Powdery mildew tolerance of 40 sainfolin (Onobrychis sativa) populations in Esfahan province

In this research، powdery mildew tolerance of 40 sainfoin populations was evaluated in the filed condition. The populations were cultivated in a randomized block design with three replications in Shahid Hamzeh station of Esfahan province in 2009. Regarding of observation، Initial disease symptoms occurred mainly in the third cut which is in September. Symptoms included presence of yellowish necrotic area around blocks borders with further whitening of all leaves of the affected plants. Field collected samples of populations were evaluated in the laboratory and the fungus Leveillula taurica was isolated and identified in Esfahan province.. Evaluation of plant samples were carried out randomly for 27 branches of 9 bushes in every block. Evaluation of the populations was carried out on the base of disease severity index (DSI): 1 (without disease symptoms as resistant populations، 2(DSI 0f 1-25 as tolerant populations، 3(DSI 0f 26-50 as semi susceptible populations، 4(severity index 0f over 50 as susceptible populations. Analysis of variance showed significance differences (P<1%) between populations، disease severity index، percent of infection and the yield. Mean comparison of Duncan test showed Polycross and Azarbayejan-Oshnavieh populations as tolerant population with disease severity index of 2. 5 and 2. 8 and three populations including: Gorajan-Ardabil، Kohleran- Ardabil and Khoramabad as highly susceptible with disease severity index of 4 and 3. 5. The remained populations were assessed as moderately susceptible with disease severity index as 3. Result of this research showed that in the first year of cultivation، infection level of powdery mildew and disease severity index of the population were low but increased in the second and third years.