The Evaluation of Marketable Tuber Yield of Potato under by Oxadiargyl Application at the Different Growth Stages in potato

In order to study the effect of Oxadiargyl (Topstar) reduced dosages efficacy as a postemergence herbicide, on marketable yield, a field experiment factorial was performed besed on randomized complete block design with three replications and potato's cultivar called Agria in the Ardabil Alarog Agriculture and Natural Resources Research Station during 2013. Factores were Oxadiargyl dosages with seven levels (0 as weedy, 0.05, 0.1, 0.2, 0.4, 0.6 and 0.8 Lit a.i/ha), and application time of Oxadiargyl at different potato growth stages, in three levels (Potato emergence, Stoloning and Potato tuber bulking) with weed free. Statistical analysis showed that 0.8 Lit a.i/ha Oxadiargyl reduced weed biomass 66.16% and it hadn,t significant with 0.6 Lit a.i/ha. Among application time of Oxadiargyl, potato emergence produced the maximum reduction percentage of weed biomass. The results showed that 0.8 Lit a.i/ha increased percent of medium tuber and total tuber yield 88.21 and 51.59%, respectively and decreased percent of small tuber 45.60 percent. According to the results, maximum percent of large tuber and marketable yield was 0.8 Lit a.i/ha at potato emergence stage.