Effect of tank mixing herbicides on Mung Bean (Vigna radiate) grain yield and weed control at North Khuzestan climatic condition

The mungbean (Vigna radiate) alternatively known as green gram belongs to legume family. Mungbean is mainly cultivated today in India, China, Iran and USA generally. Weed infestation in mungbean crop is one of the main causes of low yield per hectare against the potential yield in the world. Weeds decreased mungbean yield up to 70% compared to weed control condition. Chemical weed control is the easiest and most successful alternative method in crop yields such as mungbean. Herbicides have increasingly become a key component of weed management programs, one being the reason accounts for increased crop yields in the world. Tank mixing is scientific methods for use of two or more herbicide in the field. The correct tank mix of two or more herbicides may save time and labor and may reduce equipment and application costs. In addition, such a mixture might also control a range of pests or enhance the control of one or a few weeds. The instant studies were undertaken to evaluate the efficacy of different herbicides alone and in mixture on dynamics of weeds in Mungbean to find out the suitable tank mixture of herbicides for the control of weeds in Mungbean. Field experiment was conducted at college of agronomy, Shoushtar branch, Islamic Azad University, 2013-2014 to investigate the efficacy of some herbicide mixtures on weeds control and mung bean seed yield. The field experiment was carried out under completely randomized design with 10 treatments and 3 replications. Experimental treatments including Haloxyfop-R-methyl, Bentazone and Oxyflurophone (at recommended dose rates) mixing of Bentazone + Haloxyfop-R-methyl, bentazone + oxyflurophone, Haloxyfop R-methyl + Oxyflurophone (decrease dose to 80% and 50% of recommended dose rates). Check treatment was without any control of weeds. Experiment data were recorded on weed density, weed dry eight, Mungbean grain yield, biololgic yield, pod per plant, 100 grain weight, grain per pod and plant height. The general weeds were included Clome viscose, Echinocloa colonus and cyperusrotondus. In this study, bentazone and bentazone+ oxyflurophone (decrease dose to 80%) decreased Cyperus rotundus density to 1.3 and 2.3 plant per m-2. The lowest Echinochloa crus-galli l.density obtained in Haloxyfop-R-methyl, Bentazon + Haloxyfop-R-methyl (decrease dose to 80% and 50%) respectively 0, 1.3 and 2 plant per m-2. All herbicide treatment control Clome viscose compared control except Haloxyfop-R-methyl (0.8 l ha-1). Maximum mungbean seed yield (2733 kg ha-1) obtained in application of combination Bentazone+Haloxtphobe_R- methyl (decrease dose to 50%) but the lowest Mungbean yield showed in Oxyfluorfen (2 l ha-1). Previous studies showed that there was phytotoxicity of herbicides on mungbean cultivars. The highest phytotoxicity effects of herbicides on mungbean after 30 days showed in Oxyfluorfen were applied at recommended doses (heavy damage scale). This signifies the necessity of the tank mix application of herbicide for better weed control and improve mungbean yield. Several researchers have reported better weed. Applying herbicides at lower doses by tank mixing methods has a fit in specific situations as they might allow increased profits to be realized by growers, reduce potential injury to current and succeeding susceptible crops, and minimize risk to the environment and results of this study showed Bentazone+ Haloxtphobe_R- methyl (decrease dose to 50%) that treatment had maximum mungbean seed yield compared other treatments. Studies have demonstrated that low doses of herbicides by tank mixed herbicides could result in faster evolution of herbicide resistance. So reducing herbicide doses by tank mixing method is better combined with weed integrated management. Application doses of these post-emergence herbicides could be substantially reduced to below registered doses without sacrificing their efficacy on weeds. Results indicated that Haloxyfop-R-methyl was most effective on controlling grass weeds and Bentazone herbicides controlled broadleaf weeds efficiently. No one of these herbicides could not control of weeds effectively alone but Mixing of Haloxyfop-R-methyl + Bentazone at level 80% and 50% could reduce dry weight of total weeds (26.6 and 10.4 g m-1) and were successful in weed control. Reduction amounts depended on weed composition and herbicide due to different effectiveness of these herbicides on broadleaved and grass weeds. Results concluded that integrated application of Bebtazon + Haloxyfop-R- methyl (50% recommended dose rate) was the best treatment for weeds management in mungbean fields in Khuzestan condition.