The effectiveness of plus-tree selection for yield

Amsterdam

1994

23-34

Sonderdruck

12507S

203838

In response to recent suggestions in the literature that plus-tree selction for yield in forest trees might in general be ineffective, the empirical information contained in 24 published reports was examined. It was found that progeny of plus-trees selcted for yield traits tend to be faster frwoing than their controls. It is argued that this observed tendency is likely to be due at least in part to a response to selection. The reported values indicate that genetic gains of up to 15% in height and diameter growth, and up to 35% in volume per unit area, can readily be achieved through plus-tree selction. This is consistent with theoretical expectations. However, it should be emphasised that the amount of gain from any particular plus-tree selction system depends on the values of the parameters that determine the response to selection (selection intensity, genetic variance, heritability). In unfavourable situations, gain could be close to zero.Keywords: Genetic gain; Competition, Phenotypic selection