A MATHEMATICAL-MODEL TO PREDICT THE TISSUE-RESPONSE TO PARTHENIN - AN ALLELOCHEMICAL

Parthenin - a sesquiterpene lactone from Parthenium hysterophorus L. is an allelochemical that prevents the germination of Phaseolus aureus Roxb cv. ML-5 seeds. The response of the seed has been attributed to the inhibition of the respiratory electron transport ability of its embryo. It has been shown to depend directly not only upon concentration of parthenin, but simultaneously on the duration of exposure of the seeds to the chemical as well. A strong correlation exists between the quantum of the response and the product of the period of exposure and the concentration of parthenin. In order to predict the maximum possible germination ability of the seed exposed for a given period to a given concentration of parthenin, an expression X = 10 000 Y3/[e(Y/0.31-1)] was formulated from the equation X = AY3/[e(Y/Y0-1)], where X represents values of maximum respiratory activity, Y represents the product of concentration and time in units mg cm-3 h, A represents a dimensional constant. The trend and nature of response that is calculated on the basis of formulation coincides with that of measured response through spectrophotometry.