Abstract
Abstract Nutrient absorption and water purification by rice (Oryza sativa L.), canna (Canna indica L.), reed (Phragmites communis Trin.), and umbrella plant (Cyperus alternifolius L.), grown by the floating culture system, were compared under different pH conditions in natural water. The pH of the rooting zone in natural water changed due to the increase in the CO2 concentration associated with root respiration, which was achieved by placing the roots in a plastic pot attached beneath the float to isolate the roots from the outside water. The absorption of nutrients (N and P) by umbrella plants was higher than that by the other plant species and was not inhibited by high pH values. In addition, the absorption of nutrients (N, P, K, and Fe) by umbrella plants increased with the application of a slow-release fertilizer to the basal part of the roots. As a result, umbrella plants grown with fertilizer displayed a strong water purification effect, regardless of the pH values. On the other hand, nutrient absorption by rice was severely inhibited by high pH values when fertilizer was applied. This was because the absorption of Nand P increased with fertilizer application, while the absorption of Fe by rice was markedly reduced under high pH conditions, resulting in iron deficiency. Therefore, we suggest that species tolerant to high pH conditions, such as umbrella plants, should be selected and that fertilizer should be applied to those plants, although the levels of the nutrients contained in the fertilizer should not exceed those corresponding to the absorption capacity of the plant, for improving water quality in closed natural water bodies with high pH values
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Claims 9
Claim · model-written summary
Root respiration increased CO2 and changed rooting-zone pH in natural water.
Verbatim
e0“The pH of the rooting zone in natural water changed due to the increase in the CO2 concentration associated with root respiration”
t0“plant species”
Claim · model-written summary
Umbrella plants absorbed more N and P than the other species.
Verbatim
e0“The absorption of nutrients (N and P) by umbrella plants was higher than that by the other plant species”
Claim · model-written summary
High pH did not inhibit umbrella plant nutrient absorption.
- Taxon
- umbrella plantse1
- Treatment
- high pH valuese0
- Outcome
- absorption of nutrients (N and P)e1
- Direction
- not inhibitede0
Not reportedComparator
Verbatim
e0“was not inhibited by high pH values”
e1“The absorption of nutrients (N and P) by umbrella plants was higher than that by the other plant species”
Claim · model-written summary
Slow-release fertilizer increased umbrella plant uptake of N, P, K, and Fe.
- Taxon
- umbrella plantse0
- Treatment
- application of a slow-release fertilizer to the basal part of the rootse0
- Outcome
- absorption of nutrients (N, P, K, and Fe)e0
- Direction
- increasede0
Not reportedComparator
Verbatim
e0“the absorption of nutrients (N, P, K, and Fe) by umbrella plants increased with the application of a slow-release fertilizer to the basal part of the roots”
Claim · model-written summary
Fertilized umbrella plants strongly purified water regardless of pH.
Verbatim
e0“umbrella plants grown with fertilizer displayed a strong water purification effect, regardless of the pH values”
Claim · model-written summary
High pH severely inhibited rice nutrient absorption when fertilizer was applied.
- Taxon
- rice
Oryza sativae0 - Treatment
- high pH valuese0
- Outcome
- nutrient absorptione0
- Direction
- severely inhibitede0
- Qualifier
- when fertilizer was appliede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“nutrient absorption by rice was severely inhibited by high pH values when fertilizer was applied”
Claim · model-written summary
Fertilizer increased rice N and P absorption.
- Taxon
- riceOryza sativae1
- Treatment
- fertilizer applicatione0
- Outcome
- absorption of Nand Pe0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the absorption of Nand P increased with fertilizer application”
e1“nutrient absorption by rice was severely inhibited by high pH values when fertilizer was applied”
Claim · model-written summary
High pH markedly reduced rice Fe absorption, resulting in iron deficiency.
- Taxon
- riceOryza sativae0
- Treatment
- high pH conditionse0
- Outcome
- absorption of Fee0
- Direction
- markedly reducede0
- Qualifier
- resulting in iron deficiencye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the absorption of Fe by rice was markedly reduced under high pH conditions, resulting in iron deficiency”
Claim · model-written summary
The authors recommend selecting high-pH-tolerant species and applying fertilizer below uptake capacity to improve water quality.
Verbatim
e0“species tolerant to high pH conditions, such as umbrella plants, should be selected and that fertilizer should be applied to those plants, although the levels of the nutrients contained in the fertilizer should not exceed those corresponding to the absorption capacity of the plant, for improving water quality”
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