Different methods of weed management in Lettuce (Lactuca sativa L.)

An experiment was conducted to evaluate the effect of different methods of weed control on lettuce yield and its components, in the spring of 2014. The experiment was performed on a randomized complete block design with three replications at the educational and research field of College of Agriculture and Natural Resources of University of Tehran. Treatments were black polyethylene mulch, wheat straw mulch, trifluralin (2 L/ha), trifluralin (2 L/ha) + hand weeding, pendimethalin (2 L/ha), pendimethalin (2 L/ha) + hand weeding, paraquat (2 L/ha) (protected, just between rows), cultivation, two stages of hand weeding and a weed infested plot. Results showed that different treatments influenced lettuce head (weight, number of leaves, stem weight) and weed dry matter significantly. Black polyethylene mulch with 100%, pendimethalin + hand weeding with 89% , two stages of hand weeding with 88% and trifluralin + hand weeding with 86% influence were the best treatments in term of weed control, while cultivation with 40%, showed lowest impact on weed control compare to weed infested plot. The highest yield of lettuce head was observed in black polyethylene mulch (1063 g), pendimethalin + hand weeding (984 g) and two stages of hand weeding (999 g) which were economically practical.