Characteristics of the efficiency of leaf rust resistance genes of spring wheat in the conditions of the Republic of Tatarstan

Leaf rust is a harmful wheat disease of, which is annually identified in crops in the territory of the Republic of Tatarstan. The disease resistance of the varieties is controlled by Lr genes, of which more than 70 are known at present. Most of them have lost their effectiveness. The purpose of the current work was to study the efficiency of 54 leaf rust resistance genes and their combinations from 2011 to 2022. The object of the study was a set of isogenic lines and test-varieties with identified Lr genes. The damage degree by leaf rust was estimated according to the maximum infestation, identified in the period ‘milk – beginning of a kernel wax ripeness’ under conditions of a natural infectious background. The damage degree by leaf rust was determined as a percentage according to the Peterson scale. There has been established that the genes Lr 19, Lr 38, Lr 47, Lr 49, Lr Ag (i), Lr Ku keep showing high efficiency in the conditions of the Republic of Tatarstan. The efficiency of the gene Lr 19 has increased in pyramids with genes Lr 26, Lr 23, Lr 14a, and Lr Bz. Monogenic resistance to leaf rust has been maintained for 12 years in the sample ‘Pavon derivative’ (PI 603918), carrying the gene Lr 47. In the period of 2019–2022 there was identified a decrease in wheat damage degree by leaf rust. Though under such conditions, a field estimation of breeding material for resistance cannot guarantee the development of wheat varieties immune to this disease.