Abstract:
Weeds pose major constraints in crop production. The use of allelochemicals and allelopathic
species can provide an effective alternative for sustainable weed management. In a previous study
that evaluated the allelopathic activity of wild and cultivated plants in Turkey, Hibiscus sabdariffa
demonstrated the strongest inhibitory potential. This study aimed to estimate the phytotoxic influence
of the H. sabdariffa water crude extracts on Lactuca sativa L. in a bioassay experiment. High-performance
liquid chromatography (HPLC) analysis was used to identify two major compounds, hydroxycitric
acid lactone and hydroxy citric acid, and their plant growth inhibitory activities were evaluated by
bioassays. Hydroxycitric acid lactone had a stronger growth inhibitory activity on L. sativa L. and
was estimated as a major allelochemical in H. sabdariffa calyx. The high concentration (16.7% of
the dry weight of the calyx) and strong inhibitory effect (EC50, 73.7 ppm) of the hydroxycitric acid
lactone could demonstrate the growth inhibitory activity of the H. sabdariffa calyx extract. This study
showed that hydroxycitric acid lactone, a major compound in the calyx of Hibiscus sabdariffa, is a plant
growth inhibitor.
