الفهرس 
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Abstract
Heat is the most important factor limiting crop productivity
around the world. Hence, there are increased demands for heat tolerance
genotypes, therefore numerous plant breeders have focused on improving
genotypes of heat tolerance through understanding the effects of
morphological, physiological and biochemical mechanisms on plant
processes under heat stress conditions. Due to the complexity of heat
tolerance, a quick and effective screen for this trait has not yet to be
established. So, we need to find efficient screening method able to screen
large amounts of plant materials in the shortest time possible and select
the most efficient genotypes.
The seven cultivars; Sakha 93 (P1), Gemmeiza 11 (P2),
Gemmeiza 10 (P3), Gemmeiza 7 (P4), Misr 2 (P5), Sids 1 (P6), and Giza
168 (P7) were used in this study. The experimental field work was carried
out during the two successive seasons; 2014/2015 and 2015/2016 at the
Agricultural experiment station of Faculty of Agriculture, Ain Shams
University at Shalakan, Kalubia, Governorate. In the first season, the
seven parents were crossed in a diallel fashion to make all possible
crosses among parents, excluding reciprocals, and the 21 F1 seeds were
obtained. In the second season, the seeds of the 21 F1 hybrids and their
respective parents were sown at two sowing dates, i.e. 19th of November
(the recommended sowing date) and 17th of December (the late sowing
date). A separate complete randomized blocks design field experiment
with three replicates was devoted for each sowing date. The experimental
plot was one row; the row was 3 m in length and 25 cm width. Plants
were spaced at 20 cm within the row, and one plant was left per the hill
after about 3 weeks of sowing. Data were recorded on an individual plant
basis for days to 50% heading, days to 50% maturity, grain filling period
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SUMMARY
Asmaa, M. Badr, (2018), M.Sc., Fac. Agri., Ain Shams Univ.
(GFP), flag leaf area (FLA), plant height, no. of spikes/plant, spike length,
no. of spikelets/spike, no. of kernels/spike, 1000-kernel weight, grain
yield/plant and heat susceptibility index (HSI).
Ordinary statistical analysis was made for each sowing date and
overall the two sowings. Heterosis was estimated as the deviation of F1
mean from the better parent values. Griffing,s (1956) method 2, model 1
of diallel analysis was used to calculate general (GCA) and specific
(SCA) combining ability effects.
The seven parent seedlings were exposed to heat shock (45oC) for
4 hours in the laboratory of molecular Genetics, Department of Genetics,
Faculty of Agriculture, Ain Shams University to estimate the heat shock
proteins (HSP) and compared it with control (25oC). Expression of
candidate HSP gene (hsp22) was tested using total RNA extracts of the
two wheat varieties (Sids 1 and Gemmeiza 10) utilizing Real Time PCR.
The obtained results could be summarized as follow:
First; field experimental results:
Mean squares due to sowings, genotypes and their interactions
with sowings were significant for all studies traits with few exceptions
revealing the presence of sufficient genetic variability in the genetic
materials.
A- Mean performance of wheat genotypes under different sowing dates:
1- For earliness traits, results showed that the late sowing date in Dec.
significantly decreased (induced earliness) number of days to 50%
heading, days to 50% maturity and grain filling period than the
recommended sowing date in Nov. Among genotypes the Gemmeiza
11 and P2 X P5 exhibited good level of earliness on the overall
sowing dates for days to 50% heading, Sakha 93 and Gemmeiza
11recorded level of earliness on overall sowing dates for days to 50%
maturity and the genotypes Sakha 93, Sids 1 and P3 X P7 had level of
earliness on the overall sowing dates for grain filling period.
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SUMMARY
Asmaa, M. Badr, (2018), M.Sc., Fac. Agri., Ain Shams Univ.
2- Regarding vegetative growth traits, results illustrated that delaying
sowing date to Dec. caused significant reduction in fag leaf area
(FLA) and pant height. The two crosses; P3 X P5 and P2 X P4 had
higher mean values for FLA. Also the cv. Misr 2 and the cross P4 X
P7 recorded the highest plant height mean values among overall
sowing dates.
3- For physiological traits, delaying sowing date caused significant
increment in electrolyte leakage% of the leaves and the cross P1 X P4
recorded the lowest values of electrolyte leakage% under heat stress.
Considerable genotypic variation for cell membrane stability index
was present among the wheat genotypes. The highest value of cell
membrane stability index% was recorded by the cross P1 X P4 under heat
stress. Therefore, the cross P1 X P4 is considered heat-tolerant genotype.
4- Grain yield / plant and its contributors, i.e. number of spikes/plant,
spike length, number of spikelets / spike, number of kernels / spike
and 1000-kernel weight (seed index) significantly decreased under
heat stress. The genotypes P1 X P6 for number of spikes/plant, P2 X
P4 for spike length, Gemmeiza 11 for number of spikelets / spike, P2
X P7 for number of kernels / spike, Gemmeiza 11, P1 X P2, P2 X P4,
P3 X P4, P3 X P5 and P4 X P7 for1000-kernel weight and P5 X P7
for grain yield / plant recorded the highest values.
5- The cross P2 X P7 had the lowest value (0.36 %) of heat susceptibility
index (HSI), therefore, this cross is considered highly heat tolerant.
B. Heterosis:
Heterobeltiosis estimate revealed that there is desirable hybrid
vigor in the current study for most traits evaluated. The highest positive
useful heterosis value was 48.11% in the cross P5 X P6 for flag leaf area
on the normal sowing date followed by 40.69% in the cross P5 X P7 for
grain yield / plant at the late sowing date. However, the highest negative
useful heterosis value was -59.26% in the cross P4 X P6 for electrolyte
leakage at the recommended sowing date.
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SUMMARY
Asmaa, M. Badr, (2018), M.Sc., Fac. Agri., Ain Shams Univ.
C. General and specific combining ability:
Mean squares associated with GCA and SCA were found to be
significant for all traits under both sowing dates (except mean squares of
GCA for days to 50% maturity and electrolyte leakage (EL) at the late
sowing, GCA for grain filling period, number of spikelets / spike at the
recommended sowing date, SCA for spike length and number of
spikelets/spike and grain filling period at the recommended sowing date
and insignificant for days to 50% maturity at the late sowing). Combined
analysis for GCA and SCA were found to be significant for all traits
except mean squares of no. of spikes/ plant, spike length and no. of
spikelets/spike, this results indicating that the importance of both additive
and non-additive gene effects in the inheritance of the traits studied.
The ratios of GCA/SCA variances were greater than unity for days
to 50% heading, plant height, no. of spikes/ plant, spike length, no. of
spikelets / spike, no. of kernels / spike and 1000-kernel weight at the two
sowing dates and combined data indicating that additive and additive x
additive types of gene action were of greater importance in the inheritance
of these traits. Also it was evident that additive type of gene action was
more important part of total genetic variability for days to 50% maturity
and membrane stability index (MSI) on the recommended sowing date,
grain filling period and grain yield / plant at the late sowing date and
grain yield / plant on combined data. However, ratios were less than unity
for electrolyte leakage (EL) and flag leaf area at different sowing dates
and combined data, illustrating that both traits were mainly controlled by
the non-additive gene effects. For the rest traits; i.e. days to 50% maturity,
grain filling period, membrane stability index (MSI) and grain yield /
plant, the ratios of GCA/SCA were inconsistent across different sowing
dates and combined data.
Evaluation of different parents for GCA revealed that the cvs.
Gemmeiza 11, Gemmeiza 7 and Sids 1 are considered to be good
combiners for the most traits under study.
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SUMMARY
Asmaa, M. Badr, (2018), M.Sc., Fac. Agri., Ain Shams Univ.
Specific combining ability effects estimates for the studied traits
showed that the crosses P2 X P4, P2 X P5, P3 X P4, P3 X P7 and P4 X
P7 had negative significant effects in the recommended sowing date and
non cultivar had negative significant at the late sowing date for days to
50% heading. Positive and significant SCA effects are recorded by
crosses P1 X P3, P1 X P4, P1 X P6, P2 X P4, P2 X P7, P3 X P5, P3 X P7,
P4 X P5 and P5 X P6 under normal and heat stress treatment. The crosses
P1 X P2, P1 X P5 and P3 X P6 had Positive and significant SCA effects
under normal treatment and the crosses P2 X P5 and P2 X P6 exhibited
Positive and significant SCA effects under heat stress treatment.
Regarding plant height, Positive and significant SCA effects were
recorded by crosses P3 X P6, P3 X P7 and P4 X P7 under normal
treatment. Under late sowing date none of crosses had Positive and
significant SCA effects, this shows the importance of additive genes for
inheritance of this trait.
Concerning electrolyte leakage Negative and significant SCA
effects are recorded by P1 X P4, P4 X P6 and P4 X P7 under normal and
heat stress treatments, P2 X P5 and P4 X P5 at the recommended sowing
date and P2 X P4, P2 X P7, P3 X P4 and P5 X P7 at the late sowing date.
Such crosses could be promising under the respective environment.
Regarding membrane stability index Positive significant SCA
effects were recorded by crosses P4 X P6 under normal and heat stress
treatments, P2 X P5 at the recommended sowing and P1 X P2, P1 X P3,
P1 X P4, P1 X P5, P3 X P4, P3 X P5, P3 X P7 and P4 X P7 at the late
sowing date. Such crosses could be promising under the mentioned
environments.
Regarding the number of spikes/plant, Positive and significant
SCA effects are recorded by the cross P3 X P4 at the recommended
sowing date and P1 X P6 at the late sowing date.
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SUMMARY
Asmaa, M. Badr, (2018), M.Sc., Fac. Agri., Ain Shams Univ.
Concerning number of grains/spike, The effects of SCA for this
trait showed that the crosses P1 X P3, P1 X P4, P1 X P5, P3 X P4, P4 X
P5, P4 X P7 and P5 X P7 at the two sowing dates, P3 X P6, P3 X P7 and
P5 X P6 at the recommended sowing date and P2 X P4 and P2 X P7 at the
late sowing date recorded positive and significant SCA values. These
crosses are considered as good F1 crosses combiners for this trait.
Concerning 1000-kerenel weight, SCA effects for this trait
demonstrated that the crosses; P1 X P2, P1 X P7, P2 X P6, P3 X P5, P3 X
P6 and P6 X P7 at the normal and late sowing dates, P1 X P4, P2 X P4,
P2 X P7 and P4 X P7 at the recommended sowing date and P1 X P3, P1
X P5, P3 X P4, P3 X P7 and P4 X P6 recorded positive significant SCA
values.
With respect to grain yield / plant. Data of SCA effects grain yield
/ plant showed that the crosses; P5 X P7 and P6 X P7 under the two
sowing dates, P2 X P6, P3 X P4, P4 X P6, P5 X P6 at the recommended
sowing date and P1 X P6 and P2 X P7 under the late sowing had positive
significant SCA values.
In general, the above crosses seemed to be good F1 cross
combinations for increasing wheat grain yield.
Second; Molecular analyses:
A- Detect thermo-tolerance for wheat varieties by heat shock proteins
(HSP) using SDS-PAGE:
The cultivars Misr 2, Sids 1 and Giza 168 produced the maximum
number of heat shock proteins (two bands) 71, 83kDa, 37, 42 kDa and 36,
31 kDa respectively. Gemmeiza 11 produced the lowest number of heat
shock proteins (one band) 42 kDa. The quantity and number of proteins
produced in both varieties Gemmeiza 7 and Gemmeiza 10 affected by the
thermal shock and the number of bands decreased under treated treatment
to 8 and 10 bands compared with the control treatment 12 bands
respectively. It is suggested that HSPs have special importance in two
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SUMMARY
Asmaa, M. Badr, (2018), M.Sc., Fac. Agri., Ain Shams Univ.
points: Firstly, HSPs in cultivars showed diversity. Secondly, these
proteins may play an important role in the acquiring of thermal tolerance.
B- Genotypic response to heat stress and the expression of HSP genes:
The cultivar Sids 1 exhibited high gene expression with gene copy
number value 3.61 compared with the cultivar Gemmeiza 10 which had
low gene expression with gene copy number value 0.05. This means that
the mRNA which responsible for the synthesis of HSPs is more active in
the high temperature of 45oC