Determination of genetic parameters of resistance to cercospora leaf spot in sugar beet

A diallel cross analysis was used to estimate general and specific combining ability of resistance to cercospora leaf spot in six lines of sugarbeet. The parents and 15 hybrids (F1) were evaluated in a randomized complete block design with four replications at Safiabad Agricultural Research Center. A mixture of cercospora agent was grown in the laboratory in V8A media. The infection was created in "Khusestan", in 2001 by three times sprays. Genetic parameters were estimated by Griffing, Jinks and Hyman methods. The results showed that both additive and non-additive genetic effects contributed to the expression of this trait, but the portion of additive and heritable effects of genes are more important. Therefore, there is a relative dominance in genetic control of leaf spot infection. Broad sense and narrow sense heritability were 99% and 79%, respectively. Because of a high amount of additive gene effects and rather high narrow sense heritability, the selection efficiency would be successful in cercocpora leaf spot resistance. The results also indicated that the resistance to this infection could be controlled by recessive genes. Parents 7617 and 261 with less infection intensities have general combining abilities in resistance, so they are suitable parents for resistance increase and can be used in breeding program.