Photosynthetic Performance Indicators of Variegated Alfalfa Depending on the Sowing Method in the Forest Steppe of the Middle Volga Region

Abstract

Undercrop cultivation of alfalfa is economically justified, since in the year of sowing, cover crops give a full harvest, and also one mowing of alfalfa for hay is carried out, moreover the special preparation of the soil for grasses is not re-quired. In the conditions of the Middle Volga region, the experiment was laid on leached chernozem in 2017 - 2019, where they studied the sowing of variegated alfalfa under the crops of spring wheat, barley, oats, harvested for grain and an-nual grasses - for green fodder, and studied the options for coverless sowing, where the weeds were mowed twice and the herbicide Pivot was applied at the beginning of alfalfa branching. The total biological yield is determined by the leaf area and its photosynthetic activity. Therefore, the purpose of the research is to determine the indicators of alfalfa photosynthetic activity for an objective as-sessment of the influence of cover crops on their forage productivity. It has been established that a more intensive increase in the assimilation surface of alfalfa in the first year of life to 31.6 and 30.6 thousand m2 /ha occurs on coverless sowing with the application of the Pivot herbicide and two-fold mowing of weeds. The dry matter yield was 2.1 and 2.0 t/ha, respectively. A decrease in the illumination of alfalfa plants sown under crops, where the leaf area did not exceed 13.0...15.3 thousand ? m2 / ha, slowed down the photosynthesis processes. Moreover, a more intensive growth of its photosynthetic organs was noted under the crop of barley, the cereal-legume mixture reduced the leaf area by 0.5 thousand m2 /ha, the pho-tosynthetic potential was 898...1051 thousand m2 day/ha.