Studies of the photosynthetic activity of perennial grass mixtures allow for describing the peculiarities of the formation of perennial grass species forage productivity in the dry steppe zone. The study aimed to evaluate the cumulative effect of perennial cereal and legume grasses as part of complex grass mixtures on photosynthetic activity, productivity, and nutritional value of mowing and grazing phytocenoses. Adapting multicomponent grass created from various species of perennial grasses to the continental climate of the steppe zone of Northern Kazakhstan commenced, capable of resisting biotic and abiotic stresses due to biological characteristics and positively influencing other species in the phytocenoses. The study determined photosynthetic activity, the yield of green and dry masses, dry matter content, crude protein, metabolizable energy of natural pasture, single-species sowing of awnless brome, and multicomponent grass mixtures. The communal herbage obtained as a result of the study contained a large amount of crude protein (20.6%–24.7%), crude fat (2.0%–4.2%), crude fiber (18.0%–22.7%), crude ash (7.1%–7.7%), and nitrogen-free extractive substances (35.0%–44.1%). The results further enunciated that the perennial grass herbage in question had an average photosynthetic potential of 1,450,330 m²×day ha-¹ in single-species awnless brome crops, while in grass mixtures the said potential was higher, ranging from 1,510,250 to 1,815,250 m²×day ha-¹. The authors concluded that it was necessary to create mowing and grazing fields composed of productive and stable perennial grass mixtures on degraded pasture lands to increase available forage for farm animals and improve the system’s resistance to adverse conditions.

Keywords: Perennial grasses and legumes, grass mixtures, pastures, hayfields, photosynthesis, green and dry yield, nutritional value, chemical composition

Key findings: Multicomponent grass-and-legume concoctions of the first and second year of life ensure the formation of higher yields, the nutritional value of forage, and photosynthetic potential (PP) compared with single-species crops. Multicomponent grass mixtures with the participation of drought-, salt-, and frost-hardy crops (alfalfa, sainfoin, brome, wheatgrass) have high ecological adaptivity, grow and overwinter well, and have high viability, which allows for the successful use in improving old degraded hayfields and pastures.