Breeding strategies to decrease stripe rust epidemics in Uzbekistan

Winter wheat production in Uzbekistan is threatened by yellow rust and leaf rust. Both rusts are capable of causing substantial economic losses, but their incidence varies due to different ecological requirements. Yellow rust caused significant yield losses in 2009, 2010, 2013, and in some regions, also in 2014. Several stripe rust resistant lines with high grain yield and desirable agronomic characteristics are being introduced through the International Winter Wheat Improvement Program (IWWIP) and submitted to the State Varietal Testing Commission. A number of new yellow rust resistant varieties were released for specific epidemiological areas of Uzbekistan. These varieties planted on about 200,000 ha are helping to reduce inoculum buildup and spread of rust in farmers’ fields. The objective of the present work was to identify locally adapted yellow rust resistant wheat lines in international nurseries. In 2014 448 winter wheat lines were evaluated for response to the prevailing Pst population under controlled conditions at the Plant Industry Research Institute and field conditions at the Kashkadarya Branch of the Grain and Leguminous Research Institute. Eighty lines were immune and 73 lines showed moderate to high levels of resistance in the field. Following agronomic assessments 55 lines were promoted to advanced multi-site yield trials. A set of selected lines was also distributed to other wheat research institutions within the country. It is expected that this process will lead to the release and deployment of more resistant winter wheat varieties in Uzbekistan.