HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Carangal, V. R. Articles by Sentz, J. C. Search for Related Content PubMed Articles by Carangal, V. R. Articles by Sentz, J. C. Agricola Articles by Carangal, V. R. Articles by Sentz, J. C.

Comparison of S₁ with Testcross Evaluation for Recurrent Selection in Maize¹

We made S₁ and testcross progeny evaluations for two cycles of recurrent selection for grain yield in a 13-line maize (Zea mays L.) synthetic. In the first cycle we evaluated 60 lines at four locations in 1 year. For the second cycle we evaluated 68 lines in three trials during 2 years. Selection intensity was 17% in both cycles.

Genetic variance for grain yield in the first cycle was significantly greater for selfed progeny in comparison with testcross evaluation, but decreased in the second cycle. Variability for ear moisture, broken stalks, and root lodging was increased with both selection procedures. S₁ selection for grain yield gave greater improvement in the population per se, and was equal to testcross selection for general combining ability improvement. However, one second-cycle testcross progeny exceeded the highest-yielding parental line testcross.

Genotypic correlations were greater between related and nonrelated testcrosses than between S₁ and either testcross. However, several selections were common to both S₁ and testcross procedures. Second-cycle correlations were significantly lower than first-cycle values.

Key Words: Zea mays L. • Synthetic variety • Genotypic variance • Heritability • Combining ability • Inbreeding depression

² Assistant Professor, Division of Plant Breeding, University of the Philippines, Los Banos; Maize Breeder, Research Station, Amberpet Hyderabad, A.P., India; Manager, Northern Corn Research, Cargill Inc., St. Peter, Minn.; Research Coordinator, Northrup King and Company, Minneapolis, Minn.; and Associate Professor in Agronomy & Plant Genetics, Univ. of Minn., respectively.

Received for publication February 18, 1971.