Abstract

Up to present, a favorable groundwater level for sago palm to thrive and to produce large trunk biomass post-trunk formation is not confirmed yet. Moreover, there is also no information of how the starch content reduces during harvest transportation and how peat and sea water media affecting the change of starch content on harvested logs. The objectives of this study were to investigate the effect of groundwater level on growth of sago palm post-trunk formation and change of starch content during harvest transportation via peat and sea water media. As sago palm is a crop that thrives in wetlands, certain groundwater levels need to be investigated to elucidate the most suitable growth environment for sago. The study used stratified randomized sampling method in selecting the palm sample. Three different blocks with different annual groundwater levels of 5.3, 6.8, and 28.5 cm were used. Trunk diameter, biomass, elongation rate, node length and frond emergence rate were measured. Harvested logs were sampled to track the reduction of starch content during floating in peat water and staying on seashore for 5 weeks. The results found that groundwater level of 6.8 cm gave the best trunk diameter and its biomass, followed by 5.3 cm, and they tended to show a significant decline when the level was deeper from soil surface (28.5 cm). Those two treatments (5.3 and 6.8 cm) also produced significant increases on trunk elongation rate (1.0 m/year) and its average node length (11.7 and 10.7 cm), respectively. The reduction of starch content in harvested logs on peat water (2.16%/week) was almost twice than those stayed on seashore (1.34%/week). From the above findings, we discovered that proximity of groundwater level for sago palm to thrive post-trunk formation on peatland was close to soil surface, which in turn suggested the importance of water management on its cultivation practice. It is also recommended that harvested logs transported via peat water should reach the mill within a week to avoid greater loss of starch, while sea transportation offers a viable alternative for longer transportation periods.