No abstract

Theoretical and practical options for mutation breeding in oil palm are discussed. In theory, haploids are considered the ideal targets, as the induced mutation can be fixed instantly on conversion to doubled haploids. However, haploid/doubled haploid technology is in its infancy in oil palm and therefore other practical targets need to be considered. The two obvious targets are pollen and seed, as these are produced in large numbers in breeding and commercial seed production. Schemes for pollen and seed irradiation and subsequent mutant population development are compared. The irradiation of germinated seed is currently considered to be the better approach in terms of convenience and time. A major constraint in mutation breeding in oil palm is the long life cycle. Oil palm has a long juvenile stage, and it takes 4-5 years from sowing a seed to getting seed of the next generation. Traditionally, mutant selection has relied on phenotypic selection, which can only take place in the second mutant generation (M2) due to the presence of physiological disorders and chimeras in the M1. However, now that the oil palm genome has been sequenced, it is feasible to select for mutants genotypically in the M1. Early detection of mutants is extremely valuable in oil palm, as it saves space in growing up only selected mutants in the field. Mutation breeding is a non-GM technique that has been used for over nine decades. New methods in genetic manipulation include gene editing, which has huge potential for the future but is currently still under debate as to whether it is considered a GM method and is subject to restrictive regulations.

A central objective in Verdant's mission is to develop better, more productive and more sustainable cultivars of oil palm (Elaeis guineensis), rubber and other plantation crops, particularly through plant breeding. Field testing is an essential component in selecting and developing new varieties with superior performance for yield, quality, pest and disease resistance and in meeting new market demands, for example, specialised oil quality. This manual covers the basic and changing practices such as land preparation, planting and data recording of trials. Field trialling of oil palm includes breeding trials (selection within promising new genotypic combinations or germplasm), particularly by progeny testing to establish new commercial lines and identifying Ganoderma resistant/tolerant material (Ganoderma is the most important disease of oil palm in Southeast Asia, while Fusarium is in Africa). This manual forms part of a series in 'Techniques in Plantation Science', and fits 'in between' Nursery Practices in Oil Palm and Seed Production in Oil Palm. It follows on from Crossing in Oil Palm. Target audiences are plant breeders, planters, students and researchers in oil palm agriculture, along with plant breeders and end-users interested in the practicalities of producing high quality oil palm planting materials for breeding and commercial production.

Seed production processes for breeding follow the same basic processes as described for (Dura) commercial seed. Breeding seed may be either Dura (thick shelled) or Tenera (thin shelled). As in commercial production, oil palm breeding seeds require heat treatment before germination will start. Seed processing procedures described in Chapters 6-9 of this manual should be implemented, but the target is dependent on the numbers of germinated seeds required for breeding purposes, e.g. trialling. Also, Tenera seeds, which are thin shelled, are treated slightly differently to thick-shelled Dura seeds during the heating step to break dormancy. Normally, Tenera seeds have a lower germination rate compared to Duras, due to them being more susceptible to fungal attack.

Oil palm seeds have sessile embryos and, for germination to start, the operculum that blocks the germ pore (and essentially makes the seed dormant) has to be weakened. Seed processing procedures must be implemented and monitored to ensure maximum and uniform germinations are achieved; the usual commercial target is over 80%.