The effect of doses and application time of EPTC on weeds control and tuber yield of potato (Solanum tuberosumL.)

Weeds have a significant role in reduce yield of crops Specially potato and the effect of herbicide application has been proven on increasing of potato crop production.Choice of herbicide that can properly control weeds, It is very important. Because the herbicides and the diversity of the sites of action are limited, so herbicide resisitant is not far and that is increasing. Therefore, it is necessary to use herbicide that can control weeds and alternate with other herbicides in potato fields. Also, in this research, the best dose and application time of EPTC at different growth stages of potato is determined. Trials were conducted in order to evaluate the effect of dose and application time of EPTC in Agricultural and Natural Resources Research Station in Alaroog, Ardebil, in 2013. The experiment was conducted as factorial in a randomized complete block design with three replications, two factors and Agria cultivar. The first factor was the different doses of EPTC herbicide in six levels of 500, 1000, 2000, 4000, 5000 and 6000 g a.i/ha and the second factor, the application time in three stages of pre-plant, potato emergence and stoloning was carried out. Three weeks after spraying in each stage of growth stages, weed density and biomass were evaluated. Data analysis carried out by SAS 9.1 software and Sigma Plot 11 software was used for graphs.Mean comparison was by using the least significant difference test at the 5% probability level. Statistical analysis showed that interaction effect of doses and application time of EPTC is significant on weed density and biomass. EPTC at 6000 g a.i/ha in the pre-plant stage reduced 84% of total weed density. According to the results of this study, the highest percentage of biomass reduction was observed in treatment of 6000 g a.i/ha EPTC and pre-plant stage of potato. Among different weed treatments, application 5000 and 4000 g a.i/ha of EPTC at pre- plant and potato emergence are next rank. The highest mean weight of the tuber and total tuber yield were obtained using EPTC herbicide at 6000 g a.i/ha in the pre-plant stage. The use of EPTC herbicide in the pre-plant increased its yield to 35.04%. According to the results, the best treatments for reducing of weed density and biomass weed is 6000 g a.i/ha in the pre-plant. With the use of these treatments, the mean weight of the tuber and the total tuber yield of potato were increased.