Inter-Genotypic Competition in Forest Trees and Its Impact on Realized Gain from Family Selection

The impact of inter-genotypic competition on realized gains from tree improvement programs remains largely unknown. Empirical results for individual tree traits demonstrate generally non-significant family x plot type (e.g., block, row, and noncontiguous) interactions and moderately strong, positive, family rank correlations between pairs of plot types. Therefore, results to date seem to indicate that average family performance is stable across a range of levels of inter-family competition. Inter-family competition either increased or decreased family variance, hence the estimate of additive genetic variance. Estimated genetic parameters, including genetic gain, for the same population tested in both block plots and row or non-contiguous plots bear little resemblance. Therefore, data from row plot or non-contiguous plot tests should not be used to estimate genetic parameters, including realized genetic gain. Testable hypotheses are developed which integrate current experimental results to provide a framework for future research regarding the influence of inter-genotypic competition on realized gain from selection. Keywords: additive genetic variance, growth and yield

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Author(s): G. Sam Foster

Publication: Tree Improvement and Genetics - Southern Forest Tree Improvement Conference - 1989

Section: Invited Paper