Evaluation of slow rusting parameters in thirty-seven promising wheat lines to yellow rust

Yellow rust caused by Puccinia striiformis f. sp. tritici is an important disease that threatens wheat production in cool environments. Host resistance is the most economical way to manage wheat stripe rust; and slow rusting resistance, a kind of quantitative resistance, has been reported to last for a long time. This study was designed to evaluate slow rusting parameters including final rust severity (FRS), apparent infection rate (r), coefficient of infection (CI) and relative area under disease progress curve (rAUDPC) during 2010-2011cropping year. A set of thirty-seven promising wheat genotypes along with susceptible control was used in this investigation. The study was conducted in field plots at Ardabil Agricultural Research Station (Iran) under natural infection conditions with twice artificial inoculation. Artificial inoculation was carried out by yellow rust inoculum having virulent genes against Yr2, Yr6, Yr7, Yr9, Yr22, Yr23, Yr24, Yr25, Yr26, Yr27, YrA, and YrSU. Assessment of slow rusting parameters showed that lines SD-84-10, SD-84-12, SS-83-6, SS-85-6, SS-85-10, SS-85-11, MS-85-17, MS-87-5, MS-87-6 along with cultivars Argh, Bam and susceptible check had the highest values of r, FRS, CI and rAUDPC, therefore were selected as moderately susceptible or susceptible lines. The lines S-84-14, S-85-19, S-83-3, S-83-4, S-87-20 and DH-86-8 had low values of slow rusting parameters and MR to MS infection type, consequently these lines with low level of different parameters most probably have better level of slow rusting resistance. The remaining lines had different level of slow rusting resistance varying from moderate to low level according to values of FRS, CI, and rAUDPC.