Jamila Dirbas, GCSAR, Administration of Cotton Research
Aleppo University, Faculty of Agriculture.
In Syria, cotton is very important because it forme 4% agriculture area, 35-40% irrigated area and 18% people work its agriculture and production.
The research was Carried for two seasons 2011and 2012 at Tal-Hedya/Aleppo.
In first season: seven genotypes (Aleppo118, Raqqa5, Deir EL-zour22, Cherpan432, NIAB78, G73, Coker139) were planted in rows (5m) length, two rows for each genotypes. At the flowering stage diallel cross were done, and some flowers of each parent selfied by banding it keep its genetic pureness.
In second season the parents and hybrids were planted three rows (5m) for each entry using Randomized Complete Block Design RCBD in three replications.
Some flowers of each parent were obligated to self pollinated to get F2. Some
Earliness parameters, productivity and technological characters were assessed. The results were analyzed using the computer program Genstat 12, the heterosis, general and specific combining ability, heritability were determined estimating in broad and narrow sense, and genetic components of variance.
Heterosis analysis showed differences in between parents in the studied traits and favorite significant and highly significant values measured to mid and best parent in many crosses for each characters except fiber length. Which is due to the difference in genetic factors that control these traits depending on the different constituents parents.
general combining ability (GCA):
Study of the effects of general combining ability showed that , the parental genotype Aleppo118 has a high GCA for hight plant, load of first symobodial brunch, number of monobodial brunch, seed cotton yield, fiber strength and fiber length.
Genotype Raqqa5 for hight plant, fiber strength and fiber elongation.
Genotype Deir EL-zour22 for seed cotton yield and fiber length.
Genotype Cherpan432: for hight plant, number of total bolls , number of symobodial brunch, number of remained bolls and boll wight
Genotype NIAB78: for hight of first symobodial brunch, lint percentage and fiber elongation.
Genotype G73: for lint percentage.
Genotype Coker139: for hight of first symobodial brunch , load of first symobodial brunch, number of total bolls , number of symobodial brunch, number of monobodial brunch, number of remained bolls and boll wight This is a clear indication that these parental genotypes have the largest number of additive genes action controlling these traits. which plays important role in the inheritance of the above-mentioned traits.
Specific combining ability (SCA):
Estimated of SCA values were significantly different, this results showed that the hybrids resulted from parents which have highly significant GCA, had (additive x additive) gene action.
The crosses (Aleppo118 X Cherpan432),( Cherpan432 X Aleppo118),( Raqqa5 X Cherpan432),( Cherpan432 X Raqqa5) for hight plant
(NIAB78 X Coker139) for hight of first symobodial brunch
(Aleppo118 X Coker139),( Coker139 X Aleppo118) for load of first symobodial brunch and number of monobodial brunch.
(Cherpan432 X Coker139) for number of symobodial brunch, number of remained bolls, number of total bolls and boll wight.
(Coker139 X Cherpan432) for boll wight.
(Aleppo118 X Raqqa5) for fiber strength
On the other hand many hybrids showed high SCA ,but the interaction of genetic was (additive x non-additive) and (non-additive x non- additive), and this refers that these hybrids possessing the largest number of genes have dominance and epistasis effects in the inheritance of these traits, which means that the value of the character well decrease continuously by genetic segregation.
The importance of estimating the heritability refer to the fact that the efficiency of selection of desired trait decrease when this scale decreases, the results of estimating heritability H(bs) were
-Too high:90% for hight plant
88% for hight of first symobodial brunch
85% for number of remained bolls
85% for boll wight
-High: 80% for number of monobodial brunch .
80% for number of total bolls
77% for number of symobodial brunch
76% for load of first symobodial brunch
72% for seed cotton yield Which indicated to the importance of genetic variation in the inheritance these traits and the portion of genetic variation is greater than the portion of environmental variation in the inheritance of these traits.
-Moderate:60% for lint percentage
59% for fiber strength
45% for fiber elongation
43% for fiber length
Which indicated to the importance both of genetic variation and environmental variation in the inheritance these traits .
-Low:31% for fiber fineness
Which indicated to the importance of environmental variation in the inheritance these traits and the portion of environmental variation is greater than genetic variation the portion of in the inheritance of these traits.
The degrees of Heritability(ns) varied from Moderate to low. This is refers to depending on cross then selesction to improvement all charachtares.