Development of elite families in oil palm (Elaeis guineensis Jacq.)

Summary Data from 29 dura female parents, 14 pisifera male parents and their offspring were assembled to obtain quantitative genetic information on optimizing selection of elite families. Phenotypic values of the offspring were partitioned into general combining ability (GCA) of the parents and their specific combining ability (SCA). Parental GCA-values for leaf-Mg content (LMG), height increment (HT), leaf area ratio (LAR), leaf area (LA), frond production (FPR), vegetative dry matter production (VDM), the rate of increase in leaf area against age (k) and maximum leaf area (L_m) were entered in a multiple regression analysis as predictors of oil-and-kernel yield and Harvest Index (HI), i.e. the proportion of dry matter used for oil and kernel production, of the offspring. The analysis revealed that both selection objectives are positively influenced by indirect selection for high LAR and LMG, and for reduced VDM with FPR as main component. But palms with high values for LA, L_m and HT should not be considered to avoid selecting palms partly for their ability to compete with neighbouring palms for light. The contribution of SCA was relatively small for most of the characters studied, except HT, FPR and HI. From the standard deviations for GCA and SCA of the dura and pisifera parents, i.e. _GCA and _SCA, it was extrapolated that selection can potentially enhance bunch yield (by 24%), oil-to-bunch ratio (19%), kernel-to-bunch ratio (29%), oil-and-kernel yield (31%) and HI (56%) above the mean phenotypic value obtained for the offspring of the present investigation. Heritabilities, calculated as the square of the correlation of the GCA-and phenotypic values of the female parents, were low for bunch yield, oil-and-kernel yield and HI, but moderate for LAR, LMG and VDM; levels were high for oil and kernel extraction rate. These outcomes were confirmed by the correlations between values of the female parent and their offspring. Among the unbalanced incomplete mating designs studied, the rectangular lattice and the alpha design are most suitable to compare GCA-values of pairs of parents. A breeding strategy adapting the recently introduced practical possibility of clonal reproduction is discussed.