Salt is affecting approximately 50 million hectares of irrigated land. This accounts for a 20% of the total land. Every year nearly 1.5 million ha of land is taken out of production due to high salinity problems (Pitman and Lauchli 2002; Munns and Tester 2008). If this situation continues like that, nearly 50% of the cultivable lands will be lost by the middle of the twenty-first century (Mahajan and Tuteja 2005).

Halophytes are the plants able to survive and reproduce in environments where salt concentrations exceed 200 mM of NaCl (∼20 dSm−1) (Flowers and Colmer 2008). These plants constitute nearly 1% of the global floral diversity. These plants are capable of completing their life cycle under highly saline conditions (Stuart et al. 2012). Generally, different halophyte taxa grow in different saline regions in the world. These could be coastal saline habitats, on mangrove forest soils, wetlands, marshy areas, arid and semiarid regions, and agricultural fields (Hasanuzzaman et al. 2014).

Many halophytes have been investigated as potential crops under the sea or brackish water irrigation. Their growth on such soils includes a wide range of applications like desalination, heavy metal extraction in order to improve the soil characteristics, biomass production, food, fuel, fodder, and fiber (Debez et al. 2011; Lokhande and Suprasanna 2012; Hasanuzzaman et al. 2014). A direct halophyte plant consumption by humans is limited. However, the seeds of many halophytes have been recorded as new sources of grains or vegetable oils (Hinman 1984; Debez et al. 2011). The plants able to thrive in highly saline habitats can be used to produce materials with high economical value for being salt-tolerant. These are the essential oils, flavors, fragrances, gums, resins, oils, pharmaceuticals, and fibers (Galvani 2007; Ksouri et al. 2007; Debez et al. 2011). They are marketed for use for ornamentation because of their foliage or flowers (Messedi et al. 2004; Slama et al. 2006; Debez et al. 2011). Salt-tolerant species can be grown on land and water unsuitable for conventional crops to produce fuelwood as well as building materials (Debez et al. 2011). The use of such precious strategies can prove helpful in the reclamation of unused and marginal lands, which can be brought under cultivation, opening a new door for sustainable crop production (Hasanuzzaman et al. 2014). In this chapter, we are focusing on the potential human food and animal fodder taxa of halophytes in Southwest Asia.

11.2 General Account of Halophyte Diversity

This region is mostly arid with gravel and sandy desert areas, lying at the edges of a large tectonic plate. A total of 728 taxa of halophytes have been reported from SW Asia (Ghazanfar et al. 2014). From the data available, Turkey has the maximum number of halophytes (±420 taxa), followed by Pakistan (±410 taxa), Iran (±365 taxa), Jordan (±263 taxa), and Saudi Arabia (±250 taxa) (Table 11.1). In Southwest Asia, this group of ecologically valuable taxa is recorded as being about 50% of halophyte taxa (and families) recorded for the world (Aronson 1989; Ghazanfar et al. 2014). Chenopodiaceae, Poaceae, Leguminosae-Papiliondeae, Asteraceae, and Cyperaceae are the dominating families rich in halophytic taxa. The largest number of taxa is found in the Chenopodiaceae, which is exceeded by Poaceae with more genera but fewer species. These findings are in accordance with those recorded for the global halophyte taxa (Flowers et al. 1986; Ghazanfar et al. 2014).

Table 11.1 Number of halophytic taxa in Southwest Asian countries
Full size table

11.3 Data Analysis

A total of 16 countries included in Southwest Asian region have been selected as the study area for this investigation. The floristic data published by Batanouny (1993), Batanouny (1994), Le Houérou (1993), Khan (2003), Akhani (2006), Moghaddam and Koocheki (2003), Abbas (2006), Güvensen et al. (2006), Khan and Qaiser (2006), Weber et al. (2007), Yensen (2008), Khan and Ansari (2008), Al-Oudat and Qadir (2011), Cassaniti and Romano (2011), Ghazanfar et al. (2014), Qasem (2015), Breckle (2016), El Shaer and Attia-Ismail (2016), Ghazanfar and McDaniel (2016), Phondani et al. (2016), Öztürk et al. (2008a, b), Öztürk et al. (2014), Öztürk et al. (2016), and Öztürk et al. (2017) has been evaluated in this chapter, together with other published records on halophyte diversity. The halophyte taxa whose status or name has changed, or have become synonyms, or have been included under new combinations, have been corrected following the “Ghazanfar et al. (2014).” The existing potential of food and fodder halophyte taxa has been evaluated taking into account the floristic structure of the study area. The economic potential of the floristic data published for food and fodder halophyte taxa with potential alternative use too has been followed.

11.4 Halophytes Used as Human Food

Many wild halophytes are a rich source of nutrients and bioactive compounds with a taste similar to conventional salad crops (Petropoulos et al. 2018). These are at the same time recorded as being important mediators in various health problems (Trichopoulou et al. 2000). The lifestyle of present-day humans is creating a market niche for commercial cultivation of various halophytes, because some are handpicked as wild greens and some of these show seasonality, and therefore their availability all through the year is not in a position to meet the demands of consumers (Petropoulos et al. 2015, 2016, 2018). According to Petropoulos et al. (2018), the wild-growing halophytes in the Mediterranean Basin are a valuable genetic source with great adaptation to extreme conditions like salinity of soil and irrigation waters. These could serve as a source of alternative cash crops in a saline agriculture regime. Diversified and higher contents of bioactive compounds in some render them as very promising candidates for the food industry. These could be evaluated for designing and producing novel food products with functional and health-beneficial features like beverages, leafy salads, microencapsulated oils, food additives, antimicrobial agents, and many others (Petropoulos et al. 2018). However, there is a need for a multistep approach for implementation before such products can be produced commercially. All this includes an evaluation of various ecotypes of the candidate species for selecting the ones with most promising properties; an integration of selected genotypes in breeding programs for an improvement of selected features like enhanced bioactivity and content of bioactive compounds, improved agronomic features, and decreased content of possible antinutrients; evaluation of cultivation practices to find most suitable practical guides; assessment of the content of bioactive compounds under the conditions of commercial cultivation; clinical and model trials to know about the mechanisms of health effects together with the recommended consumption on a daily basis, for avoiding possible toxicity effects; designing and marketing of novel halophyte food products; a look-into the alternative approaches for healthy diets and well-being together with the increase of consumer awareness; the legislation regarding consumers safety issues and genetic conservation of the halophyte species is very important (Petropoulos et al. 2018).

A total of 115 halophytic taxa with potential food value have been recorded from Southwest Asia (Appendix I). The only species with halophytic ancestors among the conventional crops are beets (Beta vulgaris) and the date palm (Phoenix dactylifera). These can be irrigated with brackish water. The seed-bearing species used as food are Salvadora oleoides, S. persica, Trianthema portulacastrum, Oxystelma esculentum, and Zizyphus nummularia. The young leaves and shoots of Salicornia bigelovii, Halosarcia indica, Sesuvium portulacastrum, Chenopodium album, Atriplex hortensis, Triglochin maritima, Arundo donax, Rumex vesicarius, Apium graveolens, Portulaca oleracea, and Suaeda maritima are used as vegetables, salads, and pickles in several countries of this region. Suaeda fruticosa and Haloxylon stocksii are used to prepare a kind of baking soda, which is used in the preparation of food. According to Khan (2003) and Khan and Qaiser (2006), some of the species used as salad are the radicles of Rhizophora mucronata, Zizyphus nummularia, and Ceriops tagal and tender leaves of Thespesia populneoides and Hibiscus tiliaceus. The seeds of halophytes like Suaeda fruticosa, Arthrocnemum macrostachyum, Salicornia bigelovii, Halosarcia indica, Halogeton glomeratus, Bassia scoparia, and Haloxylon stocksii are reported to possess sufficient quantity of high-quality edible oil with unsaturation ranging from 70% to 80% (Weber et al. 2001; Weber et al. 2007). The data published by Khan (2003) and Khan and Qaiser (2006) reports that the seeds of Salvadora oleoides and S. persica contain 40–50% fat. They stress that these plants are a good source of lauric acid. The purified fat can be used for soap- and candlemaking and is a potential substitute for coconut oil.

11.5 Halophyte Taxa with a Potential as Fodder Plants

In arid and semiarid regions for millennia, halophytes and salt-tolerant plants have been used as sources of food (Le Houérou 1993; Glenn et al. 1999; El Shaer 1999, 2010; El Shaer et al. 2005). According to El Shaer (2010), a large number of halophytes, as well as salt-tolerant taxa, have been evaluated as fodder especially under drought conditions as well as fill the gap in feeding animals during fodder shortage resulting from adverse seasonal conditions. The value of certain some halophytic shrubs, legumes, and grasses has been used in pasture improvement programs as well as in many salt-affected regions at the global level (Glenn et al. 1999; ICBA 2006; El Shaer 2010). In arid as well as semiarid areas, many of the fodder plants come from several salt marsh taxa. According to Salerian et al. (1987), Malcolm (1993), and El Shaer (2010), farmers have always been making money from saline wastelands. Extension of halophytes and other salt-tolerant plants into farming practices depends on their compatibility with current land use system. It depends on the provision of enough incentive to encourage pasture and forage crop production as well as on the acceptance by farmers (El Shaer 2010).

In both arid and semiarid regions, the halophytes together with other salt-tolerant plants have been a major part of the feeding program of sheep, goats, camels, and some wildlife animals (Squires and Ayoub 1994; El Shaer 1997a, b, 2010). Shortage of fodder is a common feature in such regions, and it is the main constraint to improve livestock productivity. Tremendous efforts have been spent to find alternative resources of fodder from saline habitats (El Shaer 2006). In particular, the halophytic forage species will have better cash value if their forage qualities such as high palatability and digestibility and good nutritional value in particular high protein and less fiber, ash, and oxalate contents are significantly improved (El Shaer 2006). Generally, the majority of halophyte species contain enough quantity of crude protein, as well as essential nutrients which cover the nutritional requirements of animals (Arieli et al. 1989; El Shaer 1981, 2006). As the plants grow and reach maturity, fibrous materials and ash contents increase, whereas the gross energy and protein contents decrease (Kandil and El Shaer 1988; El Shaer 2006). It has also been reported that during wet seasons, several halophytes are nutritious and can sustain the maintenance requirements of animals, but in summer and autumn when the conditions are dry, the halophytes are poor and need to be supplemented with other ingredients, particularly with higher energy values (Atiq-ur-Rehman 2002; El Shaer 1997a, b, 2006). Although some halophytes are deficient in sulfur and phosphorus, sufficient amounts of major minerals are found in salt marsh plants, which do not produce any harmful effect even when such minerals are found in high concentrations in some of these (El Shaer 1981, 2006; Gihad and El Shaer 1994).

As individual fodder source, the halophytic taxa are not much valuable. The reason being that extended feeding periods produce adverse effects on browsing animals. Different factors are responsible for fodder consumption by different animals because of the variations in the palatability and acceptability of halophytes (Gihad and El Shaer 1994; El Shaer 2006). Some halophyte plants can be given to the animals directly, and some can be left for direct grazing as fresh fodder consumption. Some of the latter are highly or moderately palatable and nutritious, for example, Atriplex spp., Nitraria retusa, and Suaeda fruticosa. These taxa are generally overgrazed and decrease in the cover due to high grazing pressure (El Shaer 1981, 2006). Mixing halophytes as forage with other fodders rich in protein or energy can improve nutritional value to a great extent (El Shaer 2006). As against this many halophyte plants are unpalatable but do produce large biomass all through the year. In arid areas, there is a need for utilization of such plants, particularly during the dry seasons or during long-lasting droughts when other sources of fodder are lacking. Some secondary metabolites or so-called anti-nutritional factors like tannins, alkaloids, saponins, and nitrites hinder the use of some halophytes as these affect negatively (El Shaer 2006). Utilization of such halophytes has been evaluated following different approaches through different processing treatments to improve their palatability and nutritive values (El Shaer and Kandil 1990; El Shaer et al. 1991; El Shaer 2006). One of these approaches is chopping which dramatically improves the palatability of succulent taxa and allows efficient utilization of whole shrubs. Similarly, haymaking, haylage, or ensiling processes of some halophytes also improve their fodder consumption value (El Shaer 2006).

Animal protein is one of the major requirements for human beings. This makes it very important to evaluate all kinds of available pastures, including those which mainly are present in climatically unfavorable regions. Animals generally have to consume the only available fodder source, the halophytes, in such areas (Attia-Ismail et al. 2009; Attia-Ismail 2016). In both the arid and semiarid regions, a deficiency of fodder sources is one of the basic problems to improve the productivity of animals (Attia-Ismail 2016). The desert grazing sheep, camels, and goats require fodder plants with improved nutritional values particularly during the long-lasting dry seasons; this will increase the average annual animal production by more than 25% (Attia-Ismail 2016). Attempts are made to use the marginal sources, for example, saline soils and underground water for producing unconventional fodder ingredients (Attia-Ismail 2016).

The report published by Batanouny (1993) has revealed that the halophytes cover huge areas of rangelands in Algeria, Egypt, Gulf countries, Iran, Iraq, Jordan, Libya, Morocco, Pakistan, Saudi Arabia, Sudan, Syria, Tunisia, and Yemen. The rangelands in these countries are used throughout the year by sheep, goat, and camels, and the species generally consumed are Atriplex halimus, A. mollis, A. portulacoides, A. glauca, A. nummularia, Suaeda fruticosa, S. brevifolia, S. mollis, Salicornia arabica, Limoniastrum monopetalum, Limoniastrum guyonianum, Traganum nudatum, Salsola vermiculata var. villosa, Salsola sieberi, S. tetrandra, Arthrocnemum indicum, Salicornia fruticosa, Inula crithmoides, Halocnemum strobilaceum, Tamarix spp., and Nitraria retusa. Fairly good palatability has been recorded for some nonshrubby perennial halophytes such as Nitraria retusa, Suaeda fruticosa, Spergularia media, S. marginata, Hedysarum carnosurn, Puccinellia spp., and Spartina patens. Some like Aster tripolium, Heliotropium curassavicum, Suaeda maritima, Juncus spp., Schoenus nigricans, Cyperus spp., Scirpus spp., Phragmites spp., Typha spp., Arundo plinii, A. donax, Saccharum ravennae, and Ruppia spp. are almost unpalatable. Out of these, a majority are hygrohalophytes (Batanouny 1993). Very low palatability has been reported in the majority of annual halophytes as they produce little phytomass, e.g., Hordeum maritimum, Polypogon, Sphenopus, Lepturus, Pholiurus, Psilurus, Eremopyrum, Frankenia, Aizoon, Mesembryanthemum, Cressa, Zygophyllum, Tetradiclis, Halopeplis, Halogeton, Schanginia, Suaeda, Salsola, and Salicornia (El Shaer and Attia-Ismail 2016). However, any evaluation of halophytes depends on their performance both in the biological as well as its economic input (El Shaer and Attia-Ismail 2016). For an indigenous animal production, shortage of fodder is the main constraint, which therefore needs to be increased. In both arid and semiarid regions, it is a common characteristic accepted as the main constraint to improve livestock productivity (El Shaer and Attia-Ismail 2016). Main income for the people raising animal herds is based on the natural vegetation for rearing sheep, goats, and other herbivores. Although unpalatable halophytes are widely distributed in the world, the halophytic plants like Atriplex spp., Nitraria retusa, and Salsola spp. are considered extremely valuable as a source of fodder during drought periods (El Shaer and Attia-Ismail 2016). Most of the countries in the arid and semiarid regions import large quantities of fodder to fill the nutritional gap of animals. This puts a heavy burden on the farmers as well as the governments. It decreases the net profits from animal investments because of the high costs of imported fodder. Therefore, intensive efforts should be directed to find alternative resources from halophytes as fodder (El Shaer and Attia-Ismail 2016).

The foliage of species like Avicennia marina, Aegiceras corniculata, Ceriops tagal, and Rhizophora mucronata are evaluated as camel and cattle feed. Similarly the species of Acacia, Prosopis, Salvadora, and Zizyphus trees are well known as a traditional fodder of arid regions. Several species of Alhagi, Salicornia, Chenopodium, Atriplex, Salsola, Suaeda, and Kochia are well-known common fodder shrubs. The species like Leptochloa fusca, Aeluropus lagopoides, Dactyloctenium sindicum, Cynodon dactylon, Paspalum vaginatum, Sporobolus marginatus, Chloris gayana, C. virgata, Echinochloa turnerana, E. colona, and Puccinellia distans are common grass species flourishing on saline and alkaline areas and used as forages (Khan 2003; Khan and Qaiser 2006).

A total of 331 fodder halophyte taxa are distributed in the region (Appendix II). The constraints of using halophytes and other salt-tolerant plants as potential feed resource for animals have been studied at length by El Shaer (2010). The benefits outlined by him are the yield of halophytes and salt-tolerant forages as edible biomass in saline lands where non-halophytic species cannot grow varies from low to high; several halophytes are a potential source of nitrogen and major minerals for sheep and goats fed on low-quality diets; therefore energy supplementation with diets containing halophytes proves effective to overcome nutrient deficiencies in animals; the lignins, oxalates, and nitrates can prove limiting as anti-nutritive factors in the animal diets in particular while utilizing some halophytes and salt-tolerant forages in livestock feeding mainly as sole diets, appropriate mixing of different halophytic taxa, based on their complementary roles, can dilute the negative effects of the anti-nutritive factors cited here and therefore improve animal performance; and finally a wide range of halophytes and salt-tolerant grasses can prove as promising fodder resources for small ruminants raised around the saline areas or in arid and semiarid regions.

11.6 Conclusions

Halophytes are a small but diverse group of plants distributed as natural flora of saline habitats. These remarkable plants have a potential to revolutionize the future by fulfilling the human needs especially those related to food, fodder, fuel, and medicines (Hameed and Khan 2011). The cultivation and conservation of such natural resources can prove helpful in the sustainable maintenance and utilization of halophytic plant wealth. These can be evaluated to develop many small industries with small grants from the government, thereby uplifting the socioeconomic status of the poor. Both government and private sectors should invest in this venture to make halophytes as a resource for future (Hameed and Khan 2011). Sustainable use of our marginal lands and water resources for food-feed crops and forage legumes can prove fruitful for improving our global food security, reduce poverty, resilience against climate change, and enhance ecosystem health in crop-livestock systems (Qureshi 2017). Moreover, a good choice for salinity control and remediation is adoption of halophytes together with salt-tolerant plant taxa, which can have significant effect on the economic development of dry saline regions lying a waste. In addition to this, agroforestry can solve drainage problems. It will also create good environmental conditions for the desert and semidesert areas (Qureshi 2017).

The feasibility of cultivating salt-tolerant plants successfully in saline ecosystems offers unexpected opportunities for everyone including the farmers to identify the most appropriate cash crop halophyte. Their combinations can prove highly beneficial in optimizing the input/output ratios (Debez et al. 2011). In many cases the salt-affected soils and groundwaters cross national boundaries. There is a need for cooperation and coordination at regional and interboundry level. It is very important to elaborate and apply effective salinity strategies. For this purpose there is need to involve politicians, institutions, farmers, water user associations, and all beneficiaries in such applications, so that everybody is familiar with his role (Yensen 2006). In short, we must strive hard to change the general opinion of the farming communities and policy makers related to the questionability of evaluating the salt-affected soils (Debez et al. 2011).