Effects of Winter Cereal Cover Crop Mulches on Weeds of Sugar Beet (Beta vulgaris L.)

In order to study of cover crops effects on weed suppression in sugar beet, an experiment was performed in Iranian Research Institute of Plant Protection (Karaj Station), in 2007. The experiment was arranged as completely Randomized Blocks Design with four replications and seven treatments. The treatments were different cover crops (including: Wheat, barley, triticale and rye) that planted between rows. Chemical weed control, weedy and weed free plots were also used as controls. Cover crops were removed by herbicide application (paraquat at 400 g ai ha-1). Phenmedipham+ desmedipham+ethofumesat (Betanal Progress A.M, EC 27.4%) was also used in the four-leaf stage of sugar beet. Results indicated that cover crop treatments suppressed major weeds (Amaranthus retroflexus L. and Chenopodium album L.) and were similar to recommended chemical control (application of herbicide). In addition, total of weed biomass was decreased in barley, rye and control treatments. The minimum biomass of total weeds belonged to the barley+herbicide treatment. Because of synergism effects, barley+herbicide had maximum of the root and sugar yield (29.83 and 4.47 T ha-1, respectively), that was significant with other treatments. In overall, barely cover crop had the most effects on sugar concent. Therefre, sowing winter cover crops between rows for seedbed prepared in autumn (barley, rye, wheat and tritical, respectively) will suppress the dominant weeds and increase the quality and yield of sugar beet.