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Thesis (M.S.)—University of Nebraska—Lincoln, 1949. Department of Agronomy.


Copyright 1949, the author. Used by permission.


The objectives of this investigation were (1) to determine whether different testers furnished comparable measures of the prepotencies of inbred lines with respect to yield, maturity, lodging-resistance, and height, particular attention being given to the proportion of lines with high general combining ability which might have been discarded if selection for yield had been based on performance with a single tester; and (2) to determine whether the variability in yields, in root-lodged plants, and in broken plants was appreciably different with various testers.

Three sets of lines were compared in crosses with two single-cross testers, WF9 x 38-11 and 187-2 x L317.A set of seven selected lines were evaluated in crosses involving ten testers including five inbred lines, two single crosses, a double cross, and two open-pollinated varieties.

A tendency for the lines to be ranked similarly in crosses with the different testers was indicated by correlation coefficients as well as by the actual rankings of the lines in crosses with the various testers being compared.

A lodging-susceptible single cross when used as a tester provided greater opportunity for selection of lodging-resistant lines than did a more lodging-resistant single cross.

It was pointed out that no one tester should be considered universally desirable.Several factors to be considered in the selection of a tester are discussed.

Advisor:John H. Lonnquist