Kang,  KS, Lindgren.D and T.J. Mullin. 2001. Prediction of genetic gain and gene diversity in seed orchard crops under alternative management strategies. TAG in press.

Abstract Genetic gain and gene diversity of seed crops from clonal seed orchards were formulated considering genetic selection, fertility variation, and pollen contamination, and compared for five different management strategies. Genetic response was studied as a function of orchard management tactics. Management variables included the proportion of clones left after genetic thinning and/or selective seed harvesting. Formulae were derived to calculate gene diversity (expressed as group coancestry or status number) based on sex ratio in an orchard population. The influence of having different sets of clones serving as seed parents, or pollen parents, or as both was analysed. In addition, the impact on genetic gain and gene diversity of seed crops was studied quantitatively as a function of the quantity and quality of gene flow from outside the orchard. The negative impact of fertility variation among orchard genotypes on gene diversity of the seed crop was quantified. Numerical examples were given to illustrate the impact of orchard management alternatives on genetic gain and gene diversity. The formulae and results of this study can be used for identifying favourable alternatives for management of seed orchards.