The experiment was grown in a Randomized Complete Blocks
Design with three replications during two seasons. Generations
means analysis method was used to study the genetic parameters for number of days to heading, number of days to maturity, plant
height, number of spikes per plant, number of grains per spike and grain yield per plant of two bread wheat crosses Triticum aestivum L. (Gairwel7 x Douma4), (Azaz1 x Soued), Results have shown that
both additive and dominance genetic effects were high significant in most evaluated traits, with predominance of the dominance genetic effects’ values. Also, epistatic genetic effects have contributed to inheritance of most studied traits. The signs of dominance and dominance x dominance were opposite in most examined traits indicating duplicate epistasis for all studied traits of the first cross and for number of days to maturity, plant height and number of grains per spike of the second cross, that indicates that the selection for these traits should be delayed after several generations. High phenotypic variations were composed of high genotypic variations and less of environmental variations, indicating the presence of high genetic variability for different traits and less influence of environment. Highly significant heterosis relative to mid and better parents in F1 was recorded for most characters, accompanied with inbreeding depression for all traits in
F2. Narrow sense heritability and genetic advance were low in most cases due to the dominant of non-additive genetic action in controlling the genetic variation of the most studied traits.
The research was conducted at Al-Jmmaseh station – the Agricultural Research Center in Tartous- to estimate heterosis, combining ability of yield and some fruit traits. Fifteen hybrids were produced by half diallel crossing method in 2013. These
were evaluated in 2014. Most hybrids were characterized by highly significant heterosis values for all the studied traits compared with mid parents and better parents. Heterosis reached (87.76, 50.13)% for yield per plant, (71.44, 43.09)% for average of fruit weight, (19.67, 12.31)% for fruit length, (38.21, 21.43)% for fruit diameter, and (32.5, 20.46)% for number of locules per fruit in comparison with mid parents and better parents respectively.
The best hybrids were: (Ou×H) (Ou×W) (Or×H) and maybe they could be promising hybrids if they had superiority in other important traits. Variance due to general and specific combining ability were highly significant for all traits. This ensured that both types of genetic action (additive and non-additive) controlled the inheritance of these traits. σ2GCA/σ2SCA ratio of the additive genetic action overcame the one of non-additive cation in these traits: number of locules per fruit, average of fruit weight and fruit diameter, while the non-additive genetic action was superior in fruit length and total yield.
Six population seeds of three yellow maize hybrids were formed at Agricultural Research Center, Homs, during 2008 and 2009 growing seasons. Their plants were evaluated in 2010. The present work aims to determine the genetic parameters in six populati
ons (P1, P2, F1, F2, BC1, and BC2). Mean square results showed significant differences among mean values for all traits in all crosses. Significant heterosis values were positive and relative comparing to mid and better parent for most traits. The potence ratios exceeded (+1) in all traits and crosses except ear height, indicating thus over-dominance. In breeding, depression values were significant in most traits for Cross-1, while their values were non- significant in all traits for Cross-2 except plant height, and also in Cross-3 except plant height and grain yield per plant. In most traits epestasis or dominance gene action occupied the first rank in the genetic effects in order of importance to cross, with the exception of number of rows per ear, number of kernels per row and grain yield per plant where additive gene action occupied the first rank for Cross-2 and Cross-1 respectively. Therefore, it could be suggested that selection for most studied traits in the subsequent generations will be relatively more effective than in the early generations.
A half diallel set of crosses among six inbred lines of sweet corn was evaluated to study heterosis and combining ability among plant height, ear height, ear diameter, number of rows per ear and ear yield per plant. The study was carried out at the a
gricultural research center in, GCSAR, Lattakia, Snoubar Jableh, during the 2010, 2011 seasons.
Result showed that almost all crosses expressed a significant positive heterosis effect for ear yield per plant relative to mid parents and better parents; whereas, the highest positive significant percentage of heterosis for ear yield per plant were expressed by the crosses (L4xL6) which gave (198.70%, 176.81%) and (L4xL6) which gave (196.94%, 168.56%), over mid parents and better parents, respectively.
The ratio (σ2GCA/σ2SCA) which was less than (1) showed that the non-additive gene action was more important than the additive gene action in all traits except plant height and ear height. The inbred lines L3 (17.061) and L4 (12.011) seemed to be the best general combiners for ear yield. Also, based on SCA effects, many of single crosses were identified as superior for ear yield, and the best hybrid was L3xL5(50.173).
This study was conducted at the of field research station Sianow belong to the General Commission for Scientific Agricultural Research at Lattakia, to evaluate the susceptibility of maize hybrids produced by using half Diallel the cross according to
the design ofrandomized completeblocks (R.C.B.D), under industrial infection by large corn stem borer Sesamia cretica. Hybrids were compared with the control (Ghouta- 82). The hybrid (P1 × P2) Showed positive and highly significantheterosis for Ear diameter and tolerance forlarge corn stem borer compared with the average of the parents and the best parents and the check (Ghouta- 82). The hybrid (P2 × P6) showed positive and highly significant heterosis for the number of kernels per row compared with the average of the parents and the best parents and the check (Ghouta- 82). Also the hybrid (P1 × P6) showed positive and highly significant heterosis for the number of kernels per row relative to the average of the parents and the best parents and the check (Ghouta- 82). hybrid (P4 × P6) showed positive and highly significant heterosis for the recipe grain yield compared with the average of the parents and the best parents and the check (Ghouta- 82). The hybrid(P5 × P6) also showed positive and highly significant heterosis for the Percentage of dead hearts of the developing summit compared with the average of the parents and the best parents, and compared with the check (Ghouta- 82), therefore it can be considered as a sensitive hybrid.
This study was carried out through the cooperation between the Faculty of
Agriculture Tishreen University and the General Commission of Agricultural Scientific
Researches in Hama during 2013 and 2014 successive seasons.
Eight soft wheat(Triticumae
stivum)genotypes were crossed using half diallel method
.The(28) crosses were grown along with their parents in randomized complete block with
three replications to estimate general combiningability , specific combining ability, and
both mid and high parent heterosis for number of spikes /plant , number of grains /spike ,
thousand grain weight and grain yield.
The results indicated that both additive and non- additive types of gene action were
important in the inheritance of traits under study with preponderance of additive gene
effects for number of grains /spike and thousand grain weight,Non – additive gene effects
were pronounced in the inheritance of number of spikes /plant and grain yield.
High general combiners for thesecharacters were obtained and the most important
parents were: Bohouth 4- Douma 44828-Acsad1115- Golan2.
Many positive specific combiners having both mid and high parent heterosis and
derived from positive general combiners were obtained such as(Golan2×Cham10) –
(Acsad1115×Douma4)(Douma44828×Golan2) and (Douma 2×Golan2).
Results also indicated that some hybrids: (Douma44828×Golan2) (Bohouth6×Douma4)
(Douma44828×Cham10) (Douma2×Acsad1115) had heterosis compared to higher parent
for number of spikes /plant , number of grains / spike , Thousand grain weight and grain
yield..
A half diallel set of crosses among six inbred lines of maize were evaluated at the
Maize Research Department (G.C.S.A.R.) in Damascus Governorate during 2010 and 2011
growing seasons to estimate heterosis and combining ability components for the n
umber of
rows per ear, number of kernels per ear, ear length (cm), ear diameter(cm), 100-kernel
weight (g), and grain yield (ton /hec).
The inbred lines, crosses, general combining ability (GCA) and specific combining
ability (SCA) mean squares were highly significant for all the studied traits, showing the
existence of a genetic variance among lines.
The ratios of GCA to SCA detected for the studied traits showed the dominance of an
additive gene action for all the studied traits except for 100-kernel weight and grain yield
which showed the predominance of a non-additive gene action.
The heterosis percentage for the studied traits was significant based on mid and
better parents.
The GCA effects showed that the lines CML.317, CML.371, CML.373 and
CML.367 were good general combiners for grain yield, while the SCA effects showed that
seven hybrids were the best F1 cross combinations such as (CML.317×CML.371) for grain
yield.
A half diallel set of crosses among six highly diverse barley (Hordeum
vulgare L.) genotypes were evaluated at Karahta Research Station, General
Commission of Scientific Agricultural Research (GCSAR), during 2010-2011
and 2011-2012 seasons to stud
y heterosis, potence ratio, correlations among
traits and path coefficient analysis for number of spikes per plant, number of
grains per plant, number of grains per spike, biological yield ,and grain yield
per plant. Heterosis effects for seed yield ranged from%-89.52 (T-6669×S-6303)
to%16.99 (Arabi abiad mohsan×S-6689) and from%-49.94 (L-6711×S-6689)
to %-1. 35 (Arabi abiad mohsan×S-6689) relative to mid and better parents
respectively. Potence ratio values ranged from 1.14 (number of spikes per
plant) to 3.50 (biological weight) indicating that non-additive gene action was
more important in controlling all studied traits. Correlation coefficients among
traits indicated that seed yield was positively and significantly associated with
each of number of spikes per plant (0.289), number of grains per plant (0.832),
number of grains per spike (0.587), and biological yield (0.708) traits. Path
coefficient analysis indicated that number of grains per plant trait had high
positive direct effects on grain yield.
A half diallel set of crosses among six highly diverse barley (Hordeum
vulgare L.) genotypes were evaluated at Karahta station of field crops research
(GCSAR) Damascus Governorate, during 2010-2011 and 2011-2012 seasons to
study heterosis and comb
ining ability components for plant height, grain yield
per plant, number of spikes per plant, number of grains per spike and
thousand kernel weight.
The research was conducted at the Maize Researches Department, General
Commission for Scientific Agriculture Researches (G.C.S.A.R.) Damascus,
Syria during the summer growing seasons of 2010, 2011 and 2012. Treatments
were arranged in a Randomized
Complete Blocks Design with three
replications. The research aimed to evaluate genetic parameters for some traits
like days to 50% silking, plant and ear height, ear length, ear diameter, number
of rows per ear, number of kernels per row, 100 kernel weight and grain yield
per plant using generations means analysis of two maize hybrids (IL.292-06 ×
IL.565-06, IL.459-06 × IL.362-06) to detect epistasis and estimates of mean
effect [m], additive [d], dominance [h], additive × additive [i], additive ×
dominance [j] and dominance × dominance [l] parameters. Results showed that
the additive - dominance model was adequate to demonstrate the genetic
variation and its importance in the inheritance of most studied traits. Nonallelic
gene interaction was operating in the control of genetic variation in most
studied traits. The signs of [h] and [l] were opposite in most studied traits for
the two crosses. Also, the inheritance of all studied traits was controlled by
additive and non-additive genetic effects, but dominance gene effects play the
major role in controlling the genetic variation of the most studied traits,
suggesting that the improvement of those characters need intensive selection
through later generations. The phenotypic variations were greater than
genotypic variations for all studied traits in the two crosses, indicating greater
influence of environment in the expression of these traits. Highly significant
heterosis relative to mid and better parents, respectively was found for all
characters, and this accompanied with inbreeding depression for all traits.
Narrow sense heritability and genetic advance were low in most of the traits
due to the dominance of non-additive gene action in controlling the genetic
variation of the most studied traits and this predict low to medium values of
genetic advance through selection process.
