Study of the Soil Characteristics and Utilization History of Metribuzin Used in Potato Fields on its Efficiency to Control of Redroot Pigweed (Amaranth retroflexus L.)

Metribuzin is one of the most common herbicides used in potato cultivation. This experiment was conducted to study the effect of soil characterstics and utilization history of metribuzin on its efficiency to redroot pigweed control as factorial on the base of randomized complete blocks design with three replications at Institue of Plant Protection in 2012. First factor was soil type in six levels (Hamedan with 15 years and without utilization history, Jiroft with 15 years and without utilization history, Isfahan with 2 years utilization history and Mashhad with 3 years utilization history) and second factor was different concentrations of metribuzin (0, 100, 300, 700, 1000 and 1500 g ai ha-1). Before cultivating redroot pigweed seed, the pots with mentioned soils were treated with metribuzin and harvesting was done four weeks after cultivating. Then, length and dry weight of shoot and root were measured and dose-response curves were drawn. The highest and lowest damage to redroot pigweed was observed in soils of Jiroft without utilization history and Hamedan with 15 years utilization history, respectively. In Jiroft soil with 15 years utilization history, shoot dry weight reductions were 15, 29, 45, 46 and 56 percent at concentrations of 0.1, 0.3, 0.7, 1 and 1.5 kg ai ha-1 of metribuzin, while in Hamedan soil with 15 years utilization history shoot dry weight reductions in the mentioned concentrations of metribuzin were 6, 11, 25, 31 and 36 percent, respectively. Results showed in different soils, increasing the concentration of herbicide resulted in a more favorable control of redroot, but increasing the amount of clay and organic matter, as well as increasing the history of consumption, affected the severity of the effects of metribuzin residues.