DOI: https://doi.org/10.36347/sajb.2026.v14i07.006

Pages: 528-536

Weeds are one of the main factors limiting the productivity of irrigated rice in the Senegal River Valley. The objective of this study was to determine the critical period of weed competition in order to optimize the weed control schedule. The trials were conducted in 2026 and 2017 at an experimental station (ISRA/Fanaye) and on farmers’ fields, using a completely randomized Fisher block design with 16 treatments and three replications. The treatments combined different durations of cover cropping, weed-free maintenance, and weed control practices. The parameters evaluated included rice and weed biomass, plant height, number of panicles, thousand-grain weight, and yield. The results show that extending the cover crop period significantly increases weed biomass and reduces rice growth and agronomic performance. Plots kept free of weeds exhibited the highest biomass, the greatest number of panicles, and the best yields, while the weedy control plots recorded the lowest values. Thousand-grain weight was minimally affected by the treatments, unlike yield, which decreased sharply due to weed competition. The critical period shows that during the hot dry season, weeds must be controlled between 12 and 48 days after emergence (DAE), whereas during the rainy season this period ranges from 24 to 48 DAE. Prolonged competition can result in losses exceeding 70%. These results demonstrate that early weed control and maintaining a weed-free crop until approximately 48 DAE are essential strategies for maximizing the yield of irrigated rice in the Senegal River Valley.