Slow Rusting Resistance in Iranian Barley Cultivars to Puccinia Striiformis F. Sp. Hordei

Race-specific resistance of barley (Hordeum vulgare L.) to the yellow rust caused by Puccinia striiformis f. sp. hordei, has been reported to be short-lived. Slow rusting resistance has been reported to last for a long time. Twenty Iranian barley cultivars along with resistant and susceptible controls were tested during the 2009-2010 and the 2010-2011 cropping seasons, in field plots at the Ardabil Agricultural Research Station (Iran). The cultivars were tested to identify slow rusting genotypes through epidemiological variables which included: final rust severity (FRS), apparent infection rate (r), relative area under the disease progress curve (rAUDPC), and co- efficient of infection (CI). Moreover, differential sets were evaluated in order to determine effective and ineffective resistance genes to barley yellow rust. Results of the mean comparison of resistance parameters showed that cultivars Makouee, Dasht, Fasih, and Arass had low values of FRS, CI, r and rAUDPC compared with susceptible cultivars. The cultivars Walfajre, Abidar and Sahand which had moderate values of the different parameters, were marked as possessing a moderate level of slow rusting. The rest of the cultivars which had high values of different quantitative parameters, were grouped as having a low level of slow rusting or as susceptible. The correlation coefficient between different parameters of slow rusting was significantly high (r = 0.83-0.98). The virulence profile of the prevalent races revealed that rpsEm1, rpsEm2, rpsHF, Rps4, rpsVa1, rpsVa2, rpsAst were effective, and rps2, Rps1.b were ineffective resistance genes during the two year testing period.