Determining criteria of harvestable sago palm (Metroxylon sagu Rottb.) cultivated on deep peat and uptake of its macro- and micronutrients on shoot

Sago palm (Metroxylon sagu Rottb.) is normally harvested from bolting to flowering stages on a commercial scale. Since flowering stage can last for months and number of living fronds gradually reduces, proper harvest criteria need to be managed. The nutrient content of the shoot may provide knowledge to estimate the need of major and minor nutrients but information is still limited. Two experiments were performed to study harvest criteria particularly at flowerings stage and nutrient uptake on harvestable palm cultivated on deep peat. Contents of N, P, K, Ca, Mg, Fe, Mn, Zn, B, Cu, starch and moisture contents were analyzed. Fifteen selected palms at various development stages were distributed on around 350 ha cultivated area. A maximum starch content was observed at just after flowering followed by bolting stage (22.34–28.75%) and their differences were not significant. Palm at flowering stage carrying ≥5 living fronds still contained starch content above 20%. It significantly reduced to 11.96 and 8.61% when number of fronds were four and two, respectively. In 595.6 kg shoot dry matter, K (3,402.8 g) was majorly taken up followed by N (2,111.3 g), Ca (2,043.1 g), Mg (831.4 g), and P (274.0 g). Among micronutrients, Mn (60,663.6 mg) was majorly taken up followed by Fe (19,440.7 mg), Zn (11,100.0 mg), B (3,120.5 mg), and Cu (1,338.1 mg). In conclusion, palm at flowering stage carrying five number of fronds and above is still harvestable. Hence, to obtain high starch productivity, harvest should be managed on bolting and just after flowering stages.