Document Type : Research Article
Authors
1
Plant Protection Research Department, Khuzestan Agricultural and Natural Resources research and Education Center, AREEO, Ahwaze, Iran.
2
Assistant Professor of Rice Research Institute of Iran , Rasht, Iran
10.22034/ijws.2025.135815
Abstract
A two-year field study (2020-2021) was conducted in Gilan and Khuzestan provinces, Iran, to evaluate the efficacy of a new herbicide premix, penoxsulam + cyhalofop-butyl (Bernovid), against major weeds and its effect on rice yield in transplanted and direct-seeded systems. The experiment compared six rates of the premix (0, 60, 120, 180, 240, and 300 mL a.i. ha-1) with the recommended doses of standard herbicides: cyhalofop-butyl (250 mL a.i. ha-1), penoxsulam (30 and 60 mL a.i. ha-1), bispyribac-sodium (40 mL a.i. ha-1), pretilachlor (875 mL a.i. ha-1), and a mixture of pretilachlor + bensulfuron-methy (875+36 g a.i. ha⁻¹). Results in Khuzestan showed that application rates of 120–300 mL of the premix reduced the density and dry weight of key weeds, including Echinochloa colonum and Physalis divaricata, by 60–90%, whereas the efficacy of common herbicides ranged from only 23% to 57%. Furthermore, grain yield and biomass of rice treated with the premix were 30–75% higher than with cyhalofop-butyl, penoxsulam, or bispyribac-sodium alone. In Gilan, the premix demonstrated superior efficacy. All doses above 60 mL a.i. ha⁻¹ reduced the biomass of dominant weeds, Paspalum distichum and Echinochloa crus-galli, by ≥90%, significantly outperforming standard post-emergence herbicides. Paddy yield and weed control at the optimal dose of 150 mL a.i. ha⁻¹ and higher rates were statistically similar. For effective and sustainable weed management, the premixed herbicide penoxsulam + cyhalofop-butyl is recommended at application rates of 150 and 240 mL a.i. ha-1 for transplanted rice fields in Gilan and for direct-seeded rice fields in Khuzestan.
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