Effects of Varietal Competitiveness and Weed Control on Productivity in the Lowland Rice Farming System in Burkina Faso

Abstract

Weeds remain a major limiting factor for rice productivity in Burkina Faso. During the 2023 rainy season, a study was conducted at the Environmental, Agricultural and Training Research Center of Kamboinsé to study the effects of varietal competitiveness and weeding methods on the productivity of lowland rice systems. Four lowland rice varieties were evaluated under five weeding treatments, namely: no weeding or zero weeding (S0); one late manual weeding (S1); two manual weedings (S2); a chemical weeding with a pre-emergence herbicide (S3); and a chemical weeding with a post-emergence herbicide (S4). A weed species inventory identified the most abundant species including: Oryza longistaminata , Cyperus iria , Ipomoea aquatica , Echinochloa col ona , Melochia corchorifolia , and Ludwigia hyssopifolia . The effects of variety and weeding modality on grain yield, were highly significant in the lowland rice system. Furthermore, the effectiveness of weeding practices varied among the evaluated rice varieties. Two varieties, TS2 and Orylux6, exhibited the best performance when combined with post-emergence chemical weeding. This combination, resulted in reduced weed biomass at harvest, a higher panicle density per square meter, and optimal expression of their yield potential. In contrast, FKR56N and KBR8 achieved their highest yields under one late manual weeding and two manual weedings, respectively. Furthermore, FKR56N recorded the lowest weed biomass (1576.67 kg/ha) under the untreated control condition. The results indicate that two manual weedings, carried out between 21 and 49 days after sowing, are necessary under weed flora conditions dominated by Oryza longistaminata and Cyperus iria . This study highlights the importance of understanding the specific response of each variety to varying levels of weed infestation for optimize yield potential.