EVALUATION OF MEXICAN SUNFLOWER (Tithonia diversifolia) AND GUINEA GRASS (Megathyrsus maximus) MULCHES ON WEED SUPPRESSION AND KENAF (Hibiscus cannabinus) GROWTH
Keywords:
Megathyrsus maximus, Hibiscus cannabinus, Tithonia diversifolia, Mulching, Weed infestationAbstract
Weed infestation remains a major constraint to kenaf production in Nigeria, particularly under low-input systems where reliance on costly synthetic herbicides is unsustainable, prompting the search for effective plant-based mulching alternatives. Plant-based mulches were evaluated as eco-friendly weed management options in kenaf (Hibiscus cannabinus L.) under field conditions at the Faculty Garden, Adekunle Ajasin University, Nigeria. The experiment was laid out in a randomised complete block design with ten treatments replicated three times, comprising a weedy check, a weed-free control, and Mexican sunflower (Tithonia diversifolia) and Guinea grass (Megathyrsus maximus) mulches applied at 5, 7.5, 10, and 12.5 t ha⁻¹. Weed density and weed biomass were assessed at 4 and 6 weeks after sowing (WAS), while kenaf growth parameters and biomass were measured up to 10 WAS. Mexican sunflower mulch applied at either 10 or 12.5 t ha⁻¹ reduced weed fresh biomass by approximately 49–70% relative to the weedy check; Guinea grass at similar rates resulted in inconsistent suppression, ranging from 13% increase to 20% reduction in weed biomass. At 10 WAS, kenaf fresh and dry biomass in mulched plots were 42–83% lower than those from weed-free plots, indicating persistent weed interference. Mulched treatments produced up to 30% higher biomass than the weedy check, with Mexican sunflower at 10–12.5 t ha⁻¹ recording the highest dry biomass among mulched plots. Weed-free plots consistently produced the tallest plants, widest stem diameters, and greatest biomass. Overall, although higher rates of Mexican sunflower mulch partially suppressed weeds and improved kenaf biomass relative to the weedy check, mulching alone was insufficient to achieve crop performance comparable to weed-free management, underscoring the need for integrated weed management strategies in kenaf production
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