Effect of yellow rust on yield components of barley cultivars with race-specific and slow rusting resistance to yellow rust

Abstract

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 race-specific 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, race-specific 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.