The effect of green manures on weediness of sugar beet

Thіs study aimed to investigate the effect of aplying post-harvest green manure on weediness of sugar beet crop rotation. Post-harvest green manure were grown under the conditions of the Scientific Research and Production Complex (NNVK) of Sumy National Agrarian University (Ukraine, Sumy oblast, Sumy region) after harvesting winter wheat from August to October 2000‒2004. After the plowing of it in the following 2001‒2006, a hybrid of sugar beet Umansky FM-97 was grown according to the technologies recommended for the local area. Potential weediness was determined by washing seeds from the soil on sieves at the beginning of the growing season and before harvesting sugar beets, and the actual weediness ‒ by quantitative-weight method before plowing the green manure and into the main stages of growth and development of sugar beets. The experimental plot had the least weediness under oilseed radish and the largest weediness under buckwheat as green manure. During growing seasons the radish oilseed formed good biomass and the number of weeds under its cover was noticeably reduced to 4.8 pieces/m2 and their mass ‒ to 21.8 g/m2. The findings obtained from statistic program showed the strongest correlation between the above-ground mass of radish and the number of weeds ‒ r = -0.55 and their weight ‒ r = -0.56. In the spring the amount of weed seeds under radish cover in the 0‒30 cm soil layer was reduced to 11.4 %, to 101 million units/ha, compared to the control without green manure. The impact factor of the effect of the radish biomass on the potential weediness was highest in all soil layers - within 70‒90 %. The biomass of radish decreased significantly the number of weeds in the sugar beet crops – by 39 to 19.2 pc/m2, and their weight ‒ by 23 % to 354 g/m2, compared to the control without green manure. Green radish oilseed mass had the greatest impact on reducing quantity of weeds – 67 % and their mass – 80 %. Radish cover provided the most significant reduction the potential weediness before harvesting sugar beets ‒ by 12 % in the 0-30 cm soil layer, compared to the control without green manure, where the amount of weed seeds was at 112 million units/ha. The inverse correlation of the radish biomass and the potential weediness at the time of sugar beet harvest was the closest ‒ r = -0.9.