الفهرس 
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Abstract
The aim of this research is to study the heterosis, combining ability and
correlations for yield and its components beside heading date,plant height and
tiHering ability in wheat. In (,.IS~· udy, sex parental genotypes from different origins
were used as the following:
1. Giza 157 2. Pavon 3.City straws
4. Hatry 5. Floranae 6.Mario
The above-mentioned genotypes were used in a diallel cross du ri ng 1989/J 990
and 1990/1991 seasons at the agricultural research station ,Moshtohor.
Hybrid vigour were estimated as a percentage of Fl deviation in comparison
to the better parent. General and specific combining ability were est imated
according to ”Griffingll in addition to Phenotypic. Genotypic and environmental
correlation coefficients.
Results can summarized as the following :-
1. MeaDS:
Pavon was the best genotype for heading date. and had the lowest number
of tillers, spikelets number , grain number per spike and the total plant weight.
On the other hand, Hatry was the latest one for the heading date and the
1ar&eStin plant beilht and had tbe lowest Dumber of 1000 kernel weight.
Floranae had a aood titlering ability, and less spike length and less araiD yield
per plant.
City straws was tbe best one Cor1000 kernel wei&btand for the grain number
per spike beside the grain yield per plant.
Giza 157 was the best CorDumber of spikeIets per spike and to some extent
in train number per spike and craiD)’ieId per plant.
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Mario was found to be the biggest for spike number per plant, spike length
and the total plant weight.
2. Heterosis:
Heterosis was appcar-d ;l’” ~orn(’cr(’lC:’:::i”n~.1’. range from ·1.13 % to 5.89 % for
heading date and from tt.46 to 7.17 % for plant height and from 7.96 to 12.55 % for
number of tillers per plant and from 5.19 to 16.48 % for spike number per plant
and it showed negative heterosis in case of spike length. from 1.14 to 2.44 were
observed for spikelets number per spike and from 8.08 to 16.42 % for the 1000-
kernel weight per plant and from 5.30 to 29.23 % for grain yield per plant.
3. Cornbinine ability:-
The best varieties for general combining ability were:-
Pavon, Giza 157, City Straws and Mario for Flowering Date.
Mario, Pavon, Giza 157 for Shorter for stem.
Hatry, Floranae and City Straws for 1000- kernel weight.
City Strawes, Giza 157 and Mario for the Yield weight per parent.
All the studied characters showed highly significant specific combining ability
either in Positive or in negative change. The correlation between hybrid vigour and
Specific combining ability showed highly positive significant differences for all the
studied characters which revealed the superior effect for gene action for hybrid
vigour and specific combining ability.
4.Correlationi
The correlation results revealed the following :-
Flowering date showed siaoificanUy nea;ative genotypic. and phenotypic
correlation with the plant yield, Spike length , Kernel Number. Number of spikelets
per spike, lOGO- Kernel weight and the total plant weight. It revealed significantly
positive genotypic and phenotypic correlation with spike number , Tillering ability
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and plant height.
Plant height revealed significantly negative genotypic and
phenotypic correlation with yield t Spike length, kernel number, Splkelets number
per spike, 1000- kernel weight ami the total plant weight. At the sametime, It
showed positively significant and ;,.,enotypicand phenotypic correlation with spike
length, tillering ability and Flowering date.
Tillering ability character revealed that significantly negative
genotypic abd phenotypic correlation with yield, Spike length, Kernel number,
Spikeletes number and the plant weight and at the sametime , it showed Donsignificant
negative genotypic and phenotypic correlation for 1000- kernel weight.
It showed also significant positive genotypic and phenotypic correlation toward
the flowering date and plant height.
Number of spikes per plant revealed significant positive genotypic
and phenotypic correlation with number of spikeletes and non- significant
with yield It showed significantly positive genotypic and phenotypic correlation with
number of tillering per plant, 1000 - kernel weight, total plant weight , flowering
date and plant height and non - significant with the spike length.
The Spike length character showed significantly negative genotypic and phenotypic
correlation with tillering ability, Flowering date and plant height. It showed non -
significant correlation with the number of spikes per plant. IT revealed also
significantly posit ive genotypic and combining ability.