Abstract
Abstract Both calcium (Ca 2+ ) and silicon (Si) improve plant performance under salt (NaCl) stress. Although these two mineral elements share numerous similarities, the information on how their extracellular interactions in the root apoplast affect uptake of sodium (Na + ) is still lacking. Here, we investigated the effect of high Si supply in the bioavailable form of monosilicic acid (H 4 SiO 4 ) on the activity of Ca 2+ in the external root solution, and subsequent root uptake and compartmentation of Na in maize ( Zea mays L.). In the short‐term experiments (6 h), 14‐d‐old maize plants were exposed to various concentrations of Ca 2+ at three different pH‐values (6.5, 7.5, and 8.5) and two Si concentrations, i.e ., low (1 mM) and high (4 mM) supply of H 4 SiO 4 . The activity of Ca 2+ and Na + in the external solution as well as the root concentrations of total and cell sap and BaCl 2 ‐exchangeble apoplastic fractions of both elements were analyzed. The pH of the nutrient solution affected neither the ion activities nor the root accumulation of both Ca 2+ and Na + . At higher pH values (7.5 and 8.5) the interactions of Ca 2+ and Si at high Si supply led to a decrease of Ca 2+ activity and, hence, an increase of Na + : Ca 2+ activity ratio in the external root solution. Concomitantly, despite the elevated exchangeable apoplastic fraction of both Ca 2+ and Na + , the total and cell sap concentrations were remarkably decreased for Ca 2+ and increased for Na + by the addition of 4 mM H 4 SiO 4 . This work demonstrates that at high Si supply extracellular Ca‐Si interactions leading to lowered activity of Ca 2+ might rapidly compromise the ameliorative effect of Ca 2+ on Na + accumulation in roots. Practically, Si over‐fertilization of saline and, in particular, sodic soils may further promote the accumulation of Na + in root tissues hours after Si application and, hence, increase a potential risk of Na + toxicity.
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Claims 7
Claim · model-written summary
Nutrient solution pH did not affect calcium or sodium ion activities or root accumulation.
Zea maysNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The pH of the nutrient solution affected neither the ion activities nor the root accumulation of both Ca 2+ and Na + .”
t0“maize”
Claim · model-written summary
At higher pH, high silicon supply decreased external calcium activity.
- Treatment
- high Si supplye0
- Outcome
- Ca 2+ activitye0
- Direction
- decreasee0
- Qualifier
- higher pH values (7.5 and 8.5)e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At higher pH values (7.5 and 8.5) the interactions of Ca 2+ and Si at high Si supply led to a decrease of Ca 2+ activity and, hence, an increase of Na + : Ca 2+ activity ratio in the external root solution.”
t0“maize”
Claim · model-written summary
At higher pH, high silicon supply increased the external sodium to calcium activity ratio.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At higher pH values (7.5 and 8.5) the interactions of Ca 2+ and Si at high Si supply led to a decrease of Ca 2+ activity and, hence, an increase of Na + : Ca 2+ activity ratio in the external root solution.”
t0“maize”
Claim · model-written summary
The addition of monosilicic acid increased exchangeable apoplastic calcium and sodium fractions.
- Treatment
- addition of 4 mM H 4 SiO 4e0
- Outcome
- exchangeable apoplastic fraction of both Ca 2+ and Na +e0
- Direction
- elevatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Concomitantly, despite the elevated exchangeable apoplastic fraction of both Ca 2+ and Na + , the total and cell sap concentrations were remarkably decreased for Ca 2+ and increased for Na + by the addition of 4 mM H 4 SiO 4 .”
t0“maize”
Claim · model-written summary
The addition of monosilicic acid decreased total and cell sap calcium concentrations.
- Treatment
- addition of 4 mM H 4 SiO 4e0
- Compound
- Ca 2+e0
- Outcome
- total and cell sap concentrationse0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the total and cell sap concentrations were remarkably decreased for Ca 2+ and increased for Na + by the addition of 4 mM H 4 SiO 4”
t0“maize”
Claim · model-written summary
The addition of monosilicic acid increased total and cell sap sodium concentrations.
- Treatment
- addition of 4 mM H 4 SiO 4e0
- Compound
- Na +e0
- Outcome
- total and cell sap concentrationse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the total and cell sap concentrations were remarkably decreased for Ca 2+ and increased for Na + by the addition of 4 mM H 4 SiO 4”
t0“maize”
Claim · model-written summary
The authors warn that silicon overfertilization of saline or sodic soils may promote root sodium accumulation and toxicity risk.
- Outcome
- Si over‐fertilization of saline and, in particular, sodic soilse0
- Qualifier
- may further promote the accumulation of Na + in root tissuese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Si over‐fertilization of saline and, in particular, sodic soils may further promote the accumulation of Na + in root tissues hours after Si application and, hence, increase a potential risk of Na + toxicity.”
t0“maize”
The same questions in other papers
silicon atom · nutrient: content · Zea mays (maize)Positive and negative results
2 papers in the same direction as this paper · 41 in the opposite direction
- no effect
- positive
- positive
40 papers more in this group
See all 44 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.