Premium
High monosilicic acid supply rapidly increases Na accumulation in maize roots by decreasing external Ca 2+ activity
Author(s) -
Bosnic Predrag,
Pavlicevic Milica,
Nikolic Nina,
Nikolic Miroslav
Publication year - 2019
Publication title -
journal of plant nutrition and soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 87
eISSN - 1522-2624
pISSN - 1436-8730
DOI - 10.1002/jpln.201800153
Subject(s) - apoplast , chemistry , calcium , sodium , extracellular , nutrient , zea mays , magnesium , composition (language) , nuclear chemistry , inorganic chemistry , cell wall , biochemistry , agronomy , linguistics , philosophy , organic chemistry , biology
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.