ABSTRACT
This chapter reviews recent literature on selection indices and provides a background on the types of selection problems for which selection indices have been considered. Much of the recent literature on the use of selection indices for crop improvement concerns self-pollinated crops or maize, Zea mays. This reflects the amount of research being conducted with these species rather than the effectiveness of selection indices in their improvement. Smith introduced the concept of a linear selection index by developing an index for improved grain yield of wheat, Triticum aestivum. He concluded that using an index based on yield, yield components, and straw weight would result in greater response in yield than would selection for yield itself. Several authors have shown that a base index, where the relative economic weights are used as index coefficients, often gives expected responses that are similar to those of the optimum selection index.
