Document Type: Research Paper
College of Plant production, Gorgan University of Agricultural Sciences and Natural Resources, P.O. Box 386, Gorgan, Iran.
One of the major field constraints to seed production in safflower has proven to
be soil born pathogens, Phytophthora drechsleri and Pythium ultimum. In order to
evaluate the efficiency of a field-laboratory selection method to improve resistance
of safflower against soil born pathogens, Ph. drechsleri and P. ultimum, a two-year
investigation was conducted. The results showed that selection is an efficient
method for increasing resistance to seed and seedling death caused by
Phytophthora and Pythium in safflower. Selection could have improved
germination percent, days to 50% germination, percent of undamaged seedlings
and index of disease percent when genotypes were faced with both pathogens.
Regarding kind of damages, Pythium caused more seed rot and Phytophthora
induced more seedling death. It could be concluded that selection for resistance to
Pythium, could also increase resistance to Phytophthora. Safflower was, however,
more susceptible to Phytophthora than Pythium. Also, genes for resistance to seed
rot are different than those controlling resistance to seedling death, so preemergence
damping off should be considered a completely independent trait from
post-emergence damping off in safflower. It was concluded that used fieldlaboratory
selection method could well improve resistance of safflower to
pathogens Phytophthora and Pythium and hence seed yield.