The present invention relates to a synergistic composition comprising a plant growth regulator and/or fungicide and/or insecticide and/or acaricide and the preparation process thereof. Additionally, the present invention discloses the use of a plant growth regulator and/or fungicide and/or insecticide and/or acaricide to prepare a synergistic composition and the use of a composition to ensure high yield per area of a corn crop. Furthermore, the present invention provides methods to reduce excessive growth of corn plants, to strengthen stems, the root system and adventitious roots of corn plants, to combat diseases and pests and to confer resistance to pest control, as well as a method to identify a composition that ensures high corn crop yield.
