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Introduction and objectives: Rapeseed is one of the most important oilseed crops in the world, increasing the amount of seed oil content, increasing the genetic potential and yield are among the important goals of the large-scale production programs of rapeseed in different countries, the basis of plant breeding programs is diversity. The success rate depends on the presence of genetic diversity and selection. The purpose of this research was to determine the best public and private combinations, heritability and the degree of heterosis compared to the superior parent using the di-allele method in spring canola. Materials and methods: Seven canola cultivars were crossed in 1399-1400. The first generation hybrids with parents (49 genotypes in total) were evaluated in the form of randomized complete block design in three replications in 1400-1401. The studied traits included the number of days to flowering, the number of days to maturity, plant height, the number of pods per plant, the number of seeds per pod, the weight of 1000 seeds and seed yield.
Findings: The results of simple variance analysis of traits showed that the difference between genotypes for all traits was significant at the 1% probability level. which indicated the existence of diversity among genotypes. The first Griffing method (complete dialle) as well as Heyman's numerical method were used to analyze diallele. The results of the diallel analysis indicated the significance of the average general and private combinability and mutual effects for all investigated traits, which indicates the importance of the additive and non-additive effects of genes in controlling these traits. Also, the significance of the ratio of general to private combinability for all traits except the number of days to flowering and the number of days to ripening indicated the significant importance of additive effects compared to non-additive effects in controlling these traits. Also, based on this research, Safar × Dalgan can be used in the breeding program due to the positive and significant general compatibility of their parents in terms of seed yield and the negative general compatibility of parents in terms of the number of days to maturity in order to achieve high-yielding and early-maturing genotypes in tropical regions. The range of heterosis compared to the superior parent for seed yield ranged from -33.8 to 30.3 in this study. The average degree of dominance for all traits other than the trait number of days to flowering (relative dominance) indicated the presence of superdominance in controlling these traits, so the phenomenon of heterosis can be used to increase and improve these traits. The order of dominance was significant for all desired traits except the number of seeds per pod and the weight of 1000 seeds. Conclusion: The estimation of general compatibility showed that the parents of Safar, Zafar and Dalgan were the best general combinations to increase seed yield. The two heterotic combinations RGS.003 × Dalgan and Roshana × Zafar can also be the most productive due to their positive and significant private combinability in terms of yield and also the negative private combinability in terms of the number of days to maturity. Single cross rapeseed hybrids should be considered for offering to farmers. Finally, due to the highest grain yield related to Dalgan×Saffar crossbreeding equal to 3754 kg per hectare (average table is not given), it is suggested that this hybrid be directly included in breeding programs and tested for stability.
Findings: The results of simple variance analysis of traits showed that the difference between genotypes for all traits was significant at the 1% probability level. which indicated the existence of diversity among genotypes. The first Griffing method (complete dialle) as well as Heyman's numerical method were used to analyze diallele. The results of the diallel analysis indicated the significance of the average general and private combinability and mutual effects for all investigated traits, which indicates the importance of the additive and non-additive effects of genes in controlling these traits. Also, the significance of the ratio of general to private combinability for all traits except the number of days to flowering and the number of days to ripening indicated the significant importance of additive effects compared to non-additive effects in controlling these traits. Also, based on this research, Safar × Dalgan can be used in the breeding program due to the positive and significant general compatibility of their parents in terms of seed yield and the negative general compatibility of parents in terms of the number of days to maturity in order to achieve high-yielding and early-maturing genotypes in tropical regions. The range of heterosis compared to the superior parent for seed yield ranged from -33.8 to 30.3 in this study. The average degree of dominance for all traits other than the trait number of days to flowering (relative dominance) indicated the presence of superdominance in controlling these traits, so the phenomenon of heterosis can be used to increase and improve these traits. The order of dominance was significant for all desired traits except the number of seeds per pod and the weight of 1000 seeds. Conclusion: The estimation of general compatibility showed that the parents of Safar, Zafar and Dalgan were the best general combinations to increase seed yield. The two heterotic combinations RGS.003 × Dalgan and Roshana × Zafar can also be the most productive due to their positive and significant private combinability in terms of yield and also the negative private combinability in terms of the number of days to maturity. Single cross rapeseed hybrids should be considered for offering to farmers. Finally, due to the highest grain yield related to Dalgan×Saffar crossbreeding equal to 3754 kg per hectare (average table is not given), it is suggested that this hybrid be directly included in breeding programs and tested for stability.
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