greenhouse gas, it is reasonable to say that simply increasing the amount of fertilizer
application is undesirable.
Sago palm that is a tropical non-leguminous plant is cultivated without fertilizer
application in many cases and grows in peat and mineral soils. Okazaki and Toyota
(2003) supposed that a sago palm can thrive under infertile conditions, it is expected
to possess some mechanisms to obtain nutrients, especially nitrogen effectively
under such conditions. As described above, it was clarified that the nitrogen fixing
bacteria colonize various parts of the sago palm and actively fix nitrogen (Shrestha
et al. 2006; Shrestha et al. 2007). Based on acetylene-reducing activity in different
parts of sago palm, such as root, pith, leaf sheath, the amount of fixed N 2 in a mature
sago palm was estimated at 228 g N/ palm/y (Toyota 2018). The density of matured
sago palms that have a trunk ranged from 165 to 223 palms/ha, depending on the
planting density (Jong and Flach 1995), and immature sago palms before the trunk
formation also fix N through their root systems and leaf parts. Considering the
published result from Jong’s case study (1995) and our experience to monitor the
change in the number of suckers that were appeared from a leading palm (planted
sucker or seedling) in each clump at the experimental field in Kendari, Indonesia
(unpublished data), a total amount of fixed N 2 was estimated from 45 kg to 75 N/ha/
y. Yonebayashi et al. (2008) estimated using δ
15 N values that the contribution of N 2
fixation to the N content in sago leaves ranged from below 30% until 8 years old to
ca. 90% in 13 year old palm trees. In the oil palm, the contribution of biologically
fixed N 2 to total N was estimated at 63% on the whole plant basis (Zakry et al. 2012).
17.6 Starch Production
Yamamoto et al. (2003a) surveyed that the relationship between the distance from
the sea and starch yields with the growth performance in sago palms at the harvestable stage (from the flower stalk formation to the flowering stage) grown in the peat
soil in Tebing Tinggi Island, Riau, Indonesia. In their study, the sago palm grown
within 20 m from the coast had a trunk sizing 5–6 m long with 42 cm in diameter.
The sago palms growing close to the coast were much smaller than those found more
than 100 m from the coast, which have trunk sizing 9–11 m long with 46–52 cm in
diameter. Consequently, the trunk weight of the ones on the shoreline was
470–570 kg (per plant). The value was significantly smaller than that of the sago
palms found 100 m inland, namely 1140–1710 kg. However, the starch concentration in pith of the coastal sago palms was 65–84%, which was comparatively higher
than that of the sago palms inland, namely 66%. Conclusively, the starch yield of the
sago palms grown close to the coast was 86–150 kg and was smaller than that of
those inland, which amounted to 284–416 kg (per plant). It is considered that the
difference in the starch yield of sago palms grown at different distances from the
coast might be attributed to the difference in trunk volume (Yamamoto 2015b).
17 Sago Palm in Peatland
499
application is undesirable.
Sago palm that is a tropical non-leguminous plant is cultivated without fertilizer
application in many cases and grows in peat and mineral soils. Okazaki and Toyota
(2003) supposed that a sago palm can thrive under infertile conditions, it is expected
to possess some mechanisms to obtain nutrients, especially nitrogen effectively
under such conditions. As described above, it was clarified that the nitrogen fixing
bacteria colonize various parts of the sago palm and actively fix nitrogen (Shrestha
et al. 2006; Shrestha et al. 2007). Based on acetylene-reducing activity in different
parts of sago palm, such as root, pith, leaf sheath, the amount of fixed N 2 in a mature
sago palm was estimated at 228 g N/ palm/y (Toyota 2018). The density of matured
sago palms that have a trunk ranged from 165 to 223 palms/ha, depending on the
planting density (Jong and Flach 1995), and immature sago palms before the trunk
formation also fix N through their root systems and leaf parts. Considering the
published result from Jong’s case study (1995) and our experience to monitor the
change in the number of suckers that were appeared from a leading palm (planted
sucker or seedling) in each clump at the experimental field in Kendari, Indonesia
(unpublished data), a total amount of fixed N 2 was estimated from 45 kg to 75 N/ha/
y. Yonebayashi et al. (2008) estimated using δ
15 N values that the contribution of N 2
fixation to the N content in sago leaves ranged from below 30% until 8 years old to
ca. 90% in 13 year old palm trees. In the oil palm, the contribution of biologically
fixed N 2 to total N was estimated at 63% on the whole plant basis (Zakry et al. 2012).
17.6 Starch Production
Yamamoto et al. (2003a) surveyed that the relationship between the distance from
the sea and starch yields with the growth performance in sago palms at the harvestable stage (from the flower stalk formation to the flowering stage) grown in the peat
soil in Tebing Tinggi Island, Riau, Indonesia. In their study, the sago palm grown
within 20 m from the coast had a trunk sizing 5–6 m long with 42 cm in diameter.
The sago palms growing close to the coast were much smaller than those found more
than 100 m from the coast, which have trunk sizing 9–11 m long with 46–52 cm in
diameter. Consequently, the trunk weight of the ones on the shoreline was
470–570 kg (per plant). The value was significantly smaller than that of the sago
palms found 100 m inland, namely 1140–1710 kg. However, the starch concentration in pith of the coastal sago palms was 65–84%, which was comparatively higher
than that of the sago palms inland, namely 66%. Conclusively, the starch yield of the
sago palms grown close to the coast was 86–150 kg and was smaller than that of
those inland, which amounted to 284–416 kg (per plant). It is considered that the
difference in the starch yield of sago palms grown at different distances from the
coast might be attributed to the difference in trunk volume (Yamamoto 2015b).
17 Sago Palm in Peatland
499