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 to<br />be soil born pathogens, Phytophthora drechsleri and Pythium ultimum. In order to<br />evaluate the efficiency of a field-laboratory selection method to improve resistance<br />of safflower against soil born pathogens, Ph. drechsleri and P. ultimum, a two-year<br />investigation was conducted. The results showed that selection is an efficient<br />method for increasing resistance to seed and seedling death caused by<br />Phytophthora and Pythium in safflower. Selection could have improved<br />germination percent, days to 50% germination, percent of undamaged seedlings<br />and index of disease percent when genotypes were faced with both pathogens.<br />Regarding kind of damages, Pythium caused more seed rot and Phytophthora<br />induced more seedling death. It could be concluded that selection for resistance to<br />Pythium, could also increase resistance to Phytophthora. Safflower was, however,<br />more susceptible to Phytophthora than Pythium. Also, genes for resistance to seed<br />rot are different than those controlling resistance to seedling death, so preemergence<br />damping off should be considered a completely independent trait from<br />post-emergence damping off in safflower. It was concluded that used fieldlaboratory<br />selection method could well improve resistance of safflower to<br />pathogens Phytophthora and Pythium and hence seed yield.