EFFECT OF EXTERNAL AND INTERNAL FACTORS ON SECONDARY METABOLITES ACCUMULATION IN ST. JOHN’S WORTH

The effect of modified external factors such as temperature and light intensity, and plant internal factors – phenological phase and their possible interaction was investigated on accumulation of bioactive secondary metabolites in Hypericum perforatum L. The plants were grown under different temperature and light intensity conditions in a greenhouse. The results suggested that accumulation of secondary metabolites highly depends on temperature and light intensity conditions and phenological cycle, though the influence of both variables differed for the particular compounds. Phenolic compound quantities changed greatly during plant development, and the highest levels were reached at flowering phase under both experiment conditions. Changes in naphthodianthrones content at higher temperature and light intensity followed the same increasing tendency as that for phenolic compounds. The significant decrease of temperature and light intensity were found to be crucial negative factors for accumulation of naphthodianthrones. The highest level of hyperforin was accumulated at vegetative phase that fall down during phenological development of plants under both experiment conditions.