الفهرس 
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Abstract
Two experiments were designed to assess the effectiveness of
exogenous ascorbate (Asc), salicylate (Sa), and silicate (Si) and /or nanosilicon
to reduce the effect of water and salt stresses, on potato (Solanum
tuberosum L.) and tomato (Solanum lycopersicum L.), respectively.
The open field trial
Forty days-old potato plants were exogenously applied with
ascorbate (Asc) at (0, 0.25, 0.5 and 1.0 mM), salicylate (Sa) at (0, 0.25,
0.5 and 1.0 mM) , and silicate (Si) at (100, 250, and 500 ppm) to study its
efficacy under water deficit regimes; i.e. three days interval (control) ,
four days interval (4DI), and five days interval (5DI) and their interaction.
Leaf samples were collected to measure different biochemical parameters.
Effect of applied treatments under studied stress on photosynthetic
pigments
Results of ascorbate treated group showed that ascorbate (0.25
mM) showed the highest values of Chl a and b contents compared with
other concentrations at both 4DI and 5DI water regimes. In salicylatetreated
group, the highest values of Chl a and b contents were recorded by
Sa (1.0 mM), at the control water regime, also Sa (1.0 and 0.25 mM)
increased Chl a and b contents at control and 4DI. In silicate-treated
group, application of silicate (100 ppm) had the more pronounced effect
compared with other concentration where it is improved Chl a the three
water regimes and Chl b at 4DI and 5DI water regimes.
Effect of applied treatments under water deficit stress on Carotenoids
Data of ascorbate treated group showed that ascorbate (0.25 mM)
represented the highest value of carotenoid content at 4DI water level.
Regarding salicylate-treated group, Sa (0.5 mM) recorded the highest
carotenoids content at 4DI and 5DI water levels.
In silicate-treated group, Si (100 and 250 ppm) increased
carotenoids content at 4DI and 5DI water levels.
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SUMMARY
Amal Abdelmonem Mostafa (2019), Ph.D., Fac. Agric., Ain Shams Univ.
Effect of applied treatments under water deficit stress on free proline
In ascorbate-treated group, at control water regime, Asc at (0.25,
0.5, and 1.0 mM) increased proline content compared to control, in
contrast, these concentration led to reduction of the mean free proline
content At 5D water level. Regarding salicylate application, Sa at (0.5 and
1.0 mM) decreased proline content compared to control at 4DI and 5DI
water levels in addition to Sa (0.25mM) at 5DI.
Concerning silicate-treated group, a reduction in free proline
content was detected by; Si (100 and 250 ppm at control level of water, Si
(100, 250 and 500 ppm) at 4DI water level and Si (100 and 500 ppm), at
5DI water level.
Effect of applied treatments under water deficit stress on (MDA)
In ascorbate-treated group, a reduction in MDA content was
occurred by application of Asc 1.0 and Asc 0.25 under 4DI and 5DI water
regime respectively.
Concerning application with salicylate, the results showed that the
increment in MDA content with water deficit was not affected
significantly by application of salicylate, however, Sa (0.25 mM)
increased MDA content at 4DI. Regarding silicate treatments, the results
showed similar effect at control, 4DI and 5DI water regime, whereas Si
500 ppm slightly decreased MDA content by 2.48, 20.84 and 10.21%,
respectively under the studied water regimes.
Effect of applied treatments under water deficit stress on plant dry
matter
In ascorbate-treated group, Asc (0.5 mM) revealed the highest dry
matter percentage under control water regime, while the same
concentration detected the least dry matter at 5DI water regime. The result
of salicylate-treated group showed, Sa (0.5 and 0.1 mM) improved plant
dry matter by 17.83 and 10.05%, at control water regime, respectively.
However Sa (0.5 and 0.25 mM) reduced the plant dry matter at 4DI and
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SUMMARY
Amal Abdelmonem Mostafa (2019), Ph.D., Fac. Agric., Ain Shams Univ.
5DI water regimes, respectively. Silicate application affected plant dry
matter significantly, Si (250 ppm) increased plant dry matter percentage
at control and 5DI water levels. Silicate at (100, 250, 500 ppm) increased
plant dry matter by 25.52, 25.36 and 10.89 % at 4DI water level,
respectively.
Effect of applied treatments under water deficit stress on tuber dry
matter
Ascorbate application showed no significant differences on tuber
dry matter percentage.
Regarding salicylate application, the data showed the same rank
however, almost all salicylate concentrations tended to enhance tuber dry
matter percentage under all water regimes. In the case of Si-treated plants,
application with silicate under water deficit conditions showed no marked
differences on tuber dry matter percentages.
Effect of applied treatments under water deficit stress on tuber yield
Ascorbate-treated group showed that Asc at (0.25 mM) improved
tuber yield by 50.32%, 25.79% and 73.38% respectively under control,
4DI and 5DI water levels,. Ascorbate at (0.5 mM) increased tuber yield
by 19.95 and 50.44%, under both control and 5DI water regimes. In
addition, (Asc 1.0 mM) enhanced plant tuber yield by 6.7 and 24.46%
under 4DI and 5DI, compared to its control. In silicate-treated group the
effect of silicate was fluctuating between increment and decrement at both
control and 4DI water level. However, all silicate concentration (0.25, 0.5
and 1.0 mM) improved tuber yield at 5DI water regime by 65.61, 21.8
and 33.33 % compared to its control, respectively.
The greenhouse trial
The experiment was carried out to study the effect of silicon in
nano particle form (Si NPs) on transgenic tomato lines expressing
CaMV35S-ySpdSyn; i.e. C4 and C15, along with their azygous control
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SUMMARY
Amal Abdelmonem Mostafa (2019), Ph.D., Fac. Agric., Ain Shams Univ.
(L5) under 200 mM NaCl stress. Leaf samples were collected at three
time points; before starting salt (Zero), 14 day after starting salt (14
DAS), and 14 days after recovery with tap water (Recovery).
Effect of Si NPs on chlorophyll content in tomato genotypes under
salt stress
Effect of Si NPs on total chlorophyll content (SPAD), showed that
L5 represented more chlorophyll compared with C4 and C15 lines. Salt
stress tended to increase the level of chlorophyll, whereas Si NPs did not
show significant differences at zero and 14 DAS whoever, it significantly
increased chlorophyll content in C4 line at recovery phase in unstressed
plants.
Effect of Si NPs on free proline in tomato genotypes under salt stress
Effect of Si NPs on free proline exhibited that L5 has more proline
content compared with C4 and C15 transgenic lines. At zero time,
Application with Si NPs enhanced proline content significantly in both L5
and C15.
At 14 DAS, salt exposure resulted in a dramatic enhancement in
proline content, proline increment was more pronounced in C4 and C15
lines compared with L5, however, application with Si NPs decreased
proline content in these lines. At recovery phase, a sharp reduction in
proline has been occurred compared with the previous phase (14 DAS), Si
NPs reduced proline in C4 and C15 in unstressed and C4 in salt stressed
plants.
Effect of Si NPs on malonaldehyde (MDA) in tomato genotypes under
salt stress
The result indicated that at zero time point, Si NPs tended to
reduce MDA content in all tested lines. At 14 DAS, salt applied plants
accumulated more MDA content, whereas C4 and C15 slightly
accumulated more MDA compared with L5. Also, Si NPs lead to a slight
reduction in MDA content in C4 line. At recovery phase, in unstressed
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SUMMARY
Amal Abdelmonem Mostafa (2019), Ph.D., Fac. Agric., Ain Shams Univ.
plants no significant differences was observed between treatments. In
stress recovered plants Si NPs cause a reduction in C4 by 26 %.
Effect of Si NPs on hydrogen peroxide (H2O2) in tomato genotypes
under salt stress
Effect of Si NPs on hydrogen peroxide (H2O2) showed that data of
zero and 14 DAS confirmed that L5 had more H2O2 compared with the
transgenic lines. At 14 DAS, salt addition resulted in an increment in
H2O2 content ranging from 1.5 to 3.6 folds. Si NPs application reduced
H2O2 in C4 subjected to salt. At recovery phase, in unstressed plants no
significant differences was observed between treatments, while in the
stress-recovered plants C4 + Si recorded the lowest value, however L5 +
Si recorded the highest. Looking at the three points together, it is
noticeable that, Si NPs reduced H2O2 in C4 line started at 24 h after
applying Si NPs (Zero time) and continued after applying salt and at
recovery period.
Effect of Si NPs on electrolyte leakage EL% in tomato genotypes
under salt stress
Electrolyte leakage EL % at 14 DAS represented that, in
unstressed plants, EL% was in normal level ranging from 8-11 % with no
marked differences between genotypes or Si NPs treatment. In the saltstressed
plants, salt application caused increment in EL% by 2.7- 4.1 folds
between treatments. C4 and C15 lines without Si NPs had more leakage
compared with L5, while Si NPs application promoted reduction in the
leakage by 4.8, 19.77 and 15.6 % in L5, C4 and C15, respectively.
Effect of Si NPs on minerals in tomato genotypes under salt stress
Sodium content
At zero time, no significant difference was observed among
different treatments. At 14 DAS, in the unstressed plants no significant
differences was observed. Meanwhile, in salt stressed plants, salt addition
resulted in a sharp accumulation of Na+ in the leaves of all tested lines. In
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SUMMARY
Amal Abdelmonem Mostafa (2019), Ph.D., Fac. Agric., Ain Shams Univ.
addition, C4 and C15 significantly accumulated more Na+ compared with
L5.
At recovery, in the unstressed plants, L5 showed less Na+ content
compared with C4 and C15 lines, while Si NPs treatment did not show
significant influence. In stress recovered plants, the transgenic lines along
with Si NPs treatment were not associated with significant differences in
Na+ content, however the transgenic lines still showed more Na+ content
compared with L5. In conclusion, from the three time points, L5
accumulated less Na + compared with the transgenic lines, in addition the
effect of Si NPs was not significant at the three time points.
Potassium content
At zero time, C15 showed less K+ compared with C4 and L5,
however C4 plants recorded the highest values. At 14 DAS phase, in the
unstressed plants, C4 and C15 showed higher K+ content compared with
L5. In the salt stressed plants, K+ content decreased with salt addition.
Also, no significant differences were obvious among different treatments;
however C15 exhibited the highest K+ content compared with other lines.
At recovery, both unstressed plants as well as stress recovered plants
showed the same rank regarding K+ content.
Calcium content
No significant influence, at zero time, on Ca++ content was
observed regarding transgenic lines along with Si NPs treatment and their
interaction.
At 14 DAS, L5 had more calcium content compared with
transgenic lines. Also, existence of salt caused enhancement in calcium
content compared with unstressed ones. The effect of Si NPs was not
significant on Ca++ content. At recovery, in both unstressed and stressrecovered
plants, transgenic lines showed higher Ca++ content compared
with L5.
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SUMMARY
Amal Abdelmonem Mostafa (2019), Ph.D., Fac. Agric., Ain Shams Univ.
In conclusion, transgenic lines represented less Ca++ at 14 DAS,
while at recovery these lines accumulated more Ca++ than L5, furthermore
salt stress resulted in accumulation of Ca++ in salt stressed plants.
Magnesium content
At zero time, C15 line exceeded other lines in Mg++ content,
whereas Si NPs did not show significant influence on magnesium content.
At 14 DAS, L5 showed higher Mg++ content compared with transgenic
lines. Applied Si NPs decreased Mg++ content in all lines in the unstressed
plants, however increased Mg++ content in L5 and C15 lines in the salt
stressed plants. an enhancement in Mg++ content was observed by
applying salt. At recovery phase, in the unstressed plants, there was no
significant influence on Mg++ content between different treatments.
However, in the stress-recovered plants, an obvious reduction on Mg++
content was recorded in plants after using tap water for recovery.
Phosphorous content
At zero time, no significant differences among lines were
detected, while applied Si NPs reduced phosphorous content in case of L5
and C15 lines. At 14 DAS, in the unstressed plants, the differences in
phosphorous content among different treatments were not obvious at this
point. In salt stressed plants, NaCl addition caused reduction in
phosphorous content. At recovery, unstressed plants, showed the same
rank in P content. Stress recovered plants showed that higher phosphorous
content, compared with unstressed ones. C15 line had more phosphorous
content compared with other lines. Within transgenic lines Si NPs
resulted in significant reductions in phosphorous content, whereas its
effect on L5 resulted in increase in phosphorous content