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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 2
(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. 3
Page 1: Scientific registration n o. : 1768
Page 5: Plants. Ed. M. Ajmal Khan & Irwin A

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