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 Schutz, W. M. Articles by Brim, C. A. Search for Related Content PubMed Articles by Schutz, W. M. Articles by Brim, C. A. Agricola Articles by Schutz, W. M. Articles by Brim, C. A.

Inter-Genotypic Competition in Soybeans. III. An Evaluation of Stability in Multiline Mixtures¹

Yield data from four soybean [Glycine max (L.) Merrill] varieties, six two-component mixtures, and four three-component mixtures were used to study the effect of intergenotypic competition on population stability. Yield tests were conducted in three-row plots at four locations in each of four years. Stability was measured by estimating the relative contributions of pure lines and mixtures to the first and second order interactions of entries, locations, and years; by constructing frequency distributions of rank order; and by regression and deviations from regression of population performance on environmental productivity. Three of the six two-component mixtures exceeded their component means by a significant amount and were arbitrarily classified as overcompensatory. Two-component mixtures with yields similar to their component means were classified as complementary. Mixtures were generally more stable than the pure lines, with the degree of stability apparently dependent upon the type of competitive interaction involved. Variance component analysis indicated that overcompensatory mixtures made a very small contribution to the entry x location component of variance while complementary mixtures contributed heavily to ² _EL. However, overcompensatory mixtures produced a large entry x location x year interaction component in contrast to the small value obtained for the complementary group. The results suggest that overcompensatory competition effects are influenced by random environmental factors but that complementary effects are associated with environmental factors indigenous to a test location. Thus, both overcompensatory and complementary competition effects appear to be essential to obtain a high degree of stability in a heterogeneous population. Although complementary effects do not enhance reproductive output to any significant extent, their stabilizing influence may be an important factor in evolutionary population dynamics.

Key Words: Population dynamics • Glycine max (L.) Merrill • Genotype x environment interactions • Varietal mixtures • Soybean breeding

² Professor of Agronomy and Chairman, Statistical Laboratory, University of Nebraska, Lincoln, Nebr. 68503; and Research Agronomist, Plant Science Research Division, ARS, USDA, and Professor of Crop Science, North Carolina State University, Raleigh, N.C. 27607.

Received for publication March 1, 1971.