ارزيابي مقاومت نسبي تعدادي از ژنوتيپ هاي گلرنگ (Carthamus tinctorius L) به قارچ (Phytophthora drechsleri) عامل بيماري بوته ميري گلرنگ در استان اصفهان

Evaluation of Some Genotypes of Safflower (Carthamus tinctorius L.) for Tolerance to Root Rot Disease {Phytophthora drechsleri) in Isfahan Province

Root rot is an important soil-born disease of safflower in Isfahan province. The objective of this study was to evaluate some genotypes of safflower for tolerance to root rot. In this study six isolates of P. drechsleri used as causal agents in different localities of Isfahan province and their pathogenicities were tested in greenhouse. Tolerance of 21 genotypes of safflower were evaluated in laboratory and greenhouse to root rot disease in a factorial design based on randomized complete blocks with three replications. Safflower seeds germinated in the lab. for 48 hr. and then were artificially inoculated with zoospore suspension of P. drechsleri (105 zoospore/ml) for 3 hr. They were moved to glass pots filled with mixed sterile perlit and sand. One week after inoculation, length of lesions on root were measured. Safflower seedlings at 4 leaf stage were inoculated in greenhouse with a 1 cm diameter media disk of P. drechsleri. Then, the number of plants died were counted both when susceptible genotypes completely died and after 45 days. Data were analyzed and the significant differences were observed among genotypes in laboratory and greenhouse tests. A negative correlation between lesion length due to root and plant survival was observed (r = -0.76). The most resistance genotype with mean lesion length of 10.01 mm and mean damping off of 50.6% and the most susceptible genotype with mean lesion length of 15.51 mm and mean damping off of 79.2% and 82% after 5 and 45 days were found to be pure line KW12 and Koosseh, respectively.