Features of morphological reactions of collection samples of spring barley to an increase in crop density

The research was conducted in 2022–2024 in the Kirov region in order to identify a new source material for breeding based on the study of genotypic features of collectible samples of spring barley, manifested in the reaction of morphological features to changes in crop density. The object of study was 31 samples of spring barley (Hordeum vulgare L.). The scheme of the experiments: crop density 5.0 million pcs./ha (control) and 7.0 million pcs./ha. The observations and accounting of the harvest were carried out in accordance with the Methodological guidelines for the study and preservation of the world collection of barley and oats. The registered area of the plot is 1.35 m², the repeat rate is twofold. The soil is sod-podzolic medium loamy. Weather conditions ranged from arid (HTC = 0.73) in 2024 to excessive moisture (HTC = 2.03) in 2022. On average, over the years of study, 411 pcs./m² (93 %) remained in the control for harvesting, 585 pcs./m² (92 %) in the experiment. Meteorological conditions affected the change in yield, ear length, quantities grain of the ear, productivity of the ear and the plant (contribution share 43.6–69.3 %), the density of the crop affected the number of plants preserved for harvesting and productive stand (16.8–27.9 %). On average, over the years and in the sample, with an increase in crop density, there was a significant decrease in general (by 0.16) and productive (0.11) bushiness, ear length (0.2 cm), number of spikelets (0.8 pcs.) and grains (0.7 pcs.), grain weight per plant (0.06 g). Selected samples Salair, Radegast, L-223/15 and L-209/11 which significantly increased yields by 165…243 g/m², grain weight from the plant by 0.28…0.68 g, and thousand-kernel weight by 2.4…4.0 g with an increase in crop density.