Plant Soil Environ., 2012, 58(3):121-127 | DOI: 10.17221/374/2011-PSE

Calcium regulates K⁺/Na⁺ homeostasis in rice (Oryza sativa L.) under saline conditions

G.Q. Wu, S.M. Wang

State Key Laboratory of Grassland Agroecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, P.R. China

To investigate the effects of Ca²⁺ on cation accumulation and K⁺/Na⁺ selectivity, in this study, two-week-old rice (Oryza sativa L.) plants were exposed to 25 or 125 mmol/L NaCl with or without 10 mmol/L CaCl₂. At low salinity (25 mmol/L NaCl), Ca²⁺ significantly decreased Na⁺ accumulation in roots, increased K⁺ accumulation in shoots, and maintained higher K⁺/Na⁺ ratios in both roots and shoots of rice plants. At high salinity (125 mmol/L NaCl), however, Ca²⁺ did not have any effects on Na⁺, K⁺ accumulation and K⁺/Na⁺ ratios in plants. Further analysis showed that, at low salinity, the addition of Ca²⁺ significantly enhanced the selective absorption and transport capacity for K⁺ over Na⁺ in rice. Although Na⁺ efflux and Na⁺ influx were remarkably reduced by Ca²⁺ under both low and high salt stresses, their ratio was lowered only under low salt stress. In summary, these results suggest that Ca²⁺ could regulate K⁺/Na⁺ homeostasis in rice at low salinity by enhancing the selectivity for K⁺ over Na⁺, reducing the Na⁺ influx and efflux, and lowering the futile cycling of Na⁺.

Keywords: ion accumulation; selectivity; Na+ influx; futile cycling; salt stress

Published: March 31, 2012  Show citation