An investigation into the occurrence and nature of genotype by environment interaction in Pinus patula

Abstract

SYNOPSIS This study was conducted as part of a joint venture between the tree improvement teams of Safcol and the CSIR to develop a breeding, production and conservation strategy for Pinus patula. The results of the investigation into genotype by environment interaction in two progeny trials of P. patula established over 5 sites in the highveld, middleveld and lowveld regions of Mpumalanga, South Africa are presented. The data from seven and eight-year old progeny trials were analysed and the genetic colt-elations and results of regression analysis are discussed in the light of breeding strategies und genotype by environment interaction. The heritabilities for growth rate were greater than those for stem and crown form on all sites. Heritabilities for volume ranged between 0,196 (middleveld site) and 0,246 (highveld site) in trial PF4008 1 09, and 0,256 and 0,400 in trial PF4011. The genetic correlations of growth between sites on the highveld (1733m altitude) and the lower altitude site (1152m) indicated...