Studies on Phytotoxicity of Herbicides and Herbicide Mixtures and its effect on Yield of Direct-Sown Rice (Oryza sativa L.)

The present investigation was carried out at Institute Research Farm of ICAR-NRRI, Cuttack (Odisha) during wet season of 2016 to study the phytotoxicity of a new herbicide molecule XR-848 Benzyl Ester along with its mixture with Cyhalofop Butyl in different doses and its effect on yield of direct-sown rice. The experiment was laid out in Randomized Block Design (RBD) with three replications and nine treatments viz. four herbicide mixtures(T₁-XR-848 Benzyl Ester+Cyhalofop Butyl 12% EC (w/v) @ 120(20+100)g ha⁻¹, T₂-XR-848 Benzyl Ester+Cyhalofop Butyl 12% EC (w/v) @ 150(25+125)g ha⁻¹, T₃-XR-848 Benzyl Ester+Cyhalofop Butyl 12% EC (w/v) @ 180(30+150)g ha⁻¹ and T₄-XR-848 Benzyl Ester+Cyhalofop Butyl 12% EC (w/v) @ 360(60+300)g ha⁻¹), three alone herbicides(T₅-XR-848 Benzyl Ester 2.5% EC (w/v) @ 25g ha⁻¹, T₆XR-848 Benzyl Ester 2.5% EC (w/v) @ 30g ha⁻¹ and T₇-Bispyribac-Na 10% SC @ 30g ha⁻¹), one weed free (T₈)and an untreated weedy check (T₉). Under phytotoxicity analysis, visual observations (Phyotoxic score), chlorophyll content and SPAD meter readings at 10, 20 and 30 days after treatment (DAT) of herbicides were taken, in which the T₄proved to be the most phytotoxic causing a reduction of 29.41% in grain yield which was at par with the untreated weedy check. Whereas T₂ showed a minimal phyotoxicity at initial stage with a quick recovery within 30 DAT of herbicide and was proved to be the best herbicide mixture yielding at par with the weed free (T₈).