roots, (2) P cycling in leaf cells related to the carbon metabolism, enhancing high
molecular weight precursor compounds in chloroplasts and TCA/organic acids/
nitrogen in the cytosol.
Potassium: As peat (organic matter) adsorbs little K
+ at low pH, K
+ leaches over
the long term, indicating that K
+ is the most limiting nutrient factor in dome-type
peatlands. K
+ has multiple key functions in the carbon and nitrogen metabolism,
carbohydrate transportation, enzyme activity, root–shoot interactions, and osmotic
pressure adjustment in plants. Thus, K
+ is similar to inorganic PGP (plant growth
promotion) substances. Unfortunately, peat scientists and peatland managers pay
little attention to K+ in tropical peatlands, even in oil palm plantations, because they
apply large amounts of K
+ to oil palms; nevertheless, severe K
+ deficiency symptoms in leaves are frequently observed, indicating that the K
+ application method is
ineffective.
Thus, summarizing all the characteristics of tropical peat ecosystems and their
ecophysiology, the final question is which plants are most adapted to tropical
peatlands with high groundwater levels with extremely limited nutrient supply
systems (only from rain).
• The best adapted plants are forest trees grown in pure water peat: (1) O 2
absorption from aerial and mound roots, (2) N 2 fixation in the rhizosphere of
aerial and mound roots, (3) P absorption in mycorrhizae and P cycling in cells
(an advantage for producing precursors of high molecular weight compounds),
and (4) K
+ concentration modulation due to slow material transportation
(an advantage for producing lignin in the stem).
• Sago palm is moderately well-adapted when grown in brackish water peat: (1) O 2
absorption and N 2 fixation from/in aerial roots, (2) moderate P requirements
because of starch accumulation in the trunk, and (3) high K
+ requirements
(because of the large amount of sucrose transportation from the leaves to the
trunk) which are met by the brackish water.
• Oil palm is poorly adapted, even with AeroHydro culture: (1) O 2 and N 2 fixation
from/in aerial roots, (2) moderate P requirements for fruiting, and (3) high K
+
requirements (because of the large amount of fatty acid transportation from the
leaves to the fruits).
• Annual crops (especially rice and maize) are extremely poorly adapted: (1) O 2
limitations even in rice, (2) no N 2 fixation ability, requiring a large amount of
nitrogen fertilizer application, (3) high P requirements for the harvested organs
(ear or grain), and (4) high K
+ requirements due to the large amount of sucrose
transportation from the leaves and harvested organs. As annual crops require
large amounts of nutrients (N, P, K) to be applied at specific growth stages, it is
difficult to support this cultivation system in peatland ecosystems. Therefore, it is
almost impossible to grow and culture annual crops in tropical peatlands without
peat degradation.
Even in mineral soils, annual field crop (rice, wheat, maize, soybean, etc.)
productivity is still low under tropical conditions because of nutrient uptake after
flowering. During flowering, root–shoot interactions become disordered: (1) sink
1 Basic Information About Tropical Peatland Ecosystems
53
molecular weight precursor compounds in chloroplasts and TCA/organic acids/
nitrogen in the cytosol.
Potassium: As peat (organic matter) adsorbs little K
+ at low pH, K
+ leaches over
the long term, indicating that K
+ is the most limiting nutrient factor in dome-type
peatlands. K
+ has multiple key functions in the carbon and nitrogen metabolism,
carbohydrate transportation, enzyme activity, root–shoot interactions, and osmotic
pressure adjustment in plants. Thus, K
+ is similar to inorganic PGP (plant growth
promotion) substances. Unfortunately, peat scientists and peatland managers pay
little attention to K+ in tropical peatlands, even in oil palm plantations, because they
apply large amounts of K
+ to oil palms; nevertheless, severe K
+ deficiency symptoms in leaves are frequently observed, indicating that the K
+ application method is
ineffective.
Thus, summarizing all the characteristics of tropical peat ecosystems and their
ecophysiology, the final question is which plants are most adapted to tropical
peatlands with high groundwater levels with extremely limited nutrient supply
systems (only from rain).
• The best adapted plants are forest trees grown in pure water peat: (1) O 2
absorption from aerial and mound roots, (2) N 2 fixation in the rhizosphere of
aerial and mound roots, (3) P absorption in mycorrhizae and P cycling in cells
(an advantage for producing precursors of high molecular weight compounds),
and (4) K
+ concentration modulation due to slow material transportation
(an advantage for producing lignin in the stem).
• Sago palm is moderately well-adapted when grown in brackish water peat: (1) O 2
absorption and N 2 fixation from/in aerial roots, (2) moderate P requirements
because of starch accumulation in the trunk, and (3) high K
+ requirements
(because of the large amount of sucrose transportation from the leaves to the
trunk) which are met by the brackish water.
• Oil palm is poorly adapted, even with AeroHydro culture: (1) O 2 and N 2 fixation
from/in aerial roots, (2) moderate P requirements for fruiting, and (3) high K
+
requirements (because of the large amount of fatty acid transportation from the
leaves to the fruits).
• Annual crops (especially rice and maize) are extremely poorly adapted: (1) O 2
limitations even in rice, (2) no N 2 fixation ability, requiring a large amount of
nitrogen fertilizer application, (3) high P requirements for the harvested organs
(ear or grain), and (4) high K
+ requirements due to the large amount of sucrose
transportation from the leaves and harvested organs. As annual crops require
large amounts of nutrients (N, P, K) to be applied at specific growth stages, it is
difficult to support this cultivation system in peatland ecosystems. Therefore, it is
almost impossible to grow and culture annual crops in tropical peatlands without
peat degradation.
Even in mineral soils, annual field crop (rice, wheat, maize, soybean, etc.)
productivity is still low under tropical conditions because of nutrient uptake after
flowering. During flowering, root–shoot interactions become disordered: (1) sink
1 Basic Information About Tropical Peatland Ecosystems
53