Respiration: Fe, Cu
Nitrate/Nitrite reductase: Fe, Mo, Co
N 2 fixation: Fe, Mo
Superoxide dismutase (SOD*): Cu, Zn, (Fe)
*SOD in chloroplasts, called the Mehler reaction, catalyzes the dismutation of
H 2 O 2 (O 2 + 2H
+
! H 2 O 2 ! H 2 O + 1/2O 2 ) (Nobel 2019)
If plants become deficient in these micronutrients, chloroplast formation is
restricted, and chloroplasts are constructed only near the bundles because of the
low amount of micronutrients transported by the xylem (Fig. 1.20).
SOD activity in chloroplasts, called the Mehler reaction, is the most important
function to protect the plant from overcharged solar energy electrons under stress
conditions such as water stress, low nutrient conditions, and high solar radiation.
Another function related to electron overcharge is the chlorophyll-fluorescence
transfer of electrons into heat. It is hypothesized that high molecular weight compound formation also contributes to the consumption of electrons (energy) in
chloroplasts, as well as nitrate/nitrite reduction (energy from PSI) [related to N
metabolism], the formation of high molecular weight compound precursors (excess
energy consumed in chloroplasts) [related to P metabolism under P limitation], and
TCA cycle activation under light by PEPC [related P metabolism under P limitation];
this last process is effective under many types of stress in tropical areas.
Thus, micronutrient deficiencies affect the Calvin cycle and the TCA (respiration
and organic acid metabolism) cycle.
1.9 Nutrient Acquisition Strategies Under Nutrient-Poor
Conditions
1.9.1 Nitrogen (N)
1.9.1.1 N 2 Fixing
The natural abundance of stable isotope
15 N (δ
15 N) was estimated in leaves of plants
(approximately 100 species) grown in primary and secondary tropical peatland
forests in Thailand. The data clearly show that many plant species fix N 2 from the
air because the δ
15
N in the leaves is lower than the δ
15
N in the soil (Fig. 1.21). If
plants absorbed nitrogen from soil, the δ
15 N values in leaves would be similar to the
δ
15 N values in soil.
A survey of the natural abundance of δ
15 N in the peatlands of To Daeng in
Narathiwat Province in southern Thailand (Yanbuaban et al. 2007) revealed that the
soil δ
15 N (per mil) was !3.0, while that of various plant foliage was 3.0. This is
because plants prefer the lighter
14 N, thereby encouraging gaseous metabolism, and
this finding demonstrates that atmospheric nitrogen is the primary source of nitrogen. Furthermore, nitrogen compounds accumulated through nitrogen fixation are
distributed to the ground level in the form of litter. When the litter becomes
1 Basic Information About Tropical Peatland Ecosystems
35
Nitrate/Nitrite reductase: Fe, Mo, Co
N 2 fixation: Fe, Mo
Superoxide dismutase (SOD*): Cu, Zn, (Fe)
*SOD in chloroplasts, called the Mehler reaction, catalyzes the dismutation of
H 2 O 2 (O 2 + 2H
+
! H 2 O 2 ! H 2 O + 1/2O 2 ) (Nobel 2019)
If plants become deficient in these micronutrients, chloroplast formation is
restricted, and chloroplasts are constructed only near the bundles because of the
low amount of micronutrients transported by the xylem (Fig. 1.20).
SOD activity in chloroplasts, called the Mehler reaction, is the most important
function to protect the plant from overcharged solar energy electrons under stress
conditions such as water stress, low nutrient conditions, and high solar radiation.
Another function related to electron overcharge is the chlorophyll-fluorescence
transfer of electrons into heat. It is hypothesized that high molecular weight compound formation also contributes to the consumption of electrons (energy) in
chloroplasts, as well as nitrate/nitrite reduction (energy from PSI) [related to N
metabolism], the formation of high molecular weight compound precursors (excess
energy consumed in chloroplasts) [related to P metabolism under P limitation], and
TCA cycle activation under light by PEPC [related P metabolism under P limitation];
this last process is effective under many types of stress in tropical areas.
Thus, micronutrient deficiencies affect the Calvin cycle and the TCA (respiration
and organic acid metabolism) cycle.
1.9 Nutrient Acquisition Strategies Under Nutrient-Poor
Conditions
1.9.1 Nitrogen (N)
1.9.1.1 N 2 Fixing
The natural abundance of stable isotope
15 N (δ
15 N) was estimated in leaves of plants
(approximately 100 species) grown in primary and secondary tropical peatland
forests in Thailand. The data clearly show that many plant species fix N 2 from the
air because the δ
15
N in the leaves is lower than the δ
15
N in the soil (Fig. 1.21). If
plants absorbed nitrogen from soil, the δ
15 N values in leaves would be similar to the
δ
15 N values in soil.
A survey of the natural abundance of δ
15 N in the peatlands of To Daeng in
Narathiwat Province in southern Thailand (Yanbuaban et al. 2007) revealed that the
soil δ
15 N (per mil) was !3.0, while that of various plant foliage was 3.0. This is
because plants prefer the lighter
14 N, thereby encouraging gaseous metabolism, and
this finding demonstrates that atmospheric nitrogen is the primary source of nitrogen. Furthermore, nitrogen compounds accumulated through nitrogen fixation are
distributed to the ground level in the form of litter. When the litter becomes
1 Basic Information About Tropical Peatland Ecosystems
35