الفهرس 
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Abstract
The main objective of the present study was to determine the
genetic variance components for some quality traits in wheat. Five wheat
varieties and/or lines were chosen on the basis of their variabilities in the
studied traits. A half diallel set of crosses involving the five parents was
evaluated for, protein, amino acids, gluten, hydration coefficient, moisture,
ash, fiber and extracted flour, shorts, fine bran and bran (AACC, 1983).
Seventeen amino acids were determined as mg/g sample. Analysis of
variance was performed for each quality trait. Heterosis was computed as
the percentage deviation of FI mean performance from mid- parent and
better- parent. Data were genetically analyzed according to Griffing
(1956), method 2, model I, Hayman (1954 a and b) and Jinks (1954).
Heritability was estimated as Mather and Jinks (1971). The obtained
results can be summarized as follows:
1- Analysis of variance, mean and heterosis:
a: Protein and amino acids determined as mg/g sample:
1- Significant mean squares due to genotypes along with parents and
crosses were detected for protein and most amino acids (mg/g
sample).
2- The parental variety P2 gave the highest mean value for protein and
seven amino acids. The Fl cross (p3 x PS) was the best combination
for protein and-rune amino acids since it gave the highest mean values.
3- The two crosses (p3 x P4 ) and (p3 x PS) expressed the best heterosis
for protein and most of the studied amino acids.
b: Other quality traits:
1- Mean squares due to genotypes along with parents and crosses were
significant for gluten, ash, fiber, as welI as extracted flour and fine
bran.
2- The parent P2 expressed the best mean performance for gluten and
extracted flour, while parent PI had the highest value for ash and
fiber. The best FI mean values for gluten, ash, and fiber were
obtained for the crosses (p2 x P5(, (p2 x P3) and (Pl x P4),
respectively.
3- Significant and positive heterotic effects were obtained for gluten in
the crosses P3 x P4, P3 x P5 and P4 x P5 and for extracted flour in
both pl x P3 and P3 x P5.
11-Combining ability analysis:
a: Protein and amino acids determined as mglg sample:
1- Significant mean squares due to both general and specific combining
ability were detected for protein and all amino acids studied. High
GCNSCA ratios which largely exceeded the unity were obtained for
most traits, indicating that the largest part of the total genetic
variability associated with these traits was a result of additive and
additive x additive types of gene action.
2- The parents P2 and P3 seemed to be the best general combiners for
protein and alI amino acids.
3- The most desirable SeA effects for protein and most amino acids were
detected in the cross (p3 x P5), folIowedby the cross (p3 x P4).
b: Other quality traits:
1- General and specific combining ability variances were significant for
gluten, ash, fiber and extracted flour. The GCNSCA ratio revealed
that additive and additive x additive gene effects were more important
than non additive ones for such traits.
2- Parent P2 appeared to be the best general combiner for gluten, fiber
and extracted flour.
3- The best SCA effects were obtained in the crosses (p3 x P4), and (P3
x P5) for gluten, and extracted flour, respectively. Four crosses
expressed desirable SCA effects for fine bran.
111-Genetic components analysis:
a: Protein and amino acids determined as mglg sample:
1- The additive component D was appreciable for all traits except alanine
amino acid, while the two dominant components HI and H2 were
significant for all traits except serine amino acid.
2- Dominance of heterozygous loci (h2) was unidirectional in 17 out of
the studied 22 traits with increasing alleles being dominant over
decreasing ones. Overdominance was detected for all traits under
study.
3- The alleles of positive and negative effects were not equally distributed
among the parental populations for protein and most amino acids.
4- High heritability values in broad sense were detected for all traits.
However, narrow sense heritability values ranged from high to low
for the traits under study.
b: Other quality traits:
1- Appreciable values for both additive and dominance components were
detected for the traits; gluten, ash, fiber, and extracted flour and fine
bran.
2- Increasing alleles of dominance seemed to be dominant over the
decreasing ones at heterozygous loci and for fiber and fine bran
overdominance was indicated for all traits.
3- Negative and positive alleles are equally distributed among the parents
for fiber and flour traits.
4- High heritability values in broad sense accompanied by low to
moderate values in narrow sense were obtained for the traits under
study.
IV-Graphical analysis:
1- The intersection of regression line below the origin point for most
studied traits, revealed overdominance for such traits.
2- The distribution of parental varieties along the regression line showed
that varieties P2, P3, and P5 possess an excess of genes behaved as
dominant, while the variety P4 possess an excess of genes behaved as
recessive ones for most of the traits studied.
3- Significant and positive correlation values between Yr and Wr + Vr
were detected for fiber and leucine, phenylalanine, tyrosine, thrionine,
and total amino acids (mglg sample). This indicated that decreasing
genes were dominant over increasing ones for these traits.
Appreciable negative correlation values were obtained for protein,
gluten; as well as glutamic acid and proline (mg/g sample), revealing
that increaser genes were dominant over decreaser ones.