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چکیده
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Adapting integrated weed management approaches and search for new technique is of increasing demand due to development of herbicide resistant weed biotypes and environmental hazardous. As a search for new weed control measure, it was decided to study the effect of undersown Persian clover (Trifolium resupinatum L.) on weeds in rapeseed for the first time in Iran. Therefore, a field experiment was conducted in Nahavand region of Iran, where rapeseed is a common crop, during 2016 to 2017. The experiment was consisted of rapeseed sown with 25, 50, 75 and 100% of the recommended seed rates of Persian clover (50 kg/ha), rapeseed under weed free and infested treatments in two regions in a randomized complete block design with four replicates. Wild oat, field bindweed, bristly foxtail and common poppy were the dominant weeds. The results showed that undersown Persian clover caused reduction in density, fresh and dry weight of weeds significantly. Weed dry weight reductions were 12.5, 15.9, 22.4 and 30.3% for rapeseed sown with, respectively 25, 50, 75 and 100% seed rates of Persian clover in one location. In the second location, weed dry weight reductions were 5.4, 7.5, 15.4 and 16.9% for rapeseed sown with, respectively 25, 50, 75 and 100% seed rates of Persian clover. Rapeseed yield and its components were not improved by undersown Persian clover. However, undersowing of Persian clover could be a promising approach to introduce in the cultivation due to its effect on weeds, in addition to its nitrogen fixation quality and possible ecosystem services. The results suggest that the adoption of undersowing of Persian clover can be considered as a complementary component of an integrated and sustainable weed management system in rapeseed due to its effect on weed management and ability to supply several ecosystem services e.g. nitrogen fixation and carbon storage.
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