Elaeis guineensis is a species of palm commonly called oil palm but also sometimes African oil palm or macaw-fat. The first Western person to describe it and bring back seeds was the French naturalist Michel Adanson.Jean-Marie Pelt, « Michel Adanson, le baobab et les coquillages », dans La Cannelle et le panda : les grands naturalistes explorateurs autour du Monde, Fayard, 1999 .
It is native to west and southwest Africa, specifically the area between Angola and The Gambia; the species name, guineensis, refers to the name for the area called Guinea, and not the modern country Guinea now bearing that name. The species is also now naturalised in Madagascar, Sri Lanka, Malaysia, Indonesia, Central America, Cambodia, the West Indies, and several islands in the Indian and Pacific Oceans. The closely related American oil palm E. oleifera and a more distantly related palm, Attalea maripa, are also used to produce palm oil.
E. guineensis was domesticated in West Africa along the south-facing Atlantic coast. There is insufficient documentation and insufficient research to make any guesses as to when this occurred. Human use of oil palms may date as far back as 5,000 years in Egypt; in the late 1800s, archaeologists discovered palm oil in a tomb at Abydos, Egypt, dating back to 3000 BCE (but this information needs further investigation, due to recent reviews. The oil found in Abydos may be just date oil or even animal fats).
It is the principal source of palm oil. Oil palms can produce much more oil per unit of land area than most other oil-producing plants (about nine times more than soy and 4.5 times more than rapeseed). See especially this graph.
Description
E. guineensis is monocotyledonous. Mature palms are single-stemmed and grow to tall. The leaves are pinnate and reach long. A young palm produces about 30 leaves a year. Established palms over 10 years produce about 20 leaves a year. The flowers are produced in dense clusters; each individual flower is small, with three sepals and three petals.
The palm fruit takes 5–6 months to develop from pollination to maturity. It is reddish, about the size of a large plum, and grows in large bunches. Each fruit is made up of an oily, fleshy outer layer (the pericarp), with a single seed (the palm kernel), also rich in oil. When ripe, each bunch of fruit weighs between depending on the age of the palm tree.
Planting
For each hectare of oil palm, which is harvested year-round, the annual production averages 20 tonnes of fruit yielding of palm oil and of seed kernels yielding of high-quality palm kernel oil, as well as of kernel meal. Kernel meal is processed for use as livestock feed.
All modern, commercial planting material consists of tenera palms or DxP hybrids, which are obtained by crossing thickshelled dura with shell-less pisifera. Although common commercial germinated seed is as thick-shelled as the dura mother palm, the resulting palm will produce thin-shelled tenera fruit. An alternative to germinated seed, once constraints to mass production are overcome, are tissue-cultured or "clonal" palms, which provide true copies of high-yielding DxP palms.
Genetics Genome Size: 1,800 megabase. First sequence available in 2013.
Chromosomes Diploid, with a diploid number of 2n = 32.
Diversity The Asian effective population size is very limited. The cultivars comprising cultivation in Asia descend from only four trees, which are themselves probably the result of a selfing of one parent.
Breeding
Unlike other relatives, oil palms do not produce offshoots; propagation is by sowing the seeds.
Several varieties and forms of E. guineensis have been selected that have different characteristics. These include: Elais guineensis fo. dura Elais guineensis var. pisifera Elais guineensis fo. tenera
Before the Second World War, selection work had started in the Deli dura population in Malaya. Pollen was imported from Africa, and DxT and DxP crosses were made. Segregation of fruit forms in crosses made in the 1950s was often incorrect. In the absence of a good marker gene, there was no way of knowing whether control of pollination was adequate.
After the work of Beirnaert and Vanderweyen (1941), it became feasible to monitor the efficacy of controlled pollination. From 1963 until the introduction of the palm-pollinating weevil Elaeidobius kamerunicus in 1982, contamination in Malaysia's commercial plantings was generally low. Thrips, the main pollinating agent at that time, apparently rarely gained access to bagged female inflorescences. However, E. kamerunicus is much more persistent, and after it was introduced, Deli dura contamination became a significant problem. This problem apparently persisted for much of the 1980s, but in a 1991 comparison of seed sources, contamination had been reduced to below 2%, indicating control had been restored.
A 1992 study at a trial plot in Banting, Selangor, revealed the "yield of Deli dura oil palms after four generations of selection was 60% greater than that of the unselected base population. Crossing the dura and pisifera to give the thin-shelled tenera fruit type improved partitioning of dry matter within the fruit, giving a 30% increase in oil yield at the expense of shell, without changing total dry matter production."
Cros et al., 2014 find genomic selection is very effective in this crop.These reviews cite this research.
Agronomic genes
In 2013, the gene responsible for controlling shell thickness was discovered, making it possible to verify tenera (DxP) status while palms are still in the nursery.
The gene regulates floral architecture. One of its epialleles, , reduces yield.
Pollination E. guineensis is almost entirely pollinated by insects and not by wind. Elaeidobius kamerunicus is the most specially adapted pollination partner in Africa. It has been deliberately introduced into southeast Asia in 1981 and the results have been dramatic – Cik Mohd Rizuan et al., 2013 find good results in in Sabah. Contrary to earlier speculation, the introduced population was not too inbred, and inbreeding depression was not the cause of some incidences of lessened fruit set in SEA. Other causes have been proposed. E. kamerunicus and the pollination it provides can be negatively affected by nematodes.p.130
Pests Disease Worldwide the two most impactful diseases are Ganoderma orbiforme (syn. Ganoderma boninense, basal stem rot, BSR, reviewed by Chong et al., 2017 ) and Phytophthora palmivora (bud rot, reviewed by Torres et al. 2016 AGRIS id US201600293676.). The earliest stages of data gathering and investigation have been performed for disease resistance breeding however propagation material is not available and full breeding programs are not ongoing .p.425
Ganoderma boninense/orbiforme, Basal Stem Rot (BSR) Basal stem rot is the most serious disease of oil palm in Malaysia and Indonesia. Previously, research on basal stem rot was hampered by the failure to artificially infect oil palms with the fungus. Although Ganoderma had been associated with BSR, proof of its pathogenicity to satisfy Koch's postulate was only achieved in the early 1990s by inoculating oil palm seedling roots or by using rubber wood blocks. A reliable and quick technique was developed for testing the pathogenicity of the fungus by inoculating oil palm germinated seeds.
This fatal disease can lead to losses as much as 80% after repeated planting cycles. Ganoderma produces enzymes that degrade the infected xylem, thus causing serious problems to the distribution of water and other nutrients to the top of the palm. Ganoderma infection is well defined by its lesion in the stem. The cross-section of infected palm stem shows that the lesion appears as a light brown area of rotting tissue with a distinctive, irregularly shaped, darker band at the borders of this area.Turner PD. Palm oil Diseases and Disorders. Oxford University Press, 1981. The infected tissue become as an ashen-grey powdery and if the palm remains standing, the infected trunk rapidly becomes hollow.
In a 2007 study in Portugal, scientists suggested control of the fungus on oil palms would benefit from further consideration of the process as one of white rot. Ganoderma is an extraordinary organism capable exclusively of degrading lignin to carbon dioxide and water; celluloses are then available as nutrients for the fungus. It is necessary to consider this mode of attack as a white rot involving lignin biodegradation, for integrated control. The existing literature does not report this area and appears to be concerned particularly with the mode of spread and molecular biology of Ganoderma. The white rot perception opens up new fields in breeding/selecting for resistant cultivars of oil palms with high lignin content, ensuring the conditions for lignin decomposition are reduced, and simply sealing damaged oil palms to stop decay. The spread likely is by spores rather than roots. The knowledge gained can be employed in the rapid degradation of oil palm waste on the plantation floor by inoculating suitable fungi, and/or treating the waste more appropriately (e.g. chipping and spreading over the floor rather than windrowing).
Markom et al., 2009 developed and successfully used an electronic nose system for detection.
Phytophthora palmivora Phytophthora palmivora has caused a loss of of E. guineensis near San Lorenzo in Ecuador. The protozoa cause bud rot (). In reaction, growers there replanted using a hybrid of E. guineensis and E. oleifera, the South American oil palm.
Endophytic bacteria Endophytic bacteria are organisms inhabiting plant organs that at some time in their life cycles can colonize the internal plant tissues without causing apparent harm to the host. Introducing endophytic bacteria to the roots to control plant disease is to manipulate the indigenous bacterial communities of the roots in a manner, which leads to enhanced suppression of soil-borne pathogens. The use of endophytic bacteria should thus be preferred to other biological control agents, as they are internal colonizers, with better ability to compete within the vascular systems, limiting Ganoderma for both nutrients and space during its proliferation. Two bacterial isolates, Burkholderia cepacia (B3) and Pseudomonas aeruginosa (P3) were selected for evaluation in the glasshouse for their efficacy in enhancing growth and subsequent suppression of the spread of BSR in oil palm seedlings.
Little leaf syndrome Little leaf syndrome has not been fully explained, but has often been confused with boron deficiency. The growing point is damaged, sometimes by Oryctes beetles. Small, distorted leaves resembling those due to a boron deficiency emerge. This is often followed by secondary pathogenic infections in the spear that can lead to spear rot and palm death.
Cadang-cadang Cadang-cadang disease is a viral disease that also infects coconuts.
Bursaphelenchus cocophilus/Red Ring Disease (RRD) Red ring disease is caused by Bursaphelenchus cocophilus, see §Nematode pests below.
Insects as vectors
Besides direct damage to plant material, insects are also vectors of oil palm diseases.
Arthropod pests
Metisa plana M. plana is a Lepidopteran moth and a major pest of oil palms in Malaysia. M. plana outbreaks in Malaysia are highly correlated with relative humidity. Relative humidity estimates based on satellite remote sensing data were fed into both regression models and neural networks. The predictions of both were found to be closely correlated with actual M. plana appearance on plantations, with the NN producing the best results.
Raoiella indica R. indica was invading the Yucatanp.128 placing 11 states of Mexico under phytosanitary vigilance.Supplemental Table 1
Rhynchophorus ferrugineus R. ferrugineus has placed 13 states of Mexico under phytosanitary vigilance.
Other arthropods