Isotopic Tracing of Phosphorus Uptake in Oil Palm Seedlings Leaf Axil Using 32P Labelled

Abstract

Pot experiments have been carried out to investigate the distribution pattern of Phosphorus in oil palm seedlings axillary axes using 32P radioisotope technique. The experiment was conducted in the greenhouse at the Center for Application of Isotope and Radiation - National Nuclear Energy Agency, Jakarta, Indonesia. KH232PO4 solution with the activity of 5 mCi was injected into five points viz through the lowest, middle, upper leaf axil, at the base of the trunk and the soil 5 cm from the trunk. The method used was randomized complete block design with two replications.The 32P uptake is expressed in counted per minute (cpm) counted by Liquid Scintillation Counter then transformed to disintegration per minute (dpm). The results showed that at the injection point in the lowest leaf axil, the distribution of 32P was more towards the crown before heading towards the roots.In the middle of the leaf axil,the distribution of 32P was recordedhigher, nutrients were actively distributed to the top of the plant while the roots were very low. The dynamics of 32P at the upper axil injection point, the highest 32P uptake at the start of the injection was seen in the lowest leaf axil. The 32P distribution then leads to the stem, roots and finally to the canopy. At the injection point in the soil 5 cm from the trunk, the counted value shows 32P distributed to the top of the plant, while at the base of the trunk, 32P is distributed to the farthest injection point, the plant canopy. From this study, it can be concluded that 32P radioisotopes can describe the distribution of nutrients in plant parts, wherever radioisotope is applied. Phosphorus can be applied through any leaf axil and can be distributed well to the canopy of plants.