Alleviatory effects of calcium on the toxicity of sodium, potassium and magnesium chlorides to seed germination in three non-halophytes

Saline soils contain numerous salts with varying impact on seed germination. Seeds of three non-halophytic species found in Chinese sandy deserts (Artemisia ordosica, Aristida adscensionis and Bassia dasyphylla) were incubated in salt solutions (NaCl, KCl or MgCl2, each with or without CaCl2) at 20°C in the dark. The effects of each salt on the percentage of seeds from which visibly detectable radicles emerged, and the percentage of seeds with emerging radicles surviving to a length of at least 4 mm, were examined. NaCl, KCl and MgCl2 were toxic to emerging radicles in all three species, but before radicle emergence these salts reduced seed germinability only in A. ordosica. The toxic effects of each salt on the radicles were alleviated in all three species by the addition of low concentrations of CaCl2. MgCl2 was more toxic than NaCl and KCl, and the concentration of CaCl2 needed to alleviate the toxicity of MgCl2 was several times higher than that required for alleviation of NaCl or KCl toxicity. These results suggest that Ca2+ present in saline soils alleviates the toxic effects of other salt components on seed germination, and that the results of germination experiments with a single salt are not always applicable to field conditions.