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العنوان
Genetic studies on drought resistance in wheat /
المؤلف
Hanna, Nabil Sournan.
هيئة الاعداد
باحث / Nabil Sournan Hanna
مشرف / Hassan Sherif
مناقش / Ibrahim El-Shawaf
مناقش / Ismail Abd El-Monlem Ahmed
الموضوع
Wheat.
تاريخ النشر
1990.
عدد الصفحات
126 p. :
اللغة
الإنجليزية
الدرجة
الدكتوراه
التخصص
علوم النبات
تاريخ الإجازة
1/1/1990
مكان الإجازة
جامعة بنها - كلية الزراعة - نبات زراعي
الفهرس
Only 14 pages are availabe for public view

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from 126

Abstract

Twenty five genotypes of wheat (T. aestivum) were screened under
pots and field experiment at Sids Agriculture Research Station.
Beni Sweif Governorate for some agronomic and morphological
characters that are considered to be criteria for selecting
drought tolerance genotypes. The selected six wheat genotypes
from the screening experiments were used to study the genetic
system controlling the investigated characters and its relations
under different soil moisture levels. The selected genotypes for
this study were mainly based on the data of grain yield and
drought susceptibility index (5). This index was calculated from
the obtained data using the formula presnted by John et al.(1984).
These six selected lines (parents) from screening experiment
were three tolerent which produce high grain yield per plant under
moisture stress levels (01 = 225 mm) and (D2 = 175 mm) as compared
with the control treatment (DO = 500 mm). The value of drought
susceptibile index (5) was low than one. indicating that parents
were drought tolerent. These parents are NS 732- PIMA, Veery ”s”
and sakha 69. One moderate tolerent parent was selected. The parent
PVN ”s” - MN70121 and two otheres i.e. (STP-YRx WALO (3)- ERA and
Kavco. were highly susceptible to water stress.The aims of the second experiment were to study the genetic
Ivariance components. phenotypic correlations and genotypic
correlations between different characters under water stress
conditions.The studied characters included, plant height. grain yield
per plant. number of kernels per spike. 1000 kernel weight,
number of stomata on adaxial surface of flag leaf, root
length. root dry weight. harvest index, total DNA content
and total RNA content. Most of the studied characters were
affected by moisture stress treatments (D1) and (02) except
number of stomata on upper flag leaf surface. The greatest decreased in the average of plant height, grain yield. number of kernels per spike. 1000 kernel weight. total DNA content and
total RNA content were observed under (D2) treatment as compared
with the control for al~ Fl hybrids and the parents. The line . :
Veery ”s” was the most tolerent parent producing high grain yield,
number of kernel per spike, root dry weight and longest root length
under water stress treatments (01=225 mm) and (D2=175 mm). The most
affected parents were STP-YR x WALD(3)-ERA and Kavco which gave ~ >’, ;
the lowest grain yield. number of kernels per spike and 1000 kernel (,0 0’
weight. Both parents were considered susceptible ones.
Additive gene effects were more important in the inheritance
of 1000 kernel weight and of stomata on upper flag leaf surface.
Both additive and non-additive gene effects showed an equal I
importance in the inheritance of plant height, grain yield per ’;.:
plant, number of kernel/spike, root length, root dry weight,
harvest index. DNA and RNA content under (01) and (D2) treatments.The averag degree of dominance was found to be overdominance
for all characters under different water lev~ls except, (106)
for number of stomata on upper flag leaf surface which showed
partial dominance. The negative and positive alleles were not
equally distributed among the parental population for most studied
atttibutes under all treatments.
The dominant genes are in excess in the parents in case of grain
yield per plant, number of kernels/spike, root length and harvest
index under (DO and 01) treatments. Low estimates of narrow sense
heritability for the~e characters could indicate that the traits
were greatly influenced by the environmental factors.
Parent (Veery ”5”) seems to possess most of the dominant genes for
grain yield per plant. number of kernels per spike, root length.
root dry weight. harvest index and total DNA content.
KavcO ”s” posses an excess of recessive genes for grain yield
per plant, number of kernels per spike. lOOOkernel weight,
root length and total DNA content.
Highly significant positive phenotypic correlation was found
between plant height and each of grain yield per plant, number of
whereas, a highly significant negative correlation was obtained
kernels per spike ,root length, root dry weight and RNA content ,”
between plant height and harvest index. Highly significant
positive phenatypic correlation was estimated between grain yield
per plant and each of number of kernels per spike. 1000 kernel
weight. root length, root dry weight,harvest index. root length
root dry weight. harvest index, total DNA content and total RNA
content . Highly positive phenotypic correlation was found between
number of kernels/spike and each of root length, root dry
weight, harvest index and total RNA content. The same trend was found between 1000 kernel weight and root
length under all treatments, root dry weight and harvest index.
A highly significant positive phenotypic correlation was
observed between number of stomata and each of root dry weight
and total RNA content under all treatments. Highly positive phenotypic correlation was found between root
length and each of root dry weight under all treatments, DNA
DNA content, and RNA.
The same trend was observed between root dry weight and each
of total DNA content and total RNA content.
Highly positive phenotypic correlation was obtained between
total DNA and total RNA contents.
A negative genotypic correlation was estimated between plant
plant height and each of grain yield/plant, number of kernels
per spike and total RNA content. Grain yield/plant showed positive’
genotypic correlation with each of root length, root dry weight.
number of kernel per spike, 1000 kernel weight, total DNA content
and total RNA content under all treatments. A negative genotypic
correlation was found between number of kernels and 1000 kernel
weight.Positive genotypic correlation was detected between total DNA
content and total RNA content under all treatments.
It seems to be that any morphological or physiological
improvement that reduces transpiration or increase absorption of
soil water could postpone water deficit and reduce the harmful
effect of water stress.
In wheat, rabid growth, extensive root system, low number of
stomata ,1000 kernel weight and number of kernels per spike may be
considered good selection criteria for drought tolerance genotypes.
Further research is required to study the effect of water stress
on chloroplasts (cp DNA) and mitacondria (mt DNA) and RNA as well.