الفهرس 
Material and methodsOnly 14 pages are availabe for public view
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Abstract
SUMMARY
Two field experiments were conducted at Giza Agricultural Research Station.
Agric, Res. Cen., during 1991 and 1992 seasons to study the performance of three hybrids
and one open-pollinated variety under four N levels and to estimate N uptake, N use
efficiency and Nrecovery.
The soil texture was clay loam with a pH value of 8.16 and electric conductivity of
about 0.5 and available Nfrom 293 to 392 ppm.
The studied varieties were, D.C. 215, T.W.C. 310, S.C. 10 and Giza-2 (composite
variety), which were developed by Maize Research Section, Agric. Res. Center, Giza.
The Nlevels were, zero, 80, 105 and 130 kg NIfed. The normal cultural practices
of growing maize as recommended for the region were carried out.
The experimental design was randomized complete blocks with four replications.
Data on growth and agronomic characters, flowering date, grain yield and its
components and NPK content in leaf of the topmost ear as well as in grain were collected.
Results could be summarized as follows :
1 - The increase in N levels significantly increased plant height of maize at 35 and 50 days
from planting as well as at harvest. AlSiOear height was significantly increased due to
Napplication.
2 - Number of leaves/plant at 35 and 50 days from planting was significantly increased
with the increase in N level. Also area of the topmost ear was significantly and
consistently increased due to the increase in N level from °to 80, 105 and 130 kg/fed.
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3 - Nitrogen application induced early tasseling and silking of maize plants. The earliest
tasseling and silking dates were achieved by the highest N level namely, 130 kg N/fed.
4 - Nitrogen application significantly reduced barren plants % and increased number of
ears/plant, which indicates the effect of B, good supply ofN on the prolificacy of maize
plants.
5 - Ear characters studied namely, ear length, ear diameter, ear weight and number of
rows/ear were significantly increased with the increase in Nlevel.
6 - Grain index, shelling % and grain yield per feddan were significantly increased due to
the increase in NleveL Applying N at 80, 105 and 130 kg/fed increased grain yield
over the check treatment by 18.4, 26.1 and 36.7 % in the first season, corresponding
to 20.5, 32.1 and 48.9 % in the second. season, respectively. The average grain yield
produced under the 130 kg/fed N level was 3.05 and 3.82 tlfed in 1991 and 1992
season, respectively.
7.- The increase in N level significantly increased N and K % in leaves, whereas P % in
leaves was not significantly affected by N application. Also, increasing N level
significantly increased N, P, K and protein content in grain.
8 - The four tested varieties showed differences in plant height at different growth stages.
S.C 10 was the tallest variety in both seasons. Also ear height was higher in S.C. 10
while Giza-2 had the lowest ear height.
9 - Number ofleaveslplant was higher in S.C. 10 followed by T.W.C. 310, D.C. 215 and
Giza-2 in a descending order. Also, area of the topmost ear was higher in hybrids
compared with the open-pollinated vari’ely Giza-2.
10 - S.C 10 was the earliest variety in tasseling and siJkiug dates.
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11 - S.C. 10 recorded the lowest barren plants % in both seasons, whereas Giza-2
recorded the highest percentage. Similarly, S.C. 10 recorded the highest value for
number of ears/plant followed by T.W.C. 310, D.C. 215 and Giza-2 in a descending
order.
12 - Varieties differed significantly in ear characters. S.C. 10 had the longest ears and
Giza-2 the shortest ears, whereas T.W.e. 310 and D.C. 215 were in between. The four
evaluated varieties did not differ in ear diameter and number of rows/ear, while ear
weight was higher in S.c. 10 and T.W.c. 310 compared with Giza-2 and D.C. 21 S.
13 - S.C 10 was superior to the other varieties in grain index, whereas Giza-2 was the
worst in this trait.
14 - Shelling % was higher with D.C. 215 and lower with Giza-Z and S.C. 10 and T.W.C.
310 were in-between.
15 - S.C. 10 was the best variety in grain yield/fed and outyielded T.W.C. 310, D. C. 215
and Giza-2 by 27.9, 38.3 and 47.5 % in 1991 season and by 4.4, 13.2, and 18.1 % in
1992 season, respectively.
16 - The four tested varieties did not show significant differences in N, P and K contents
in leaves. Also, N, P and kOlO in grain did not differ significantly in the tested varieties,
whereas P % in grain of T.W.C. 310 was significantly higher in the second season
compared with the other three varieties.
17 - No significant differences were detected in protein % in grain of the four evaluated
varieties.
18 - NItrogen uptake in grain was markedlly affected by N level. Applying N at 80, 105
and 130 kglfed increased N uptake ill grain over the cbeck treatment by 41.2, 53.5
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and 77.6 in 1991 season, respectively, corresponding to 38.0, 66.7 and 113.6 % in
1992 season.
19 - Nitrogen uptake in grain ofS.C. 10 surpassed that ofT.W.e. 310, D.C.21S and Giza-
2 by 25.7, 37.6 and 47.7 % in the first season and by 2.6, 13.1 and 25.6 for the three
other varieties, respectively. Nitrogen uptake in grain averaged over the four N levels
in S.C. 10, T.W.C. 310, D.C. 215 and Giza-2 was 50.0,39.8, 36.4 and 33.9 kg/fed in
1991 season, respectively corresponding to 67.9, 66.1, 60.0 and 54.0 kg/fed in 1992
season.
20 - Nitrogen use efficiency markedly increased due to the increase in N level. In 1991
season, applying Nat 80, 105 and 130 kg/fed produced N use efficiency of 5.84, 6.31
and 7.17, whereas the same N levels resulted in N use efficiency of 7.80, 9.31 and
11.46 in 1992 season, respectively. The results indicate that a level of 130 kg N/fed is
an optimum level under the conditions of the experiment.
21 - The four evaluated varieties could be arranged in the following descending order
with regard to N use efficiency as, S.c. 10 (7.16), T.W.C. 310 (7.41), D.C. 215 (6.4)
and Giza-2 (4.28) in 1991 season. In 1992 season, the arrangement was S.C. 10
(12.37), T.W.C. 310 (11.55), Giza-2 (8.95) and D.C. 215 (5.41), in a descending
order.
22 - Nitrogen recovery was recorded as 14..42, 14.25 and 16.69 for the N levels of80, 105
and 135 kglfed in 1991 season. The same N levels produced N recovery of 19.03,
25.44 and 35.24 %, respectively in 1992 season.
23 - S.C. 10 was the best variety in N recovery followed by D.C. 215 in 1991 season and
T.W.e. 310 in 1992 season. N recovery values were 17.01, 13.03, 17.21 and 13.21
for S.C. 10, T.W.C. 310, D.C. 215 mid Giza-2 in 1991 season, respectively. In 1992
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season, N recovery values were 33.38, 30.30, 20.99 and 21.52 for S.C. 10, T.W.C.
310, D.C. 215 and Giza-Z, respectively.
24 - The interaction between N levels and varieties had significant effect on leaf area of
the topmost ear leaf in 1991 season. other studied characters were not significantly
affected by the interaction.
25 - The present results showed clearly the superiority of growing S.C. 10 as well as
T.W.C. 310 and the application of 130 kg N/fed for maximizing maize grain yield.