Allelopathic potential of Jatropha curcas
Aqueous extracts of Jatropha curcas leaves and roots inhibited the growth of corn (Zea mays L.) and tobacco (Nicotiana tabacum L.). Increased inhibition by increasing the concentration of extracts suggests that the extracts may have inhibitory substance which possesses allelopathic potential. Different extracts of leaves and roots of J. curcas were bio-assayed and analyzed. The main allelopathic substance was determined by gas chromatography-mass spectrometry (GC-MS) data as azelaic acid. This compound inhibited the germination of Z. mays L. seeds at concentrations greater than 500 μg ml-1, but the shoot and root growth were inhibited at concentrations greater than 100 μg ml-1. The root and shoot growth were inhibited by 50% at 270 and 654 μg ml-1, respectively. The percentage of azelaic acid in distilled water extracts of leaves was at least 0.94%, which indicated that azelaic acid may provide a competitive advantage to J. curcas in the defense mechanism by inhibiting the growth of neighboring crops.
Key words: Allelopathy, Jatropha curcas, growth inhibitor, azelaic acid.