الفهرس 
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Abstract
Two field experiments were laid out in the field of Giza Agric.
Exp. Station to evaluate sixteen flax genotypes for total weight! plant
and other eleven attributed characters during the two successive
seasons 1995/ 96 and 1996/ 97. The sixteen flax genotypes comprised
the two commercial varieties Giza 7 and Giza 8, twelve local
pronusmg strains introduced to microyield trails in addition to the
Indian introduction Gawhar 552 and the Belgium introduction Ariane
R3
. The breeding materials can be classified as fourteen of dual
purpose type, one of oil type and one of fiber type.
The objectives of this study were: (i) to throw the light on the
magnitude of variability for total weight and its two main components,
.i.e. straw yield and seed yield! plant in addition to earliness and other
yield component characters, (ii) to study the nature of phenotypic,
genotypic and environmental correlation coefficients among total
weight/ plant and several important agronomic traits, (iii) to find out
the component characters that can be used as selection criteria to
Improve total weight, straw and seed yields through path coefficient
analysis, (iv) to set up a prediction model for total weight! plant using
stepwise regression analysis, and (v) to use factor analysis to
determine the dependence structure of component characters which
could be related to total weight! plant.
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The results and conclusions obtained could be summarized as
follows:
5. 1. Analysis of variance revealed that the sixteen flax genotypes
differed significantly for total weightl plant, earliness, straw yield
and seed yield as well as their eight component characters in both
seasons.
5.2. Mean performance of Giza 8 variety was higher than that of
Giza 7 for all characters under study except total weight and seed
yield! plant where the mean values of the two varieties were
almost the same. However, the differences between the two
commercial varieties did not reach the level of significance for all
studied characters.
5. 3. The four strains 2821 371 141 8, 329/21 18/7, 402/3/ 5/ 10 and
402/ 211 201 3 gave higher total weight! plant than tile two
commercial varieties Giza 7 and Giza 8 in both seasons. However,
the differences in total weight! plant between the four strians and
the two commercial varieties Giza 7 and Giza 8 only reached the
level of significance in the second season, The former two
strains characterized by their relative earliness to the two
conunercial varieties. Therefore, these four strains are
reconunended for commercial release as new outstanding
cultivars.
5. 4. The two flax strains 3291 2/ 23/ 6 and 402/ 3/ 3/ 10 were supenor
in seed yield and its two main components, number of capsules/
plant and 1000- seed weight for the first season or capsules
number and basal branches number/ plant for the second one. The
Indian introduction Gawhar 552 was the earliest genotype and
exceeded all other genotypes for this character in both seasons.
5. 5. Combined analysis for the data of the two seasons showed
significant differences among the sixteen genotypes for total
weight! plant and its eleven related characters over both seasons.
The component of variance due to years was significant for all
characters under study except earliness and 1000- seed weight.
On the other hand, genotype x year component of variance was
insignificant for total weight! plant ant its eleven attributes.
5. 6. Variability measurements exhibited wide range of means wihin
total weight! plant, earliness, straw yield and seed yield! plant as
well as their eight component characters. Heritability estimates in
broad sense ranged form 75.41 % for stem diameter to 99.88 % for
1000- seed weight and almost similar values of PCV and GCV for
all characters studied. Maximum genetic advance expressed as
percentage of mean was recorded in number of basal branches/
plant followed by seed yield! plant, technical length and 1000-
seed weight. On the other hand, values of expected genetic
advance for stem diameter, number of seeds/ capsule and earliness
were comparatively low, however, these three characters had
high heritability estimates.
5. 7. Significant positive phenotypic and genotypic correlation
coefficients were detected between: Total weight! plant and each
of straw yield, seed yield, stem diameter and 1000- seed weight.
Straw yield! plant and each of earliness, plant height, technical
length, fruit zone length and stem diameter. Seed yield! plant and
each of capsule number and 1000- seed weight. Earliness and
each of plant height, teclmical length, fruit zone length and stem
diameter. Plant height and each of technical length, fruit zone
length, stem diameter, and seeds/ capsule. Technical length and
each of stem diameter and seeds/ capsule. Number of capsules/
plant and 1000- seed weight.
5. 8. Significant positive environmental correlations were detected
between total weight! plant and each of straw yield, seed yield!
plant, stem diameter and number of basal branches/ plant. Straw
yield with each of seed yield! plant, stem diameter, number of
capsules and number of basal branches. Seed yield with stem
diameter, number of capsules and number of basal branches/
plant. Stem diameter with number of capsules and number of
basal branches/ plant. Number of capsules and number of basal
branches.
5.9. Genetic path coefficient analysis of total weight! plant and its
related characters indicated that straw yield had the strongest
positive direct path to plant total weight followed by seed yield.
The sources of both straw and seed yields as well as their
interaction accounted for about 93.0 % of the total plant weight
variation. Adding up this value to the interaction of straw yield
with earliness increased the contribution percentage to 97.29 % of
total weight! plant variation.
5. 10. Genetic path coefficient analysis of straw yield! plant and its four
components showed that plant height had the strongest positive
direct effect followed by stem diameter. The direct path in percent
of both plant height and stem diameter, in addition to their
interaction accounted for 36.69 of plant straw yield variation. So,
flax breeder should make efforts to combine in one plant genes
that are responsible for maximum plant height and large stem
diameter.
5. 11. Genetic path coefficient analysis of seed yield! plant and its four
components revealed that number of capsules/ plant had the largest
positive direct effect on plant seed yield, followed by 1000- seed
weight and number of seed! capsule. The direct effects of number
of capsule/ plant and 1000- seed weight and their interaction
accounted for 68.18 percent of the total seed yield variation. This
indicates that during the selection process more stress must be laid
on capsules/ plant and 1000- seed weight to enhance seed yield in
flax.
5. 12. The stepwise regression analysis for total weight! plant and its
eleven component characters indicated that the three variables, i.e,
straw yield! plant, seed yield! plant and number of seeds/ capsule
were responsible for reducing most of the total weight! plant
vanance. These three traits were responsible for reducing 98.08 %
of the total weight! plant. On the basis of reducing time and
efforts by using fewer characters, the equation which combines
straw and seed yield! plant as well as number of seeds/ capsule
is considered the best prediction equation for total weight! plant
since they accounted for 96.94 % of the total weight! plant.
5. 13. Factor analysis divided the eleven variables affecting totally
weight! plant into two groups or factors. Factor 1 consisted of
earliness, straw yield! plant, and its four components, i.e. plant
height, technical length, fruit zone length and stem diameter and
accounted for 55.18 5 of the total variability in the dependence
structure of total weight! plant. Factor 2 consisted of seed yield!
plant and its two main components, i.e. number of capsules/ plant
and 1000- seed weight, and accounted for 29.0 % of the total
variability in the dependence structure of total weight! plant. Thus
nearly 84.18 % of the variation in the dependence structure of total
weight! plant was explained by these two factors and the
remammg 15.82 % being attributable to trait- specific effects and
errors.
Generally, the three statistical methods used to investigate the
relationship between total weight! plant and yield determining traits
emphasized that both straw yield and seed yield! plant are the most
important factors affecting total weight! plant, and that the first
character was of higher importance than the second one. However,
factor analysis provided more information than either path- coefficient
analysis or stepwise multiple linear regression due to groups of
variables (factors) and percentage contribution of variables to each
factor. Moreover, factor analysis clarified the relationship between
correlated characters in the dependence structure.