Journal of Applied Sciences Research, 4(10): 1276-1284, 2008 © 2008, INSInet Publication Assessment of Selected Species along Al-Alamein-Alexandria International Desert Road, Egypt A.A. Morsy, A.M. Youssef, H.A.M. Mosallam and A.M. Hashem Department of Botany, Faculty of Science, Ain Shams Univ., Cairo, Egypt Abstract: The present study aim at identifying the ecophysiological behavior of ten xerophytic species in relation to different habitat and stress conditions during winter and summer along Al-Alamein-Alexandria international desert road. Physical and chemical changes in soil along the different examined sites were reflected in changing plant community types. The selected plant species comprise: Haloxylon salicornicum, Anabasis articulata, Zygophyllum decumbens, Agathophora alopecroids, Cornulaca monocantha, Artemisia monosperma, Echinops spinosus, Thymelia hirsuta, Deverra triradiata and Noaea mucronata. Mechanical analysis revealed that soil associated with the studied plants is consisted of different fractions; coarse and fine sand being the dominant fractions for all samples. The contents of succulence, photosynthetic pigments, carbohydrates, nitrogenous compounds, proline and minerals were analyzed and the results showed that, although the studied species belonging to one ecological group; xerophytes, there were wide difference in their metabolism, indicating the wide range of adjustment mechanism behaved by such plants under comparable habitat conditions. In contrast to organic solutes, inorganic ions (in some of the selected species) formed the largest component contributing to osmotic adjustment. Key words: Succulents, Osmotic Adjustment, Al-alamein,, Plant Communities INTRODUCTION to tolerate stress is related to leaf age. Drought in sub- tropical conditions is aggravated by the higher Differences in water relation characteristics temperature and results into a reduction in stomatal reflected the differences between the species and are conductance associated with changed in water content, considered as an indicator of drought resistance or xylem water potential and water potential. William and tolerance in arid regions [13,37]. Osmotic adjustment is a Sharon (1981) observed that under water stress, mechanism that significantly contributes towards drought chlorophyll formation was markedly depressed and there resistance [11]. In order to keep osmotic balance, specific is no linear relationship between the amount of water and types of organic molecules (such as soluble sugars, chlorophyll content. nitrogenous compounds, proline, polyols and betains ) are Solutes known to accumulate with water stress accumulated in the cytoplasm. These compounds are and to contribute to osmotic adjustment of non- termed compatible solutes and have a larger hydration halophytes include inorganic cations, organic acids, shell than denaturing molecules [36]. carbohydrates and free amino acids [34,41]. Proline is the Desert plants generally follow two main strategies most common amino acids accumulating with water i.e., they tolerate the drought through phonologic and stress and may increase 100 fold in concentration physiological adjustments referred to as tolerance or over the pre-drought levels [7]. Proline may be utilized avoidance mechanisms contribute to the ability of a plant for chlorophyll synthesis and may serve as reserve to survive drought but it also depends on the frequency substance for the synthesis of chlorophyll upon relief and severity of the drought periods [47,22]. Plants under of the stress suggesting that proline has some role in such conditions regulate their water status using several drought protection and salt tolerance [22]. While many tactics viz., osmotic adjustment, stomatal aperture, turgor researches have done much more work for plants' maintenance, root distribution and leaf canopy properties. osmotic adjustment in the past 30 years, osmotic Leaves developed under drought conditions generally adjustment is an important function for drought exhibit small cell size, thick cell walls, small vacuoles resistances [41]. Free proline and soluble sugar and higher concentration of osmotica. The water relation accumulation in the plant leaf under stress conditions parameters, therefore, do not differ significantly between are of utmost importance for plant adaptation during young and old leaves. However in other species the ability stress. Corresponding Author: A.A. Morsy, Department of Botany, Faculty of Science, Ain Shams Univ., Cairo, Egypt 1276 J. Appl. Sci. Res., 4(10): 1276-1284, 2008 MATERIALS AND METHODS The work was carried out during winter and summer seasons, of three successive years 2005-2007. Climate: The climatic data of the area under study was collected from three meteorological stations El-Dabbaa, Wadi El-Natron and Gianaclis. Maximum and minimum mean values of temperature (°C), annual precipitation (mm) and the relative humidity (%) were determined for the selected sites. Study Area: The area extending along the international Alex-Al-Alamein road is located between latitude 30°29'74'' to 30°43'65'' North and 30°08'71'' to 29°01'14'' East. It extends about 133 km from Marina-Al Alamein (on the Mediterranean coastal region) in the North to Wadi El- Natron in the south (Fig. 1). Except for the narrow Mediterranean coastal belt which is the wettest region of Egypt, the whole western desert (including the studied area) is one of the extremely arid parts of the world. Geomorphology of the Studied Area: The studied area Fig. 1: Map showing the Cairo – Alexandria Desert Road is located in the Libyan portion of the Sahara which is (modified after Zahran and Willis 1992) called now the western desert of Egypt as it occurs west of the river Nile. The aridity of the area is resulted from Zygophyllum decumbens Del.: Shrublet with prostrate or its distance position from seas, coupled with the absence decumbent branches. Leaves of one pair of broadly of high altitudes which may attracts orographic rains obovate, flattened, fleshy leaflet. Flowers small, capsule (Except the northern part of the studied area) Omayed pear-shaped, deeply 5-parted, apex entire. Agathophora biosphere. The physiographic similarity of the studied alopecroids (Del.) Bge Shrub with continuous stem. area leads to the distinction of few types of habitats. Leaves fleshy. Spiny-tipped. Flowers in globose clusters. These habitats are more or less arranged in the same Fruit-perianth with 5 wings. Branches white, glabrous. sequence from the northern Mediterranean coast to the Varying from globose to prismatic-cylindrical, at tip south as following: 1) Slightly littoral salt marshes which obtuse with a needle-like, easily deciduous, small spine, comprise the areas of land near the sea and are subjected axils wooly. to some maritime influences. The substratum of this ecosystem is saline and favors the growth of salt tolerant Cornulaca monacantha Del.: Blue-green, intricate shrub. plants (Halophytes); 2) Depression; 3) Sand flat; 4) Road Leaves short, recurved, tapering from a clasping base into sides and 5) Road dividers. a rigid spine, axils woolly. 1 or 2 of perianth-segments in fruit with along stout spine. Plant Materials: The plant materials used in the present investigation were obtained from the following selected species and collected from their natural habitats. Artemisia monosperma Del.: Glaucous glabrous low shrub, 0.4-1.2m;stems numerous branched, erect or Haloxylon salicornicum (Moq.) Bunge: Shrub 25-60cm; ascending suculate; leaves0.6-2.5x0.2-1.8, rather fleshy, stem richly branched, the old branches with yellowish- variable. white cracking bark; leaves scales- like shortly triangular, connate into a cup. Echinops spinosus L.: Richly branched. Leaf-lobes narrow, linear, revolute-margined, terminated by rigid Anabasis articulate (Forssk): Shrub 30-80cm; stem with spines. Flowers pale blue or white in rather large heads. spit bark; branches opposite, brittle; nodes pale green, Desert thistles with out latex. Flowers surrounded by leaves reduced to a 2-lobed cupules, with obtuse- special involucres and together forming a large, mucronatetips. compound, globose head. 1277 J. Appl. Sci. Res., 4(10): 1276-1284, 2008 Thymelia hirsuta (L.) Endl.: Dioecious or monoecious calculated as mg g-1 fresh weight of plant material. Total evergreen shrub, 0.5-1.8m; stem rigid, fibrous, much carbohydrate: Total carbohydrate content was estimated branched, the young branches white woolly; leaves 2-5x as the method described by Chaplin and kennedy [15] and 1-2mm, imbricate, sessile, leathery ovate, triangular; expressed as mg 100g-¹ dry weight. Soluble sugars were flowers 3-4mm diam., sessile. determined colourimetrically by the anthrone method as described by Spiro, 1966 and expressed in g 100 g-¹ dry Deverra triradiata (Desf.): strongly aromatic glabrous wt. Determination of proline: Free proline was determined according to the method described by Bates et al., (1973) shrub, 30-80cm; stems dichotomously branched; leaves and expressed as ìmole gr-1.d.wt. Determination of caduceus; flowers hardly opening. soluble nitrogen. The soluble nitrogen contents of the plant samples was determined according to Hassanein[21]. Noaea mucronata (Forssk): Shrub 20-80cm; stem sprawling, branched, the old branches with grayish RESULTS AND DISCUSSION fissured bark, young branches glabrous; leaves narrowly linear. Climate: Climate of the region under investigation belongs to the warm coastal desert climate. According to Soil analysis: Soil samples were collected