Category Archives: 1993 Vol 5 No 2

The root system of the oil palm (Elaeis guineensis, Jacq.) II : Indirect estimations of root length, diameter and surface area

Direct measurements of oil palm root length, diameter and surface area are time consuming and laborious in the absence of a sophisticated image analyser. A study to examine indirect estimations of these root parameters with and without elutriation was therefore conducted.
The results showed that two non-elutriation methods (which were extensions of Tennant’s formula and Drew and Sakers’ method respectively) did not provide accurate estimates of root length per soil core. The correlations between direct measurements of root length and lengths obtained by each of the above methods were low.
Root length per soil core could be estimated from root dry weights by regression if the roots were categorized into different diameter classes: primary roots > 7 mm (XI), 4-7 mm (X2) and < 4 mm (X3); secondary roots > 1.2 mm (X4) and < 1.2 mm (X5); and feeder roots (X6). Their coefficients of determination (r2) ranged from 0.86 to 0.95.
Step-wise regression analysis showed that total root length (cm) per soil core (Y) could be estimated by the equation:

Y = 15.8 + 14.2 X3 + 95.6 X4 + 364.9 X5 + 394.6 X6 with an r2 of 0.91.

Root diameters and surface areas were also highly correlated with root dry weights.

Effect of cocoa butter on the compatability of specialty fats

Selected commercial samples of vegetable specialty fats, i.e. palm mid-fraction (PMF), Borneo tallow(IP) and sal stearin(SLs) were blended with cocoa butter (CB) in multi-component system. The compatibility of the blends was monitored from the changes of solid fat content (SFC). With the addition of 50% CB to the systems, the eutectic effect among the specialty fats was no longer detected. The maximum amount of PMF that can be used in the formulation of a final product may not be directly correlated with its perforamnce in the formulation of cocoa butter equivalent (CBE). In order to comply with the requirement of 50% SFC at 30°C in blends of 50% CBE and 50% CB, the maximum level of PMF in the CBE formulation itself was 50 percent.

Pathogenicity test on Beauveria bassiana (Balsamo) against oil palm bagworm (Metisa plana Wlk)

The pathogenicity of Beauveria bassiana (Balsamo) Vuillemin towards bagworm, Metisa plana Wlk. second and fourth instars of Metisa plana Wlk. was confirmed. The larvae were sprayed with different concentrations of conidia suspension and exposed at a temperature of 28±1°C and a relative humidity of 65%-75% and 85%-100% (‘ambient’ and ‘humid’ respectively). The percentage mortality, lethal concentration (LC50) and the leaf area damaged (LAD) were calculated. B. bassiana was capable of infecting both stages of M. plana. The percetage mortality increased with increasing concentration of coxidia suspension. The LC50 of B. bassiana for second instar was 4.2 x 104 conidia/ml under humid, and 1.5 x 106 conidia/ml under ambient moisture conditions. For fourth instar the LC50 was 2.4 x 106 conidia/ml under humid and 2.5 x 107 conidia/ml under ambient moisture conditions. Second instar of Metisa plana Wlk. was thus more susceptible to the pathogen than fourth instar. Increased humidity enhanced the pathogenicity of B. bassiana and lowered the feeding activity of M. plana.

Micronutrients in peat : 1 preliminary analysis by different extraction methods

Micronutrients especially Zn and Cu, are normally present in too low a concentration in peat to be adequately available to a crop.

This study was conducted to compare the characteristics of several classes of peat and to do a preliminary assessment on the actively and potentially plant-available form of micronutrients as a guide to the use in peat of fertilizers containing micronutrients.

Five different extractants, namely ammonium acetate-EDTA, ‘double acids’ (0.05 N HCl/0.025 N H2SO4, 0.5 M HNO3, 0.1 M HCl and 0.2 N NaOH, were investigated on six different classes of peat.

The amounts of micronutrients extracted differed with the extractants used, depending on the nature of the peat, its drainage status and its agricultural utilization. Ammonium acetate-EDTA and NaOH were effective in extracting Cu and Fe: for example NaOH removed about 70%-93% of total Cu from peat. Ammonium acetate-EDTA, double acids, HCl and nitric acid were comparable, and appeared to be good extractants to displace Zn and Mn from peat. However, all the extractants studied merit further investigation to correlate the micronutrients extracted with the actual uptake by crops to obtain more useful and meaningful information on their availabilities in peat.

Neutral lipid composition of oil from two varieties of oil palm in India

The neutral lipids were isolated from palm oil from dura and pisifera varieties of Elaeis guineensis grown in India. On examination by TLC, they were found to be composed of triacylglycerols (87.7% and 89.8% respectively), diacylglycerols (4.5%, 3.8%) monoacyglycerols (1.2%, 1.0%), free fatty acids (4.0%, 3.0%) and sterol esters (1.6%, 1.4%), along with hydrocarbons and free sterols (1.0%, 1.0%).

GLC analysis of the sterols and sterol esters revealed the presence of β-sitosterol, stigmasterol, campesterol and brassicasterol, identified by reference to the relative retention time values of the standards. GLC analysis of the triacylglycerols, diacylglycerols, monoacyglycerols, free fatty acids, and sterol esters showed the presence of mainly palmitic and oleic acids, along with some stearic, linoleic and linolenic acids.

Effect of trans fatty acids on plasma lipid and lipoprotein levels in cynomolgus monkeys

Nine cynomolgus monkeys (Macaca fascicularis) were fed a purified diet containing 30 en % as cococut oil for three months and then rotated through three different cholesterol-free purified diets in which 30% energy was derived from fat. The dietary fats used were partially hydrogenated soyabean oil rich in trans-fatty acids (PHSBO), palm olein (Poo) and an American Heart Association (AHA) Step I fat blend. Total cholesterol and LDL-C increased significantly (P<0.02) when the monkeys were fed the PHSBO diet as compared with the AHA diet. No significant differences in TC or LDL-C were seen as between the POo and AHA diets.

To evaluate the effect of limited linoleic acid in the PHSBO diet, the monkeys were again fed PHSBO, but blended with safflowerseed oil (SFO) to provide linoleic acid at 3.72 en per cent. Cholesterol levels decreased substantially by comparison with the coconut oil (CNO) and PHSBO diets, suggesting that inadequate 18:2 intake was an important factor in the hypercholesterolemia induced in these monkeys.

Palm Oil Abstracts

This article compiles abstracts of articles and papers related to palm oil/ oil palm and other oils and fats, published in journals, books, conference proceedings and other publications.