الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 125 |  |  |
| | | from | 125 | | |
Abstract
The aim of this investigation was to determine the
heterosis and types of gene action and their interaction with
planting dates for some growth and yield characteristics, i.e.
heading dates, plant height number of tiller and spikes per plant,
height of flag region, flag leaf area, spike length, number of
grains per spike, total plant weight grain yield per plant, straw
yield per plant, harvest index and lOOO-kernel weight. To
achieve this target F 1 of a half diallel cross between six parental
genotypes namely; Sids 4 (PI), Line-l (P2), Line-2 (P3),
Gemm~iza 3 (P4), Sakha 69 CPs) and Gernrneiza 1 (P6) having
wide range of variability in most of the studied traits were
utilized.
In 1997/98 season crossing was made with all possible
combinations between the six parents and hybrids and their F1’s
were evaluated in successive season 1998/1999 in a randomized
complete block design with three replications in three planting
dates. Data were recorded on 10 guarded plants, from each plot.
Analysis of. variance was performed for the studied
characters in each date and then combined analysis was carried
out whenever homogeneity of error variance was realized.
Heterosis mean squares were significant and effects for both
mid, better parent were calculated.
The data were genetically analysed by the procedures of
Griffing (1956), method-2, model-I. The obtained results can be
summarized as follows:
A- Analysis of variance, means and heterosis:
1. Planting date mean squares were significant for all the
studied characters.
2. Significant genotype mean squares were detected for all
studied characters in the separate planting dates as well as
the combined analysis. Significant genotype x planting date
interaction mean squares were obtained for all the studied
characters.
3. Mean squares due to parents and hybrids were significant for
all the studied characters except stem diameter in the three
planting dates and in the combined analysis, lOOO-kemel
weight in the third date planting date and main spike weight
for parents in the second, third and the combined data and
hybrids in the third planting date and lOOO-kernel weight in
the first and second planting dates for hybrids.
4. Significant mean squares due to interaction between planting
date and both parents and hybrids were detected for all
characters except for stem diameter and lOOO-kemelweight.
5. The highest values for number of tillers and spikes per plant
were detected in crosses Sakha 69 x Gemmeiza 1,
Gemmeiza 3 x Gemmeiza 1, Sids 4 x Sakha 69, Gemmeiza 3
x Sakha 69. The lowest values for this trait were recorded for
Line-I x Line- 2 and Sids 4 x Line-I .
6. Earlines in heading was detected in the FI hybrids of Line-l
x Sids 4, Sids 4 x Line-2, Line-2 x Gemmeiza 3 and Line-2 x
Gemmeiza 1.
7. Four hybrids Sids 4 x Sakha 69, Line-l x Gemmeiza 3, Sids
4 x Gemmeiza 3 and Sakha 69 x Gemmeiza 1 gave the
highest mean values for grain yield per plant, number of
spikes/pant, heading date, flag leaf area and lOOO-kelnel
weight.
Heterosis:
8. For heading date, 12 ’12, 11 and 11 eros es had significant
negative heterotic effects relative to mid-parent in the first,
second, third planting dates as well as the combined analysis,
respectively. Significant negative heterotic effect relative to
better parent was detected in crosses Gemmeiza 3 x Sakha
69 Line-I x Sakha 69 and Line-l x Gemmeiza 3.
9. For flag leaf area, 14, 15 13 and 14 hybrids exhibited
significant positive heterotic effects relative to mid-parent
value in the first, second and third planting dates as well as
the combined analysis, respectively.
10. For number of tillers and spikes/plant, 14, 12, 14 and 14
hybrids expressed significant positive heterotic effect
relative to mid-parent value in the first, second and third
planting dates and the combined analysis, respectively.
Also, 8, 5, 5 and 5 crosses expressed significant positive
heterotic effects relative to better parent in the same order.
11. Concerning number of grains per spike tell parental
combinations expressed significant positive heterotic
effects over mid-parent or better parent values in the three
planting dates and the combined over them.
12. For lOOO-kernel weight, aU parental combinations exhibited
significant positive heterotic effect relari ve to either mid-
parent or better parent values in the three planting dates and
the combined analysis.
13. Regarding, grain yield per plant, 13, 11, 15 and 15 hybrids
significantly exceeded mid-parent value in the first, second
and third, planting dates as well as the combined analysis,
respectively. Also, 10, 6, 8 and 8 hybrids from the previous
parental combinations showed significant positive heterotic
effects relative to better parent value in the same order.
14. For total plant weight, 13, 13 15 and 15 hybrids showed
significant positive heterotic effects over the mid parent
value in the first, second and third planting dates as well as
the combined analysis. Also, 8, 8, 11 and 9 crosses from the
previous parental combinations gave significant positive
heterotic effects relative to better parent value in the same
order.
15. For harvest index, 3, 8, 7 and 6 hybrids showed significant
positive heterotic effects relative to mid-parent in the first
second. and third planting dates as well as the combined
analysis. Also, 3, 4, 5 and 4 hybrids from the previous
crosse’; expressed significantly positive heterotic effects
over better parent in the same order.
B- Combining ability:
16. The mean squares associated with general combining ability
(G.C.A.) and specific combining ability (S.C.A.) were
significant for all studied characters. Low G. .A./S.c.A.
ratios of less than uni ty were detected for stem diameter for
the three planting dates as well as for combined analysis.
Moreover, for lOOO-kernel weight in the se and and third
planting dates, weight of main spike in the third planting
date and harvest index in the fast, second planting date and
the combined data they were also significant. Low
G.C.A./S.C.A ratio of less than unity indicated the
functioning of non-adrutive gene action in the inheritance
of such characters. On the other hand, high G.C.A.lS.C.A.
ratio which exceeded the unity were detected for other
cases. Such results indicated that additive and additive x
additive types of gene actions which are more important
than non-additive gene actions in controlling these
characters.
17. The mean squares of interaction between planting dates and
both types of combining ability were significant for all
traits except stem diameter, revealing that the magnitude of
additive, additive x additive and non-additive types of gene
action varied from planting dates to another.
General combining ability effects:
18. Line-2 could be considered as an excellent parent in
breeding programs towards releasing varieties with higher
of plant height, stem diameter and flag leaf area.
19. Parental varieties Sids 4, Line-I and Line-2 expressed
significant negative effects for heading date in the three
planting dates as well as the the combined analysis,
indicating that the three varieties could be considered as
good combiners for developing breading programe for
earliness.
20. For number of spikes and tillers/plant Sakha 69 and
Gemmeiza 1 could be considered as an excellent parents in
breeding programes towards releasing varieties
characterized by high number of spikes/plant.
21. Sids 4 seemed to be good combiner for number of
kemeJ.s/spike and spike length.
22. For grain and straw yields and total plant weight Sakha 69
gave the highest significant positive effects followed by
Gemmeiza 1 and then by Gemmeiza 3 in the three planting
dates as well as in the combined data for these character
and some of their components.
23. Significant correlation coefficient values between the
parental performance and its (gi) effects were obtained for
heading date, plant eight, number of spikes and tillers per
plant, spike length, main spike weight, straw and grain
yield/plant in the three planting dates as well as the
combined analysis, nurnber of grains/spike ill the third
planting date and in the combined analysis. Likeness, the
same result was obtained for peduncle length in the second,
third planting dates and the combined analysis and stem
diameter in the first, second planting date and the combined
analysis.
Specific combining ability effects:
24. The crosses Line-2 x Gemmeiza 1. Sids 4 x Gemmeiza 1
and Line-I x Sakha 69 gave the highest desirable CSij)
effects for heading ate in the three planting dates and in
the combined analysis.
25. Crosses Sids 4 x Line-2, Sids 4 x Gemmeiza 3, Sids 4 x
Sakha 69, Sids 4 x Gemmeiza 1, Line-I x Gemmeiza 3,
Line-2 x Gemmeiza 3, Line-2 x Gernmeiza 1 gave
significant positive CSiJ effects for grain, straw yields/plant
and total plant weight in the three planting dates and in the
combined analysis.
26. The cross Sids 4 x Line-l had the highest positive value (Sij)
effect followed by Genuneiza 3 x Saka-69 and then by cross
Line-1 x Line-2 in the combined analysis for flag leaf area.
27. Regarding plant height, eight eleven, eleven and twelve
crosses exhibited significant positive CCSij) effects in the
three planting dates and in the combined analysis. The
highest positive effects was obtained from crosses Line-2 x
Gemmeiza 1, Sids 4 x Line-I, Line-2 x Sakha 69 and Line-
1 x Gemmeiza 3 in the combined analysis. However 2, 2, 3
and 3 crosses expressed significant negative effects in the
same order. The best cross was Gemmeiza 3 x Salcha 69
which gave the lowest value of (5;) effect in the combined
analysis.
28. For number of tillers and spikes per plant, the highest
positive (Sij) effects was detected for the three crosses Sids
4 x Gemmeiza 1, Line-2 x Gemmeiza 1 and Sids 4 x
Gemmeiza 3 in the combined analysis for both traits.
29. For peduncle length, the best combinations were Line-l x
Gemmeiza 3, Line-2 x Gemmeiza 1 and Sakha 69 x
Gemmeiza 1 in the combined analysis.
30. For spike length and number of grains/spike the best crosses
were Line-2 x Genuneiza 1 and Sakha 69 x Gemmeiza 1
and had the highest positive value of (Sij) effect in the
combined analysis for both traits.
31. The two crosses Line-I x Line-2 and l.ine-I x Gemmeiza 3
showed the highest positive val ues of (Sjj) in the combined
analysis for weight of main spike.
32. For harvest index, the three crosses Sids 4 x Line-I,
Gemmeiza 1 x Gemrneiza 3 and Gemmeiza 3 x Sakha 69,
gave the highest (Sij) values in the combined analysis.