الفهرس 
Material and methodsOnly 14 pages are availabe for public view
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Abstract
SUMMARY
The aim of this investigation was to determine the extent of heterosis
and combining ability estimates and their interactions with four nitrogen
levels (four environmental conditions) for heading date, number of grains
per spike, 1000 kernel weight, number of spikes per plant, grain yield per
plant, plant height, straw yield per plant, biological yield per plant and leaf
rust reaction, and susceptibility index for low nitrogen levels four grain,
straw and biological yields. Also, path coefficient analysis was calculated
for yield and some of its components on seven barley genotypes and their
21- hybrid.
Seven parental lines and/or varieties of barley (Hordeum vulgar L.),
representing wide range of variability in most of the studied traits, were
utilized. These lines and varieties were local pure line (Pi), Giza 123 (P2),
Giza 125 (P3), Giza 121 (P4), lines CP5, P6 and P7) introduced from
ICARDA. Crossing among the parental material by means of diallel system
was initiated at 1994/95 season. In 1995/96 season, half diallel set of
crosses involving seven parents and 21 F1 hybrids were evaluated under
four nitrogen levels as 0.O,30,45and 60 kg N/fed. respectively (N1,N’2,N3
and N4) as urea 46.5% at four separate experiment. Each experiment
included the seven parents and their twenty-one FI hybrids were sown on
18/12/1995 in the first season and 25/12/1996 in the second one. In
1996/97 season the same four experiments in the previous season was
repeated. In both seasons each experiments was designed in randomized
complete block design with three replications in the experimental farm at
Sakha Agric.Res.Stn, Kafr EI-Sheikh Governorate. In both seasons of
evaluation i.e. 1995/96 and 96/97, each plot consisted of two rows, each
row was I.S-m long and 30-em width plants within row were15em apart.
The dry method of planting was used in this concern. Field plots were
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fertilized by IS kg P2 O, I fed added before sowing. Nitrogen fertilization
added in three times, the first was with sowing (25 % of total nitrogen), the
second with first irrigation (37.5 % of total N) and the third with second
irrigation (37.5 % of total N).
All other agricultural practices were carried out as usual in the
conventional barley fields. Data were recorded on ten individual plants
chosen at random from each plot except heading date and leaf rust reaction
were determined on the main plot basis.
The results obtained can be summarized as follows: -
A- Yield and its components.
I-Nitrogen levels mean squares were significant for all the studied traits .In
both seasons all traits, increased significantly with increasing nitrogen
levels up to 60 kg Ifed. Also, increased nitrogen fertilizer significantly
increased susceptibility to leaf rust.
2-Significant genotypes mean squares were detected for all the studied
traits in the separate nitrogen levels and their combined analysis except
number of spikes per plant at NI, N2 and N4 as well as the combined
analysis in the first season. Significant genotype x nitrogen level
interaction mean squares were obtained for all traits.
3-The parental variety G 125 (P3) gave the highest mean values for number
of grains per spike, 1000 kernel weight, number of spikes per plant, grain
yield per plant, plant height, straw yield and biological yield also, it was
moderate for earliness and leaf rust resistance. The two parental lines
(P6 and P7 ) behaved as the earliest and resistant for leafmst.
4-The two crosses between P3 (G. 125) and each of Pi and Ps had the
highest grain yield per plant in each separate nitrogen levels as well as
the combined analysis over them in both seasons.
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5-Mean squares for parent vs. crosses as an indication to average heterosis
overall crosses was of appreciable magnitude in the four fertilizer levels
as well as their combined in separate season for all investigated traits
except heading date at NJ, N2 and N3 in the second season, number of
grains per spike at Nain the first season and four N fertilizer levels as
well as the combined analysis in the second season, 1000- kernel weight
at N] and N2 in the second season, number of spikes per plant and grain
yield at N, in the second season, plant height at N], N2, N3, N4 as well as
the combined analysis in the first season and N3 in the second season.
straw yield at N2, N3, N4 and combined analysis in the second season,
and biological yield at N, and N3 in the second season.
6-Significant mean squares due to interaction between parents vs. crosses
and nitrogen fertilizer were detected for all traits except heading date and
number of grains per spike in second season and plant height in the first
season.
7-The crosses (PIX P2), ( P2xPs )and( P3x P, )gave the highest values of
heterotic effects for grain yield per plant in the first season. Also, the
cross (P2xP3) gave the highest negative heterotic effects relative to better
parent followed by cross (P2xP6) for leaf rust reaction.
8-The mean squares associated with general and specific combing ability
were significant for most cases. Also, the results showed that all traits
expressed high GCA/SCA ratios, which exceeded the unity indicating
the predominance of additive and additive by additive gene action in the
inheritance of these traits.
9-The mean squares of interaction between nitrogen levels and both types
of combining ability were significant for all traits except plant height in
the first season which showed insignificant interaction between SeA and
nitrogen fertilizer levels.
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10-The parental varieties G.l25 (P3) seemed to be good combiner for
number of kernels per spike, 1000- kernel weight, grain yield / plant,
straw and biological yields for all nitrogen levels in both season. Also,
A
it gave significant negative (gi) effects for leafmst reaction at N2, N3,
N4 and combined analysis in the second season.
II-The cross (P3X P, )had the highest positive (s~) effects for grain yield at
different nitrogen levels and the combined analysis in both seasons
followed by cross (P2xPS).Also, the five crosses( P,xPs ),(P1xP7),(P2xP3),
A
(P2xP6 )and( PsxP6 )gave significant negative ( Sij) effects for all
nitrogen levels and the combined analysis for leaf rust disease.
B-Susceptibilitv index :-
I-Season mean squares were insignificant for the three studied (grain, straw
and biological yields).
2-Mean squares of genotypes and its components, parents and hybrids and
interaction between genotypes and season for fertilizer SI (FSI) were
significant for the three traits.
3-The parental variety P3 (G. 125) gave the desirable (FSI) for grain, straw
and biological yields. Also, the best cross was (P1XP3) followed by cross
( P3XPS ) and then by cross (P2XP3) for (FSI) of biological yield per
plant. While the crosses (p,XP3), (P3XPS), and (P2XP3) for (FSI) of grain
and straw yields gave low (FSI).
4-The three Crosses (P,xPs), (P2xPS) and (P2xP7) exhibited significant
negative heterotic effects relative to better parent for (FSI) of straw and
biological yield, Also, the four crosses (plxP5), (PlxP6), (P2xP6) and
(PsxP6) exhibited significant negative heterotic effects relative to better
parent in the first season for (FSI) of grain yield.
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5-The variance associated with general and specific combining ability were
significant for (FSI) in the three traits. High GCAJ SeA ratios than unity
were obtained for the three traits. Also; the mean squares of interaction
between season and specific combining ability were significant for (FSI)
of the three traits.
6-The parental variety (P3) G. 125 seemed to be the best combiner for
(FSI) in the three characters studied. While, the crosses (PtxP6), (P2xP3),
A
(P2xP4), and (PSxP6) in the first season, gave significant negative (Sij)
effects for (FSI) of grain yield.
C-Association studied
I-Significant positive phenotypic correlation values were detected between
grain yield per plant and each of heading date, number of grains per
spike, 1000- kernel weight, number of spikes per plant, plant height,
straw and biological yields at four N- levels as well as the combined
analysis, except for correlation values between grain yield and heading
date at N2 in the second season and leaf rust at four nitrogen levels and
the combined in the second season.
2-Based on path coefficient analysis, the most important sources of
variation in plant yield were: 1) indirect effect of number of spikes
through 1000-kernel weight at the four nitrogen levels in both season ,2)
direct effect of 1000- kernel weight at the four nitrogen levels in both
seasons except at 60 kg N/ fed. in the first season,3) The direct effect of
number of grains per spike in most cases and 4) The direct effect of
number of spikes per plant at N1(zero N-Ievel) in both seasons and N2 in
the second season.