Abstract
This paper deals with the theoretical construction of a selection index for single individuals on the basis of individual measurements, Iine means and line-group means in a hybrid population of autogamous plants. Let the genetic va.1ue of an individual be Y and its phenotypic value be x1, the mean value of the line involving the individua] be x2, and the mean value of the group of the lines be x3. Weight factors to be given to x1, x2 and x3 for construc-ting a selectioh index X are denoted as b1, b2 and b3.