Васильев 1Университет Белграда, Республика Сербия, e-mail: savovuck@agrif.bg.ac.rs 2Институт растениеводства в Нови Саде, Республика Сербия В течение 3 лет (2007-2010 гг.) было организовано изучение воздействия двух сортов (K-17 и UNA) клевера красного с целью установления оптимального срока сева для устойчивого управления конкурентоспособностью по борьбе с сорняками. <...> Сорт клевера K-17 более эффективен в сравнении с UNA. <...> В ботаническом составе травостоя клевера этого сорта содержалось в среднем около 99% сорных растений, а в травостое клевера UNA – 93%. <...> EFFECT OF DIFFERENT SOWING TIME ON RED CLOVER DRY MATTER YIELD AND WEED CONTENT A. Simić1, S. Vučković1, S. Prodanović1, S. Vasiljević2, V. Maklenović1, B. Vasiljev1 1University of Belgrade, Republic of Serbia 2Institute of Field and Vegetable Crops, Novi Sad, Republic of Serbia A three-years study (2007-2010) was organized to examine the effect of two red clover (RC) varieties (K-17 and UNA) with the aim to find optimal time of establishment for high production and sustainable management with competitiveness against weeds. <...> Modern trends in Europe promote clover crops to produce more farm grown proteins and to decrease the use of mineral fertilizers. <...> The trial was established by the method of randomized complete block design of plots (3 х 4 m) with 3 replications, sown in the autumn of 2007 and spring of 2008 at Institute for Animal Husbandry, Belgrade. <...> The highest total dry matter yield was obtained by autumn sowing of variety K-17 (15,7 t/ha). <...> The low development rhythm of RC with spring sowing in the first year of vegetation (dry spring) permitted the installation of weeds, the crops were harvested twice without the assessment of production. <...> Weeds content decreased in the botanical composition at the first cut by the production years, while at the second cut their ratios decreased by less than 5% in the both varieties. <...> Red clover varieties gave the highest forage yield in the second production year and they had good regrowth and reached high yield in the second cuts during seasons 2008-2009. <...> It <...>