ONTOGENIC CHANGES IN HYPERICIN CONTENT OF SOME HYPERICUM SPECIES IN NATURAL PASTURELAND OF TURKEY

Changes in hypercin content of six Hypericum species available in Turkey, namely H. perforatum L., H. aviculariifolium Jaup. et Spach (endemic), H. pruinatum Boiss. el Bal., H. perfoliatum L., H. montbretii Spach and H. origanifolium Willd were studies with the aim of suggesting a Suitable period for grazing on Hypericum infested pastures. The plants were harvested at vegetative, floral budding, full flowering, fresh fruiting and mature fruiting stages and total hypercins was assayed. H. aviculariifolium, H. perforatum and H. montbretii produced higher amount of hypericin at all stages of plant development than the level regarded as safe for Merino sheep. Hence, pastures heavily infested by these species were not recommended for grazing. Hypericin content of the plants changed significantly and highest accumulation level was reached during floral development in all species. Therefore, April and September for pastures dominated by H. perfoliatum and April, September and October for pastures dominated by H. pruinatum were Suggested as suitable period for grazing.