Author: Ronald N. WalejkoPublisher:
ISBN:
Category :
Languages : en
Pages : 334
Book Description
To decide upon the most efficient breeding and testing procedures to improve maize populations, the plant breeder must have adequate knowledge of the type of gene action involved in yield heterosis. Two types of gene action have been postulated to account for yield heterosis in maize: dominance and overdominance. Recurrent selection of specific combining ability and for general combining ability have been proposed as methods to improve maize populations. Recurrent selection for specific combining ability uses a narow genetic base tester and originally was proposed on the assumption that overdominance is the main type of gene action responsible for yield heterosis. Conversely, selection for general combining ability uses a broad genetic base tester and assumes that dominant, favorable factors are concerned in yield heterosis. A procedure was proposed to compare the relative importance of dominance and overdominance in yield heterosis. This procedure involved recurrent relection for specific combining ability in two heterozygous source populations with a common inbred line tester. The purpose of this study was to evaluate progress in 5 cycles of recurrent slection for specific combining ability in two open-pollinated maize varieties and to determine the type of gene action involved in yield heterosis. The two source populations were the open-pollinated varieties, Kolkmeier and Lancaster, and the inbred line, Hy, was used as the common tester. After 5 cycles of recurrent selection, 6 population (C0 to C5) from (...).