Introduction.

Abstract

Abstract Field testing - trialling - of oil palm is subject to many factors, chief among them being the basic biological features of the crop (it is a long-lived perennial) and the traits to be assessed (mainly yield, thus mature palms need to be produced). Trialling is the next step after breeders have produced progeny from deliberate crosses, and this in turn is dependent upon the genetic variation available to the breeder (see Setiawati et al., 2018, this series). Trialling allows the selection of progenies and palms based on field performance, and these can then be promoted to variety status and commercial production (see Kelanaputra et al., 2018, this series). Oil palm, Elaeis guineensis, is the world's most important oil crop. Although it has been used to some extent as a food since ancient times in its centre of origin (West Africa), it is a relatively modern crop, with Southeast Asia now being the main production region. A brief history of the development of the oil palm crop (significant dates and eras) is given. Improvement of the crop through breeding and trialling is relatively recent, with beginnings in the early 20th century. Since breeding is dependent upon access to traits of interest, germplasm collections from the centre of origin have been made. In addition, variation is being produced by mutation induction and selection (see Nur et al., 2018, this series). Thus, oil palm breeders have access to a rich germplasm base and can create progenies which combine novel traits (e.g. disease resistance) with traditional traits (e.g. thin-shelled fruit type), which then need to be tested in field trials.