Wheat and barley resistance to head smut

. In the conditions of the central part of the Krasnoyarsk forest-steppe, the resistance of 114 varieties and lines of spring common wheat and spring barley to regional populations of loose smut U.tritici and U.nuda was studied for 3 years. The studied samples in the phase of the beginning of flowering were infected by a syringe with a 0.005% suspension of the pathogen chlamydospores. Pathogen damage was recorded according to the VIR scale after the manifestation of visible symptoms of the disease. The sources of resistance to the disease were identified varieties and lines of barley and wheat, the defeat of which by loose smut did not exceed 5%. These are 41 samples of wheat: varieties


Introduction
The causative agents of such harmful diseases as wheat loose smut and barley loose smut are basidiomycetes Ustilago tritici (Pers.)Jens and Ustilago nuda (Jens.)Kell.and Swing, respectively.These diseases belong to a subgroup of typical seminal infections [1][2][3].Grasses are infected with chlamydospores during flowering, resulting in the introduction of the fungus into the developing embryo.The following year, when the grain germinates, the mycelium of the pathogen also begins to develop.The course of the infectious process is highly dependent on weather conditions.The most favorable factors for the development of micromycetes r.Ustilago is a high relative humidity and a temperature of 18-24°C.An additional condition for the spread of the pathogen during the season is air currents, with which spores are transferred from the affected organs of the host to healthy ones.In diseased plants, complete or partial destruction of the ear is observed, instead of which a spore mass of olive-black color is formed.In addition to such a clear crop shortage, hidden losses are added due to a decrease in productivity parameters in plants without visible symptoms of damage [4][5][6][7].
To prevent the development of the described diseases on grain crops, various methods are used: seed dressing, compliance with agrotechnical recommendations, timely variety change and testing of crops, etc. [8].However, despite all the protective measures taken, the damage from loose smut is observed in all regions of the cultivation of barley and wheat.To reduce crop losses, it is necessary to constantly search for sources of resistance to the disease and create resistant varieties.Why is the annual assessment of the resistance of samples to the defeat of U. tritici and U. nuda relevant [9].
The aim of the research was to assess the resistance of samples of wheat and barley from the nurseries of the KrasNIISH to regional populations of loose smut pathogens.

Materials and methods
The studies were carried out in 2020-2022, in the conditions of the central part of the Krasnoyarsk forest-steppe in the fields of the pilot production "Minino".The studied objects were varieties and breeding lines of spring soft wheat and spring barley from the nurseries of competitive variety testing (CVT) and the collection nursery of the Krasnoyarsk Research Institute of Agriculture, both local and foreign selection.
An artificial infectious background for loose smut was created using the syringe method.Samples were inoculated in the phase of the beginning of flowering of the studied crops with a suspension of freshly harvested chlamydospores of a mixture of pathogen populations of 0.005% concentration.After ripening, the infected ears were harvested and threshed in the usual way.The next year, to account for infection, inoculated seeds were sown in an infectious nursery in an amount of at least 100-150 grains of each sample (Figure 1).
After the development of visible symptoms of the disease, the damage by the pathogen was recorded.The classification of resistance to loose smut was determined according to the VIR scale [10]:  0 -high resistance, no damage. I -practical stability, damage does not exceed 5%. II -weak susceptibility, damage does not exceed 25%. III -medium susceptibility, damage does not exceed 50%. IV -strong susceptibility, defeat more than 50%.The final characteristic for resistance to loose smut was given to the samples according to the maximum lesion obtained over 3 years of study.Varieties and lines in which the pathogen damage did not exceed 5% were classified as sources of resistance and recommended for inclusion in further stages of the breeding process.

Results and Discussion
Analysis of samples of wheat and barley from the infectious nursery for head smut revealed both highly susceptible and highly resistant lines and varieties (Tables 1-3).
Thus, out of 38 accessions of wheat from the VIR collection, 16 showed high resistance; 15 -weak susceptibility; cultivars Stepnaya 53, Lutetia and Mandarynapractical resistance; Khazine, LT-11, Aktobe 14 -average susceptibility to regional races of the U. tritici population.The defeat of loose smut of wheat Niva Priirtyshya was 58.3%, which corresponds to the indicator of a highly susceptible variety (Table 1).In the nursery of the competitive variety testing of spring soft wheat, 13 accessions were isolated, which were not at all affected by the pathogen.The same number of samples showed an average susceptibility, and in 8 the percentage of damage did not exceed 5% (Table 2).Variety Kuraginskaya 2 and line K-734-8 stood out as moderately susceptible, and K-727-8 and KP-8 as highly susceptible.
A three-year study of damage to specimens by loose smut makes it possible to classify all practically resistant and highly resistant specimens as sources of resistance.However, to include breeding lines in the next stages of the breeding process, it is necessary to study their full range of economically valuable traits.

Fig. 1 .
Fig. 1.Infectious nursery of spring barley and spring soft wheat for loose smut.

Table 1 .
Resistance of samples of the collection nursery of spring soft wheat to loose smut.

Table 2 .
Resistance of samples of the nursery of competitive variety testing of spring soft wheat to loose smut.Resistance of samples of the nursery of the competitive variety testing of spring barley to loose smut.