الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Wheat (Triticum aestivum L.) is one of the most important food
crops in Egypt and in the world. It is of importance to protect the crop
from only loss by controlling the diseases and pests which attack the
plants. Stripe rust is one of the most dangerous diseases which affect the
grain production of the susceptible genotypes.
Rust response to yellow rust infection:
Eleven wheat varieties were used to study their response to yellow
rust infection under field conditions at two locations i.e. Shibin El-Kom
and Itay El-Baroud for three growing seasons (2018/2019 – 2020/2021).
Results obtained could be summarized as following:-
Final rust severity (FRS):
- The tested wheat varieties could be classified into two main
groups. The first group included the wheat varieties Misr 3,
Sakha 95, Giza 171, Gemmeiza 12, Sids 14 and Giza 168 which
showing low values of FRS (less than 30.00 %).
- The second group included the wheat varieties showing high
values of FRS i.e. Misr 2, Misr 1, Shandweel 1, Gemmeiza 11
and Morocco (more than 30.00 %).
- Wheat varieties Misr 3, Sakha 95, Misr 1, Misr 2, Giza 171,
Gemmeiza 12, Sids 14 and Giza 168 showed lower rates of
disease increase (r-value).
- The wheat varieties Shandweel 1, Gemmeiza 11 and Morocco
showed the highest rates of r-values.
Summary
108
Area under disease progress curve (AUDPC):
- The wheat varieties Misr 3, Sakha 95, Giza 171, Gemmeiza 12, Giza
168 and Sids 14 exhibited the lowest values of AUDPC (did not
exceed up to 300),
- The wheat varieties Misr 2, Misr 1, Shandweel 1, Gemmeiza 11 and
Morocco exhibited the highest values of AUDPC (more than 300).
Effect of yellow rust on grain yield of wheat:
- In present study to estimate grain yield loss due to yellow rust
infection and characterize the relationship between yellow rust
incidence and wheat yield components, based on three years of
data obtained from 11 wheat varieties in field experiment of split
plot design, where protected plots were included with infected
ones in which the disease was allowed to develop using field plots
as experimental units.
- The effect of yellow rust infection on grain yield in terms of grain
yield per plot of wheat varieties i.e. Shandweel 1, Giza 168, Giza
171, Gemmeiza 11, Gemmeiza 12, Sids 14, Misr 1, Misr 2, Misr 3,
Sakha 95 and the highly susceptible variety Morocco in the three
seasons showed the same trend. In general yield components of the
tested wheat varieties were significantly affected by yellow rust
infection.
- According to the level of disease severity of yellow rust. However,
the wheat varieties showed high yellow rust severity exhibited the
maximum values of area under disease progressive curve
(AUDPC) and yield loss% while the wheat varieties showed low
yellow rust disease severity exhibited the minimum values of area
under disease progressive curve (AUDPC) and yield loss%.According to the obtained data, it was clear that the six wheat
varieties; Misr 3, Sakha 95, Giza 171, Gemmeiza 12, Sids 14 and
Giza 168 exhibited lower levels of yield loss in yield per plot.
Therefore, these wheat varieties could be classified as posses
adequate levels of partial (field) resistance and exhibited lower
levels of yield losses% compared to the highly susceptible five
wheat varieties; Misr 2, Misr 1, Shandweel 1, Gemmeiza 11 and
check variety Morocco, which showed the highly level of loss%.
Correlation between environmental factors and yellow rust:
a. Solar radiation:
The relationship of solar radiation with yellow rust severity was
negative in all of the 11 tested wheat varieties (r = -0.015to -0.245).
b. Precipitation:
The relationship of precipitation with yellow rust severity was
positive in all of the 11 tested varieties (r = 0.619 to 0.892).
c. Average wind speed:
The relationship of average wind speed with yellow rust severity
was positive in all of the 11 tested varieties (r = 0.231 to 0.709).
d. Maximum wind speed:
The relationship of maximum wind speed with yellow rust severity
was positive in all of the 11 tested varieties (r = 0.253 to 0.720).
e. Minimum air temperature:
The relationship of minimum air temperature with yellow rust
severity was positive in all of the 11 tested varieties (r = 0.650 to 0.899).
Summary
110
f. Maximum air temperature:
The relationship of maximum air temperature with yellow rust
severity was positive in all of the 11 tested varieties (r = 0.138 to 0.593).
g. Minimum relative humidity:
The relationship of minimum relative humidity with yellow rust
severity was negative in all of the 11 tested varieties (r = -0.132to -0.610).
h. Maximum relative humidity:
The relationship of maximum relative humidity with yellow rust
severity was positive in all of the 11 tested varieties (r = 0.837 to 0.959).
Linear regression models:
a- Prediction models for yellow rust severity (%):
Eleven regression models were developed based on environmental
conditions for forecasting yellow rust severity (%) and explained different
amounts of variation in rust severity in the tested wheat varieties. The
best models for forecasting rust severity were in the wheat varieties Sids
14 (R2 = 90.60), Giza 171 (R2 = 84.50), Shandweel 1 (R2 = 84.20), Misr
1, (R2 = 83.90), Misr 3 (R2 = 81.90) and Gemmeiza 12 (R2 = 81.70) ,
followed by model in the wheat varieties Giza 168 (R2 = 77.50), Sakha 95
(R2 = 77.40), Morocco (R2 = 77.10), Gemmeiza 11 (R2 = 76.70) and Misr
2 (R2 = 72.20).
Correlation between environmental factors and final rust severity
(%) with yield loss:
a. Solar radiation:
The relationship of solar radiation with yield loss was negative in
all of the 11 tested wheat varieties (r = -0.015 to -0.315).b. Precipitation:
The relationship of precipitation with yield loss was positive in all
of the 11 tested varieties (r = 0.559 to 0.821).
c. Average wind speed:
The relationship of average wind speed with yield loss was positive
in all of the 11 tested varieties (r = 0.030 to 0.299).
d. Maximum wind speed:
The relationship of maximum wind speed with yield loss was
positive in all of the 11 tested varieties (r = 0.012 to 0.324).
e. Minimum air temperature:
The relationship of minimum air temperature with yield loss was
positive in all of the 11 tested varieties (r = 0.639 to 0.908).
f. Maximum air temperature:
The relationship of maximum air temperature with yield loss was
positive in all of the 11 tested varieties (r = 00.056 to 0.303).
g. Minimum relative humidity:
The relationship of minimum relative humidity with y yield loss
was negative in all of the 11 tested varieties (r = -0.023 to -0.252).
h. Maximum relative humidity:
The relationship of maximum relative humidity with yield loss was
positive in all of the 11 tested varieties (r = 0.804 to 0.969).
i. Final rust severity:
The relationship of final rust severity with y yield loss was positive
in all of the 11 tested varieties (r = 0.872 to 0.982).
b- Prediction models for yield loss (%):
Summary
112
Eleven regression models were developed based on environmental
conditions and rust severity (%) for forecasting yield loss due to yellow
rust and explained different amounts of variation in yield loss in the
tested wheat varieties. Most of yield loss forecasting models are best
which showed coefficient of determination (R2) more than 90 % i.e. the
regression model in the wheat variety Misr 1 (R2= 91.10) followed by
regression model in the wheat variety Shandweel 1 (R2= 90.40) followed
by regression model in the wheat variety Misr 2 (R2= 90.50). While, the
coefficient of determination (R2) values for the eight regression models of
the wheat varieties Morocco, Giza 171, Sids 14, Giza 168, Sakha 95,
Gemmeiza 12, Gemmeiza 11 and Misr 3 showed i.e. R2 = 82.60, 77.10,
77.00, 71.00, 70.70, 65.90, 61.70 and 60.80, respectively.
Validation of yellow rust severity (%) and yield loss (%) models:
For validation of models, data of yellow rust severity (%) and yield
loss (%) at Shibin El-Kom location during 2021/2022 growing season
were used. These data did not use in stepwise analysis to produce linear
regression models for yellow rust severity (%) and yield loss (%).
a. Validation of yellow rust severity (%) models:
Eleven models for prediction of yellow rust severity (%) were also
validated by comparing the values of actual yellow rust severity (%) at
Shibin El-Kom location during 2021/2022 growing season and predicted
yellow rust severity. All of predicted yellow rust severity (%) models
were close to the actual yellow rust severity (%) for each variety. So,
these equations were considerably accurate in forecasting yellow rust
severity (%). Coefficient of determination (R2) value of the relation
between predicted and actual yellow rust severity (%) for all models was
high i.e. 0.890, these mean the accuracy of all of these prediction models
are 89.00%.b. Validation of yield loss (%) models:
Eleven models for prediction of yield loss (%) were also validated
by comparing the values of yield loss (%) at Shibin El-Kom location
during 2021/2022 growing season and predicted yield loss (%) and
coefficient of determination (R2) for all models. All of predicted yield
loss (%) model were close to the actual yield loss (%) for each variety.
So, these equations were considerably accurate in forecasting yield loss
(%). Coefficient of determination (R2) values of the relation between
predicted and actual yield loss (%) for each model was 0.918, these mean
the accuracy of all of these prediction models are 91.80%.