Abstract
The aim of the research is to investigate the comparative productivity of mono-specific and binary plantings of Poterium polygamum and Festulolium in association with perennial leguminous grasses during their first year of growth. Field experiments were conducted from 2022 to 2024 in the forest-steppe zone of the Central Caucasus (Vladikavkaz) on medium-depth heavy clay bleached chernozems overlaid with pebble beds. The area falls within the III agro-climatic zone, characterized as moderately warm with unstable moisture conditions. The objects of the study included: Poterium polygamum (‘Slava' cultivar), Festulolium (‘Vik-90’ cultivar), Galega orientalis (‘Bimbolat’ cultivar), Medicago varia (‘Bagira’ cultivar), Onobrychis arenaria (North Caucasian two-cut cultivar), and Trifolium pratense (‘Daryal’ cultivar). A narrow-row sowing method was employed in the experiment. Seeding rates were established at 2 million viable seeds/ha for Poterium polygamum, 10 million seeds/ha for Festulolium, and 4 million viable seeds/ha for perennial leguminous grasses. In the mixtures, the seeding rate of each component was reduced by 50 %. The research indicated that mixed sowings exhibited lower seedling emergence and plant survival rates compared to monocultures. Notably, the decline in the survival of leguminous grasses in mixtures with Poterium polygamum was particularly pronounced, with survival rates dropping by 11.9 to 18.5 % compared to mono-specific plantings. However, despite the reduced survival of legumes by the end of the first year of growth, their productivity in mixed sowings was found to be higher. Leguminous grasses in combination with Poterium polygamum achieved green mass yields ranging from 21.1 to 21.8 t/ha; the collection of feed units was between 3.87 to 4.12 thousand/ha, and the accumulation of dry matter in both aerial and subterranean biomass ranged from 7.16 to 7.85 t/ha. The yield of digestible protein amounted from 747 to 840 kg/ha, with metabolizable energy output ranging from 63.14 to 67.41 GJ/ha. Mixtures containing Festulolium also surpassed monocultures in all productivity parameters. The maximum yield was observed in the Festulolium and Galega orientalis mixture, which achieved a green mass yield of 17.5 t/ha, along with a high nutritional value of 4.62 thousand/ha feed units and 752 kg/ha of digestible protein.