A METHOD FOR PREPARING A PLANT WITH INCREASED HARVEST INDEX USING A PLANT GROWTH REGULATOR The present invention relates to a method for preparing a plant with increased harvest index using a plant growth regulator glutathione is disclosed. The method comprises the steps of a) applying glutathione to plant or to soil with which a plant is to be cultivated b) cultivating the plant c) measuring amount of harvest of plant d) calculating harvest index of plant and e) selecting plant having harvest index higher than harvest index of wild strain or untreated plant. The concentration of applied glutathione is in the range between 0.5mM to 10 mM for plant or between 0mM to 5mM for soil. The plant has mutation in a function for synthesizing a plant hormone or a function for responding to a plant hormone. The glutathione used is an oxidized glutathione. The use of plant growth regulator increases number of seeds or flowers and number of shoots or tillers of plant.
