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Showing 2 results for Genetic Variance
Reza Amiri, Sohbat Bahraminejad, Kianoosh Cheghamirza,
Volume 8, Issue 1 (8-2021)
Abstract
The study of the genetic structure controlling agronomic traits is one of the preconditions for selecting the appropriate breeding method. In order to analyze genetic of some agronomic traits of bread wheat using generation mean analysis, parents and different generations resulting from the cross of Marvdasht × MV-17 wheat cultivars were assessed in a randomized complete block design with three replicates under normal and terminal drought stress conditions in Research Farm of Razi University (Iran) during 2015-2016 cropping season. Based on the results of weighted ANOVA, a significant difference was observed between different generations for most of the studied traits under both conditions. Generations mean analysis revealed that in addition to the additive and dominance gene effects, a variety of epistatic effects also played a role in the inheritance of most traits, and therefore cannot hope for the success of selection in first generations. The role of additive gene effect was greater than the dominance one for plant height, peduncle length and awn length, indicating usefulness of using recurrent selection to aggregate these genes followed by selecting lines with favorable agronomic characteristics. The model of genetic control for most of the traits was similar under both conditions in terms of the presence or absence of non-allelic interactions and it has not been widely affected by drought stress. The broad-sense heritability for plant height, peduncle length and awn length was estimated to be high under both conditions. The broad-sense heritability for kernel yield was moderate estimated under both conditions, but the narrow-sense heritability was very low. In general, considering the greater role of the non-additive gene effect for most of the traits, the selection is suggested in advanced generations and after access to a high level of gene fixation.
Jawed Rahimi, Fatemeh Amini, Hossein Ramshini, Mahyar Abedi, Mahmood Lotfi,
Volume 9, Issue 2 (3-2023)
Abstract
Tomato is the second most important vegetables, after potato, which has the highest area of cultivation worldwide. Acording to FAO statistics, Iran is the sixth producer of tomato cultivation in the world. However, more than 95 percent of vegetable seeds are imported into the country. The present study was conducted in order to evaluate commercial imported hybrids (8320, Eden, Matin and Xaman) and the F2 and F3 generations resulting from their self-breeding. In this regard, after the production of F2 and F3 generations, three generations (F1, F2 and F3) together with the control variety (Early Orbana y) were evaluated in the research farm of Seed and Plant Improvement Institute, Karaj, Iran, based on a randomized complete block design with four replications during 2019-2020. The analysis of variance showed that the difference among genotypes for single plant yield, days to flowering, average single fruit weight, number of fruits harvested and acidity (pH), was significant at the level of 1% probability and total soluble solids (TSS) was significant at the level of 5%. The results of the mean comparison showed that the highest mean of single plant yield belonged to 8320 F1 (10920/10g), the highest days to flowering was observed in Xaman F2 (47.01 days), the highest mean weight of single fruit was observed in Xaman F1 (115.50 g), the highest number of fruits harvested was in Xaman F1 (106.62), the highest amount of total soluble solids was in Matin F3 generation (4.96) and the lowest amount of acidity (pH) was in 8320 F1 (4.10). The results of estimating genetic parameters showed that most of the evaluated traits had high genetic and phenotypic variances, but a slight difference was observed between the coefficient of phototypic variation and the coefficient of genotypic variation, which indicates a small effect of environment on the control of these traits. Higher variance of dominance than additive variance in most traits caused the degree of dominance to be greater than one, Therefore, the possibility of control of traits by genes with dominance or over-dominance effects is high, and in order to improve these traits, the methods for hybrid development are suggested.
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