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A strategy of Ca2+ alleviating Na+ toxicity in salt-treated Cyclocarya paliurus seedlings: photosynthetic and nutritional responses |
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| Authors: | Ruiling Yao Shengzuo Fang Doland J Nichols |
| Institution: | 1. Guangxi Forestry Research Institute, Nanning, 530002, China 2. College of Forest Resources and Environment, Nanjing Forestry University, Nanjing, 210037, China 3. Key Laboratory of Central South Fast-growing Timber Cultivation of Forestry, Ministry of China, Nanning, 530002, China 4. Forestry program, School of Environmental Science and Management, Southern Cross University, Lismore, 2480, Australia |
| Abstract: | Cyclocarya paliurus seedlings were subjected to 85?mM NaCl and 0, 6, 12 or 18?mM Ca(NO3)2 treatments to study changes in plant growth, photosynthetic parameters and distribution and/or accumulation of organic and inorganic solutes. Na+ toxicity symptoms were observed in plants non-treated with Ca(NO3)2, while 12?mM Ca(NO3)2 supplementation produced a significant promotion of shoot growth; meanwhile chlorophyll content, photosynthetic rate and optimum quantum yield of photosystem II (PSII), represented by the Fv/Fm ratio and pigments content as well as proline and soluble sugars, significantly increased. Ca(NO3)2 supply increased K+ and Ca2+ concentration, whereas the Na+ transport to the shoot was inhibited. There was a strong increase in the K+/Na+ ratio in shoot of Ca(NO3)2-treated plants. X-Ray microanalysis of roots showed that K+, Ca2+ and Na+ accumulated mainly in the epidermal cells and cortical cells of roots with 12?mM Ca(NO3)2 supply, and low accumulation was observed in stelar parenchyma, indicating exogenous Ca2+ possibly induced or strengthened effects of Casparian bands on ion transport. These results suggest that Ca(NO3)2 supplement increased inorganic and organic solutes accumulation in shoot and leaf, and restricted Na+ transport to the shoot by reinforcing barrier effects for attenuating salt injuries in plants, which could be a strategy of Ca2+ alleviating Na+ toxicity in C. paliurus seedlings subjected to salt stress. |
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