Phytotoxic effect of aqueous extracts and essential oils from southern marigold (Tagetes minuta)

The phytotoxic effects of aqueous extracts and essential oils derived from southern marigold (Tagetes minuta L.), were studied using test species bioassays. The phytotoxic potential of the chemical substances was evaluated on callus induction and growth of four receptor plant species Oryza sativa (Dongjinbyeo), Brassica campestris subsp. napus var. pekinensis, Raphanus sativus var. acanthiformis, and Sesanum indicum (Ansanggae). The receptor plants were grown on MS (Murashige & Skoog) media supplemented with 2 mg/litre 2,4-D and 0.5 mg/litre kinetin containing aqueous extract and essential oil extracted from T. minuta. The introduction of calluses was significantly inhibited proportional to the concentrations of aqueous extract and essential oil used. The callus induction and growth were rapidly decreased in 30 and 50% of original aqueous extract, and in 10 and 20 mul essential oil. The allelopathic potential of aqueous extract from T. minuta may be more than that of essential oil. It was concluded that the inhibitory allelophatic effects of marigold exhibited species-specific inhibitory trends.