Allelopathic Effects of Ageratum conyzoides Root Exudates on Germinability of Selected Crops: A Comparative Analysis

This study investigates the allelopathic effects of aqueous root exudate extracts of Ageratum conyzoides on the germination, shoot length, and root length of various agricultural crops. The study reveals how different species respond uniquely to varying concentrations, uncovering complex dynamics in crop-allelopathic interactions. The germination analysis reveals distinct sensitivities among the tested crops. C. sativus demonstrates resilience, displaying minimal germination reduction even at higher exudate concentrations. C. arietinum exhibits moderate susceptibility, while Z. mays emerge as the most sensitive crop, displaying a profound reduction in germination. L. esculentum and P. vulgaris also exhibit sensitivity, with adverse impacts on germination rates. A. esculentus consistently shows reduced germination rates with increasing exudate concentrations. Shoot length dynamics show that all crops experience greatest elongation without A. conyzoides root exudates, suggesting inhibition of growth by these exudates. Shoot growth declines with higher exudate concentrations across most crops, with varying sensitivities. C. sativus consistently decreases, while C. arietinum, Z. mays, and P. vulgaris show concentration-dependent inhibition. S. lycopersicum significantly reduces shoot elongation, and A. esculentus remains consistently sensitive. Root length patterns further elucidate the allelopathic effects. Responses vary across species and concentrations. A. esculentus roots thrive at lower concentrations but decline at higher ones. S. lycopersicum shows initial reduction, significant decline, followed by recovery. Z. mays and C. arietinum exhibit fluctuating responses. P. vulgaris consistently grows, while C. sativus persistently displays reduced root elongation. These findings highlight the complex and species-specific allelopathic interactions between A. conyzoides and agricultural crops, emphasizing the need for a comprehensive understanding of these dynamics for effective crop management in A. conyzoides-infested areas.