Efficacy of Pendimethalin Rates on Barnyard Grass (Echinochloa crus-galli (L.) Beauv) and Their Effect on Photosynthetic Performance in Rice

Pendimethalin herbicide toxicity to rice plants and barnyard grass invasion have increasingly affected the productivity of direct-seeded (DSR) in fields. Whether how promote DSR sustain weed management depend on appropriate pre-emergence application rate minimise its ecosystem. Pot experiments were conducted determine effects pendimethalin rates (1.5, 1.75, 2.0 kg a.i. ha−1, two control treatments include untreated treated with 1.5 ha−1 S-metolachlor) (Echinochloa crus-galli (L.) Beaux) their potential risk photosynthetic performances (Topaz Sen pidao). All provided excellent grass. Among treatments, 1.5, S-metolachlor (treated control) decreased leaf area significantly by 38.9, 49.6, 49.6 46.2%, respectively, compared at 40 days after sowing (DAS). The above-ground biomass 40% (1.48 g plant−1) 46.2% (1.33 when ha−1S-metolachlor was applied DAS pots. Higher increased Topaz pidao varieties, reduced effective quantum yield (light-adapted) photosystem (PS) II 18% (0.58) 19% (0.52), control. Application maximum (dark-adapted) (0.66) (0.68) including suppressed 55 DAS, but 59.9% Although (0.55) a small percentage (8%) than (0.65), it non-toxic for both varieties pendimethalin. Therefore, use can be used direct seeding an early growth stage.