Abstract: Mapping and monitoring of weed seeds on agricultural and non-agricultural areas is long lasting praxis in many countries. A study of weed seed bank under various cultures provides opportunities of prediction, which weed species, in what volume and in what time will occur on the field. In such a manner, it is possible to make more efficient end economical plan of measures for their control. During vegetation period 2008-2009, at locality Ratkovo (Vojvodina), studies of the weed seed bank were performed under wheat, sugar beet and clover crops. Plots were nearby, and therefore, the influence of climatic and edaphyic factors was identical. In average, samples were heavy 1.5 kg, they were taken from each plot in four repetitions, diagonally, and separately from depths of 0-10 cm, 10-20 cm and 20-30 cm. After sieving of the samples through copper sieves that differed in diameter followed their drying and determination. The obtained data were statistically processed in the program Statistica 9. Under wheat crop seeds of 15 weed species were separated, of which in the greatest measure dominated seeds of weed species Amaranthus retroflexus, Datura stramonium and Solanum  nigrum, in all of the studied layers. Seeds of A. retroflexus were the most numerous in the top soil layer (314 seeds/m2), as well as seeds of D. stramonium (134 seeds/m2), while seeds of Solanum nigrum proved to be dominant in the deepest studied layer (234 seeds/m2). The greatest total seed quantity of all weed species was extracted from the top layer of 0-10 cm (854 seeds/m2), and the lowest from the deepest layer of 20-30 cm (715 seeds/m2). In sugar beet were found seeds of 12 different weed species, and dominant were seeds of Amaranthus retroflexus in all studied depths of the soil layer.  The highest seed quantity of A. retroflexus was established in soil layer of 10-20 cm (221 seeds/m2), and somewhat lower in the layer of 20-30 cm (209 seeds/m2), and the lowest in the top arable soil layer (187 seeds/m2). Beside this, seeds of Chenopodium album ere dominant in the top soil layer (89 seeds/m2), while seeds of other weed species occurred in significantly lower number. Total number of all separated seeds was the highest in the studied top soil layer (502 seeds/m2). Under clover crop seeds of 12 weed species were also separated, and dominant were seeds of Amaranthus retroflexus in the top layer (144 seeds/m2) and Chenopodium album in the deepest soil layer (95 seeds/m2). The highest number of all seeds was found in the soil layer of 0-10 cm (288 seeds/m2). In all three studied plots, the highest quantity of weed was established in the top layer of 0-10 cm, which is the consequence of inadequate application of cultural practices, above all, lack of deep soil cultivation. Based upon obtained results it is possible to predict occurrence and volume of weed species on the studied plots in the following vegetation season. This enables making of the most efficient plan of cultivation and chemical weed control.

clover; sugar beet; weed seed bank; wheat

Presentation: oral