Effect of Irrigation and Herbicides on Most Tenacious Weed Cyperus rotundus in Wheat

Abstract

To manage the Cyperus rotundus (Purple nut sedge.) is a troublesome, economically damaging weed, widely naturalized in the tropical and subtropical regions of the world. A field experiment was done at Students Instructional Farm of Chandra Shekhar Azad University of Agriculture & Technology, Kanpur (U.P).The study was conducted to investigate the competitive effects of C. rotundus in wheat (Triticum aestivum L.) under varying irrigation regimes and herbicides in field conditions at Kanpur during Rabi 2017-18 and 2018-19 in a split plot design.  The experiment was laid out in split-plot design with four irrigation schedule viz. irrigation at CRI and active tillering stage (I1), irrigation at CRI + jointing + booting (I2), CRI + active tillering + booting + flowering stage (I3) and  irrigation at CRI + jointing + booting + flowering + milking stage (I4) were assigned to main plots and weed management practices viz. W1-weedy check, W2-two hand weeding at 20 and 40 DAS, W3-sulfosulfuron @25 g/ha , W4- pendimethalin (pre emergence) fbWCPL-15(clodinafop- propargyl 15 %) @400 g/ha , W5- carfentrazone ethyl 20% + sulfosulfuron 25%WG @ 100 g/ha , W6- halauxafen + penxasulam 23.5% @ 75 g/ha , W7- halauxafen - methyl 1.21% w/w + fluroxypyr @  and W8- clodinafop- propargyl 15% + metsulfuron 1% @ 400 g/ha  were allocated to sub plots. Application of two irrigations at CRI and active tillering stage (I1) significantly reduced the density of C. rotundus and their fresh and dry weight with highest weed control efficiency (WCE) over irrigation at CRI+ jointing+ booting+ flowering+ milking stage (I4), irrigation at CRI + active tillering + booting + flowering stage (I3) and irrigation at CRI + jointing + booting (I2). However, maximum yield was recorded with the application of five irrigation at CRI+ jointing+ booting+ flowering+ milking stage (I4). Among herbicidal treatments, lowest density, fresh and dry weight of C. rotundus with  the highest WCE resulted in higher  yield of wheat was recorded with the application of carfentrazone ethyl 20% + sulfosulfuron 25%WG as post emergence (35 DAS) at 100 g/ha as compared to other treatments. However, none of the herbicidal treatments as effective as hand weeding twice at 20 and 40 DAS.