الفهرس 
Material and methodsOnly 14 pages are availabe for public view
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Abstract
The aim of this investigation was to determine the extent of
heterosis and combining ability estimates and their interaction with three
spacings (densities) 35000 (Dl) 23333 (D2) and 17500 (D3) plants/fed.
in two locations, namely, Sakha (Ll) and EI-Serw (L2), for 50%
flowering date, physiological maturity date, plant height, stern diameter,
head diameter, lOfl-seed weight, seed husk percent, number of
seeds/head, seed yield/plant, oil percentage, oil yield/plant and seed
yield/fed.
Six cytoplasmic male sterile (eMS) lines (A-lines), two introduced
from USDA (AI and A..) and the others produced in El-Serw, Egypt (A3,
A6, A9, and AI0), and five fertility restorer lines (RF-lines), three of
them introduced from USDA (R3, R4 and R8) and two from EI-Serw
Station Egypt (R12 and R14) of sunflower were planted at Sakha Agric.
Research Station in 1996 summer season for developing 30 top crosses.
In 1997 summer season, the thirty hybrids, the five testers, the six
fertile lines (B-lines) and the three hybrids (Eirflor, Malabar and Vidoic)
were sown in two locations i.e., Sakha on 3rd July and El-Serw on 17th
June. In each location, a split plot design with three replications was used.
The main plots were assigned to plant spacings (densities) while sub-plots
were allocated to forty four genotypes of sunflower. Each sub-plot
consisted of five ridges, each ridge was 420 em. long and 60 em wide.
Calcium superphosphate (15.5% P20S) was added during seed bed
preparation at the rate of 1DO-kg/fed. All agricultural practices were
carried out as usual in the convential sunflower fields. Ordinary analysis
of variance was performed for the data collected from top crosses in each
location to test the significance of all genotypes. Homogeneity of error
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· variances was tested for each trait. When differences among top crosses
were significance, line by tester analysis according to Kempthome (1957)
was done for each density and over the three densities in each location.
Heterosis percentage for seed and oil yield/plant, oil percentage and seed
yield/fed was computed for individuals crosses as the percentage increase
of each top cross relative to Eirflor, Malabar and Vidoc commercial
sunflower hybrids.
Data were recorded on twenty guarded plants chosen at random from
each sub-plot. The characters studied were:’ 50% flowering date,
physiological maturity date, plant height, stem diameter, head diameter,
weight of 100 seeds, seed husk percent, no. of seeds/head, seed
yield/plant, oil percentage, and seed yield/fed.
The results obtained can be summarized as follows:
1- The highest mean values for flowering and maturity dates, stem
diameter, head diameter, IOO-seed weight, no. of seeds/head, seed
husk percentage, seed yield/plant and oil yield/plant were obtained
when hills were spaced 40 em apart on the ridge. While, plant
height, oil percentage and seed yield/fed were significantly increased
by decreasing spacing between hills from 40 to 20 em.
2- The mean squares of interaction between densities (spacing) and
location were significant for most studied traits. The density (D 1)
(20 em between hills) had the highest mean values for oil percentage
and seed yield/fed. in EI-Serw followed by D I in Sakha location.
3- Genotypes mean squares were significant for all the studied traits at
both locations as well as the combined analysis. Also, significant
genotypes X location mean squares was detected for all traits.
4- The top crosses Al x R3, Al x R4, AI, RI2, Al x RI4, A9 x RI2,
A9 x R14 and AIO x RI4 showed significant increase in seed
yield/fed. compared to the best check hybrids in both locations as
well as the combined analysis.
5- The crosses mean squares were significant for all the studied traits in
separate density as well as the combined analysis in both locations.
6- The estimates of cr2GCA played the major contribution in
inheritance for plant height in separate density as well as the
combined data in both locations, flowering date at D 1 and D2 as
well as the combined data in Sakha location, flowering date at D I
and the combined data in EI-Serw location, stem diameter and head
diameter at DI, D2, D3 and the combined data in Sakha location,
and at DI in El-Serw location, IOO-seedweight at the three densities
and the combined analysis in El-Serw location and at D 1 in Sakha
location, seed yield/plant at D2 and D3 in El-Serw location and seed
yield/fed. at D3 in El-Serw location.
7- The parental inbred lines Al and A6 and the parental testers RI2 and
RI4 gave significantly positive gAi effect for seed yield.
8~ The top cross A1 x R3 in both locations and top cross A6 x R8 in the
second location (El-Serw) expressed significantly positive Sij effects
for seed yield/plant and yield kg/fed.
9- For seed yield/fed., thirteen, five and eitht top crosses in Sakha
location, seven, six and fourteen crosses in El-Serw location showed
significant positive heterotic effects relative to Eirtlor, Malabar and
Vidoic, respectively. The four top crosses (AI x R3), (AI x R4), (AI
x R12) and (A9 x RI4) outyielded the check hybrids in both
locations. The heterotic effect over two locations of the three check
hybrids ranged from 11.6% for (AI x R4) to 21.82% for (AI x R3).
It could be concluded that these crosses may be useful for improving
seed yield of sunflower.