Multi-locations variability in Pakistan for partial resistance in wheat to <I>Puccinia striiformis</I> West. <I>tritici</I>

Abstract

Expression of plant resistance to diseases varies according to the prevalent pathotypes and climatic conditions at different locations. This variability in partial resistance expression across locations must be known to elucidate the disease status of crop plants in field conditions. We report on the field assessment of partial resistance in wheat to yellow rust, studied at six locations in 37 wheat varieties along with the susceptible control ‘Morocco’ during the yellow rust season of 2007. The high disease severity of ‘Morocco’ revealed considerable disease pressure at all locations. The field resistance of these varieties varied across locations, with no variety being immune at all locations. Based on the average coefficients of infection, representing overall partial resistance expression, the tested varieties were grouped into high (27 varieties), moderate (9 varieties) and low levels of partial resistance (one variety). Stability in the expression of leaf tip necrosis, a marker of partial resistance to yellow rust, was recorded for the varieties Suleman-96 and Sindh-81. Kohsar-93, Bakhtawar-93, Saleem-2000, Fakhre-Sarhad, Tatara, Frontana and Karwan had an overall good level of partial field resistance across the locations. There was also considerable variation in the expression of partial resistance to yellow rust resistance across the locations.