الفهرس 
Materials and mithodsOnly 14 pages are availabe for public view
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Abstract
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SUYMARY
The present Lnv est.i.g at.i cn was carried out during 1979
and 1980 seasons to study the effect of salinity and drought
on the growth, yield and chemical composition of two
range plants nrunely, Pennesitum cilia1’e and Chloris gayana. i
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The two range plant species were grovfllin pots filled I
wi th Mariut soil in the greenhouse at Desert Insti tute, III
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Matareya, Cairo, Egypt. i:
Three different irrigation intervals and five differeut
salinity levels were used. Irrigation intervals were
J, 6 and 9 days. Salinity levels were: ),0,1500,3000,
4000 and 5000 ppm of sal ts mixture. The experiment ’.’las
factorial of a split plot design where irrigation treatments
were the main factor and salinity levels were the subfactor.
Results were as follows
I. Effect of irrigation intervals
1. The fresh weight/pot of the two studied range plants
was reduced wi th prolonging the irrigation interval. The
relative yield of fresh weight decreased to 84, 72% aDd 92
and 73% for P.ciliqre and 88, 70% and 94 and 60% for C.gayana
by extending the irrigation interval from 3 to 6 and J to 9
days in the two seasons. I··i;
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2. Extending the irrigation interval from 3 to 6 and
J to 9 days reduced the dry matter by 7.0, 22.5% and 3.7
and 15.5% for P.ciliare and by 1.7, 24.4% and 5.3 and 25.9%
for C.gayana in both seasons.
3. The depression in dry matter was high for P.ciliare
and low for Q.gayana by increasing the irrigation interval
to 6 days. However, the reverse was true when the irrigation
interval was increased up to 9 days. This indicate that
P.ciliare is more drought tolerant.
4.P.rolonging the irrigation interval caused greater
reduction in plant height which was more pronounced in
C.gayana than P.ciliare.
5. Generally, a reduction was observed in leaf area as
well as number of tillers/plant of both range plants, with
increasing irrigation interval.
6. Total carbohydrate concentration decreased constantly
with extending irrigation intervals. However, the
difference between treatments in some cuttings was not large
enough to reach the 5% level of significffilce.
7. Generally _ prolonging irrigation interval increased
the concentration of total protein in the tissues of
P.ciliare and C.g!lana.
8. A progressive increase in sodium c0l1c8ntration
occurred in the shoots of both P.ciliare and C.c;o.yanawith
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e~tending the irrigation intervals. On the other hand, pota-
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s ium concentration decreased under drought conditions.
II. Effect of Salinity
1. Increasing salillity depress ed the fresh and dry matt er
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of both range plants. rr’he re.l ative yi eld of the
ccumulated dry weight in both growth seasons ~~ounted to
and 63% for P.ciliQI’e and 100, 83, 79, 79,
d 75% for C.gayana for salt treatments, control, Sl’ S2’
respectively. The relative yield of P.ciliare plants
than that of C.gayana and consequently the latter
more salt tolerant than P.ciliare.
2. Salinity had a reducing effect on growth characters
f P.ciliare and C.gayana,namely, plant height, Iftaf area and
umber of tillers/plant.
Itration of total carbohydrate and total protein in the tissues
3. A progressive and consiste~t decrease in the concenof
shoots occurred with increasing the concentrations of salts
in root medium.
4. Sodium concentration increased in plant tissues by
increasing salinity levels in root medium. However, the
reverse was observed’with potassiwn concentration.
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III. Effect of the interaction
1. The interaction of different salinity levels and
different irrigation intervals on growth parameters was
significant in all cases. The effect was such that salinity
depressed the growth of both P.ciliare and .Q..gayanaunder
narrow and wide intervals.
2. Maximum plant growth was obtained by growing plants
on non-saline soils and narrow-Irrigation intervals (3 days).
Whereas, minimal growth was obtained in soil of high salinity
(5000 ppm) and the wide irrigation interval (9 days) .