Category Archives: 1996 Vol 8 No 2

The genetic improvement of the Deli Dura breeding population of the oil palm Elaeis guineensis Jacq.

The Deli dura breeding population of Elaeis guineensis has a restricted genetic base, with limited heritable genetic variation for the improvement of bunch yield and its two components, mean annual bunch number and single bunch weight. The introgression among Deli sub-populations as a means of improving heritability is here investigated.

Analysis of variance with the estimates of the expectation of mean squares was carried out on three populations: intra-Deli, inter-Deli and inter-dura. Estimates of total and heritable genetic variance (VG and h2 respectively) for total bunch yield and the two components were obtained for the three populations.

Over a four-year period total yield was highest in the inter-dura population (80.3 kg/palm/year) and least in the inter-Deli population (42.4 kg/palm/year). VG was absent for total yield and its two components in the intra-Deli population, but highly significant for all three traits in the inter-Deli and inter-dura populations. For average bunch number h2 was highly significant and accounted for most of the genetic variation for these two populations. Similarly, for single bunch weight in the inter-dura population, h2 accounted significantly for the VG. In the inter-Deli population h2 and non heritable genetic variation significantly determined the average bunch weight. The total yield of fresh fruit bunches was determined mainly by non heritable genetic variation in the inter-Deli population, while heritable genetic variance was high and significant in the inter-dura population.

The continual exploitation of the Delis in the various breeding programmes will not result in genetic improvement for bunch yield. Future progress must rely on the creation of new high yielding populations with a broad genetic base for which heritability for total yield can become significant, as is the case with the inter-dura population evaluated in this study.

Parasitoids and predators of insects associated with oil palm (Elaeis guineensis Jacq.) in India

Oil palm nurseries and plantations in India were surveyed from April 1985 to February 1992 and 57 species of natural enemies of insects associated with the oil palm were recorded. These included 24 species of parasitoids, 17 species of predatory insects and 16 species of spiders. In the majority of the insects infesting the oil palm in India, native natural enemies could be found and the highest number of such natural enemies were reported on the diaspids encrusting fruits and leaves and the psychids causing defoliation. The role of these parasitoids and predators in naturally suppressing populations of limacodids, psychids and diaspids was highlighted. Infestations of the defoliating psychids and limacodids in Little Andaman Island were attributed to a lower incidence of parasitism by their natural enemies, thus augmenting these parasitoids from the main land in Little andaman Island is suggested.

Crystallisation behaviour of palm oleins

The tendency for palm oleins to cloud when subjected to cold temperatures has long been a problem for the palm oil industry. In the present study, the crystallisation behaviour of palm oleins was evaluated by means of differential scanning calorimetry (DSC), X-ray diffraction and nuclear magnetic resonance (NMR) spectrometry. While the ratio of saturated to unsaturated triacylglycerols in the olein was an important criterion affecting costallisation at low temperatures, the content of diacylglycerols particularly 1,3 dipalmitoylglycerol, was also important in the crystallisation behaviour.

Variation of dielectric properties of oil palm mesocarp with moisture content and fruit maturity at microwave frequencies

Dielectric properties at frequencies from 0.2GHz to 20 GHz of mashed mesocarp of oil palm fruits at various stages of maturity are presented.

Measurement of microwave permittivity was done by using open-ended coaxial line probe and automated network analyzer. The accuracy of measurement is about 5% for dielectric constant, ε’ and 3% for dielectric loss factor, ε”. Results of measurement show that the ionic conductivity dominated in the region less than 3GHz, while above 3GHz the dipole orientation of water molecules becomes dominant. The effect of ionic conductivity is higher in young fruit and decreasing as degree of maturity increases.

Permittivity of oil palm mesocarp over the frequency range was found to increase with moisture content. A significant variation of ε’ and ε” with maturity at 0.2GHz and 10GHz respectively make it suitable to form a maturity index as suggested by Nelson et al.. With moisture content ranging pom 25% to 85%, the ε’ at 2GHz varies from 11 to 61 and the ε” varies from 2.1 to 24.6 at 10 GHz. Based on the above values the permittivity-based maturity index for young and fully ripe fruits are 1 and 0.3 respectively.

The results of the dielectric properties of mashed mesocarp also agree reasonably with predicted values from mixture model especially at frequencies above 3 GHz. At 10 GHz the difference between predicted and measured values are within 5%.

This study gives valuable information for the analysis and design of microwave sensor for quality assessment of the oil palm fruits and could also be used for estimating microwave absorption during fruit sterilization and fruit loosening.

Rapid callus proliferation, somatic embryogenesis and organogenesis of oil palm (Elaeis guineensis Jacq.)

Modified Eeuwens (1976) medium containing 5mg/l NAA (Y3(3A))promoted the fast growth of callus tissues of Elaeis guineensis Jacq. at the first passage. Subsequent passages of the cultures on Y3(3A) produced callus nodules, green embryoid nodules and few plantlets but callus nodules were predominant. Spontaneous somatic embryogenesis of the callus tissues was stimulated at the first passage on DM(1) which was the modified Eeuwens (1976) basic medium (Y3(0)) supplemented with NAA (0.5mg/l) and Kinetin (2.0mg/l). Embryoids were also obtained from callus on the initiation medium (Y3(3)) and the maintenance medium (Y3(3A)). Subsequent passages on DM(1) resulted in the formation of more green embryoid nodules, leaf primordia, well developed leaves, roots and plantlets. Furthermore, the transfer of the embryogenic tissues from Y3(3A) and DM(1) media to Y3(0) enhanced the production of more plantlets. Also, the formation of adventitious roots by shoots and plantlets was stimulated on the Murashige and Skoog medium (1962) as modified by Hyndman et al. (1982). Pneumathode-like structures were occassionally observed in the callus cultures particularly on the explant with callus. The plantlets have subsequently been planted in the field where they are growing satisfactorily.

Clarity of single and double fractionated palm oleins

The clarity of single and double fractionated palm oleins of different iodine values (IV) were studied. At 5°C, all samples crystallized within a day; two samples (DfPOo IV 65 and 67) were cloudy while the rest became solid. On the other hand, all samples were clear at 20°C except SfPOo IV 56 and 58. Samples DfPOo IV 62, 65 and 67 remained clear at 20°C until day 60. Fatty acid composition and the content of diglycerides seemed to have an influence on the clarity of palm oleins.