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Showing 5 results for Diallel
Mohtasham Mohammadi, Mozafar Roustaie,
Volume 2, Issue 2 (3-2016)
Abstract
For development of high yield wheat cultivars, this study was conducted to estimate the general combining ability (GCA) of parents, specific combining ability (SCA) of hybrid progenies, heritability and heterosis of grain yield and some agronomic traits. A partial diallel crosses which obtained in a set of six wheat genotypes were sown in randomized complete block design at Gachsarann agricultural research station in 2013-14 growing season under dryland condition. The results of this study revealed a significant difference among the genotypes for all of the traits that indicating considerable genetic variation. Significant effects of GCA and SCA indicated role of additive and non-additive gene action in the control of all considered traits. The mean square ratio of GCA to SCA and Baker genetic ratio showed a preponderance of non-additive gene action for all of the studied traits. Broad-sense heritability was high (0.67-0.99) for all of them, which indicated the role of genetic factors compared with non-genetic factors for controlling of these traits. Narrow-sense heritability was low to moderate (0.06–0.37). Among the parents, Koohdasht was the best general combiners for early growth vigor, days to maturity, spike length, peduncle length, flag leaf extrusion and grain yield. The Koohdasht × DAMARA-6 hybrid showed the best specific cross for days to heading, days to maturity, grain filling period, plant height, chlorophyll content, canopy temperature, grain length and grain yield. These hybrids showed positive and significant heterosis for grain yield, chlorophyll content and grain length and negative heterosis for plant height. It is expected to produce desirable segregants and could be exploited successfully in wheat improvement programs. In addition, because of preponderance of non-additive gene action for studied traits, particularly in the early generations, efficiency of genetic selection was low and selection for genetic improvement of these traits must be retraced in advanced generations.
Dr Mohammad Motamedi, Ms Parviz Safari,
Volume 4, Issue 2 (3-2018)
Abstract
Drought stress is one of the most important factors involved in reducing wheat production and identifying genetic structure and gene action type in controlling grain yield in water stress condition is essential for choosing appropriate breeding methods. In this study, 9×9 one way diallel crosses were used to study the genetic structure of wheat grain yield at stress and non- stress conditions. Combining ability analysis by the second Griffing method for both conditions resulted in significant GCA and SCA variances, representing grain yield may be controlled by additive and non- additive effects of genes. The results of applying combining ability analysis indicated that among the parents, genotypes Ghods and Bam had the highest GCA for grain yield and the best specific crosses were Arg × Ghods, Navid × Moghan, Bam × Alvand (for both irrigation regimes) and Bam × Ghods (in stress condition). Biplot analysis of diallel data was used to display GCA and SCA for parents and to determine heterotic groups and the best crosses. In general, according to the results, Bam, Ghods and Arg were tolerant cultivars and had the ability to maintain yield in drought stress condition as well as to transfer these properties to the hybrids. So these genotypes can be used to improve stress tolerance in breeding programs.
Amir Gholizadeh, Hamid Dehghani, Mostafa Khodadadi,
Volume 5, Issue 1 (9-2018)
Abstract
In any breeding program, knowledge of the nature of gene action involved in the inheritance of traits is a basic requirement. In this research, diallel crosses progenies of six coriander landrace were evaluated in F1 and F2 generations. The genotypes were evaluated in different irrigation conditions in three separate experiments, in which each experiment was conducted in a randomized complete block design with three replications during the growing season of 2016. Results of genetic variance analyses revealed significant mean squares of general and specific combining ability for all traits, indicating the importance of additive and non-additive genetic effects for these traits. Additive gene actions played a more important role in controlling of plant height, leaf number, branch number and biological yield, whereas the role of non-additive gene actions was more conspicuous than those of additive gene actions in controlling of harvest index and fruit yield. Therefore, providing superior hybrids using breeding methods based on progeny test will be effective to improve these traits. Also, among selected parents, P4 parent in normal irrigation and moderate water stress and P6 parent in sever water stress were the best parents for crosses in the development of high-yield varieties in coriander.
Somayeh Dadashi, Reza Darvishzadeh, Mojtaba Nouraein, Hamid Hatami Maleki,
Volume 6, Issue 1 (9-2019)
Abstract
For the purpose of graphical analysis and estimation of genetic parameters related to yield and its components, six tobacco genotypes was crossed in half -diallel mating design. In this study, the F2 progenies and their parents were evaluated in a randomized complete block design with three replications. The results of analysis of variance indicated a significant difference between genotypes for plant height, leaf number, leaf dry weight and leaf fresh weight. Hayman graphical method was utilized for analysis of data. Diallel analysis indicated existence of an additive and dominant actions in inheritance of all studied traits. Traits including plant height, leaf number, leaf length and width, stem diameter, internode distance and leaf dry weight possessed greater additive effects meanwhile in the leaf weight the dominance effect was greater. The additive gene action detected for leaf dry weight (yield) manifested the influence of selection methods in breeding of this trait. Due to the fact that the fresh weight of the leaf was controlled by dominance effects, so hybrid-based methods are effective in modifying this trait. Also, additive and dominance gene action were contributed in heritability of yield, plant height and number of leaves. Regarding the mean values of dominance degree and results of graphical analysis, the gene action for leaf fresh weight was over-domnance and so, the heterosis phenomenon could be used to increase and improve this trait. For the traits including plant height, leaf number and yield, the gene action type was relative dominance.
Mohammad Zabet, Amir Ebrahimzade, Zohreh Alizadeh, Ali Reza Samadzadeh,
Volume 6, Issue 2 (3-2020)
Abstract
The production of new and compatible cultivars to different environments is one of the most important goals for the breeders. The crossing new cultivars and the selection of superior genotypes for desirable traits among their offspring is a method that has always been used by breeders. 28 genotypes obtained from the crossing of a 7 × 7 one-way diallel experiment consisting of seven parents (Alvand, Anfarm9, Chamran2, BC Roshan, Qods, Ofogh, local variety Sorkh-dane) and their 21 hybrids were investigated in a randomized complete block design with three replications in the research field of the Faculty of Agriculture of University of Birjand (Iran) under non-stress and drought stress conditions. The analysis of variance showed a significant difference among genotypes for all traits. Mean squares of GCA and SCA were significant for all traits under non-stress and stress conditions, so, there were additive and non-additive components of heritable variance in all traits. The BC Roshan parent had the high combining ability and Ofogh parent had the lowest combining ability in most traits in non-stress and stress conditions. In both conditions, BC-Roshan × Chamran2, Sorkh-dane × Qods and Ofogh × Anfarm9 hybrids had the highest yield and yield dependent traits. Hayman's variance analysis showed that component a (additive genetic diversity), component b (dominance genetic diversity), component b1 (heterosis), component b2 (heterosis specifically for each parent), and component b3 (specific dominance deviation per cross) were significant in both conditions in all traits.The Hayman's analysis confirmed the results of Griffing's analysis.
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