Plant Protection Institute, BG-2230 Kostinbrod, Bulgaria
NAKOVA, R., 2004, Effect of Xanthium strumarium (L). position on the competition with beans. Bulg. J. Agric. Sci., 10: 299-304
The importance of the position of weed with respect to crop rows in the determination of crop yield - weed density relationship were studied in beans (Phaseolus vulgaris) competing with Xanthium strumarium. Field experiments were carried out during 2002, 2003 at the Plant Protection Institute - Kostinbrod. Both experiments consisted of four replicates of randomized block design. The beans (cv. Dobrudjanka) artificially infected by increasing density (0, 5, 15, 25 plants m-2) of Xanthium strumarium. The positions of the weed were: a) 12.5 cm from nearest crop row b) in the middle of the inter row 25 cm from the crop row. The beans height, fresh weight, dry weight and leaf area were determined during the second trifoliate growth, flowering stage and formation of pods. The effect of the positions of Xanthium strumarium at different densities on yield loss was established. The results of the investigation show that Xanthium strumarium was strong competitior against beans crop at two position (12.5 and 25 cm from the crop row) at studies densities. The position of the weed is key factor in the determination competitive relationship between beans and Xanthium strumarium. The beans height, fresh weight, dry weight and leaf area in studies growth phases and densities were more suppressive in weed arrange nearest from the crop row. Yield loss of beans as function of two Xanthium strumarium positions increase when distance between the crop and weed decrease. Statistical models formulations to predict the decrease beans yield at different weed positions may have practical applications.