Saline Agriculture: Salt-Tolerant Plants for Developing Countries (BOSTID, 1990, 130 p.) Food Introduction Grains and oilseeds Tubers and foliage Leaf Protein Fruits Traditional crops References and selected readings Research contacts

Saline Agriculture: Salt-Tolerant Plants for Developing Countries (BOSTID, 1990, 130 p.)

Food

Introduction

Saline agriculture can provide food in several ways. Appropriate salt-tolerant plants currently growing in saline soil or water can be domesticated and their seeds, fruits, roots, or foliage used as food. When the foliage is too high in salt for direct consumption, the leaves can be processed to yield salt-free protein, which can be used to fortify traditional foods. In addition, conventional food crops can be bred or selected to tolerate mildly saline water.

This section will examine some of the little-known seed-bearing plants that grow in saline environments and their special characteristics, the use of foliage from salt-tolerant plants to produce leaf protein, some salt-tolerant fruits, and the performance of some conventional food crops with saline water.

Of conventional crops, the only ones with halophytic ancestors are sugar-, fodder-, and culinary beets (all Beta vulgaris) and the date palm (Phoenix dactylifera). These plants can be irrigated with brackish water without serious loss of yield. Of about 5,000 crops that are cultivated throughout the world, few can survive with water that contains more than about 0.5 percent salt, and most suffer serious losses of yield at about 0.1 percent salt. In searching for crops for saline agriculture, those that currently comprise the bulk of human food should be considered as models - maize, wheat, rice, potatoes, and barley. If these major crops can be grown using saline resources, or if new, salt-tolerant crops that are acceptable substitutes can be developed, the world's food supply will have a more diverse and vastly expanded base.

Along with significant technical impediments to the widespread use of saline resources for food production, social barriers may exist as well. Food preparation is one of mankind's most culture-bound activities. Food selection, cooking method and participants, flavor, consistency, and serving time and place are often established by long tradition, and practitioners are resistant to change. New foods that require significant changes in any of these practices are unlikely to be readily accepted.

Grains and oilseeds

Many seed-bearing halophytes have an interesting characteristic: although they may have significantly greater levels of salt in their stems, branches, and leaves than conventional plants, their seeds are relatively salt-free. Seeds of halophytes and salt-sensitive plants have about the same ash and salt content, as shown in Table 2.

TABLE 2 Protein, Oil, and Ash Contents of Seeds from Salt-Sensitive and Salt-Tolerant Plants.

	Percent of Dry Weight as
Seed	Protein	Oil	Ash
Salt-Sensitive
Safflower	14.3	30.4	2.5
Sesame	18.6	49.1	53
Soybean	40.0	18.8	4.8
Sunflower	17.5	36.0	3.6
Salt-Tolerant
Atriplex canescens	5.4	1.0	6.5
Atriplex triangularis	16.4	9.4	3.5
Cakile edentula	28.6	52.2	5.2
Cakile rnaritima	21.5	47.1	5.0
Chenopodium quinoa	12.1	7.5	3.1
Crithmum maritimum	21.5	41.4	8.0
Kosteletzkya virginica	23.8	18.1	5.0

SOURCE: O'Leary, 1985.

This has valuable consequences. Although the direct consumption of halophyte vegetative tissue by humans and animals can be limited by its salt content, the seeds of many halophytes present no such obstacle. This allows consideration of a wide variety of seed- producing halophytes as new sources of grains or vegetable oils.

Some salt-tolerant grains and oilseeds have already been used or examined.

Almost fifty species of seed-bearing seagrasses grow in nearshore areas of the world's oceans. One of these, Zostera marina, grows fully submerged in seawater.

Eelgrass (Zostera marina) grows well in the Gulf of California in North America. In this region, seawater temperatures seldom fall below 12°C and can reach 32°C in summer.

Sunlight is intense. At maturity in the spring, the reproductive stems bearing the seed break loose and are washed ashore. Harvest involves collecting these stems and separating the seeds. The seeds, 3-3.5 mm long and weighing up to about 5.6 ma, contain about 50 percent starch, 13 percent protein, and 1 percent fat. The Seri Indians used this seed as one of their major foods.

Although the potential for growing a food crop directly in seawater is attractive, there are obstacles to broader cultivation of eelgrass. Coastal deserts offer the best possibility, but tidal action is required; these grasses apparently cannot grow in stagnant water. In warm, dry climates the plants can tolerate only short exposure to the air.

Palmer saltgrass (Distichlis palmer)) grows in tidal flats and marshy inlets in the Gulf of California, and thrives with tidal inundations of seawater. It is a perennial with tough rhizomes from which emerge densely crowded stems about 0.5 m tall. The spikelets, which bear the seed, readily shatter and are also dislodged by tidal action. Although this shattering is generally undesirable in a crop (because seed on the ground is difficult to gather), with Palmer saltgrass, the spikelets float and are washed ashore. These seeds were gathered by the Yuman Indians, ground into flour, and consumed as a gruel. It can also be used to make bread.

Once established, Palmer saltgrass should not need replanting. Preliminary observations indicate that it is fast-growing and the standing crop is extremely dense. These dense stands along with the saline conditions should reduce competition from weeds. Field tests with hybrid cultivars of this crop yielded about 1,000 kg of grain per hectare when irrigated with water containing 1-3 percent salt. Optimum yields are projected to be obtained at about 2 percent salinity. The nutritional characteristics of D. palmer) are summarized in Table 3.

TABLE 3 Nutritional Composition of Distichlis palmer) vs. Wheat and Barley.

	Percent of
Crop	Protein	Fiber	Fat	Ash	Carbohydrate
D. palmer)	8.7	8.4	1.8	1.6	79.5
Wheat	13.7	2.6	1.9	1.9	79.9
Barley	13.0	6.0	1.9	3.4	75.7

SOURCE: Yensen, 1985.

The grain from a D. palmer) variety developed by NyPa, Inc. has a well-balanced amino acid profile and three times the fiber of common wheat. Antinutritional physic acid is very low, and gluten, a potentially allergenic protein, is not present in detectable amounts.

Alkali sacaton (Sporobolus airoides) is a widespread perennial grass in the western United States and northern Mexico, often occurring on alkaline or semisaline soils. Its 0.95-1.2 mm grain is edible and was probably a significant food resource for Hopi and Paiute Indians of the North American Southwest. The grain is readily separated, produced in large quantity, and should be suitable for harvesting with a basket. Although S. helvolus and S. maderaspatanue also grow on saline soils, the use of their grain as food has not been reported.

Pearl millet or bajra (Pennisetum typhoides), a popular food grain in Africa and India, has been grown on coastal dunes near Bhavnagar using seawater (EC = 26.6-37.S dS/m) for irrigation. When seedlings were established with fresh water and fertilizer applied, multiple irrigations with seawater gave yields of 1.0-1.6 tons per hectare of grain and 3.3-6.5 tons per hectare of fodder.

Quinoa (Chenopodium quinoa) is a staple of the Andean highlands. An annual herb, quinoa grows 1-2.5 m tall at altitudes of 2,500-4,000 m. The plant matures in 5-6 months, producing white or pink seeds in large sorghum-like clusters. Although the seeds are small, they comprise 30 percent of the dry weight of the plant. Yields of 2,500 kg per hectare have been reported. Quinoa has a protein content that is higher, and an amino acid composition that is better balanced, than the major cereals. Although quinoa has bitter tasting constituents - chiefly saponins - in the seed's outer layer, these can be removed by washing the seeds in cold water. The seeds are traditionally used in soup or ground into flour for bread and cake. They have also been used for brewing beer and for animal feed.

Somers (1982) reported that quinoa germinated in a mixture of one-third seawater and two- thirds fresh water but would not grow at this salinity. In the salt flats of southern Bolivia and northern Chile, quinoa is one of the few crop plants grown. In this arid region (230 mm annual rainfall), quinoa is planted in holes about 40 cm deep where the soil is damp. As the plant grows, soil is filled in around it. With wide stretches of salt beds nearby, the environment is certainly saline, but no measurements have been reported.

Seashore mallow (Kosteletzkya virginica) is a perennial surviving about five years in cultivation. Although the seeds must be germinated at low salinity, the plant can tolerate 2.0-2.5 percent salinity during growth. Hulled seeds, which resemble millet, contain as much as 32 percent protein and 22 percent oil. Grain yields from plots irrigated with water containing

2.5 percent salt have ranged from 0.8 to 1.5 tons per hectare.

TABLE 4 Acacia Composition.

	Percentage of
Species	Energy(kJ)	Protein	Fat	Carbo-hydrate	Water	Ash
A. aneura	2220	23.3	37.0	25.5	4.3	9.7
A. coriacea	1491	23.8	7.7	48.1	17.1	3.7
A. cowleana	1507	22.2	10.1	44.6	15.6	7.2
A. dictyophleba	1519	26.8	6.3	49.0	11.2	6.5
Wheat*	13.7	1.9	79.9	--	1.9

*Water-free composition SOURCE: Peterson, 1978.

Many Acacia seeds are rich in nutrients with higher energy, protein, and fat contents than wheat or rice. The high protein levels (~20 percent) suggest breadmaking potential, and the high fat contents (up to 37 percent) indicate potential as oilseeds.

About 50 of the 800 species of Acacia found in Australia have been used as food by Australian aborigines. Twenty of these were staple foods. In most cases dry ripe seeds were ground to a coarse flour that was then mixed with water to give an unleavened dough, which was baked on hot stones or in the ashes of a fire. Table 4 provides some information on a few Acacia seeds.

Seeds from salt-tolerant Tecticornia species were also used by Australian aborigines. The small (1.5-1.8 mm) seeds were ground to flour and used for making bread. T. australasica and T. verrucosa grow to about 40 cm in coastal mudflats above the normal tidal level.

Germination of the seed appears to be dependent on seasonal rains leaching the salt from the upper soil layer. T. verrucosa also occurs inland on moderately saline flats.

Indian almond (Terminalia catappa) is an erect tree reaching 15-25 m. It probably originated in Malaysia and was spread by its fruits carried on ocean currents. It is cultivated in much of

India and Burma and has become common in east and west Africa, the Pacific Islands, and in coastal areas of tropical America. Its ellipsoidal fruit is 4-7 cm long and 2.5-3.8 cm wide, the edible kernel is 3-4 cm long and 3-5 mm thick, and, in many varieties, the fruit is sweet and palatable. The nut is used as an almond substitute, and the wood is valued for construction and furniture use. The tree seems well adapted to sandy and rocky coasts. In Florida, it is known to withstand flooding, wind, and ocean spray, as well as saline soils.

Argan (Argania spinosa) covers an area of about 600,000 hectares of bushland in southwest Morocco. It can develop as a shrub or tree, usually in dense clumps. It has an important role as a browse and an edible oil is produced from its seeds. Preliminary work to determine its salt tolerance has been initiated in Israel.

A Salicornia species, described as SOS-7, has been grown in field trials in Mexico, Egypt, and the United Arab Emirates to produce an edible, safflower-like seed oil. When irrigated with seawater, about 20 tons of plant material per hectare are obtained. The oilseeds comprise about 2 tons of this total. The straw can be used for about 10 percent of the feed for cattle, goats, and sheep.

Prior to planting this Salicornia on salt flats near Kalba, United Arab Emirates, the soil was leached with seawater to reduce the salt level. Salicornia was then grown with seawater irrigation, and used to feed Damascus goats. The researchers estimate that one hectare of

Salicornia could raise up to twenty goats or sheep.

Tubers and foliage

Wild water chestnut (Eleocharis dulcis) occurs in saline coastal swamps in Southeast Asia and Oceania. The tubers, smaller and harder than those of superior varieties cultivated in fresh water, are traditionally gathered from shallow waters and cooked as delicacies or pounded to meal.

The roots and stems of saltwort (Basis maritima) were used as food by the Seri Indians in the southwestern United States. Using seawater irrigation, dry weight yields of 17 tons per hectare have been obtained.

Seaside purslane (Sesuvium portulacastrum) is a wide-spreading, succulent, perennial herb valued as an edible wild plant in tropical coastal areas of the United States and the Caribbean. It is cultivated and consumed as a vegetable in India, Indonesia, and southern

China. Boiling with several changes of water is necessary to eliminate excess salt. Analysis of the edible portion shows high values for calcium, iron, and carotene. In India, it is also used as fodder.

Common purslane (Portulaca oleracea) is also used as a potherb and in salads and soups. It is reported to contain 29 mg per 100 g of vitamin C and a vitamin A potency of 7,500 I.U. per 100 g.

The leaves of sea fennel (Crithmum maritimum) have been used as a medicinal herb, a spice, and as a salad ingredient. They contain significant amounts of vitamin C and have traditional use in protecting sailors from scurvy. About 100 g of fresh leaves provides the recommended daily allowance of vitamin C.

The leaves of Atriplex triangularis are similar to spinach in appearance and nutritional composition. It is a leafy annual vegetable that grows on the edge of coastal marshes in eastern North America. Selection among collected lines at the University of Delaware has resulted in a cultivar that gives an estimated yield of 21,300 kg per hectare (fresh weight) using seawater for irrigation. A. hortensis is also cultivated in India for its spinach-like leaves.

The ice plant (Mesembryanthemum crystallinum) is native to South Africa. A succulent annual herb, it grows on sea coasts and salty deserts. The leaves and seeds of the plant are reported to be edible.

Common Indian saltwort (Suaeda maritima) occurs in saline soils along the eastern and western coasts of India. It has been used for fixing seashore sand dunes. Its green leaves are considered a wholesome vegetable.

Leaf Protein

Although the leaves and shoots of some salt-tolerant foliage crops can be used in salads or as a garnish with minimal processing, most halophytes retain enough salt in their leaves to inhibit their consumption. One solution to this problem is to extract leaf protein from the salt- containing foliage.

To produce leaf protein, fresh foliage is fed into a press and the juice extracted. The fibrous material remaining after the juice is extracted from the leaves can be used as ruminant feed.

The juice is heated until a coagulum is formed and this curd is filtered, washed, and separated. The watery residue (containing most of the salts) is discarded. The material recovered on the filter is the leaf protein. Figure 2 shows this process.

Carlsson observed that the expressed juice of some plants coagulated spontaneously at ambient temperatures.

This reaction correlates with an undesirably high tannin and polyphenol content and can serve as screening technique to eliminate candidate plants.

Leaf protein can be used as an additive to enhance the protein content of many food products. In India, for example, leaf protein is cooked with sugar and corn flour to make a confection; in Mexico, it is used to make a fortified spaghetti. Other leaf protein facilities have been set up in villages in Bolivia, Ghana, Pakistan, and Sri Lanka.

In Sri Lanka, hand- and foot-powered presses are used to extract leaf protein from local plants. This leaf protein is used to fortify a local traditional dish, kola kenda, prepared from cooked rice and coconut. Children who received this fortified food were found to be significantly healthier than children from a nearby village who were not given leaf protein. After initial introduction in one village, the production and use of leaf protein spread to thirty villages.

In Ghana, a village cooperative was established to produce leaf protein for food use, silage from the fibrous residue, and alcohol from the residual liquid fraction. Leaf protein was sold at a price comparable with other protein-rich foods. Further economies (or profits) will be possible when income is obtained from the sale of the silage. Villagers participating in the cooperative derived as much as a fivefold increase in income.

FIGURE 2: Leaf protein production. Freshly gathered leaves are pulped and pressed to yield juice and fiber fractions. The fiber can be used for ruminant feed. The juice is heated to coagulate the protein and this is filtered for use as a food supplement. Yield figures are typical of field results. SOURCE: Fellows, 1987.

Various salt-tolerant plants have been used for leaf protein production including Kochia scoparia, Salsola kali, Beta maritima, Salicornia spp., Mesembryanthemum spp., and Atriplex spp. (Carlsson, 1975). Some of the nutrients in leaf protein concentrate are shown in Table 5.

TABLE 5 Leaf Protein Composition.

Component	Per 100 g Dry Matter
True protein	50-60 g
Lipids	10-25 g
Beta Carotene	45-150 mg
Starch	2-5 g
Monosaccharides	1-2 g
B-vitamins	16-22 mg
Vitamin E	15 mg
Choline	220-260 mg
Iron	40-70 mg
Calcium	400-800 mg
Phosphorus	240-570 mg
Ash	5-10 g

SOURCE: Carlsson, 1988.

Fruits

Ahmad has described a technique developed in Pakistan and India to grow salt-sensitive fruits on saline land.

This involves grafting a salt-sensitive shoot on a salt-tolerant rootstock. For example, shoots of Ziziphus mauritiana (salt sensitive, but yielding fleshy berries) have been grafted on the roots of Z. nummularia (salt tolerant, but yielding smaller berries) to allow fruit production on saline land. Similarly, shoots of Manilkara zapota (salt sensitive, but bearing large fruit) have been grafted on rootstocks of M. hexandra (salt tolerant, but bearing small fruit) to combine the desirable qualities of both. Pasternak (1987) reported that pear cultivars can tolerate irrigation water of 6.2 dS/m when grafted on a quince rootstock.

Salvadora persica and S. oleoides are small evergreen trees or shrubs. Both species yield edible fruits. Their seeds contain about 40 percent of an oil with a fatty acid composition (lauric, 20 percent; myristic, 55 percent; palmitic, 20 percent; oleic, 5 percent), which makes an excellent soap. The seed oil is inedible because of the presence of various substituted dibenzylureas. Both are multipurpose trees in India and Pakistan, providing fodder and wood as well as fruit. In India, S. persica occurs on saline soils and in coastal regions just above the high-water line. Before the introduction of canal irrigation in Pakistan, S. oleoides occupied much of the worst saltaffected land.

There are about a dozen species of Lycium in the United States. Although most bear edible fruit, they are commonly cultivated as ornamentals. l. fremontii seems to have agronomic promise. It is a thorny shrub native to southern Arizona and the Gulf of California region in adjacent Mexico. It thrives on desert soils, upper beaches, and semisaline and alkaline flats both near the coast and on inland deserts.

The quandong (Santalum acuminatum) is widely distributed across Australia's arid inland. This small tree averaging about 4 m high, has bright red cherry-sized fruit with edible flesh and a stone with an edible kernel. The flesh is a good source of carbohydrate (19-23 percent). It was a staple of the aboriginal's diet and has been popular with other Australians in jam and pie. The kernel is roasted before being consumed and has a high oil (58 percent) and energy content. The quandong is reported to be highly resistant to drought, high temperatures, and salinity. An experimental orchard in southern Australia has been irrigated for seven years with water with a conductivity of 4.7 dS/m.

The seagrape (Coccoloba uvifera) is readily established on sandy shores. When fully exposed on windswept seacoasts, the seagrape is dwarfed and bushy (to 2.5 m high) and forms dense colonies.

Inland, it becomes a spreading, low-branched tree (to 15 m high). The wood makes excellent fuel and can also be used for furniture and cabinetwork. The fruits are popular in the Caribbean and are sold in local markets. The flowers yield abundant nectar and result in a fine honey.

Traditional crops

In Israel, a number of commercial crops are grown with underground brackish water. These include melons, tomatoes, lettuce, Chinese cabbage, and onions. A study on market tomatoes showed that fruits produced under saline conditions were smaller than the controls, but developed a better color and had a much better taste. However, their shelf life tended to be shorter. Taste testing of other crops grown in brackish water showed that in melons, the fresh fruits were tastier than the controls. For lettuce, the salinity of the irrigation water had no discernible effect on the taste. Yields obtained in seventeen saline irrigation experiments are shown in Table 6.

TABLE 6 Expemnental Yields of and Grains at the Ramat Negev Experimental Station.

		Yield (t/ha) at
Crop	System*	EC (irrigation water)					Species
		1.2	3.5-5.5	6-8	8-10	10-15
Vegetables
Asparagus	d	6.6	6.6	--	--	--	A. officinalis;
							4-year-old plot.
Broccoli	d	23.4	21.8	--	19.0	14.3	Brassica oleracea
Beetroot	s	55.5	52.7	--	--	--	Beta vulgaris
Carrot	d	45.8	41.2	33.8	0	--	Daucus carota
Celery	s	155.0	171.0	--	--	--	Apium graveolens
Chinese cabbage	d	135.0	118.0	108.0	109.0	--	Brassica pekinenis
Chinese cabbage	d	58.0	58.0	55.0	65.0	--	Brassica chinensis
Kohlrabi	d	30.0	20.3	17.4	11.7	--	Brassica caulorapa
Lettuce	d	67.7	64.5	52.8	58.3	--	Lactuca sativa
Melon	d	27.0	24.0	24.0	22.0	--	Cucumis melo
Onion	d	50.1	28.4	4.1	0.4	--	Allium cepa
Onion	d	50.1	34.0	27.9	22.4	--	A. cepa; saline
							irrigation from
							64th day after
							planting.
Tomato	d	86.5	72.9	--	62.7	53.0	Lycopersicon
							esculentum
Grains	(Yield of grain at 12% moisture)
Maize	d	7.1	4.6	3.1	1.3	--	Zea mays
Maize	d	7.0	6.7	7.0	5.2	--	Z. mays; saline
							irrigation from
							21st day after
							germination.
Sorghum	s	10.0	8.4	--	--	--	Sorghum vulgare
Wheat	s	6.8	6.7	--	--	--	Triticurn vulgare

* d = drip irigation, s = sprinkler irrigation.
SOURCE: Pasternak and De Malach, 1987.

Asparagus (Asparagus officinalis) is commonly considered a temperate crop, dormant in the winter with spears harvested in the spring, and summer fern growth terminated by cooler fall weather. In tropical areas it can be grown using the "mother fern" technique. After plants are established, the first two or three spears are allowed to grow to fern; thereafter, spears are harvested as they develop. Twice during the year old fern is replaced by new fern, but asparagus is produced year-round with annual yields exceeding those obtained in temperate climates.

In Tunisia, asparagus is grown near Zarzis, where the salinity the irrigation water is 6.5 g per liter. Yields (4-8 tons per hectare) are about the same as in areas irrigated with fresh water. It has also been grown experimentally in Israel's Negev desert.

In the United States, University Delaware researchers found A. officinalis growing wild at the edge of a salt marsh. Using commercial asparagus varieties, they germinated thousands of seeds in fresh water and transferred the seedlings to salt water. Most died, but some grew well at salinities of 30 parts per thousand.

Asparagus is an excellent crop for developing countries because it is relatively labor intensive. Although several years are required before a marketable crop is obtained, production continues for 15-25 years. Water requirements for asparagus are somewhat greater than for cotton, and a light soil and careful management are required.

Rice (Oryza saliva) is a staple crop in many developing countries. It has been observed that coastal-grown rice generally gives lower yields than inland rice, presumably because of the effects of saline soil or salty ocean mists. Rice cells subjected to salt stress and then grown to maturity had progeny with improved salt tolerance - up to 1 percent salt.

Barley (Hordeum vulgare) is the most salt-tolerant cereal grain. At the University of Arizona, a special strain of barley yielded about 4,000 kg per hectare when irrigated with groundwater with half the salinity of seawater. At the University of California, specially selected strains of barley were grown on sand dunes with seawater and diluted seawater irrigation. Yields were 3,102 kg per hectare for fresh water, 2,390 kg per hectare for one-third seawater, 1,436 kg per hectare for two-thirds seawater, and 458 kg per hectare for full-strength seawater.

Wheat ( Triticum aestivum) is an important source of human nutrition, and the improvement of salt tolerance in this crop deserves attention. Traditional cultivars from salt-affected areas may serve as sources for salt resistance in modern wheat varieties. There is a need to collect and evaluate cultivars from lands where salt stress has been exerting selection pressure over long periods. In India, researchers at the Central Soil Salinity Research Institute have collected and evaluated more than 400 indigenous cultivars from salt-affected regions of the Indian subcontinent.

In addition, many wild relatives of wheat show outstanding adaptation to saline environments. For example, tall wheatgrass (Elytrigia [Agropyron] elongatum) and E. poetica have been reported to survive salt concentrations higher than seawater. The salt tolerance of wheat may be enhanced through hybridization and selective transfer of gene complexes from these valuable resources.

TABLE 7 Salt-Tolerant Plants for Haney Production.

	Honey Production
Species	(kg per colony per year)
Agave americana	41 (Mexico)
Cajanus cajan	--
Dalbergia sissoo	4-9 (India)
Eacalypus camaldulensis	55-60 (Australia)
E. gomphocephala	--
E. paniculata	100 (Australia)
Gleditsia: triacanthos	250* (Romania)
Lotus corniculatus	--
Parkinsonia aculeata	--
Pithecellobium dulce	--
Pongamia pinnata	--
Prosopis cineraria	--
P. pallida	120-363 (Hawaii)
Trifolium alexandrinum	165* (Bulgaria)

*Kg per season from one hectare covered with the plant.
SOURCE: Crane, 1985.

Researchers at the Institute of Plant Science Research (Cambridge, England) have succeeded in crossing salt-tolerant sand couch (Thinopyrum bessarabicum) with wheat. Sand couch grows on the sand dunes of the Black Sea and can withstand salt concentrations that would be lethal for wheat. The sand couch/wheat hybrid can grow and set seed at salt levels of 1.1 percent.

A recent report by Rawson and coworkers (1988) suggests that absolute NaCl tolerance in wheat, barley, and triticale is not so much due to the greater ability to grow in the presence of NaCl, but to grow well per se. In many cases, productivity in NaCl can be estimated from the size of seedling leaves on the control plants.

Maas and coworkers (1983) have examined the effects of saline water on germination, growth, and seed production in maize (Zea mays). At germination, salinities of up to 10 dS/m can be tolerated, but dry matter production is decreased if the EC exceeds 1 dS/m during seedling growth. Increasing the salinity of the irrigation water to 9 dS/m at the tasseling and grain filling stages did not significantly reduce yields.

Some salt-tolerant plants are suitable for honey production, with the honey being used directly by the farmer or sold for added income. Although it would probably not be cost effective to establish salt tolerant plants solely for honey production, it could be a valuable adjunct while plants are maturing for other uses. The black mangrove

(Avicennia germinans), example, has an intense summer flow of nectar heavily gathered by honeybees. Fourteen other tropical and subtropical plants that are valuable honey sources are listed in Table 7.

References and selected readings

General

Downton, W. J. S. 1984. Salt tolerance of food crops: prospectives for improvements. CRC Critical Reviews in Plant Sciences 1(3):183-201.
Epstein, E. and D. W. Rains. 1987. Advances in salt tolerance. Plant and Soil 99:17-29.
Gallagher, J. L. 1985. Halophytic crops for cultivation at seawater salinity. Plant and Sod 89:323-336.
Gamborg, O. L., R. E. B. Ketchum and M. W. Nabors. 1986. Tissue culture and cell biotechnology for increased salt tolerance in crop plants. Pp. 81-92 in: R. Ahmad and A. San Pietro teds.) Prospects for Biosaline Research. University of Karachi, Karachi, Pakistan.
Jain, S. C., R. K. Gupta, O. P. Sharma and V. K. Paradkar. 1985. Agronomic manipulation in saline sodic soils for economic biological yields. Current Science 54(9):422-425.
Maas, E. V. 1986. Crop tolerance to saline soil and water. Pp. 205-219 in: R. Ahmad and A. San Pietro (eds.) Prospects for Biosaline Research. University of Karachi, Karachi, Pakistan.
Mizrahi, Y. and D. Pasternak. 1985. Effect of salinity on quality of various agricultural crops. Plant and Sod 89:301-307.
O'Leary, J. W. 1985. Saltwater crops. CHEMTECH 15(9):562-566.
O'Leary, J. W. 1987. Halophytic food crops for arid lands. Pp. 1-4 in: Strategies for Classification and Management of Native Vegetation for Food Production in Arid Area,. Report RM-150, Forest Service, USDA, Ft. Collins, Colorado 80526, US.
Pasternak, D. 1987. Salt tolerance and crop production - a comprehensive approach. Annual Review of Phytopathology 25:271-291.
Pasternak, D. and Y. De Malach. 1987. Saline water irrigation in the Negev Desert. in: Agriculture and Food Production in the Middle East. Proceedings of a Conference on Agriculture and Food Production in the Middle East, Athens, Greece. January 21-26, 1987.
Somers, G. F. 1982. Food and economic plants: general review. Pp. 127-148 in: A. San Pietro (ed.) Biosaline Research Plenum Press, New York, New York, US.

Grains and Oilseeds

Zostera marina
de Cock, A. W. A. M. 1980. Flowering, pollination and fruiting in Zostera marina. Aquatic Botany 9(3):210-220.
Felger, R. S. and a. P. McRoy. 1975. Seagrasses as potential food plants. Pp. 62-69 in: C. F. Somers (ed.) Seedbearing Halophytes ad Food Plants. College of Marine Studies, University of Delaware, Newark, Delaware, US.
Thorhaug, A. 1986. Review of seagrass restoration efforts. Ambio 15(2):110-117.

Distichlis

Yensen, N. P., S. B. Yensen and C. W. Weber. 1985. A review of Distichlis spp. for production and nutritional values. Pp. 809-822 in: E. E. Whitehead, C. F. Hutchinson, B. N. Timmermann, and R. G. Varady (eds.) Arid Land, Today and Tomorrow, Westview Press, Boulder, Colorado, US.
Yensen, N. P. 1988. Plants for salty soil. Arid Lands Newsletter 27:3-10. University of Arizona, Tucson, Arizona, US.
Yensen, N. P. 1987. Development of a rare halophyte grain: prospects for reclamation of salt-ruined lands. Journal of the Washington Academy of Sciences 77(4):209-214.

Sporobolus airoides

Chadha, Y. R. (ed.). 1976. Sporobolus. The Wealth of India X:24-25. CSIR, New Delhi, India.
Doebley, J. F. 1984. "Seeds" of wild grasses: a major food of Southwestern Indians. Economic Botany 38:52-64.
Ezcurra, E., R. S. Felger, A. D. Russell and M. Equihua. 1988. Freshwater islands in a desert sand sea: the hydrology, flora, and phytogeography of the Gran Desierto oases of northwestern Mexico. Desert Plants 9(2):35-44,55-63.
Heizer, R. F. and A. B. Elsasser. 1980. The Natural World of the California Indians. University of California Press, Berkeley, California, US.

Quinoa

Atwell, W. A., B. M. Patrick, L. A. Johnson and R. W. Glass. 1983. Characterization of quinoa starch. Cereal Chemistry 60(1):9-11.
Risi, J. and N. W. Galwey. 1984. The Chenopodium grains of the Andes: Inca crops for modern agriculture. Advances in Applied Biology 10:145-216.

Kosteletzkya virginica

Gallagher, J. L. 1985. Halophytic crops for cultivation at seawater salinity. Plant and Soil 89:323-336.
Islam, M. N., C. A. Wilson and T. R. Watkins. 1982. Nutritional analysis of seashore mallow seed, Kosteletzkva virginica. Journal of Agricultural and Food Chemistry 30(6):1195-1198.

Acacias

Orr,T. M. and L. J. Hiddins. 1987. Contributions of Australian acacias to human nutrition. Pp. 112-115 in J. W. Turnbull (ed.) Australian Acacia, in Developing Countries. ACIAR Proceedings no. 16. Canberra, Australia.
Brand, J. C., V. Cherikoff and A. S. Truswell. 1985. The nutritional composition of Australian Aboriginal bushfoods - 3, seeds and nuts. Food Technology in Australia 37:275-279.
Peterson, N. 1978. The traditional patterns of subsistence to 1975. Pp. 22-35 in: B. S. Hetzel and H. J. Frith (ens.) The Nutrition of Aborigines, in Relation to the Ecosystem of Central Australia. CSIRO, Melbourne, Australia.

Terminalia catappa

Morton, J. F. 1985. Indian almond (Terminalia catappa), salt-tolerant, useful, tropical tree with "nut" worthy of improvement. Economic Botany 39:101-112.

Argan

Morton, J. F. and G. L. Voss. 1987. The argan tree (Argania sideroxylon, Sapotaceae), a desert source of edible oil. Economic Botany 41:221-223.

Salicornia

Charnock, A. 1988. Plants with a taste for salt. New Scientist 120(1641):41-45.

Tubers and Foliage

Batis maritima

Glenn, E. P. and J. W. O'Leary. 1985. Productivity and irrigation requirements of halophytes grown with seawater in the Sonoran Desert. Journal of Arid Environments 9(1):81-91.

Sesuvium portulacastrum

Chadha, Y. R. (ed.). 1972. Sesuvium. The Wealth of India 1X:304. CSIR, New Delhi, India.

Portulaca oleracea

Sen, D. N. and R. P. Bansal. 1979. Food plant resources of the Indian deserts. Pp. 357-370 in: J. R. Goodin and D. K. Northington (eds.) Arid Plant Resources. Texas Tech University, Lubbock, Texas, US.

Crithmum maritimum

Franke, W. 1982. Vitamin a in sea fennel (Crithmum maritimum), an edible wild plant. Economic Botany 36:163-165.
Okusanya, O. T. 1977. The effect of sea water and temperature on the germination behavior of Crithmum maritimum. Physiologia Plantarum 41(4):265-267.

Atriplex triangularis

Islam, M. N., R. R. Genuario and M. Pappas-Sirois. 1987. Nutritional and sensory evaluation of Atriplex triangularis leaves. Food Chemistry 25:279-284.
Khan, M. A. 1987. Salinity and density effects on demography of Atriplex triangularis Willd. Pakistan Journal of Botany 19(2):123-130.
Riehl, T. E. and I. A. Ungar. 1983. Growth, water potential, and ion accumulation in the inland halophyte Atriplex triangularie under saline field conditions. Acta Oecologica,

Oecologia Plantarum 4:27-39.

Mesembryanthemum crystallinum

Sastri, B. N. (ed.). 1962. Mesembryanthemum The Wealth of India VI:349. CSIR, New Delhi, India.

Suaeda maritima

Chadha, Y. R. (ed.). 1976. Suaeda. The Wealth of India X:70-71. CSIR, New Delhi, India.

Leaf Protein

Carlsson, R. 1988. Leaf Nutrients for Human Consumption: A Global Overview (Swedish). University of Lund, Lund, Sweden.
Carlsson, R. 1980. Quantity and quality of leaf protein concentrates from Atriplex hortensis, Chenopodium guinea and Amaranthus caudatus grown in southern Sweden. Acta Agriculturae Scandinavica 30(4):418-426.
Carlsson, R. 1975. Centrospermae Species and Other Species for Production of Leaf Protein. Ph.D. thesis. University of Lund, Lund, Sweden.
Fellows, P. 1987. Village-scale leaf fractionation in Ghana. Tropical Science 27:7784.
Martin, C. 1987. Leaf extract boosts nutritional value. VITA News (July):11-12.
Maddison, A. and G. Davys. 1987. Leaf protein - a simple technology to improve nutrition. Appropriate Technology 14(2):10-11.
Pirie, N. W. 1987. Leaf Protein and its By-Products in Human and Animal Nutrition. Cambridge University Press, New Rochelle, New York, US.
Singh, A. K. 1985. The yield of leaf protein from some weeds. Acta Botanica Indica 13(2):165-170.
Valenzuela, J. 1988. Protein for the young and needy. South 88:99.

Fruits

Salvadora

Gupta, R. K. and S. K. Saxena. 1968. Resource survey of Salvadora oleoides and S. persica for non-edible oil in western Rajasthan. Tropical Ecology 9:140-152.
Ezmirly, S. T. and J. C. Cheng. 1979. Saudi Arabian medicinal plants: Salvadora persica.Planta Medica 35(2):191-192.
Chadha, Y. R. (ed.). 1972. Salvadora. Wealth of India 1X:193-195. CSIR, New Delhi, India

Lyciums

Felger, R. S. and M. B. Moser. 1984. People of the Desert and Sea. Ethnobotany of the Seri Indians. University of Arizona Press, Tucson, Arizona, US.
Greenhouse, R. 1979. The Iron and Calcium Content of Some Traditional Pima Food, and the Effects of Preparation Methods. (Thesis) Arizona State University, Tempe, Arizona, US.

Santalum acuminatum

Jones, G. P., D. J. Tucker, D. E. Rivett and M. Sedgley. 1985. The nutritional potential of the quandong (Santalum acuminatum) kernel. Journal of Plant Foods 6(4):239-246.
Possingham, J. 1986. Selection for a better quandong. Australian Horticulture 84(2):55-59.
Sedgley, M. 1982. Preliminary assessment of an orchard of quandong seedling trees.

Journal of the Australian Institute of Agricultural Science 48:52-56.

Traditional Crops

Asparagus

Nichols, M. A. 1986. Asparagus coming into its own as a high-value field crop. Agribusiness Worldwide 6(8):15-18.
Robb, A. 1984. Asparagus production using mother fern. Asparagus Research Newsletter (New Zealand) 2(1):24.

Rice

Akbar, M. 1986. Breeding for salinity tolerance in rice. Pp. 37-55 in: R. Ahmad and A. San Pietro (eds.) Prospects for Biosaline Research. University of Karachi, Karachi, Pakistan.
Dubey, R. S. and M. Rani. 1989. Influence of NaCl salinity on growth and metabolic status of protein and amino acids in rice seedlings. Journal of Agronomy and Crop Science. 162(2):97-106.
Ponnamperuma, F. N. 1984. Role of cultivar tolerance in increasing rice production on saline lands. in: R. C. Staples & G. H. Toenniessen (ads.) Salt Tolerance in Plants. John Wiley, New York, New York, US.
Wong, C.-K., S.-C. Woo and S.-W. Ko. 1986. Production of rice plantlets on NaCl-stressed medium and evaluation of their progenies. Botanical Bulletin Academia Sinica 27:11-23.

Barley

Anonymous. 1982. New variety yields 1.2 tonnes/ha when irrigated from the ocean. International Agricultural Development 2(3):29.
Iyengar, E. R. R., J. Chikara and P. M. Sutaria. 1984. Relative salinity tolerance of barley varieties under semi-arid climate. Transaction, of Indian Society of Desert Technology 9(1):27-33.
Norlyn, J. D. and E. Epstein. 1982. Barley production: irrigation with seawater on coastal soil. Pp. 525-529 in: A. San Pietro (ed.) Biosaline Research. Plenum Press, New York, New York, US.

Wheat

Dvorak, J., K. Rose and S. Mendlinger. 1985. Transfer of salt tolerance from Elytrigia Pontica to wheat by the addition of an incomplete Elytrigia genome. Crop Science 25:306-309.
Forster, B. 1988. Wheat can take on more than a pinch of salt. New Scientist 120(1641):43.
Gorham, J., E. McDonnell and R. G. Wyn Jones. 1984. Salt tolerance in the Triticeae: Leymus sabulosus. Journal of Experimental Botany 35:1200-1209.
Gulick, P. and J. Dvorak. 1987. Gene induction and repression by salt treatment in the roots of the salinity-sensitive Chinese Spring wheat and the salinity tolerant Chinese Spring x Elytrigia elongata amphiploid. Proceedings of the National Academy of Sciences 84:99-103.
Maas, E. V. and J. A. Poss. 1989. Salt sensitivity of wheat at various growth stages. Irrigation Science 10:29-40.
Rana, R. S. 1986. Genetic diversity for salt-stress resistance of wheat in India. Rachis 5(1):32-37.
Rana, R. S. 1986. Evaluation and utilisation of traditionally grown cereal cultivars of salt affected areas of India. Indian Journal of Genetics 46:121135.
Rawson, H. M., R. A. Richards and R. Munns. 1988. An examination of selection criteria for salt tolerance in wheat, barley and triticale genotypes. Australian Journal of Agricultural Research 39:759-792.
Sajjad, M. S. 1986. Evaluation of wheat germplasm for salt tolerance. Rachis 5(1):28-31.

Maize

Ahmad, R., S. Ismail and D. Khan. 1986. Use of highly saline water for irrigation at sandy soils. Pp. 389-413 in: R. Ahmad and A. San Pietro (eds) Prospect for Biosaline Research University of Karachi, Karachi, Pakistan.
Mass, E. V., G. J. Hoffman, G. D. Chaba, J. A. Poss and M. C. Shannon. 1983. Salt sensitivity of corn at various growth stages. Irrigation Science 4:45-57.
Pasternak, D., Y. De Malach and I. Borovic. 1985. Irrigation with brackish water under desert conditions. II. Physiological and yield response of maize (Zea mays) to continuous irrigation with brackish water and to alternating brackish-fresh-brackish water irrigation. Agricultural Water Management 10:47-60.
Pessarakli, M., J. T. Huber and T. C. Tucker. 1989. Dry matter yields, nitrogen absorbtion, and water uptake by sweet corn under salt stress. Journal of Plant Nutrition 12(3):279-290.
Totawat, K. L. and A. K. Mehta. 1985. Salt tolerance of maize and sorghum genotypes. Annals of Arid Zone Research 24(3):229-236.

Tomato

Mizrahi, Y. 1982. Effect of salinity on tomato fruit ripening. Plant Physiology 69:966-970.
Jones, R. A. 1987. Genetic advances in salt tolerance. Pp. 125-138 in: D. J. Nevins & R. A. Jones (eds.) Tomato Biotechnology. Alan R. Liss, Inc., New York, New York, US.

Onion

Miyamoto, S. 1989. Salt effects on germination, emergence, and seedling mortality of onion. Agronomy Journal 81(2):202-207.

Honey

Crane, E. 1985. Bees and honey in the exploitation of arid land resources. Pp. 163-175 in: G. E. Wickens, J. R. Goodin and D. V. Field (eds.) Plants for Arid Land,. George Allen & Unwin, London, UK.
Morton, J. F. 1964. Honeybee plants of South Florida. Procecdings of the Florida State Horticultural Society 77:415-436.

Research contacts

General

Rafiq Ahmad, Department of Botany, University of Karachi, Karachi 32, Pakistan.
James Aronson, 12 rue Vanneau, 34000 Montpellier, France.
Akissa Bahri, Centre de Recherches du Genie Rural, BP No. 10, Ariana 2080, Tunisia.
John L. Gallagher, College of Marine Studies, University of Delaware, Lewes, DE 19958, US.
Oluf L. Gamborg, Tissue Culture for Crops Project, Colorado State University, Ft. Collins, CO 80523, US.
E. R. R. Iyengar, Central Salt and Marine Chemicals Research Institute, Bhavnagar 364 002, India.
T. N. Khoshoo, Department of Environment, Bikaner House, Shahjahan Road, New Delhi 110 011, India.
Gwyn Jones, Human Nutrition Section, Deakin University, Victoria 3217, Australia.
S. Miyamoto, Texas Agricultural Experiment Station, 1380 A&M Circle, El Paso, TX 79927, US.
Yosef Misrahi, Boyko Institute for Research, Ben Gurion University, PO Box 1025, Beer-Sheva 84110, Israel.
Gary P. Nabhan, Office of Arid Lands Studies, University of Arizona, Tucson, AZ 85719, US.
Dov Pasternak, Institute for Desert Research, Ben Gurion University, Sede Boger 84990, Israel.
James D. Rhoades, USDA Salinity Research Laboratory, Riverside, CA 92501, US.
M. C. Shannon, USDA Salinity Research Laboratory, Riverside, CA 92501, US.
G. E. Wickens, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AE, UK.
Xie Cheng-Tao, Institute of Soil and Fertilizers, 30 Baishiqiao Road, Beijing 100081, People's Republic of China.

Grains and Oilseeds

Zostera marina

Richard S. Felger, Office of Arid Lands Studies, University of Arizona, Tucson, AZ 85719, US.

Distichlis

N. Yensen, NyPa, Inc., 727 North Ninth Avenue, Tucson, AZ 85705 US.

Quinoa

Roff Carlsson, Institute of Plant Physiology, University of Lund, Box 7007, S-220 07 Lund, Sweden.
Instituto Interamericano de Ciencias Agricolas OEA, Andean Zone, Box 478, Lima, Peru.
John McCamant, Sierra Blanca Associates, 2560 South Jackson, Denver, CO 80210, US.
Ministerio de Asuntos Campesinos y Agropecuarios, Biblioteca Nacional Agropecuria, La Paz, Bolivia.
E. J. Weber, Agriculture, Food and Nutrition Division, IDRC Regional Office, Apartado Aereo 53016, Bogota, Colombia.

Pennisetum typhoides

E. R. R. Iyengar, Central Salt and Marine Chemicals Research Institute, Bhavnagar 364 002, India.

Kosteletzkya virginica

J. L. Gallagher, College of Marine Studies, University of Delaware, Lewes, DE 19958, US.
M. N. Islam, Department of Food Science, University of Delaware, Newark, DE 19716, US.

Acacia

Janette C. Brand, University of Sydney, Sydney, NSW 2006, Australia.

Tecticornia

Paul G. Wilson, Western Australian Herbarium, PO Box 104, Como, WA 6152, Australia.

Terminalia catappa

Julia F. Morton, Director, Morton Collectanea, University of Miami, Coral Gables, FL 33124, US.

Argan

Julia F. Morton, Director, Morton Collectanea, University of Miami, Coral Gables, FL 33124, US.

Salicornia

James O'Leary, University of Arizona, Tucson, AZ 85719, US
Carl Hodges, Environmental Research Laboratory, Tucson International Airport, Tucson, AZ 85706

Leaf Protein

Walter Bray, 13-15 Frognal, London NW3 6AP, UK.
Rolf Carlsson, Institute of Plant Physiology, University of Lund, Box 7007, S-220 07 Lund, Sweden.
Peter Fellows, Oxford Polytechnic, Gipsy Lane, Oxford OX3 OPB, UK
Shoaib Ismail, Department of Botany, University of Karachi, Karachi 32, Pakistan.
Carol Martin, Find Your Feet, 345 West 21st Street, Suite 3D, New York, NY 10011, US.
A. K. Singh, S 4/50 D4, Tajpur, Orderly Bazar, Varanasi, 221 002, India.

Fruits

Quandong

Margaret Sedgley, Waite Agricultural Research Institute, University of Adelaide, Glen Osmond, SA 5064, Australia.

Lycium

Richard S. Felger, Office of Arid Lands Studies, University of Arizona, Tucson, AZ 85719, US.

Coccoloba uvifera

Centro Agronomico Tropical de Investigacion y Ensenaza, Turrialba, Costa Rica.
Institute of Tropical Forestry, PO Box AQ, Rio Piedras, Puerto Rico 00928, US.
Instituto Forestal Latino-Americano, Apartado 36, Merida, Venezuela.

Traditional Crops

Asparagus

Yoel De Malach, Ramat Negev Regional Experimental Station, Doar Na Halutza 85515 Israel.
M. A. Nichols, Department of Horticulture and Plant Health, Massey University, Palmerston North, New Zealand.

Rice

I. U. Ahmed, Department of Soil Science, University of Dhaka, Dhaka 2, Bangladesh.
M. Akbar, International Rice Research Institute, PO Box 933, Manila, Philippines.
F. N. Ponnamperuma, International Rice Research Institute, PO Box 933, Manila, Philippines.
R. S. Rana, Genetics Research Center, Central Soil Salinity Research Institute, Karnal 132001, India.
C.-K. Wong, Institute of Botany, Academia Sinica, Nankang, Taipei, Taiwan.

Barley

E. Epstein, Department of Land, Air and Water Resources, University of California, Davis, CA 95616, US.
R. T. Ramage, College of Agriculture, University of Arizona, Tucson, AZ 85721, US.
E. R. R. Iyengar, Central Salt and Marine Chemicals Research Institute, Bhavnagar 364 002, India.
H. M. Rawson, Division of Plant Industry, CSIRO, PO Box 1600, Canberra, ACT 2601, Australia

Wheat

E. Epstein, Department of Land, Air and Water Resources, University of California, Davis 95616, CA, US.
S. Jana, Department of Crop Science and Plant Ecology, University of Saskatchewan, Saskatoon SN7 0W0, Canada.
R. Munns, Division of Plant Industry, CSIRO, PO Box 1600, Canberra, ACT 2601, Australia
R. S. Rana, Genetics Research Center, Central Soil Salinity Research Institute, Karnal 132001, India.
M. Siddique Sajjad, Nuclear Institute for Agriculture and Biology, PO Box 128, Faisalabad, Pakistan.
J. P. Srivastava, Cereal Improvement Program, International Center for Agricultural Research in Dry Areas, Aleppo, Syria.
R. G. Wyn Jones, Department of Biochemistry and Soil Science, University College of North Wales, Bangor LL57 2UW, Wales, UK.

Maize

D. Khan, Shoaib Ismail, Department of Botany, University of Karachi, Karachi 32, Pakistan.
Yoel De Malach, Ramat Negev Regional Experimental Station, Doar Na Halutza 85515 Israel.
K. L. Totawat, Department of Soil Science, Rajasthan College of Agriculture, Udaipur 313 001, India.

Tomato

Yoel De Malach, Ramat Negev Regional Experimental Station, Doar Na Halutza 85515 Israel.
Richard A. Jones, University of California, Davis, CA 95616, US.

Honey

Eva Crane, International Bee Research Association, Hill House, Gerrards Cross, Bucks SL9 ONR, UK.