الفهرس 
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Abstract
Two field experiments were conducted at the
Experimental Research Center, Faculty of Agriculture
Moshtohor, Zagazig University (Benha Branch), Kaluibia
Governorate during 1993 and 1995 growing seasons. The
present work aimed to study the performance of four cultivars of
maize under seven topping treatments to estimate grain yield,
yield components, protein and oil content in grains. The
treatments were as follows:
1- Maize Cultivars :
V1- Single Cross 10 (S.e. 10).
V2- Double Cross 215 (D.e. 215).
V3- Three Way Cross 310 (RT.W.e. 310)
V4- Giza 2 (composite variety)
11- Topping treatments:
Seven topping treatments where shoots were cut with the
first node above the upper ear were as the following:
1- Without topping (control)
2- Topping at 72 days from planting.
3- Topping at 79 days from planting.
4- Topping at 86 days from planting
5- Topping at 93 days from planting.
6- Topping at 100 days from planting.
7- Topping at 107 days from planting.
Each experiment included 28 treatments which were the
combination of four maize cutivars and seven topping treatments
with four replications. These treatments were arranged in split
plot design. The main plots were assigned for four cultivars of
maize, whereas topping treatments were randomly assigned
among the sub plots. The area of each sub plot was 21 m2 (3.5 x
6 m) 11 200 feddan which contained 5 ridges of 6 m length and
70 em width. Maize cultivars under study were sown on 18 th
and 6 th of June in 1993 and 1995 seasons, respectively. The
distance between hills was 25 em apart. Plants were thinned to
one plant! hill before the first irrigation. Nitrogen fertilizer was
applied in the form of ammonium nitrate (33.5 % N) at the rate
of 105 kg NI feddan whic was divided to two equal portions,
one half was applied before the first irrigation and the rest before
the second one. The phosphorus fertilizer was applied at a rate
of 24 kg P20s1 feddan in the form of calcium super phosphate
(15.5 % P20S) during seeded preparation. The other
recommended cultural practices for growing maize in the region
were done properly.
Characters Studied:
1- Stern diameter (em).
2- Percentage of barren plants.
3- Percentage of plants carrying one ear.
4- Ear length (em).
5- Ear diameter (mm).
6- Number of rowsl ear.
7- Number of grainsl row.
SUNfJl.!fAR Y - 65 -
SUMMARY - 66 -
8- Ear weight (gm).
9- Grain weight per ear (gm).
10- Cob diameter (mm).
11- Shelling percentage
12- 100- grain weight (gm).
13- Ear yield in kg/ feddan.
14- Grain yield in kg/ feddan, adjusted to 15.5%
moisture content.
15- Crude protein percentage.
16- Oil percentage.
The important results of this study could be summarized
as follows:
1- The three maize hybrids, i.e., S.c. 10, D.C. 215 and
T.W. C. 310 gave higher values of stem diameter when
compared with Giza 2 variety. The differences between the
mean values of stem diameter was not significantly affected
by dates of topping in both seasons.
2- S.C. 10 cultivar gave the lowest percentage of barren
plants, whereas D.C. 215 variety gave the highest one. No
significant differences were obtained between D.C. 215,
T.W.C. 310 and Giza 2 varieties on the percentage of
barren plants. Topping treatments had a significant effect
on the percentage of barren plants when compared without
topping. The lowest percentage of barren plants was 7.93
and 8.25%, obtained from the control treatment in the first
and second seasons, respectively.
3- No significant difference was obtained between the four
varieties of maize on the percentage of plants carried one
ear in both seasons. The control treatment (no topping)
gave the maximum percentage of plants carried one ear
(89.20 and 88.17%) in the first and second seasons,
respectively).
4- D.C. 215 variety surpassed significantly the other maize
varieties in the mean values of ear length, while Giza 2
variety produced the lowest value in ear length. The mean
values of ear length was not significantly affected by
different dates of topping when compared with the control
treatment.
5- Giza 2 variety gave the maximum mean values of ear
diameter, whereas the minimum one was obtained from
S.C. 10 cultivar in the fust season and D.C. 215 variety in
the second season. Without topping treatment gave the
thickest in ear diameter, but early topping of maize plants at
72 days after sowing produced thinner ears.
6- There was a significant differences between the four
maize varieties under study in the mean values of rows
number per ear in both seasons. S.c. 10 cultivar gave the
lowest number of rows/ ear, while Giza 2 and D.C. 215
varieties gave the highest rows number per ear. Number of
rows/ ear was not significantly affected by topping
treatments in both seasons.
7- Giza 2 variety ga e the lowest mean values of grains
number per row, whereas no significant differences were
obtained between S.c. 10, D.C. 215 and T.W.c. 310
varieties. There was no marked difference in the mean
values of grains number per row between early and late
topping.
8- D.C. 215 variety gave the highest values of ear weight and
grain weight per ear in the first season, while S.c. 10
cultivar surpassed significantly the other maize varieties in
ear weight and grain weight per ear in the second season.
On the other hand, the differences between the three maize
hybrids in ear weight and grain weight per ear did not reach
the level of significance. Topping treatment had a
significant effect on ear weight and grain weight per ear in
the two growing seasons compared to the control treatment
(no topping), the reduction percentage in the grain weight!
ear amounted 30.34, 24.40, 24.74, 22.85, 23.19 and
20.27% when topping maize plants at 72, 79, 86, 93, 100
and 107 days after sowing in the first season. Whereas, in
the second season, the same topping dates decreased grain
weight per ear by ] 1.53, 10.62, 7.99, 8.49, 4.01, and
8.96%, respectively when compared with the control
treatment.
9- Giza 2 cultivar gave the maximum values of ear cob (25.26
and 25.25 rom in the first and second seasons,
respectively). On the other hand, S.c. 10 gave the
minimum one (21.67 and 22.42 mm, respectively). The
mean values of cob diameter was significant affected by
topping dates in one season out of two. The control
treatment gave thinner of cob than those of topping dates in
the first season.
10- S.c. 10 cultivar significantly surpassed the other maize
varieties under study in the mean values of shelling
percentage, whereas TW.C. 310 cultivar gave the lowest
one. No. significant difference was obtained between D.C.
215, TW.C. 310 and Giza 2 varieties on the mean values of
shelling percentage in both seasons. Dates of topping had a
significant effect on the mean values of shelling percentage
in the first season only. The means of shelling percentage
was decreased by delaying the topping of maize plants.
11- S.C. 10 cultivar produced the heaviest 100- grain weight,
whereas, D.C. 215 v iety gave the lowest value. No
significant difference was obtained between D.C. 215,
T.W.c. 310 and Giza 2 varieties on 100- grain weight.
The mean values of 100- grain weight was significantly
affected by topping treatments in the two growing seasons.
The highest mean values of 100- grain weight were 36.17
and 35.8 gm, obtained from without topping of maize in the
first and second seas ns, respectively, while the lowest
mean values were 33.7% and 33.82% gm, respectively
produced from early topping of maize plants at 72 days
after sowing.
12- Double Cross 215 surpassed the other varieties in ear and
grain yield! feddan (3576.86 and 3030.80 kg/ feddan,
respectively), in the first season. No significant difference
was obtained between the three maize hybrids namely, S,c.
10, D.C. 215 and TW.C. 310 varieties. On the other hand,
SUMMARY - 69 -
Single Cross 10 cultivar was significantly superior to the
other maize varieties in the second season. While, Giza 2
was significantly inferior to the other varieties in ear and
grain yield per feddan in both seasons. The mean values
of ear and grain yield per feddan were significantly
decreased by different dates of topping as compared with
the control treatments in both seasons. In the first season,
topping of maize plants at 72,79, 86, 93, 100 and 107 days
after sowing significantly decreased by 23.68%, 20.37%,
19.85% , 19.09%,20.06% and 10.96%, respectively when
compared with the control treatment. In the second season,
the same dates of topping decreased grain yield! feddan by
23.15%, 20.36%, 17.45%, 16.53%, 16.05% and 16.29%,
respectively. The mean values of grain yield per feddan
was significantly affected by the interaction between date
of topping and maize varieties in one season out of two.
S.c. 10 cultivar without topping gave the maximum mean
values of grain yield per feddan (5010.18 kg), whereas
early topping at 72 days after sowing with maize variety of
D.C. 215 produced the minimum one (2254.86 kg! fed.).
13- The mean values of protein and oil content in maize grains
were not significant affected by maize varieties, topping
treatment and their interaction.
14- Highly significant and positive correlation coefficients were
obtained between grain yield per feddan and each of ear
length, number of grains/ row, ear weight, grain weight! ear
and ear yield per feddan in the first season. . Whereas, in
the. .second season, significant positive phenotypic
correlation coefficients were detected between grain yield
per feddan and each of ear diameter, number of grains/ row,
ear weight, grain weight! ear, 100- grain weight, ear yield/
feddan and shelling percentage under the interaction
between maize varieties and topping treatments.