DYNAMICS OF SUCROSE PHOSPHATE SYNTHASE AND FRUCTOSE BISPHOSPHATE SYNTHASE IN OIL PALMS FERTILISED WITH LOW NITROGEN [(NH2)2CO] DOSE WITH NPPTNBPT COATING IN RED-YELLOW PODZOLIC SOIL

One of the predominant deterrents of oil palm cultivation in Indonesia, especially in red-yellow podzolic soils, is nitrogen constraint, which is accelerated by heavy persistent rainfall and severe tropical temperature. This study was conducted with the objective to determine the effect of low-dose urea fertilisation with 0.12% N-(n-propyl) thiophosphoric triamide (NPPT) and N-(n-butyl) thiophosphoric triamide (NBPT) coating on the metabolic characters, the yield components, and the total yield of the oil palm. The field experiment was conducted for twelve months between November 2016 and November 2017 at the Seruyan Tengah Oil Palm Plantation, Seruyan Regency, Central Kalimantan Province, Indonesia. The experimental design utilised a single factor complete randomised block design with three blocks as repeatition. The applications consisted of the untreated one, without [(NH 2 ) 2 CO], with 195 kg ha −1 [(NH 2 ) 2 CO], 195 kg ha −1 [(NH 2 ) 2 CO] + 0.12% NPPT and NBPT, 156 kg ha −1 [(NH 2 ) 2 CO], and 156 kg ha −1 [(NH 2 ) 2 CO] + 0.12% NPPT and NBPT. The results demonstrated that low-dose fertilisation of 156 kg ha −1 [(NH 2 ) 2 CO] + 0.12% NPPT and NBPT elevated the N content of the leaf tissue, nitrate reductase activity (NRA), sucrose phosphate synthase (SPS), fructose biphosphate synthase (FBS), reducing sugar, sucrose, and invertase activity while reducing the dosage of [(NH 2 ) 2 CO] by 20.00% in comparison to the high dose treatment of 195 kg ha −1 [(NH 2 ) 2 CO].