Tolerance of submerged germinating rice to 50–200 mM NaCl in aerated solution

Authors

  • Budiastuti Kurniasih,

    Corresponding author
    • School of Plant Biology (MO84), The University of Western Australia, Crawley, Western Australia, Australia
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    • Present address: Faculty of Agriculture, Gadjah Mada University, Yogyakarta 55281, Indonesia

  • Hank Greenway,

    1. School of Plant Biology (MO84), The University of Western Australia, Crawley, Western Australia, Australia
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  • Timothy David Colmer

    1. School of Plant Biology (MO84), The University of Western Australia, Crawley, Western Australia, Australia
    2. Institute of Agriculture, The University of Western Australia, Crawley, Western Australia, Australia
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Correspondence

Corresponding author,

e-mail: budiastutik@hotmail.com

Abstract

This paper concerns tolerance to 50–200 mM NaCl of submerged rice (Oryza sativa cv. Amaroo) during germination and the first 138–186 h of development in aerated solution. Rice was able to germinate and the seedlings even tolerated exposure to 200 mM NaCl, albeit with severe growth restrictions. After return to 0.3 mM NaCl, growth increased, indicating that even at 200 mM NaCl there was no irreparable injury. Osmotic adjustment was achieved by using Na+ and Cl as the major osmotica. At 200 mM NaCl commenced at sowing, the shoot Na+ and Cl concentrations between 50–110 h were about 210 and 260 mM, respectively, i.e. above the external concentration. Thus, there was a high tissue tolerance to NaCl. The internal concentrations declined subsequently, concurrent with a decline in growth. At 50–200 mM NaCl, the contributions from ions to πsap were 81–92% in roots and 62–74% in shoots. The assessed turgor pressures at 200 mM NaCl were 0.33 MPa in shoots and 0.15 MPa in roots, compared to 0.62 and 0.43 MPa at 0.3 mM NaCl. In the General Discussion section, we compare the different responses of submerged seedlings to the responses of transpiring rice plants, reported in the literature, and suggest that the submerged system is useful to evaluate effects of NaCl on turgor pressure and particularly to establish whether there are specific effects of Na+ and Cl in tissues.

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