Summary

Practical aspects of implementing a three-step selection procedure in oil palm are described; these steps are: (i) phenotypic selection of dura and pisifera parents, (ii) further selection on the basis of General Combining Ability (GCA) values obtained from a progeny test and (iii) testing crosses between elite families to exploit both GCA and Specific Combining Ability (SCA).

A detailed account is given of the statistical method to estimate the GCA and SCA values of the parents from the tenera crosses. Parents can only be compared if the crosses are connected; this aspect is clarified. Incomplete block designs as for example alpha-designs are most suitable to compare the GCA values of the parents.

To compare sources of planting material, reliability can be enhanced by increasing the number of progenies per source rather than the number of replications.

Crossing work can be speeded by assigning the parents according to the sequence of emergence of inflorescenses. The large number of crosses involved usually dictates the use of incomplete block designs, the choice and the statistical analysis of which are reviewed.

Among the statistical selection procedures studied, the Subset Selection Procedure of Gupta is most flexible and permits the elimination of inferior progenies.

The ultimate objective is to select parent palms for high yield of oil and kernels per ha. Selection for maintaining a high Harvest Index (HI), the proportion of dry matter used for the production of oil and kernels, is advocated. This can best be achieved through indirect selection for high GCA values of Leaf Area Ratio (LAR), (i.e. the ratio of new total leaf area produced to new Vegetative Dry Matter (VDM) ), low GCA values for VDM, low values of height increment and high values of magnesium content in the leaves. A further aim is to achieve optimal Leaf Area Index (LAI), (i.e. the total leaf area per unit ground area), quickly after planting by the selection of parameters derived from a logistic growth function fitted through mean leaf area against palm age. Leaves are best measured 6, 42, 66 and 90 months after planting; precision is enhanced by including measurements 12 months later.

Palm height with time also fits a logistic growth function, so actual height must be measured to compare progenies.

Recording techniques of palm characteristics are described, illustrated by technical drawings, and a recording schedule is proposed.

Introduction

Relevant aspects

Steps in selection

Estimating genetic effects of the parents

Evaluating mating designs

Implementing a crossing program

Progeny trials in incomplete blocks

Statistical selection procedures

Character for selection

Selection strategy

Plot size and shape

Arragement of progenies in the field

Comparison of sources of planting material

Arragement of progenies to compare sources of planting material

Statistical analysis for comparing sources of planting material

Recording of traits for selection

Technique of selection

Measurements to estimate growth parameters

Timing of measurements

Components of growth

Calculation of growth parameters

References

ACKNOWLEDGEMENTS
The assistance of the staff of the Bah Lias Research Station, North Sumatra, Indonesia, with the development of the equipment for measuring palms is highly appreciated; thanks are particularly due to Mr. F.X. Soebagjo and Mr. P. Sembiring.
Further appreciation and thanks are due to Mr. C. Rijpma of the Drawing Office of the Wageningen Agricultural University, the Netherlands, for the technical drawings of the equipment and the other figures illustrating oil palm measurements.