Teng K.C.,University Tunku Abdul Rahman |
Koay J.Y.,Copenhagen University |
Tey S.H.,University Tunku Abdul Rahman |
Lim K.S.,Applied Agricultural Resources Sdn. Bhd |
And 2 more authors.
IEEE Transactions on Geoscience and Remote Sensing | Year: 2015
Very little work has been carried out to examine the potential of synthetic aperture radar (SAR) imaging data for growth monitoring, disease monitoring, and yield prediction of oil palm plantations. In this paper, we present a scattering model for oil palm based on the radiative transfer equations, solved iteratively up to the second order, to better understand the backscattering behavior of oil palm canopies for SAR image interpretation. The oil palm canopy is modeled as a multilayer background host medium embedded with discrete scatterers of different shapes, with elliptic disks representing the leaves and cylinders representing the fronds and trunks. We consider the effects of coherent scattering through the dense medium phase and amplitude correction theory, as well as the near-field interactions between closely spaced scatterers through the Fresnel phase and amplitude corrections. Ground-truth data are used as input parameters for the model. The model is used to calculate the backscattering coefficients of oil palm canopies at different stages of growth and for different polarizations, frequencies, and incident angles. Comparisons between model calculations and C-band scatterometer measurements of multipolarization backscattering coefficients of 4-year-old oil palm canopies in Bangi, Malaysia show good agreement. Our model also predicts that SAR images at L-band are more sensitive to changes in the structure of the canopies, particularly that of the fronds, so will be the best frequency for oil palm growth monitoring and disease detection. © 1980-2012 IEEE.
Teh C.B.S.,University Putra Malaysia |
Goh K.J.,Applied Agricultural Resources Sdn Bhd |
Husni M.H.A.,University Putra Malaysia |
Ishak C.F.,University Putra Malaysia
Annals of Applied Biology | Year: 2014
The decomposition and nutrient release temporal patterns of three oil palm residues used as soil mulch were studied. Empty fruit bunches (EFB; 1000 kg plot-1), Eco-mat (processed EFB carpet; 30 kg plot-1), and pruned palm fronds (180 kg plot-1) were left to decompose (and sampled monthly) on the soil surface for 8 months. The frond's leaflets had the highest initial concentration for most nutrients, and the frond's rachis and Eco-mat the lowest. The order of residue quality and rate of residue mass loss were: leaflets > fronds > EFB > Eco-mat > rachis. EFB however had a higher mass loss rate than the fronds. Residue mass loss and nutrient release rates were faster at the beginning than at the end of the decomposition period. Leaflets released the highest total amount of nutrients (except for K), and rachis the lowest. The fronds released either significantly higher (for N and Ca) or not significantly different (for P and Mg) total amount of nutrients than EFB. Converting EFB into Eco-mat had resulted in nutrient losses (e.g. N, K and Mg) and a residue quality reduction in Eco-mat. This study's results would aid in better soil and oil palm fertilisation management. © 2013 Association of Applied Biologists.
Teng K.-C.,University Tunku Abdul Rahman |
Koay J.-Y.,Copenhagen University |
Tey S.-H.,Applied Agricultural Resources Sdn. Bhd |
Ewe H.-T.,University Tunku Abdul Rahman |
Chuah H.-T.,University Tunku Abdul Rahman
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2014
The development of microwave remote sensing models for the monitoring of vegetation has received wide attention in recent years. For vegetation in the tropics, it is necessary to consider a dense medium model for the theoretical modelling of the microwave interaction with the vegetation medium. In this paper, a multilayer model based on the radiative transfer theory for a dense vegetation medium is developed where the coherence effects and near field interaction effects of closely spaced leaves and branches are considered by incorporating the Dense Medium Phase and Amplitude Correction Theory (DM-PACT) and Fresnel Phase Corrections. The iterative solutions of the radiative transfer model are computed with input based on ground truth measurements of physical parameters of oil palm plantations in the state of Perak, Malaysia, and compared with the SAR images obtained from RADARSAT2. Preliminary results are analyzed for dominant scattering mechanisms as well as monitoring of growth variation of oil palm trees for further development of operation models for long term monitoring of oil palm plantations. © 2014 IEEE.
Soh A.C.,Applied Agricultural Resources Sdn Bhd |
Wong G.,Applied Agricultural Resources Sdn Bhd |
Tan C.C.,Applied Agricultural Resources Sdn Bhd |
Chew P.S.,Applied Agricultural Resources Sdn Bhd |
And 6 more authors.
Journal of Oil Palm Research | Year: 2011
The announcements of breakthroughs in plant regeneration from tissue cultures of oil palm in the 1970s ushered in a new chapter in oil palm genetic improvement with projected yield increase of clones exceeding 30° over hybrid seeds. Howevei the subsequent ubiquitous appearance of the mantled fruit somaclonal variant in regenerated palms resulted in the early commercial oil palm tissue culture laboratories reverting tofurt her research and development (R&D). Applied Agricultural Resources Sdn Bhd persisted and, through its R&D, circumvented the impeding issues of unacceptably high fruit mantling, and low efficiencies of tissue culture amenability and selection of elite palms. In the process, it has established viable large-scale commercial propagation of oil palm clones by gel and liquid culture methods by the late 1990s. This achievement has since been emulated by more than a dozen commercial laboratories in Malaysia and elsewhere, producing about 3.5 million ramets per yeai This apparent success has led industry to believe that oil palm cloning is an established and efficient technology, and that more tissue culture laboratories to produce more high-yielding clones to replace hybrid seeds in planting and replanting will resolve the stagnating national yields. Much of the increased ramet production comes from more laboratories culturing more palms than in improved cloning efficiencies. Most of the clones currently produced are also derived either from advanced dura (D) x pisifera (P) hybrids or from commercial DxP fields with low heritability for yield. Consequently, the expected yields of the clones would not be much different from those of near true Fl and clonal hybrids which are currently available at a much reduced cost and without the attendant mantling risk. The agro-management needs of clonal plantings to maximize their fruit bunch yield potential have yet to be systematically addressed through scientific experimentation. Cloning ortets from the early or recombinant phases of hybrid breeding programmes would be more efficient with the wider genetic variability and higher heritability for yield and other desirable traits. Perhaps the biggest advantage of cloning would be in the early commercial exploitation of new genetic materials from introgression programmes of wide intra- or inter-specific crosses which would also broaden the genetic base of the commercial plantings to reduce the risk of genetic vulnerability to pests, diseases and environmental stress. Clones are unlikely to supersede hybrid seeds as the dominant oil palm planting material until the amenability and fidelity deficiencies in tissue culture have been furt her resolved or circumvented, and their field performance advantage over concurrent improved hybrids clearly demonstrated.