Study of emergence and seedling survival of safflower genotypes in soil infested with pathogen Pythium ultimum

This study was performed to answer the questions about the possibility of finding genetic sources of resistance to damping off in safflower. To do this, response of 15 genotypes of safflower to P. ultimum was evaluated in research farm of Agricultural science and Natural resources university of Gorgan between 2009-2010. The experiment was done as a split plot arranged in a randomized complete block design with two levels of sterility (sterile and non-sterile) as main plot, and 15 safflower genotypes as sub plot. For inoculation, pieces of fungi in sterile sand along with zoospores suspension at concentration of 105 per ml were used. The results showed that 10 genotypes had resistance more than 90%. Among them resistance of higher than 98% were observed in two genotypes, viz. LRV-55-255 and 34040. The results obtained revealed that infection caused by P. ultimum was effective on speed of emergence in the field. Genotypes grouping showed that genotypes of the third group (Zaeghan-259 and 34040) were relatively resistant.