Meeting the Challenge of Yellow Rust in Cereal Crops - ICARDA

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Study of diverse winter wheat germplasm for resistance to
yellow rust in severe epidemics in Uzbekistan
S. Alikulov, 1 A. Amanov, 1 Z. Ziyaev, 1 Z. Khalikulov 2 and R.C. Sharma 2
1. Uzbek Research Institute of Plant Industry, Tashkent, Uzbekistan; 2. ICARDA,
Central Asia and the Caucasus Regional Programme, Tashkent, Uzbekistan
Yellow rust, caused by Puccinia striiformis f.sp. tritici, is a serious disease
constraint on successful wheat (Triticum aestivum L.) cultivation in Central
Asia. In the past 20 years, Uzbekistan has often experienced more severe
epidemics of yellow rust than other central Asian countries. This study was
conducted to examine sources of resistance among diverse winter wheat
germplasm in severe epidemics of yellow rust that swept through a large part
Uzbekistan during February to May 2009. Continual precipitation during late
winter continuing through the spring months created highly favourable
conditions for development of a yellow rust epiphytotic; this also provided an
opportunity to identify sources of resistance to this disease. Several sets of
wheat experiments, including advanced yield trials, screening nurseries and
segregating materials, were evaluated under severe yellow rust epidemic
conditions, as confirmed by the >80% disease severity on a number of
commercial cultivars. The results show that among more than 20 cultivars
under cultivation in Uzbekistan, most of them are susceptible to yellow rust.
The major cultivars showing susceptibility to yellow rust include Kroshka,
Polovchanka, Tanya, Kupava, Umanka and Pamyat, which together occupied
40% of the irrigated wheat area in Uzbekistan in 2009. The local cvs Saidaziz
and Zamin 1 were moderately resistant. Among 195 genotypes tested in the
12th IWWYT-Irrigated, 11th IWWYT-Semi-Arid, 16th FAWWON-Irrigated and
16th FAWWON-Semi-Arid nurseries of winter and facultative wheat,
approximately 40% of the genotypes showed a high level of resistance to
yellow rust in Uzbekistan. Many yellow rust-resistant genotypes showed
resistance to leaf rust as well. Based on agronomic performance of the yellow
and leaf rusts-resistant material, a number of advanced breeding lines have
been selected either to further evaluate their suitability as candidate cultivars
or to use them in hybridization programmes. This yellow rust-resistant winter
wheat germplasm could also be valuable for yellow rust research in other
countries in Central Asia.