Application of Sorghum, Sunflower and Rice Water Extract Combinations Helps in Reducing Herbicide Dose for Weed Management in Rice

Weeds pose a major threat to good harvests in transplanted rice. Conventionally weeds are controlled by herbicides, but this practice is costly and having generated environmental concerns demands to look for alternative methods that at least reduce herbicide usage without compromising yields. Allelopathic crop water mixtures in combination with reduced doses of three herbicides have been evaluated in 3-year field study carried out at Agronomic Research Area, university of Agriculture, Faisalabad, Pakistan. Mixture of allelopathic crops water extracts of sorghum, sunflower and rice each at 15 L ha-1 was tank mixed with reduced rates (V> & V3 of recommended rate) of three pre-emergence herbicides viz. butachlor, pretilachlor and ethoxysulfuronethyl for this purpose. Results revealed that combined application of mixture of allelopathic water extracts with V> of the recommended dose of pre-emergence herbicides butachlor (600 g a.i. ha-1), pretilachlor (313 g a.i. ha-1) and ethoxysulfuronethyl (15 g a.i. ha-1) reduced barnyard grass, flat sedge and crowfoot grass density by 75, 67 and 74% and their dry weight by 66, 71 and 76%, respectively, while V3 of the recommended dose of butachlor (400 g a.i. ha-1), pretilachlor (208 g a.i. ha-1) and ethoxysulfuronethyl (10 g a.i. ha-1) in combination with mixture of allelopathic water extracts reduced the density and dry weight of these weeds by 68, 60 and 67% and 63, 67 and 72%, respectively. Application of water extracts mixture with V of the label rates of pre-emergence herbicides improved rice grain yield by 61, 59 and 41%, respectively, while mixture of allelopathic extracts alone enhanced rice grain yield by 29% as compared with control. Study concluded that herbicide dosage can be reduced by 20-67%, when used in combination with mixture of allelopathic water extracts of sorghum, sunflower and rice. © 2010 Friends Science Publishers