TY JOUR TI PHOTOSYNTHETIC ACTIVITY OF MIXED SEEDING OF GRASSES, THEIR PRODUCTIVITY AND INFLUENCE ON FERTILITY OF SODDY-PODZOLYC SOIL IN THE CONDITIONS OF THE UPPER VOLGA KW perennial grasses KW mixed crops KW leaf area KW photosynthetic potential KW leaf surface index KW weight of roots and aerial parts KW productivity KW fertility JO Adaptive Fodder Production AU Esedullaev, S.T. PY 2021 IS 2021 PB Federal Williams Research Center of Forage Production and Agroecology