الفهرس 
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Abstract
SUMMARY
A field experiment was conducted at Sakha Agricultural Research
Station, Agricultural Research Center, Kafr EI-Shiekh, Egypt, to study the
response of four Dew promising soybean genotypes under two planting
dates and five plant i lopulation densities compared with the two grown
varieties, i.e. Clark and Crawford during 1992and 1993 seasons.
In each season , a split-split plot design with tour replications was
used. Sowing dates (May 15and June 15) occupied the main plots. The sub
plots comprised the six genotypes (L 13, L 21, L 24, L 4, Clark and
Crawford), whereas the sub-sub plots were devoted to plant population
densities (5, 10, 15, 20 and 25 plants per meter of linear ridge (ridges
spaced 60 cm apart) which are equivalent to 35, 70, 105, 140 and 175
thousand plants per feddan .
The results obtained could be summarized as follows:
1. Growth characters
1. Plant height (em) : May 15planting produced taller plants than did
June 15. Plants ofL 21 genotype were the tallest, whereas those of
Clark and L 4 were the shortest. Plant height was remarkably
increased with increasing plant population density in both seasons.
Planting date x genotype, planting date x plant population density
and genotype x plant population density interactions had significant
effects on plant height. L 21 genotype produced the tallest plants in
both dates of planting in the first season; plant height at both
planting dates was gradually increased with increasing plant
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population density and the tallest plants were produced from L 21
when planted at the most dense population.
2. Number of branches per plant: Planting on May 15 significantly
produced plants that have more branches than did those of June 15
planting. L 21 genotypes exceeded the other genotypes in number
of branches produced per plant. Number of branches per plant was
generally decreased with increasing plant population density.
Planting date ’C genotype, planting date x plant population density
and genotype x plant population density interactions had significant
effects on number of branches per plant. The greatest number of
branches per plant was produced from L 21 genotype in both
planting date and from planting on May 15 at the lowest plant
population density in 1992 season. In addition, it was produced
from L 21 grown at the lowest population density.
3. Height of the first pod (em) : Plants of May 15 set their first pod
far distant from soil surface than did those of June 15. Plants of L
21 set their first pod higher on the main stem compared to L 24t L
13t L 4, Crawford and Clark genotypes in a descending order.
Height of the first pod was obviously increased with increasing
plant population density. Planting date x plant population density
and genotype x plant population density interactions had a
significant effect on height of the first pod in both seasons. The
height of the first pod was gradually increased with increasing plant
population density in both planting dates. Plants of L 21 set their
first pod far distant from soil surface at the highest population
density.
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per plant. Seed number per plant was significantly decreased with
increasing plant population density. Planting date x genotype,
planting date x plant population density, genotype x plant
population density and planting date x genotype x plant population
density interactions had significant effects on seed number per
plant. L 21 was superior to other genotypes in number of seeds
produced per plant in both May and June plantings. The greatest
number of seeds per plant was obtained from planting on May 15 at
a population density of 5 plants per meter (35,000 plants per
feddan) in 1992 season, L 21 produced the highest number of seeds
per plant when grown at the lowest population density and the
highest seed number per plant was obtained from L 21 genotype
planted on May IS at the lowest population density in 1993 season.
J. Seed weight per plant: Heavier seed weight per plant was
produced from planting on May 15 compared to June 15. L 21 gave
the highest weight of seeds per plant followed by Crawford, L 24 ,
L 13. Clark and L 4 in a descending order. Seed weight per plant
was reduced with increasing plant population density. Planting date
x genotypes, planting date x plant population density and genotype
x plant population density interactions had significant effects on
seed weight per plant in both seasons. L 21 surpassed the other
genotypes in plant seed weight in both sowing dates. May 15
exceeded June 15 in seed weight per plant at the same level of
population density and L 21 genotype was superior to the other
genotypes at the same population density level.
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4. Weight of 100 seeds (seed index): The heaviest weight of lOa
seeds was produced from sowing on May 15 in both seasons. L 21
genotype had the heaviest seed index followed by Crawford, L 24,
Clark, L 13 and lAo Increasing plant population density led to
significant reductions in seed index. Planting date x genotype,
planting date x plant population density and genotype x plant
population density interactions had significant effects on weight of
100 seeds. L 21 genotype had the heaviest weight of 100 seeds
when planted on May 15. The heaviest loo-seed weight was
obtained from planting on May 15 at the least plant population
density and L 21 genotype surpassed all other genotypes in seed
index at the same plant density.
III. Seed and straw yields
1. Seed yield per feddan: May IS planting yielded significantly more
seed yield per feddan than did June 15. Yield increases were 25.5
and 29.6% in 1992and 1993 seasons, respectively. L 21 genotype
outyielded all the other tested genotypes. Yield increases of L 21
over Clark and Crawford (presently grown varieties) were 24.0 and
15.2% in 1992 and 23.5 and 17.3% in 1993, respectively. Seed
yield was significantly increased with increasing plant population
density up to 25 plants per meter of linear ridge. Planting date x
genotype, planting date x plant population density and genotype x
plant population density interactions had significantly effects on
seed yield per feddan. L 21 had significant higher seed yield per
feddan than any other genotype in mid-May planting. Seed yield
per feddan was significantly increased with increasing plant density
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up to 25 plants per meter in both dates and all genotypes yielded
more with the increase in plant population density up to 175,000
plants per feddan.
2. Straw yield per feddan: Planting on May 15 produced 29.2 and
29.~!<I more yield of straw in 1992 and 1993, respectively
compared with June 15 planting. L 21 surpassed the other
genotypes. Straw yield per feddan was greatly increased with
increasing plant population density up to 25 plants per meter.
Planting date x genotype, planting date x plant population density,
genotype x plant population density and planting date x genotype x
plant population density interactions had significant effects on
straw yield per feddan. L 21 genotype was superior to other
genotypes in straw yield per feddan at the two sowing dates. Straw
yields of all plant densities reduced as sowing date was delayed
from May 15 to June 15. The highest value of straw yield was
obtained from L 21 grown at the most dense population of 25 plants
per meter and the highest straw yield per feddan was obtained from
L 21 when planted on May 15 at the most dense population of
175,000plants per feddan.
IV. Seed chemical composition
1. Seed oil percentage: Optimal planting on May 15 produced seeds
that had higher oil content compared to non-oprimal planting on
June 15. Crawford had the highest seed oil content followed by
Clark. Seed oil content was inversely related to plant population
density. Planting date x genotype, planting date x plant population
density, genotype x plant population density and planting date x
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genotypes x plant population density interactions had significant
effects on seed oil percentage. Crawford was superior to the other
genotypes in seed oil content in the optimal planting date (May 15).
Seed oil content was reduced with increasing plant population
density in both planting dates in 1993 season. Crawford gave the
highest oil percentage when planted at the least plant density on
May 15.
2. Seed oil yield per feddan: Oil yield per feddan was greater when
sowing took place on May 15 compared to June 15 sowing. L 21
genotype outyielded all the other genotypes. Oil yield per feddan
increased with increasing plant population density. Planting date x
genotype and planting date x plant population density interactions
had significant effects on oil yield per feddan in both seasons. The
highest value of oil yield per feddan was obtained from L 21 when
planted on May 15 and from a plant population density of 175,000
plants per feddan planted on May 15.
3. Seed crude protein percentage: Crude protein percentage
increased with delayed sowing date. Crawford had the highest
crude protein content followed by L 13, L 21, Clark, L 24 and L 4
in both seasons. Seed crude protein content increased with
increasing plant population density.
4. Seed protein yield per feddan: Protein yield was greater when
sowing took place on May 15 compared with June 15. L 21 gave
the highest protein yield per feddan followed by Crawford, L 24,
L13, Clark and L 4 in both seasons. Protein yield per feddan was
significantly increased with increasing plant density up to 175,000
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plants per feddan. Planting date x genotype, planting date x plant
population density and genotype x plant population density
interactions had significant effects on seed protein yield per feddan
in both seasons. The highest protein yield per feddan was obtained
from planting L 21 on May 15, and from sowing on May 15 at a
population density of 175,000 plants per feddan, or growing L 21 at
a plant density of 175,000 plants per feddan.