Theory of nucleus breeding schemes with overlapping generations.

Explicit methods are derived for estimating steady-state genetic responses and genetic differences between nucleus and base progeny crops in open nucleus breeding schemes which utilize genetic differences between progeny groups with parents of different ages or between age groups. Explicit methods are also given for estimating proportions which should be selected from the different nucleus and base selection groups so as to maximise genetic responses under each of a range of selection methods. Some basic differences between selection programmes utilizing genetic differences between progeny groups with parents of different ages and those utilizing genetic differences between age groups in nucleus breeding schemes are summarized.