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Thesis (M.S.)—University of Nebraska—Lincoln, 1959. Department of Agronomy.


Copyright 1959, the author. Used by permission.


The top-cross method for evaluating inbred lines is at the present time widely used in corn breeding programs. Numerous studies have been conducted to determine the effectiveness of the top-cross test as a method for evaluating new lines of corn. There are no reported studies pertaining to the influence of the early versus late portions of the tester population of plants that supply pollen which effects fertilization of a group of inbred lines being topcrossed. This influence, if variable, could be important since any group of lines being topcrossed usually vary considerably in time of flowering and might therefore be fertilized by different fractions of the gamete population from the tester parent.

The study reported herein deals with the effect of early, intermediate and late pollen samples collected from two tester varieties when crossed to each of four inbred lines of corn differing in maturity.

Advisor: John H. Lonnquist