No abstract

Trace elements phytoavailability depends on the physical and chemical propertiesof soil. At the Crocker range of West Coast Sabah, Malaysia, the Pandasan paddyvariety can be cultivated as flooded rice paddies or upland rice on acidic soil.Pandasan paddy samples were collected in Kiulu subdistrict from traditionalfarmer at two different locations. Available sources of trace elements were fromweathering, fertilizers and pesticides. Soil and plant samples were collected aftertwo months of seed sowing and during harvest season which was five months oldfor heavy metal analysis by inductively coupled plasma optical emissionspectrometry (ICP-OES). Translocation factor of arsenic from root to grainindicated this trace element was very mobile in Pandasan paddy cultivated at drysoil compared to wet soil followed by zinc. Although, cadmium was not detected inpaddy cultivated at flooded field for both, soil and plant, cadmium was detected insoil and plant roots cultivated in dry condition. Enrichment factor results suggestedthat Pandasan plant cultivated on dry soil was only a good bioindicator for leadand zinc. Pandasan grain was rich with iron followed by zinc. Selected heavymetals accumulation in Pandasan grain cultivated in flooded field did not exceededthe permissible limit of Malaysia Food Regulation 1985. However arsenic andplumbum concentration in Pandasan grain harvested from dry soil exceeded thepermissible limit of Malaysia Food Regulation 1985. Health risk of heavy metalstoxicity can be reduced if Pandasan paddy is cultivated in flooded field comparedto dry soil.

The prospect of three native upland paddy landraces known as Bokilong, Ponsulak and Taragang as heavy metals accumulator for phytoremediation was determined. Bioaccumulation of heavy metals (As, Cd, Cr, Cu, Fe, Pb, and Zn) in various parts of paddy plants collected from Kiulu valley, North Borneo in the natural conditions during the vegetative phase and harvest season were analysed by Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). All selected heavy metals were traced in soil samples of all three paddy landraces rhizosphere where the most available heavy metals were Fe followed by Zn. Heavy metals bioavailability in soil seemed to be influenced by the local climate of the cultivation field. Bokilong landrace is an accumulator of As, Cd, Cu, Pb and Zn. Ponsulak paddy can help clean up the soil by phytoextraction of As, Cr, Cu, Fe and Zn. Taragang paddy has a prospect in phytoextraction of Cd and Pb to remediate excess amount of this element in the soil. Different heavy metals concentration trends were accumulated in these three paddy landraces in grain indicated different nutritional values. Heavy metal uptake characteristic differs between upland paddy landraces and there was also environmental influence affecting the mobility rate of these elements in paddy plant depending on the element type and paddy genotype.