Improving field establishment of safflower in soils infected by Phytophthora drechsleri and Pythium ultimum

Abstract

One of the major field constraints to seed production in safflower has proven tobe soil born pathogens, Phytophthora drechsleri and Pythium ultimum. In order toevaluate the efficiency of a field-laboratory selection method to improve resistanceof safflower against soil born pathogens, Ph. drechsleri and P. ultimum, a two-yearinvestigation was conducted. The results showed that selection is an efficientmethod for increasing resistance to seed and seedling death caused byPhytophthora and Pythium in safflower. Selection could have improvedgermination percent, days to 50% germination, percent of undamaged seedlingsand index of disease percent when genotypes were faced with both pathogens.Regarding kind of damages, Pythium caused more seed rot and Phytophthorainduced more seedling death. It could be concluded that selection for resistance toPythium, could also increase resistance to Phytophthora. Safflower was, however,more susceptible to Phytophthora than Pythium. Also, genes for resistance to seedrot are different than those controlling resistance to seedling death, so preemergencedamping off should be considered a completely independent trait frompost-emergence damping off in safflower. It was concluded that used fieldlaboratoryselection method could well improve resistance of safflower topathogens Phytophthora and Pythium and hence seed yield.