الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
SUMMARY
Two field experiments were carried out during 2012 and 2013
seasons at Agricultural Experimental Station in Ras Sudr Research
Station, Desert Research Center, at South Sinai Governorate, Egypt, to
study the effect of interaction between three periods of irrigation (4 day -
8 day – 12 day ) and four soil additives ( Potassium humate, silicon,
mixture of both and control tap water) on the growth, yield and chemical
composition of two pearl millet cultivars (Shandawyl 1 and Sudan pop I)
under saline condition. The main results could be summarized as follows:
1. Growth Traits
Irrigation intervals had significant effect on growth parameters
(plant height, number of tillers/ plant, fresh weights, dry weights and leaf
area) of pearl millet cultivars. The increase in growth was achieved with
irrigation every 4 day treatment as compared with the other two irrigation
treatments (8 day and 12 day) during 1st cut and 2nd cut in both growing
seasons.
All growth traits significantly increased with all soil additives as
compared with the control during both seasons. However, silicon
treatment recorded the higher mean values for plant height, number of
tillers/m2, fresh and dry weights as well as leaf area during 1st cut and 2nd
cut in both growing seasons. Meanwhile, potassium humate and the
mixture (silicon + Potassium humate) recorded the 2nd and 3rd order,
respectively.
Generally, significant response was shown in all growth
characters of the two pearl millet cultivars. However, Sudan pop I
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cultivar exhibited the highest mean values for all growth traits during 1st
cut and 2nd cut in both growing seasons.
Concerning the effect of interaction between irrigation intervals
X soil additives X pearl millet cultivars on growth traits under Ras Sudr
conditions, the interaction between 4 day irrigation interval with silicon
as a soil additive for Sudan pop I cultivar gave the highest mean values
of plant height, number of tillers/m2, fresh and dry weights as well as leaf
area during 1st cut and 2nd cut in both growing seasons. Also, application
of potassium humate as a soil additive with 4 day irrigation interval for
Sudan pop I cultivar recorded the 2nd order during 1st cut and 2nd cut in
both growing seasons. Generally, plant height, number of tillers/m2, fresh
and dry weights of pearl millet plant recorded the highest mean values
during the 1st cut in 1st season while leaf area recorded the highest mean
values during the 1st cut in 2nd season.
2. Chemical composition
Plant hormones:
Concerning endogenous phytohormones, the interaction between
4 day irrigation intervals with silicon as a soil additive for Sudan pop I
cultivar gave the highest mean values of IAA and GA3 followed by The
interaction between 4 day irrigation interval with silicon as a soil
additives for Shandawyl 1 cultivar. Also, application of tap water as a
soil additive with 12 day irrigation interval for Shandawyl 1 cultivar
recorded the lowest mean values of IAA and GA3. Concerning ABA
level, the highest mean value for ABA was produced from the interaction
between tap water as a soil additive with 12 day irrigation interval for
Shandawyl 1 cultivar followed by the interaction between 12 day
irrigation interval with tap water as a soil additive for Sudan pop I
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204
cultivar. However, the lowest mean value for ABA was produced from
the interaction between 4 day irrigation interval with silicon as a soil
additive treatment for Sudan pop I cultivar.
Photosynthetic pigments:
Irrigation interval treatments increased significantly pigment
contents as compared with the control. Chlorophyll (a), chlorophyll (b),
carotenoids, chlorophyll (a+b) and total pigments recorded the highest
mean value due to 4 day irrigation interval, whereas the lowest value of
these parameters were recorded due to irrigation interval every 12 day.
All soil additives increased significantly pigment contents as
compared with the control. Silicon treatment recorded the highest mean
values for chlorophyll (b) contents compared with other treatments.
However, Potassium humate produced the highest mean values for
chlorophyll (a), chlorophyll (a+b), carotenoids and total pigments. Sudan
pop I cultivar significantly exceeded Shandawyl 1 cultivar in chlorophyll
(a), chlorophyll (b), chlorophyll (a+b), carotenoids and total pigments.
The interaction between 8 day irrigation interval with potassium
humate as a soil additive for Sudan pop I cultivar gave the highest mean
values of chlorophyll a, chlorophyll a+b and total pigments. Also,
application of potassium humate as a soil additive with 4 day irrigation
interval for Sudan pop I cultivar recorded the highest mean values of
chlorophyll b. However, the interaction between 4 day irrigation interval
with control as a soil additive for Sudan pop I cultivar gave the highest
mean values of carotenoids.
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205
Carbohydrate contents:
Irrigation interval treatments had significant effect on
carbohydrate contents. It is clearly shown that 4 day irrigation interval
produced the highest mean values for total carbohydrate and nonsoluble
carbohydrate contents. While, 12 day irrigation interval treatment
marked the highest mean values for soluble sugars.
All soil additives had significant effect on carbohydrate contents
as compared with the control (tap water). It is clearly shown that silicon
produced the highest mean values for carbohydrate contents (total
carbohydrate, soluble sugars and non-soluble carbohydrate contents)
followed by soil additive with potassium humate.
Sudan pop I cultivar produced the maximum value of total
carbohydrate and non-soluble carbohydrate contents. While, Shandawyl
1 cultivars marked the highest mean values for soluble sugars.
It is evident from these results that the interaction between 4 day
irrigation interval with silicon as a soil additive for Sudan pop I cultivar
recorded the highest mean values of total carbohydrate and non-soluble
carbohydrate contents followed by the interaction between 4 day
irrigation interval with silicon as a soil additive treatment for Shandawyl
1 cultivar. Meanwhile, the interaction between 12 day irrigation interval
treatment with silicon as soil additives treatment for Shandawyl 1
cultivar recorded the highest mean value for total soluble sugars contents
followed by the interaction between 12 day irrigation interval with
silicon as a soil additive for Sudan pop I cultivar.
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206
Protein and proline contents:
Irrigation interval treatments had significant effect on total
protein, soluble and non-soluble protein and proline contents. Irrigation
every 12 day marked the highest mean values for proline content and
irrigation every 4 day recorded the highest mean values for total protein,
soluble and non-soluble protein in pearl millet plants.
All soil additives had significant effect on proline and Proteins
(total, soluble, non-soluble) contents as compared with the control (nontreated).
It is clearly shown that silicon produced the highest mean values
for proteins (total, soluble, non-soluble) contents as compared with the
other treatments.
Generally, significant response was found in proline and proteins
contents of the two pearl millet cultivars. However, pearl millet Sudan
pop I cultivar exhibited the highest mean values of proline and proteins
(total, soluble, non-soluble) contents.
The highest values of total protein, soluble and non-soluble
protein contents were recorded by the interaction between 4 day
irrigation intervals with silicon as soil additive for Sudan pop I pearl
millet cultivars as compared with the other treatments. While, the
interaction between 12 day irrigation interval with silicon as a soil
additive for Shandawyl 1 cultivar recorded the highest mean value of
proline content.
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207
Amino acids content:
Seventeen amino acids were detected in shoots of pearl millet
plant. They are aspartic acid, glutamic acid, arginine, alanine, proline,
leucine and valine appeared in higher amounts in the shoots of pearl
millet plant. Water stress induced a massive increase in total amino acids
detected in the shoot of two pearl millet cultivars.
Soil additives with potassium humate, silicon and mixture of
potassium humate and silicon and their interaction induced additional
increases in the detected amino acids content when compared with
control (tap water) in shoots of two pearl millet cultivars. The interaction
between silicon as soil additive with 12 day irrigation interval treatment
for Sudan pop I cultivar recorded the highest value of total amino acids
content followed by the interaction between potassium humate as soil
additive with 12 day irrigation interval treatment for Sudan pop I
cultivar. Whears, the interaction between tap water as soil additive with 4
day irrigation interval treatment for Shandwyl 1 cultivar recorded the
lowest value of total amino acids content.
Minerals composition:
Irrigation interval treatments had significant effect on minerals
composition. It is clearly shown that 4 day irrigation interval produced
the highest mean values for Mg, Ca, P and and K contents. While, 12 day
irrigation intervals treatment marked the highest mean value for Na
contents.
Mg, K, Ca and P contents were significantly increased with all
soil additive treatments as compared with the control . On the contrary,
Na content was decreased with all soil additive treatments. Soil additives
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208
with silicon produced the maximum value of Mg, K, Ca and P contents
as compared with the other treatments. On the other hand, control
marked the highest mean value for Na content.
Sudan pop 1 cultivar produced the maximum value of Mg, Ca, K
and P contents. A reverse effect was observed for Na content.
It is evident from present results that 12 day irrigation interval
with control as a soil additives treatment for Shandawyl 1 cultivar
recorded the highest mean value of Na content. Meanwhile, 4 day
irrigation interval treatment with silicon as soil additives treatment for
Sudan pop I cultivar recorded the highest mean value for P, Ca and Mg
contents. Also, 4 day irrigation interval treatment with potassium
humate as soil additive treatment for Sudan pop I cultivar recorded the
highest mean value for K contents. The above results revealed that soil
additives with potassium humate, silicon and mixture of potassium
humate + silicon and their interaction with irrigation interval treatments
increased Mg, K, Ca, and P contents, while, decreased Na level when
compared with control . This response is much more pronounced in
Sudan pop I cultivar indicating that Sudan pop I cultivar is more tolerant
than Shandawyl 1 cultivar.
Antioxidant enzymes:
The activities of catalase (CAT), ascorbate peroxidase (APX) and
peroxidase (POX) were increased in response to drought stress. Irrigation
at 12 day interval treatment recorded the highest main value of these
enzymes as compared to 8 and 4 day irrigation interval treatments. In
general, all soil additives increased the activities of catalase (CAT),
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ascorbate peroxidase (APX) and peroxidase (POX) as compared to the
control.
SOD patterns revealed the presence of three bands for the two
pearl millet cultivars. The more intensive band is presented at band
number 2 followed by band number 1 in two pearl millet cultivars with
all treatments under drought stress. Concerning band intensity, data
showed that irrigation intervals had a positive effect on band intensity
under salinity stress. Band intensity increased in all samples under 12
day irrigation interval compared with the 8 day and 4 day irrigation
intervals treatments. Also, all soil additives by potassium humate, silicon
and the mixture between both increase band intensity as compared with
the control.
Lipid peroxidation (Malondialdehyde), Ascorbic acid, total phenols
and total flavonoids:
Irrigation at 12 day interval produced the highest mean values for
Malondialdehyde, ascorbic acid, total phenols and flavonoids followed
by 8 day irrigation interval treatment as compared with 4 day irrigation
interval treatment.
Ascorbic acid, total phenols and total flavonoid conents were
significantly increased with all soil additives as compared with the
control (tap water). While, malondialdehyde significantly decreased with
all soil additives as compared with the control (tap water). Soil additives
with silicon produced the maximum value of ascorbic acid, phenols and
flavonoid conents as compared with the other treatments.
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210
Generally, significant response was found in malondialdehyde,
ascorbic acid, total phenol and total flavonoid contents of the two pearl
millet cultivars. However, pearl millet Sudan pop I cultivar exhibited the
highest mean values of ascorbic acid, total phenols and total flavonoid
contents. Whereas, pearl millet Shandawy l cultivar exhibited the highest
mean values of malondialdehyde.