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Showing 9 results for Additive
Pariya Dorri, Saeed Khavari Khorasani, Mahmood Vali Zadeh, Parisa Taheri,
Volume 1, Issue 2 (2-2015)
Abstract
Selection of breeding methods for plant genetic improvement largely depends on the genetic basis of selected traits. This research was carried out in order to study the genetic parameters of phenological and morphological traits , yield and yield components of maize using generation mean analysis of inbred lines derived from crosses KE72012 (P1) × K1263 / 1 (P2) inbred lines. This study was conducted at Torough Station of Khorasan Razavi Agriculture and Natural Resources Research Center, Mashhad, Iran, during 2012. Six maize generations include BC2, BC1, F2, F1, P2 and P1 was evaluated in a randomized complete block design (RCBD) with three replications. Analysis of variance showed higher dominance gene effects than additive effects. Average dominance gene effects (H / D) ½ in all measured traits, showed complete and over dominance gene effects indicating the importance of dominance effect in studied traits. A simple additive-dominance model performed using weighted least square analysis. Results showed not it’s adequacy for traits, indicating the importance of epistatic effects in controlling genetic variations. Broad sense heritability for all measured traits in crosses KE72012 (P1) × KE1263 / 1 (P2) ranged between 0.10 to 0.88 and the range of narrow sense heritability in this cross was between 0.02 to 0.59. Estimation of number of genes controlling grain yield showed that the one to five genes are involved in KE72012 (P1) × K1263 / 1 (P2).
Davoud Sadeghzadeh-Ahari, Peyman Sharifi, Rahmatollah Karimizadeh, Mohtasham Mohammadi,
Volume 2, Issue 1 (5-2015)
Abstract
To estimate the genetic components and the mode of inheritance for some morphological traits, six rainfed durum wheat genotypes (Chehel daneh, Gerdish, Zardak, Syrian-1, Waha and Knd1149//68/ward) and their complete diallel progenies were grown in a randomized complete blocks design with two replications in 2005-06 cropping season in Maragheh Dryland Agricultural Research Station. Results of diallel analysis revealed that additive variance were important for inheritance of grain yield, number of grain per spike, spike length and number of fertile tiller than dominance variance. The positive value of ‘F’, indicated that there were excess of dominant alleles in comparison to recessive ones in the parents for all of the studied traits. The average degree of dominance (H1/D) 0.5 showed partial dominance for grain yield, number of grain per spike, spike length, 100 grains weight and number of fertile tiller and over-dominance for peduncle length. Graphic analysis indicated that increase of grain yield, number of grain per spike, spike length, 100 grains weight and number of fertile tiller were under the control of combination of recessive and dominance alleles. Predominance of additive effects for grain yield demonstrated that breeding methods based on selection may be advantageous in improving of this trait. The highest value of this trait relevant to Gerdish (10.33 g/plant), therefore this genotype can be used as cross parent in breeding programs for receiving to lines with high yield and yield components. The cross of Waha × Knd1149//68/ward with high value of GY and GCA for this trait can be used as a suitable cross for hybrid production.
Dr Reza Darvishzadeh, Dr Hadi Alipour, Dr Ahmad Sarrafi,
Volume 4, Issue 2 (3-2018)
Abstract
Black stem disease is one of the most important fungi diseases in sunflower. Information about the mode of heritability and the effects of genes controlling trait could be most important for selecting breeding methods to black stem disease resistance. In this study, genotypes ENSAT-B5 and AS613 and a mutant genotype M5-54-1 with different response to MP8 and MP10 isolates were selected and F1, F2, BC1 and BC2 generations were made from ENSAT-B5×AS613 and ENSAT-B5×M5-54-1 crosses. Generations of crossing and parents of each set were planted in a completely randomized design with three replications and infected by M8 and M10 isolates. With the exception of the [(♀) M5-54-1 × ENSAT-B5 (♂)-MP10] cross, the lack of fit test of simple three parametric additive-dominance models for the [(♀) AS613 × ENSAT-B5 (♂)-MP8] and [(♀) AS613 × ENSAT-B5 (♂)-MP10] crosses were significant, indicating the presence of non-allelic interactions in the inheritance of the black stem disease resistance. In the estimated models for the different crosses, high and significant amount of dominant effects and dominant × dominant interactions suggested the importance of non-additive genetic effects. Therefore, selection for this trait in early generation could not be effectively successful and hybrid development is highly recommended for increasing the resistance to the black stem disease.
Saeed Khavari Khorasani, Abdonaser Mahdi Poor,
Volume 5, Issue 1 (9-2018)
Abstract
Selection based on proper selection indices can be one of the most effective methods for indirect selection of yield and yield components, simultaneously. In order to determination of selection index for improvement of maize yield, 60 single cross maize hybrids were planted in two separate experiments (drought stress and normal conditions) based on randomized complete block design (RCBD) with three replications in Torogh agricultural station of Khorasan Razavi agricultural and natural resources research and education center, Mashad, Iran in 2013-2014. Morphological and phenological traits, yield and yield components were recorded. Selection indices were calculated based on results of stepwise regression considering to phenotypc, genotypic and economic values. Based on stepwise regression results in normal condition, physiological maturity, plant height, kernel depth, kernel no./row and tassel length totally could explain 60.68 percent of gain yield variation, then these traits were used to calculate selection index. In drought stress condition, kernel no./row, plant height, ear height, 1000 kernel weight, ear length and leaves no. above ear could explain 63.77 percent of grain yield variation that these traits were used to calculate of selection index. We used 5 optimum selection indices (smith-hazel) and one basic selection index as Pesk-Baker to screen the maize genotypes. The results showed that the relative efficiency of selection index based on yield and expected genetic gain for all of measured traits in selection index 2 was higher than others in both normal and drought stress conditions. Based on grain yield and selection indices, 20 percent of the best genotypes were selected by each selection indices. Based on derived results in normal condition, genotype no. 60 (ksc704 commercial hybrid) were selected by all of selection indices as the best genotype, but in drought stress condition, different genotypes were selected by different selection indices like genotypes 16 (ME77006/1×K1263/1), 22 (ME77006/1×K1263/1) and 34 (ME78005/2× A679), that these genotypes at least were selected by 2 or 3 selection indices.
Mehdi Rahimi, Maryam Abdolinasab,
Volume 6, Issue 2 (3-2020)
Abstract
Biochemical and physiological traits are affected by environmental stresses and therefore the breeding of these traits will play an effective role in stress tolerance. In this study, hybrids of five S7 lines of maize in a 5 × 5 half-diallel design were investigated in order to study the combining ability of biochemical and physiological traits of maize at the Research Farm of Graduate University of Advanced Technology, Kerman, Iran during the 2017-18 crop year based on randomized complete block design with three replications. The results of analysis of variance by fourth Griffing's method showed that the general (GCA) and specific (SCA) combining ability variances were significant for protein, proline, sugar content, carotenoid, chlorophyll a, chlorophyll b and total chlorophyll traits. Therefore, the role of additive and non-additive effects was identified in controlling these traits. Protein, proline, chlorophyll a and total chlorophyll traits were more controlled by additive effects, whereas the carotenoid trait was more controlled by non-additive effects and the role of additive and non-additive effects in controlling other traits was almost equal. The KSC704-S7-11 line showed positive and significant general combining ability for most of the studied traits, suggesting this line can be used in breeding programs to improve and increase stress tolerance. In addition, P1 × P3 and P4 × P5 crosses showed the most positive and significant specific combining ability for proline, chlorophyll a, total chlorophyll and carotenoid traits; thus they can be considered as the best hybrids to improve and increase stress tolerance in corn.
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.
Jamal Rahimi Darabad, Varahram Rashidi, Hossein Shahbazi, Mohammad Moghaddam Vahed, Ebrahim Khalilvand,
Volume 7, Issue 2 (3-2021)
Abstract
In order to determine the heritability and genetic parameters of some agronomic traits in barely (Hordeum vulgare L.) cultivars, a seven-parent half diallel (F1 crosses + parents) was conducted in the non-stress and salt stress (8 and 12 ds m-1) conditions in a randomized complete block design with three replications. Genetic analysis was performed by Hayman’s method and Griffing’s fixed model, method 2. The slope of linear regression of Wr on Vr were significantly higher than 0 and had not significant difference with 1 indicating the additive-dominant model was satisfied in all cases. The narrow-sense heritability of traits was medium to high (0.4-0.8) but their broad-sense heritability was estimated relatively high (0.7-0.9). Results of regression graphs showed that Afzal parent had the most dominant allele. The significance of “a” component in most of the studied traits indicated the presence of the additive effects in controlling of traits. The significance of “b” component in most of the studied traits indicated the presence of the dominance effects in controlling of traits. The proportion of positive and negative genes was lower than 0.25 in all of the traits (except for grain weight per spike in 12 ds m-1 salinity), indicating the presence of asymmetry in the distribution of the positive and negative alleles in the parents. Based on general combining ability effects, it was concluded that under salinity, cultivar “Kavir” had favorable alleles in plant height, grain weight per spike and 100 grain weight traits and can be used as a general parent in breeding programs. Estimates of high broad-sense heritability and narrow-sense heritability in most traits indicated that these genetic materials were promising for breeding under normal and salinity stress conditions.
Seyede Sharare Arianezhad, Hamid Hamid Najafi Zarini, Mehdi Ghaffari, Gholamali Ranjbar,
Volume 9, Issue 1 (9-2022)
Abstract
This research was carried out to estimate the genetic variance components for sunflower fatty acids in two separate optimum and drought stressed conditions in Karaj during 2020 and 2021 growing seasons. The plant materials consisted of 12 hybrids derived from crossing of four restorer lines by three cytoplasmic male sterile lines (Testers) that were evaluated in two separate experiments as randomized complete block design with three replications. Drought stress made a reduction in oil yield (34 percent), oil content (six percent), stearic acid (4.7 percent) and oleic acid (10.6 percent) and an increase in palmitic acid (12 percent) and linoleic acid (2.8 percent). Line × tester interaction effect had a major role in explanation of the variance of the hybrids in terms of fatty acid content in both conditions, indicating the critical role of non-additive effects in genetic control of these traits. Under optimum irrigation, oil yield, oil content and stearic acid content were under control of both additive and dominant gene action and palmitic, oleic and linoleic acids were under control of dominant gene action. Under drought stress, except oil content which was under control of additive effects, all the other traits were under control of dominant gene action. According to the results of this study, fatty acid composition of sunflower was under control of non-additive genetic effects and the crossing-based methods and hybrid breeding could be used for improvement of sunflower in terms of fatty acid composition.
Mohammad Zabet, Fahime Barazandeh, Alireza Samadzadeh,
Volume 10, Issue 1 (9-2023)
Abstract
To investigate the genetic structure of different sesame traits, 7 genotypes, including Ardestan, Sirjan, Fars, Sabzevar, Jiroft, Oltan and TS-3 were studied in the form of a 7 x 7 one-way diallel design in the research farm of the Faculty of Agriculture at University of Birjand during 2015-2018.The traits measured included plant height, height to the first capsule, number of auxiliary branches, number of leaves, leaf length, days to 50 % flowering, days to 90 % flowering, days to physiological maturity, number of capsules per plant, biological yield, grain yield, harvest index, number of seeds per capsule, capsule weight, capsule length, capsule width, chlorophyll a, b and total chlorophyll, oil and protein percentage.Hayman′s variance analysis showed that there were significant components a, b and b3 in all traits and components b1 and b2 in most traits. Parameters D, H1, and H2 were significant and the parameters F, h2 and E were not significant for most traits. The average degree of dominance (√H1/D) showed incomplete dominance and over dominance for all traits. The H2/(4H1) parameter was less than 0.25 in all traits except the day to 50 % flowering, suggesting that increasing and decreasing genes did not have symmetrical distribution among the parents. The parameter (√(4DH1)+F)/√(4DH1)-F ) showed symmetrical and asymmetrical distributions for the studied traits. In most of the traits, there was a dominant gene block controlling the traits. Broad sense and narrow sense heritabilities ranged 0.47-0.99 and 0.17-0.98, respectively. In general, all traits were controlled by genes with additive and dominance effects, so it is possible to select and produce hybrids in sesame. Considering that Fars, Oltan and TS-3 genotypes had the most dominant alleles, it is recommended that in future studies, attention should be paid to these three genotypes.
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