ABSTRACT
This chapter introduces the reader to concepts of genotype, environment, phenotype, and genotype-by-environment interaction (GEI). Contributions and implications of GEI in crop breeding and causes of GEI are briefly discussed. Examples provided show how even the highly heritable qualitative traits can be influenced by the environment. The concept of norm of reaction or plasticity is illustrated. The entire chapter is designed to help understand and appreciate GEI.
GEI is an extremely important issue in crop breeding and production (Kang, 1990; Kang and Gauch, 1996; Cooper and Hammer, 1996). To understand the relationship between crop performance and environment, we begin with the fundamentals — definitions of genotype (G), environment (E), phenotype (P), and GEI. We show how environment has an influence on qualitative and quantitative traits. We also discuss the implications and causes of GEI relative to crop breeding.
