Study the possibility of using undersown persian clover in oilseed rape for weed control

A field experiment was carried out to investigate the effect of Persian clover (Trifolium resupinatum L.) as an undersown cover crop on weed control in winter oilseed rape. The experiment was conducted in a randomized complete block design with four replications in Nahavand region (km: 35) of Iran during 2017-2018. The treatments were included oilseed rape with four levels of Persian clover density (25, 50, 75 and 100 percentages of the optimum sowing rate) and two levels of weed management (weedy and weed-free). The results showed that the undresown Persian clover has a significant effect on reducing the density and aboveground dry weight of the weeds compared to the control. Oilseed rape + 25, 50, 75 and 100 percentages of Persian clover sowing rate, respectively, caused 63, 66, 80 and 91 percent reduction in weed density. The same treatments also caused 35, 51, 58 and 75 percent reduction in weed aboveground dry weight, respectively. Oilseed rape yield undersown with Persian clover was lower than oilseed rape in weed free treatment. However, oilseed rape yield in oilseed rape +75 and 100 percentages of Persian clover sowing rate was higher than oilseed rape weed infested treatment. The percentages of oil seed content in oilseed rape in all treatments undersown with Persian clover was equal to oilseed rape weed free treatment and higher than oilseed rape weed infested treatment. The land equivalent ratio in oilseed rape +75 and 100 percentages of Persian clover sowing rate was 0.92 and 1.09, respectively.