ABSTRACT
This chapter illustrates how an understanding of crop responses to environment can guide an ideotype approach to plant breeding. It utilizes a broad definition of an ideotype as being a plan of the phenotype of a cultivar that will perform optimally in a specific set of climatic, soil, biotic, and sociocultural conditions. Ideotype approaches should be regarded as complementing, not replacing, traditional approaches to plant breeding that place strong emphasis on empirical performance-testing procedures. The exploitation of emergent properties by plant breeding is constrained by difficulties in selecting for them and the limited information concerning their mechanisms. Prior to widespread use of specific phenological, physiological, or morphological traits in breeding programs, their value must be clearly established. Obtaining a comprehensive estimate of the value of the ideotype trait also requires that the different pairs of isogenic lines be evaluated in different target production environments with consideration of potential interactions with pest and disease problems.
