283 Bulletin USAMV-CN, 63/2007 (-) RESEARCH CONCERNING THE WEEDING LEVEL OF AUTUMN WHEAT-POTATO-MAIZE AND SOYBEAN CROP ROTATION, IN CLUJ COUNTY Bogdan Ileana, Gu P., Rusu T., Paula Moraru, Pop A. University of Agricultural Sciences and Veterinary Medicine, Faculty of Agriculture 3-5, Manastur Street, 400372, Cluj-Napoca, Romania, ileana2105@yahoo.com Key words: Cluj County, crop rotation, weed degree, weed composition Abstract: The paper presents the results of researches that were done during 2003-2005 period, on the experimental field of Agrotehnics from Cluj-Napoca, whose objective was to establish the weed characteristics from the crop rotation: autumn wheat - potato – maize – soybean and its fluctuation by the crop rotation. The weed level from the rotation is followed in terms of flourish spectrum composition aspect, species frequencies, species ponderosity and the achieved covered degree. It is appreciated the crop rotation of its contribution to rationalize the technologies of these four crops through the crop rotation, and also to assure the premise of durable capitalization and the zone resource and the elimination of the risk of the agroecological possible derangements in the situation of omission of the rational weed control importance INTRODUCTION Weeds are natural restrictive factors for agricultural crops in all eco climatic conditions and as much in the case of degraded fields at which the cultivated plants habitat may be more severe affected. The hilly area around Cluj is an agricultural area in which we must take action both for the conservation and breeding of the soil fertility, erosion prevention, and for efficacy control of the very rich weed spectrum. To each agricultural area are characteristic certain species of weeds, specific weeding being influenced by climatic, soil conditions and technologies used at preemergent and current crops. It is unanimous recognized the fact that to choose the most efficient control method for the weeds and especially, to choose correctly the herbicides which must be used in several crops, so that none of risk factors interfere regarding the ecological balance of the agroeco system, is absolutely necessary to establish the infestation level with weeds for each plot and to know the species of weeds which achieve this infestation under the ecological aspect and especially under their sensibility to several control methods. The tam of the Agrotechnics department in Cluj-Napoca has among its research programs goals the rationalization of the crop technologies for the main agricultural crops in the centre of Transylvania, rationalization which includes the improving of those technological links which are important to assure the durability of the agricultural environment: crop rotations specific to the area, rationalized soil tillage systems, control strategies for the weeds adapted to the place and its characteristics. So, knowing the specificity of each crop weeding from an efficient crop rotation in the area it is important under the aspect of agro ecological information and also of the cultivation technologies safety to ensure the economical efficiency and natural resources durability.