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Scientific registration n o. : 1768
Symposium n o. : 29
Presentation : Poster
Growing halophytes in Egypt for forage production
and desertification control
Production fourragère et contrôle de la désertification
en Egypte par la culture de plantes halophytes
ASHOUR Nabih(1), ARAFAT Sayed(2), ABD EL-HALEEM Awad(3),
SERAG Mamdoh(4), MANDOUR Safwat(5), MEKKI Bahaa(6)
(1), (2), (3), (5), (6) National Research Centre, Dokki, Cairo, Egypt
(4) Faculty of Science at Demietta, Mansoura Univ., Egypt.
Introduction
Egypt, like other developing countries of the arid and semi-arid regions, faces four
major problems namely: (i) high rate of population increase (ii) limited natural resources
of good quality water, (iii) existence of salt affected soil and (iv) shortage of food and
feed. Therefore, studies should be oriented towards solving these problems and in
particular to the management of salt affected soils. The cultivation of halophytic plants
seems to be an ideal management practice of such soil types, when fresh water is not
sufficient. Halophytes have attracted the attention of several workers in many countries
(Aronson, 1989; Ashour, 1993 and Ashour and Thalooth (1993). Number of plant
species have been screened for their productivity and/or nutritional potential when
irrigated with saline water and even sea water (Glenn and O’Loary, 1985 and Gallagher,
1985). Some halophytic species have been demonstrated as forage plants (Ashour et al.,
1994 and Joshi et al., 1995).
Therefore, the aim of this work was to investigate the growth response of some
halophytic forage plants in coastal salt-affected soils by using diluted sea water for
irrigation, in order to overcome the desertification as well as to solve the discharge of
fresh water irrigation in Egypt.
Materials and Methods
Field trials were conducted during 1993-1996 seasons in the Saline Agriculture
Experimental Station of the National Research Centre at Suez Gulf Coast to study the
effect of salinity on growth and plant composition of five halophytic plants namely:
Diplachne fusca, Spartina patens, Sporobolus virginicus (Smyrna-smooth), Sporobolus
virginicus (Dixe-coarse) and Medicago sativa for comparison. Soil characteristics of the
experimental site were as follows: pH 8.6, EC 1.2 dS.m -1 (1:1 W/V H2O), CaCO3 1.8%,
sand 93.5%, silt 4.8% and clay 1.7%. Four salinity levels of diluted sea water being,
12.5%, 25.0%, 37.5 and 50% were used in irrigation. Chemical characteristics of the
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diluted sea water were determined using the methods described by the U.S. Salinity Lab.
Staff (1954) and presented in Table (1).
Table (1) Chemical characteristics of diluted sea water used in the Saline Agriculture
Experimental Station at Suez Gulf Coast.
Character Sea water proportion (%)
12.5 25.0 37.5 50.0
pH 8.0 8.0 8.1 8.1
T.D.S. (g.L -1 ) 6.0 13.5 19.5 25.5
Na (mg.L -1 ) 1910.0 3660.0 5470.0 7180.0
K (mg.L -1 ) 54.6 117.0 172.0 217.0
Ca (mg.L -1 ) 96.0 160.0 200.0 252.0
Mg (mg.L -1 ) 216.0 420.0 593.0 806.0
HCO3 (mg.L -1 ) 597.0 683.0 683.0 767.0
Cl (mg.L -1 ) 3690 7460.0 10580.0 13490.0
Each plant type was grown in four plots. Each plot was 4 m 2 and subjected to one
of the salinity treatment.
Several cuttings were taken from all tested plants during 12 months. Fresh weight of
biomass was recorded. the harvested shoots were oven-dried at 65 o C, weighed, ground
and analyzed for crude protein, fat and fibre, soluble carbohydrates and ash using the
method of A.O.A.C. (1965).
A field application was carried out to grow Diplachne fusca in salt affected soils
(EC more than 17 dS.m -1 ) at the south coast of Qaroan Lack to emphasize the
potentiality of this local halophyte as a forage crop under field conditions. Agricultural
drainage water was used for irrigation (EC 2.8 dS.m -1 )
Results and Discussion
Effect of salinity on plant growth:
Figure (1) shows that irrigation with diluted sea water affected the fresh and dry
weights of biomass. Fresh and dry weights of the tested forage plants, except Medicago
sativa increased by increasing the proportion of sea water in irrigation water from 12.5%
to 25.0%. Further increase in salinity level in the irrigation water tended to decrease the
fresh and dry weights of the forage halophytic plants. Yet even under 50% sea water in
irrigation water the halophytic forage plants produced more than 50% of the fresh and
dry weights as compared with control treatment (12.5%). The stimulatory effect of
moderate salinity level on the growth of some halophytic plants was also reported by
O’Leary (1988). Such growth stimulation at moderate salinity in halophytes may be
attributed to improve shoot osmotic status as a result of increased ion uptake (Naidoo et
al., 1995). Reduced growth at high salinities is probably associated with reduced turger
and the high energy cost of massive salt secretion and osmoregualtion.
Data also showed that all tested plant types tolerated diluted irrigation sea water up
to 50% level. It was noticed that Sporobolus virginicus (Dixe) produced the highest
biomass when the plants were irrigated with water containing either 25 or 37.5% sea
water, followed by Spartina patens and Diplachne fusca. Sporobolus virginicus
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(Smyrna) gave the lowest yield. However, Leith et al. (1994), conducted field
experiments in the United Arab Emirates to grow the halophytic grass Sporobolus
virginicus utilizing sea water of the Arabian Gulf. The results of their experiment
indicated that Sporobolus virginicus has the ability to grow in highly saline environments
which exceed even those found under our experiment.
Effect of salinity on plant composition :
The effect of salinity on the content of crude protein, fibre, fat and ash as well as,
soluble carbohydrates of all tested forage halophytic plants are illustrated in Fig. (2).
Increasing salinity level in the irrigation water tended to increase crude protein content
while tended to decrease crude fiber. Crude fat and soluble carbohydrates contents
seemed to be unaffected by changing the salinity level in the irrigation water. In this
concern Leigh (1986) reported high crude protein content of several halophytic plants.
He also speculated that halophytic plants could serve as valuable protein supplement to
livestock when the associated grasses were dry and possibly protein deficient.
Data also showed that Medicago sativa had relatively higher content of crude
protein and lower soluble carbohydrates content. Diplachne fusca and Spartina patens
contained a higher amount of soluble carbohydrates. The lowest crude fat content was
recorded in Spartina patens. Whereas Sporobolus virginicus (Smyrna) and (Dixe) gave
the highest ash content. At all levels of salinity concentration succulence of the tested
halophytic plant types were more or less similar.
Field application :
Table (2) summarizes the change occurred in some chemical properties of saltaffected
soil as result of Diplachne fusca cultivated for two growing seasons
successively. Data showed that soluble salts markedly decreased after harvesting. The
percent decrease in soluble salts was 34.5% in the surface layer. The most striking
change was tremendous decrease in soluble Na and Cl. This phenomenon could be
explained by the ability of halophytic plant to absorb high amounts of these elements.
Table (2) Some chemical properties of salt-affected soil before planting and after
harvesting of Diplachne fusca.
pH EC Soluble cations and anions meq 100 g -1 soil
dS.m -1
Na K Ca Mg HCO3 Cl
Before planting 8.0 17.4 63.6 0.75 15.0 11.0 9.0 67.2
After harvesting 8.0 11.2 41.2 2.1 8.8 6.0 3.2 41.7
Plant composition recorded in Table (3) show that Diplachne fusca grown in salt
affected soil contained considerable amounts of crude protein, fibre, fat, soluble
carbohydrates as well as nutritional elements. The high sodium content (2.14%) has not
presented a problem to forage species due to the presences of specific internal osmotic
adjustment mechanisms.
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Table (3) Fresh, dry weight and chemical composition of Diplachne fusca grown in salt
affected soil at the south coast of Qaroan Lack.
Character Value Character Value
Fresh weight (ton acre -1 /year) 8.2 Phosphorus % 0.16
Dry weight (ton acre -1 /year) 3.2 Calcium % 0.54
Crude protein % 9.2 Magnesium % 0.40
Crude fibre % 31.4 Potassium % 1.02
Crude fat % 1.83 Sodium % 2.14
Soluble carbohydrate % 42.9 K/Na ratio 0.48
Ash % 14.7
Therefore, Diplachne fusca seemed to be promising forage crops as well as to overcome
the desertification problems particularly in arid and semi arid regions of Egypt.
References
A.O.A.C. (1965). Official Methods of Analysis of Association Analytical Chemists.
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Plants. Ed. M. Ajmal Khan & Irwin A. Ungar, Dept. Bot., Univ. Karachi, Karachi,
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Key words : halophytes, salt-affected soil, sea water, forage production, desertification,
Egypt
Mots clés : halophytes, sols salés, eau de mer, production de forage, désertification,
Egypte
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