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Showing 3 results for Dominance Effect
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).
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.
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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