Yellow rust caused by Puccinia striiformis f. sp. tritici is undoubtedly, the most important fungal disease of wheat especially in central and Western Asia that causes significant annual yield losses. Production and use of cultivars with durable resistance is the best controlling method. For this purpose, study on reaction of 19 promising lines to yellow rust was carried out in Ardabil in 2008-2009 cropping year. Assessment of adult plant reaction was conducted under field condition with artificial inoculation. Seedling test was also conducted in greenhouse. Slow rusting resistance at adult plant stage was assessed through the Infection Type (IT), Disease Severity (DS), Relative Area Under Disease Progress Curve (rAUDPC) and Coefficient of Infection (CI). Results of mean comparison of CI and rAUDPC indicated that the lines; C-87-1, C-87-2, C-87-3 and C-87-18 had the highest CI and rAUDPC. The lines C-87-6, C-87-8 and C-87-11 had the susceptible reaction at seedling test and were moderately resistant to moderately susceptible at adult plant stage. Consequently, these lines with low rAUDPC (15.2 to 27.8%) most probably could have slow rusting resistance. The lines C-87-4, C-87-5, C-87-13, C-87-14 and C-87-17 had not any infection or were at low level of infection, thus, they were selected as immune or resistant lines. The rest lines were moderately resistant to moderately susceptible. In this study, correlation analysis of different parameters also showed highly strong relationship of CI with rAUDPC and disease severity (R2 = 0.91 and 0.98, respectively).
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 coefficient 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.
2012) Effect of yellow rust on yield components of barley cultivars with race-specific and slow rusting resistance to yellow rust, Archives Of Phytopathology And Plant Protection, Yellow rust caused by Puccinia striiformis f. sp. hordei is an important disease of barley (Hordeum vulgare L.) in some parts of the world. We compared the effectiveness of different types of resistance in field plots at Ardabil Agricultural Research Station (Iran) during 2010-2011. Yield components along with slow rusting parameters including final rust severity (FRS), apparent infection rate (r), relative area under disease progress curve (rAUDPC) and coefficient of infection (CI) were evaluated for 25 barley cultivars. In all, two barley cultivars with racespecific resistance, 19 cultivars with different levels of slow rusting resistance and four susceptible cultivars were included in two experiments with and without fungicide protection under high disease pressure. Barley cultivars with slow rusting resistance displayed a range of severity responses indicating phenotypic diversity. Mean thousand kernels weight (TKW) losses for susceptible, racespecific and slow rusting genotypes were 31, 3 and 12%, respectively, and mean kernels per spike (KPS) losses for susceptible, race-specific and slow rusting genotypes were 19, 0.2 and 8%, respectively. Correlation coefficient of mean TKW and KPS losses with epidemiological parameters; rAUDPC, r, CI and FRS were highly significant. Slow rusting cultivars with low values of different parameters as well as genotypes with low yield component losses despite moderate disease levels were identified. Such genotypes can be used for breeding barely genotypes with high levels of resistance and negligible yield losses.
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