Jalil et al. (1991) reported that the starch yield of sago palm varies depending on
the distance from the coast. Such a finding was suspected to be related to both a high
groundwater level and salt concentration that affect the growth of sago palms in
coastal habitat with a sustained high soil water table according to Okazaki and
Kimura (2015). Sago palms show a considerably high resistance against brackish
water with salt avoidance mechanism (Ehara et al. 2006).
Sago palms thrive in mineral soils and thin layers of peat soil (Sato et al. 1979).
As Okazaki and Kimura (2015) explained, the argillaceous subsoil contains many
elements that are considered to be beneficial to the growth of the sago palm.
According to Yamaguchi et al. (1997) and Jong et al. (2006), sago palms growing
in thick peat layers require a longer time to reach maturity and hence their starch
yield per unit area per year is lower than those growing in the thin peat layers. Sim
and Ahmed (1978) compared the starch production of sago palms in different soil
types in Sarawak, Malaysia and reported that the starch yield reached a maximum
immediately after the flowering stage in mineral and peat soils. In their study, there
was no significant difference in starch yields per trunk between the mineral soil
(189 kg) and the peat soil (179 kg). Kueh et al. (1991) also compared the starch yield
in sago palms growing in deep peat soils (over 150 cm) and mineral soils, and
reported that the sago palms in the peat soil showed comparatively low starch
concentration in the pith (56.6%), but the longer trunk by 24% compared to those
in the mineral soil. Then, the starch yield was higher in the deep peat soil (277 kg)
compared to those in the mineral soil (219 kg). The years for harvesting the sago
palms however were 12.7 years in the peat soil and 9.8 years in the mineral soil.
From these results, Yamamoto (2015b) suggested that there is no big difference in
the starch production per year (final starch yields per plant divided by years for
harvesting) between the sago palms grown in the peat soil (21.8 kg/year) and the
mineral soil (22.3 kg/year).
Yamamoto et al. (2003b) compared the starch yield of sago palms grown in
different soil types in Tebing Tinggi Island, Indonesia: mineral soil, shallow peat soil
(20–120 cm), and deep peat soil (350–450 cm), and reported as follows: the trunk
weight: 899, 830, and 734 kg; the starch concentration: 55, 59, and 70%, respectively. In their case, although the starch yield was 164–180 kg in sago palms grown
in the three types of soil and there was no apparent difference among them, the years
for harvesting were comparatively long in the sago palms grown in the deep peat soil
by 4–5 years compared to that in the mineral soil and the shallow peat soil.
Moreover, the yearly starch production was low in the deep peat soil. Regarding
to this tendency, Yamamoto (2015b) later explained that the result in the deep peat
soil was subject to specific environment of sago palm plantation which had been
operating for a short time, had a low trunk population density, and good light
condition.
According to the former studies, the large variations in the growth performance
and starch yields of sago palms grown in different soil types, i.e. peat and mineral
soils, were reported as described above. The main points are summarized as follows:
500
H. Ehara et al.
the distance from the coast. Such a finding was suspected to be related to both a high
groundwater level and salt concentration that affect the growth of sago palms in
coastal habitat with a sustained high soil water table according to Okazaki and
Kimura (2015). Sago palms show a considerably high resistance against brackish
water with salt avoidance mechanism (Ehara et al. 2006).
Sago palms thrive in mineral soils and thin layers of peat soil (Sato et al. 1979).
As Okazaki and Kimura (2015) explained, the argillaceous subsoil contains many
elements that are considered to be beneficial to the growth of the sago palm.
According to Yamaguchi et al. (1997) and Jong et al. (2006), sago palms growing
in thick peat layers require a longer time to reach maturity and hence their starch
yield per unit area per year is lower than those growing in the thin peat layers. Sim
and Ahmed (1978) compared the starch production of sago palms in different soil
types in Sarawak, Malaysia and reported that the starch yield reached a maximum
immediately after the flowering stage in mineral and peat soils. In their study, there
was no significant difference in starch yields per trunk between the mineral soil
(189 kg) and the peat soil (179 kg). Kueh et al. (1991) also compared the starch yield
in sago palms growing in deep peat soils (over 150 cm) and mineral soils, and
reported that the sago palms in the peat soil showed comparatively low starch
concentration in the pith (56.6%), but the longer trunk by 24% compared to those
in the mineral soil. Then, the starch yield was higher in the deep peat soil (277 kg)
compared to those in the mineral soil (219 kg). The years for harvesting the sago
palms however were 12.7 years in the peat soil and 9.8 years in the mineral soil.
From these results, Yamamoto (2015b) suggested that there is no big difference in
the starch production per year (final starch yields per plant divided by years for
harvesting) between the sago palms grown in the peat soil (21.8 kg/year) and the
mineral soil (22.3 kg/year).
Yamamoto et al. (2003b) compared the starch yield of sago palms grown in
different soil types in Tebing Tinggi Island, Indonesia: mineral soil, shallow peat soil
(20–120 cm), and deep peat soil (350–450 cm), and reported as follows: the trunk
weight: 899, 830, and 734 kg; the starch concentration: 55, 59, and 70%, respectively. In their case, although the starch yield was 164–180 kg in sago palms grown
in the three types of soil and there was no apparent difference among them, the years
for harvesting were comparatively long in the sago palms grown in the deep peat soil
by 4–5 years compared to that in the mineral soil and the shallow peat soil.
Moreover, the yearly starch production was low in the deep peat soil. Regarding
to this tendency, Yamamoto (2015b) later explained that the result in the deep peat
soil was subject to specific environment of sago palm plantation which had been
operating for a short time, had a low trunk population density, and good light
condition.
According to the former studies, the large variations in the growth performance
and starch yields of sago palms grown in different soil types, i.e. peat and mineral
soils, were reported as described above. The main points are summarized as follows:
500
H. Ehara et al.