Wadi Quena, unique in its north-south orientation among other wadies of the eastern desert of Egypt constitutes a vast catchment system of sporadic rains over the Red Sea mountains. The present study concerns a part of this catchment area, including some eastwest tributaries pouring flood waters into the lower part of the main trunk of the wadi. Due to local physiographic factors, these tributaries harbour two communities newly recognized in this desert. These are: community of Salsola haryosma-Tamarix aphylla and community of Cilrullus colocynlhis-Cleome droserifolia. Elements of the alliance Zygophyllaeion coccini, previously identified in this series of investigations, are well represented in the area under consideration.

The effect of treatment combinations of decreased soil osmotic water potential (Ips) and increased sodicity (SAR) on chlorophyll (ChI) characteristics (ChI a and b contents, Chi a/b ratio, and Chi stability to heat - CSI) of three crop plants (Gossypium barbadense L., Hibiscus sabdarifJa L. and Sorghum bicolor L.) was studied. Chi characteristics in different plant species responded variably to both changes in 1jJs and sodicity. Generally, Chi content was not sensitive to sodicity but both ChI a and b were significantly affected by osmotic stress. Accordingly, the Chi a/b apparent changes at different SAR levels were due to osmotic rather than sodic effects. CSI showed variable trends in response to both decreased 1jJs and increased sodicity according to ChI type and plant species. Decreasing ChI content and increasing CSI, under reduced 1jJs, might indicate the adaptations of plants toward enduring salinity stress, particularly in reference to the ecological origin of such crop plants.

The effect of treatment combinations of decreased soil osmotic water potential (Ips) and increased sodicity (SAR) on chlorophyll (ChI) characteristics (ChI a and b contents, Chi a/b ratio, and Chi stability to heat - CSI) of three crop plants (Gossypium barbadense L., Hibiscus sabdarifJa L. and Sorghum bicolor L.) was studied. Chi characteristics in different plant species responded variably to both changes in 1jJs and sodicity. Generally, Chi content was not sensitive to sodicity but both ChI a and b were significantly affected by osmotic stress. Accordingly, the Chi a/b apparent changes at different SAR levels were due to osmotic rather than sodic effects. CSI showed variable trends in response to both decreased 1jJs and increased sodicity according to ChI type and plant species. Decreasing ChI content and increasing CSI, under reduced 1jJs, might indicate the adaptations of plants toward enduring salinity stress, particularly in reference to the ecological origin of such crop plants.

Sand culture technique was employed to investigate the effect of soil salinity and kinetin on chlorophyll a and b contents, the a/b ratio and the chlorophyll stability to heat in Sorghum bicolor and Gossypium barbadense cultivars. Levels of osmotic potential of the soil solution between -3 and -13 bar were adjusted by irrigation with certain amounts of saline solutions containing NaCI and CaCI2. Kinetin solutions (10 ppm) were applied by 3 methods: treatment of the seeds (presoaking), shoot treatment (spraying) and by irrigation. Kinetin can retain the chlorophyll content and even increases them in the two investigated plants when applied by presoaking method. The a : b ratio seems to be affected by salinity stress rather than by kinetin treatment. Kinetin enhances significantly the stability index of both chlorophyll types in particular when applied by presoaking method. The results proved that kinetin can alleviate salinity stress on chlorophyll parameters in both investigated plants when applied by presoaking method rather than by the other methods

Five wadis proliferate in the area surveyed (latitudes 27°-28 N and longitudes 33°-34 E) drain this part of the Red Sea mountains into the sea (lower Gulf of Suez)./This wadi system have distinguished variation in geomorphological and edaphic characteristicS. ACcordingly four associations phytosociologically identified are reflections of such variations. Such associations are not repetitions to those identified before in this series of investigations. Also, they have no analogues among communities recognized in this desert by other investigators.

Five wadis proliferate in the area surveyed (latitudes 27°-28 N and longitudes 33°-34 E) drain this part of the Red Sea mountains into the sea (lower Gulf of Suez)./This wadi system have distinguished variation in geomorphological and edaphic characteristicS. ACcordingly four associations phytosociologically identified are reflections of such variations. Such associations are not repetitions to those identified before in this series of investigations. Also, they have no analogues among communities recognized in this desert by other investigators.

Five wadis proliferate in the area surveyed (latitudes 27°-28 N and longitudes 33°-34 E) drain this part of the Red Sea mountains into the sea (lower Gulf of Suez)./This wadi system have distinguished variation in geomorphological and edaphic characteristicS. ACcordingly four associations phytosociologically identified are reflections of such variations. Such associations are not repetitions to those identified before in this series of investigations. Also, they have no analogues among communities recognized in this desert by other investigators.

Twelve wadis proliferate in the area surveyed drain this part of the Red Sea mountains into the Sea at Qusseir province. Phytosociological study of these wadis is based on the analysis of 55 stands using the Zuarich-Montpellier technique. The vegetation survey revealed the prevailance of perennials in this area. Two distinct community types are recognized in the stands studied in the investigated wadis, each of which seems to have its own ecological characteristics especially concerning the water factor. The community type dominated by Capparis decidua and Tamarix nilotica covering the deltaic areas and the end parts of the wadis traversing the inland basement complex country. Some members of this community type are halophytic plants. The other community type dominated by Pulicaria undulata and Pulicaria crispa was found inhabiting most of the wadis courses especially the high localities. Members of this community type reflect the prevailing xerophytic conditions. Elements of the alliance Zygophyllaeion coccini previously recognized in other wadis of this desert are well represented in these wadis. Within the area surveyed, the individuals of most species covered in this study exhibit a wide range of variation in size and vitality.These differences are related mainly to differences in water resources.

Twelve wadis proliferate in the area surveyed drain this part of the Red Sea mountains into the Sea at Qusseir province. Phytosociological study of these wadis is based on the analysis of 55 stands using the Zuarich-Montpellier technique. The vegetation survey revealed the prevailance of perennials in this area. Two distinct community types are recognized in the stands studied in the investigated wadis, each of which seems to have its own ecological characteristics especially concerning the water factor. The community type dominated by Capparis decidua and Tamarix nilotica covering the deltaic areas and the end parts of the wadis traversing the inland basement complex country. Some members of this community type are halophytic plants. The other community type dominated by Pulicaria undulata and Pulicaria crispa was found inhabiting most of the wadis courses especially the high localities. Members of this community type reflect the prevailing xerophytic conditions. Elements of the alliance Zygophyllaeion coccini previously recognized in other wadis of this desert are well represented in these wadis. Within the area surveyed, the individuals of most species covered in this study exhibit a wide range of variation in size and vitality.These differences are related mainly to differences in water resources.

The ldfu-Marsa Alam road crosses through six wadis in the Eastern Desert in upper Egypt. Three, namely wadi Abbadi, Wadi Kanayis and wadi Barramiya drain their water in the Nile Valley, while the other three, wadi Beizah, wadi Duber and wadi Abu Qaraiya drain their water in the Red Sea. The phytosociological study of these six wadis along the road was based on the analysis of vegetation in 20 stands using the Ziirich- Montpellier technique. The vegetation survey indicated the prevalance of perennials. The phytosociological tableau revealed four community types in the wadis, one of which seemed to be a segetal part of an "AIliance" wide-spread in other wadis of this desert. These communities are: I. Zilla spinosa - Aerva javanica, 2. Pulicaria undulata-Schouwia thebaica, 3. Cleome arabica-Crotalaria aegyptiaca 4. Acacia tortilis-Zygophyllum coccinewn.