The quantitative effects of temperature and light intensity on hyperforin and hypericins accumulation in Hypericum perforatum L

The quantitative effects of temperature and light intensity on accumulations of hyperforin, hypericin and pseudohypericin were examined in greenhouse-grown Hypericum perforatum L. plants. Polyethylene cover of 50% transparency was used for shading. Temperature values and light intensities were measured daily in both shaded and un-shaded parts during experiment. Plants were harvested weekly and assayed for the chemical concentrations by HPLC after being dried at room temperature. Multi regression analyses were performed to describe the quantitative effects of temperature and light intensity on accumulation of phytochemicals. According to the results, increases in temperatures from 24 - 32 degrees C and light intensities from 803.4 - 1618.6 mu molm(-2)s(-1) resulted in a continuous increase in hyperforin, hypericin and pseudohypericin contents. The relationships between temperatures & light intensity and accumulation of phytochemicals were formulized as PC = [a + (b(1) x t) + (b(2) x l) + (b(3) x l(2)) + (b(4) x (t x l))] where PC - phytochemicals, t - temperature (degrees C), l-light intensity (mu molm(-2)s(-1)), and a, b(1), b(2), b(3) and b(4)-coefficients of the produced equations. R-2? Values were 0.80 for hyperforin, 0.93 for hypericin and 0.96 for pseudohypericin. All R-2 values and standard errors of the equations were found to be significant at the p < 0.001 level.