الفهرس 
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Abstract
SUMMARY
Two field experiments were carried out during 1987 and
1988 seasons at the Demonstration Fields of Meet Ghamr, Dakhlia
Governorate. The aim of this study was to investigate the effect
of .N levels and time of nitrogen application on growth and yield
of sunflower plants.
The soil type of the experiments was clay loamy alluvial
with a pH of 8.0 and organic matter content of 2.0 % •
Each experiment included 24 treatments which were the
combination of four levels of nitrogen and six treatments of application
time of nitrogen. Factors under study were:
I. Nitrogen levels were:
a. Control, without N.
b. 20 Kg N/fed.
c. 40 Kg N/fed.
d. 60 Kg N/fed.
(No).
(N 1)’
(N2)·
(N 3)’
II. Time of nitrogen application :
a. Nitrogen was added in single application before sowing.(T 1)’
b. Nitrogen was added in single application before the first
irrigation.
c. Nitrogen was added in single aplication before the second
irrigation.
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d. Nitrogen was added in 2-split dressings, 50 % before sowing
+ 50 % before the 19 irrigation. (T 4).
e. Nitrogen was added in 2-split dressings, 50 % before sowing
+ 50 % before the 2nd irrigation. (T 5).
f. Nitrogen was added in 2-split dressings, 50 % before the
Inirrigation + 50 % before the 2nd irrigation. (T6)
The design of the experiments was randomized complete
block with four replications. The plot size was 21 m2 (_l_ fed.).
200
Results could be summarized as follows:
1. Nitrogen levels showed significant effect on flowering date in
1987, while in 1988 this effect was not significant. Number of
days from planting to floweirng decreased as the N levels increased
up to 20 kg/fed.
Application time of nitrogen had no significant effect on
the flowering date of sunflower in the two successive seasons.
2. Nitrogen fertilizer had significant effect on plant height in the
first season only. The height of sunflower plants increased significan~
ly as the N level increased up to 60 kg/fed. (N 3).
Similarly, the effect of application time of N exhibited significant
effect on height of sunflower planting in 1987 only. Application
of N in 2-split dressings, 50 % before sowing + 50 % before
th.e 2nd irrigation (T 5) tended to increase plant height than the
other treatments.
3. Nitrogen had significant effect on the number of green leaves/
plant in the two seasons, where the number of green leaves/plant
increased significantly as the N level increased up to the rate
of 20 kg/fed.
On the other hand, number of green leaves/plant was not
significantly affected by the time of N application.
4. Nitrogen fertilization significantly reduced the number of dry
leaves/plant in the two successive seasons. The application of
20 kg N/fed. decreased significantly the number of dry leaves/plant
as compared with the control treatment.
Nevertheless, time of N application had no significant influence
on the number of dry leaves/plant.
5. Number of leaves/plant was not significantly affected by N levels
as well as time of N application in the two successive seasons.
6. Nitrogen levels showed significant effect on stem diameter of
sunflower plants in the two successive seasons. The stem diameter
significantly increased as the N level increased up to the rate
of 20 kg/fed. -
Application time of N had significant effect on stem diameter
10 the, first season only. Application of N in 2-spJit dressings
50 % at sowing + 50 % before the 2nd irrigation (T5) or 50 %
before 1st irrigation + 50 % before 2nd irrigation (T6) produced
thicker stalks than other treatments.
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7. Leaf area of the fourth leaf increased significantly as the N
level increased up to the rate of 60 kg/fed. in the two successive
seasons.
On the contrary, time of N application had no significant
effect on leaf area in both seasons.
8. Nitrogen level increased the percentage of lodging significantly
in the two seasons. Higher lodging percentages were produced
from application of 40 and 60 kg N/fed. in 1987 and 1988 seasons,
respectively.
On the other hand, application time of N had no significant
effect on the percentage of lodging of sunflower plants in the
two successive seasons.
9. Nitrogen level had significant effect on the percentage of broken
sunflower plants in the second season only. The percentage of
broken plants increased significantly as the N level increased
to 20 kg/fed.
On the other hand, application time of nitrogen had no significant
effect on the percentage of broken plants in the two seasons.
10. Nitrogen fertilizer showed significant effect on head diameter
of sunflower plants. Application of 20 and 40 kg N/fed. increased
head diameter of sunflower plants significantly in the first and
second seasons, respectively.
j
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Whereas, head, diameter of sunflower plants was not significantly
affected with time of N application in the two successive.
11. Weight of head as weU as weight of seeds/head increased significantly
with increasing N levels up to 20 kg in the first season
and 40 kg in the second season.
While, application time of N had no significant effect on
the head weight and weight of seeds/head of sunflower plants
in the two seasons.
12. Nitrogen level increased significantly the weight of 100 seeds
in the two seasons. Maximum significant increase in the’ weight
of lOO-seed was obtained by application of 20 kg/fed.
On the contrary, time of N application had no significant
effect on the weight of 100 seeds in the two successive seasons.
13. Shelling percnetage was not significantly affected by the nitrogen’
levels in the both seasons.
Time of N application had no significant effect on shelling
percentage of sunflower plants in the two successive seasons.
14. Weight of seeds/plant was greatly influenced by application of
nitrogen, in 1987 and 19.88 seaSORS,.Application of 20 and 40 kg
N/fed. increased significantly the weight of seeds/plant in the
first and second seasons, respectively.
Weight of seeds/plant was not significantly affected by the
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time of N application in the two successive seasons.
15. Nitrogen level showed significant effect in increasing the seed
yield of sunflower. The highest seed yield was obtained by application
of the rate of 20 and 40 kg!fed. in 1987 and 1988 seasons.
In the first season, application of 20, 40 and 60 kg N!fed.
increased the seed yield significantly by 43, 49 and 47 % over
the control.
In the second season, seed yield was increased significantly
by 23, 35 and 27 % over the control due to the application of
20, 40 and 60 kg N!fed., respectively.
Whereas, seed yield of sunflower plants was not significantly
affected by the application time of N fertilizer in the two successive
seasons.
16. Nitrogen level showed significant effect on the yields of straw
and biological/fed. in the two successive season. Straw as well as
biological yields. of sunflower increased significantly as the N
level increased up to 20 and 40 kg/fed. in 1987 and 1988 seasons,
respectively.
. Application time of N had a significant effect on straw and
biological yield in the first seasons only. Application of N in
2-split dressings, i.e., 50 % before sowing and the remainder
before the 2nd irrigation (T5> gave higher yields than when N
was applied in otherwise dressings.
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17. Nitrogen fertilizer had significant effect on the harvest index
in sunflower plants. Harvest index decreased as N-level increased
in the two successive seasons.
Harvest index was not significantly affected with the application
time of N in both seasons.
18. Seed oil content of sunflower seeds decreased significantly by
increasing N-level up to 20 kg/fed.
On the other hand, application time of N had no significant
effect on oil content of sunflower seeds.
19. Protein content of sunflower seeds increased significantly as
the N level increased up to the rate of 40 kg/fed.
Nevertheless, application time had no significant effect
on the protein content of sunflower seeds.
20. Oil characters, namely, acidity value and saponification value
were not significantly affected by N level as well as application
time of N.
21. There was highly significant positive correlations between seed
yield/fed. and leaf area, stem diameter, head diameter, head
weight, weight of seeds/head as well as weight of 100-seed.