ADAPTIVE POTENTIAL AND PRODUCTIVITY OF THE AWNLESS BROME GRASS IN MIXED AGROPHYTOCENOSES ON CHESTNUT SOILS

Abstract

Studies conducted in the dry-steppe zone of the Stavropol region with its high heat supply and low water availability have shown that legume-cereal grass mixtures consisting of three components (awnless brome grass, changeable alfalfa and yellow sweet clover) are much more productive in collecting the dry matter of the brome grass single-species crops, are better eaten by all animal types and are harvested for food with less losses. At the optimum seeding rate for each component of the grass mixture (50% from the full seeding rate), the amplitude of air temperature fluctuations in the agrophytocenosis during the day decreased. The legume-cereal grass mixtures, in comparison with single-species crops of the brome grass, differed in the plant stand, the power of the shoots development, which contributed to a significant increase in the productivity of seeded herbs. In the agrophytocenosis of various optical densities, competitive relations are an important biotic factor for both the suppression and the intensification of growth processes in legume-cereal grass mixture. Correlation analysis for relationships of seeding rates, type of culture and plant height shown that they are reliable, substantially curvilinear and characterized by the correlation relation for the awnless brome grass (η= 0,62), changeable alfalfa (η = 0,87) and yellow sweet clover (η = 0,57). The closeness of the connection between the seeding rate and the yield of the grass mixture herbage changed from quite low at the beginning of growth (η = 0,38-0,42) to rather high at the moment of reaching the grass stand of hay cutting ripeness (η = 0,78-0,85). Optically dense agrophytocenosis at optimum seeding rates of each component (50% of the full seeding rate) in the conditions of dry-steppe zone turned out to be more stable and reliable as a photosynthetic optical and biological system than single-species crops, and provided a total yield over three life years of 1281 kg/hectare of crude protein, 12,3 tons/hectare of dry matter and 103,6 GJ/hectare of exchange energy. The crop structure of such an agrophytocenosis fully met the requirements of zoo technical norms in animal feeding.