الفهرس 
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Abstract
The aim of the present investigation is
the responses of some desert plants to
conditions under natural conditions.
to clarify
the adverse
The chosen area was that extended from km 30 to km
70 on the left side of Cairo-Alexandria desert road from
Cairo. Climatic changes during the seasons extended from
1986 till 1989 was discussed.
Edaphic factors was also examined in the terms of
physical and chemical properties. Some Eco-physiological
studies were also discussed. The following results could
be detectd :
1. The main prevailing plant species under the conditions
of this work are Calligonum comosum, Polycarpaea
repens, Bassia muricata. Cornulaca monocanthd.
Eremobium aegyptiacum, Neurada procumbens, Zygophyluum
album. Monsonia nivea, Moltkiopsis ciliata. Ifloga
specata, Cotula cinerae. Reichardia tingitana. Launaea
nudicaulis. Launaea mucronata. Launaea capitata,
Stipagrostis plumosd, Senecio disfontianei. Pennisetum
divisum.
2. The macromorphological characters are quite
differences within the tested plant species. in
addition every plant having its own morphogenesis
which completely adaptable to the adverse conditions
prevailing under the study area.
3. The variable changes in different plant species
phenology. indicating the dynamic changes of such
plant morphogenises tolerating the adverse conditions.
as the following
a) Root system: most of the studied plants. the
length of the root exceed the height of the aerial
plant except Stipagrostis plumosd and pennisetum
divisum. which they have fleshy. thick and fibrous
adventesious root and depth not great. The other
plants have the root system exceeds the shoot
system to help the plant to absorb water. minerals
and nutrients. The extension of root horizontally
or vertically depending upon either the· soil
physical properties or the direction of relative
more soil moisture.”The regulation balances between
root system and shoot system according to the
contents of soil moisture only in Launaea
mucronata.
b) Plant length
It is shorter than the root system in most of the
plants except Pennisium divisum and Stipagrostis
plumosa. which they live in clusters which may
contain more than one plants (tillers/clusters).
Also Ifloga spicata. Cotula cinerea have very
shorter compacting shoot system and deep root
extension. i.e the longer the water absorption
organ as the shorter of transportaion organ.
c) The changes in the climatic factors from season to
another representing the variable morphogenesis
which differ from plant species to another. This
indicates that different species regulate their
macromorphology to adaptate them-selves to survival
under varied conditions.
4. The vegetation of the plant species in the studied
area was founded Conulacia monacantha is the most
abondant plant in the community in defferent studied
area and the only exception Spot III of km 50, at the
cultivated area. This is due to partially conti’nouse
control of weeds ,by the farmers or due the excess of
soil moisture over its need. The number of vegetation
was higher during season of 1988 due to the amount of .
rainfall and air relative humidity it must be
mentioned that the Cornulaca monacantha community havy
also many of the dominant plants such as Bassia
muricata. Polycdrpaea repens. Maltkiopsis Ciliata,
Monsonia Nivea and Cotula cinerea. The abondance of
these species were completely differ with the
different spotarous.
It must be mention that the cultivation of des ert
plant affected greatly the natural vegetation.
5. The water saturation deficit was varied with the
different plant species, variable tested plant organs
and the prevailing environmental conditions.
6. Total ash contents and crude fiberous percentage
changes under drought conditions.
The total ash content ahd crud fibers were varied with
plant species and play important role for preservation
the water wither the plant.
It could be revealed that the accumulation of
different salt (ash) increased during the more dry
season. The crude fibers composed mainly cellulose for
preserving water in plant tissues and can adheir and
adsorb water.
Such plant constituents added more additional
toleration to the different plant species againest the
adverse conditions.
7. The main dominant element in different tested plant
species was calcium which paly an important role for
minimizig the accumulation of many elements such as K.
P. Mg. Fe, Zn and Mn. The study of mineral status in
the different ’plant tissues indicated that eu was
found in high proportion. the relations between the.
accumulation proportions of different elements were
discussed in details with the possible roles of them
for the adaptability of the studied plants under the
conditions of the tested area.
8. The chloroplast pigments was discussed in detailed
with the correlation of their. rate to the adverse
conditions.
9. The protein carbohydrates fractions and amino acids
content are discussed on the basis of their role for
adding more supportes to the plants to survival under
adverse conditions.