Abstract: The new single-hybrid variety of maize "Ji Dan 18" is derived from Huangzao₄×CB₅. It is characterized by stable aud high yield, fine adaptation,strong resistance to diseases and middle early stage of mature. This variety is sensitive to fertilizer and water, but nonsensitive to light,temperature and air. It is fit for interplanting with wheat and summer sowing. Planting area of the hybrid amounted to one million mu in 1988. The study was carried out with the help of parent germ plasm basis analysis method and under the direction of ecotype evolution theory. In this paper the authors have probed into the selecting targets of main ecological character in current maize ecological phase.

Key words: Ji Dan 18, Selecting target