Abstract
Summary To investigate the mechanisms by which rice plants growing in alternately flooded and drained soils absorb soil phosphate, we grew rice in moist, flooded and flooded then moist soils, and compared the measured uptake of phosphorus (P) with that calculated using a mathematical model of uptake allowing for solubilization by various means. The theory and equations for the model are given, together with a method for solving diffusion equations near roots in a root system of increasing density. The diffusion coefficients and buffer powers of P in the soil under the different water regimes are measured by following diffusion of P to a resin sink, and the parameters describing solubilization are estimated from previously published results. In all the water regimes studied, the plants relied upon solubilization for most of their P. The roots were not mycorrhizal, as they will often not be in intermittently flooded soils. In the flooded soil, uptake was three times that in the moist soil, and was consistent with solubilization by acidification caused by roots as a result of oxidation of iron and imbalance between the intake of cations and anions. In the moist soil, the uptake was consistent with solubilization by excretion of organic anions from the roots. In the flooded then moist soil, uptake declined sharply as the soil dried because P became immobilized in the soil. However, the final uptake was similar to that in the continuously moist soil, indicating that some of the immobilized P was re‐solubilized by roots, possibly by excretion of organic anions.
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Claims 8
Claim · model-written summary
In all water regimes studied, rice relied on solubilisation of soil phosphate for most of its phosphorus.
- Taxon
- rice
Oryza sativat0 - Treatment
- water regimese1
- Outcome
- solubilizatione1
- Qualifier
- for most of their Pe1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Phosphorus uptake by rice from soil that is flooded, drained or flooded then drained”
e1“In all the water regimes studied, the plants relied upon solubilization for most of their P”
Claim · model-written summary
Phosphorus uptake by rice in flooded soil was three times that in moist soil.
- Taxon
- riceOryza sativat0
- Treatment
- flooded soile3
- Outcome
- uptakee3
- Direction
- higherinferrede3
- Value
- three timese3
- Comparator
- moist soile3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Phosphorus uptake by rice from soil that is flooded, drained or flooded then drained”
e3“In the flooded soil, uptake was three times that in the moist soil”
Claim · model-written summary
Phosphorus uptake in flooded soil is consistent with solubilisation by root-induced acidification.
- Taxon
- riceOryza sativat0
- Treatment
- flooded soile3
- Outcome
- uptakee3
- Qualifier
- solubilization by acidification caused by rootse4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Phosphorus uptake by rice from soil that is flooded, drained or flooded then drained”
e3“In the flooded soil, uptake was three times that in the moist soil”
e4“was consistent with solubilization by acidification caused by roots as a result of oxidation of iron and imbalance between the intake of cations and anions”
Claim · model-written summary
Phosphorus uptake in moist soil is consistent with solubilisation by excretion of organic anions from the roots.
- Taxon
- riceOryza sativat0
- Treatment
- moist soile5
- Outcome
- uptakee5
- Qualifier
- solubilization by excretion of organic anions from the rootse5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Phosphorus uptake by rice from soil that is flooded, drained or flooded then drained”
e5“In the moist soil, the uptake was consistent with solubilization by excretion of organic anions from the roots”
Claim · model-written summary
Phosphorus uptake by rice declined sharply as flooded then moist soil dried.
- Taxon
- riceOryza sativat0
- Treatment
- flooded then moist soile6
- Outcome
- uptakee6
- Direction
- declinede6
- Qualifier
- because P became immobilized in the soile6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Phosphorus uptake by rice from soil that is flooded, drained or flooded then drained”
e6“In the flooded then moist soil, uptake declined sharply as the soil dried because P became immobilized in the soil”
Claim · model-written summary
Final phosphorus uptake by rice after flooded then moist soil was similar to that in continuously moist soil.
- Taxon
- riceOryza sativat0
- Treatment
- flooded then moist soile6
- Outcome
- final uptakee7
- Direction
- similare7
- Comparator
- continuously moist soile7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Phosphorus uptake by rice from soil that is flooded, drained or flooded then drained”
e6“In the flooded then moist soil, uptake declined sharply as the soil dried because P became immobilized in the soil”
e7“However, the final uptake was similar to that in the continuously moist soil”
Claim · model-written summary
Some immobilised phosphorus was re-solubilised by rice roots, possibly by excretion of organic anions.
- Taxon
- riceOryza sativat0
- Outcome
- immobilized Pe2
- Qualifier
- possibly by excretion of organic anionse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Phosphorus uptake by rice from soil that is flooded, drained or flooded then drained”
e2“indicating that some of the immobilized P was re‐solubilized by roots, possibly by excretion of organic anions”
Claim · model-written summary
Rice roots in this study were not mycorrhizal.
- Taxon
- riceOryza sativat0
- Outcome
- mycorrhizale2
- Qualifier
- as they will often not be in intermittently flooded soilse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Phosphorus uptake by rice from soil that is flooded, drained or flooded then drained”
e2“The roots were not mycorrhizal, as they will often not be in intermittently flooded soils”
The same questions in other papers
flooding · nutrient: content · Oryza sativa (rice)Positive and negative results
29 papers in the same direction as this paper · 42 in the opposite direction
- positive
- no effect
- positive
68 papers more in this group
See all 72 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.