Effects of sodium, magnesium and calcium salts on seed germination and radicle survival of a halophyte, Kalidium caspicum (Chenopodiaceae)

Abstract

Kalidium caspicum (L.) Ung.-Sternb. is a common species of highly saline habitats of north-western China, which in previous germination research has been shown to be rather sensitive to NaCl toxicity. To investigate the effects of different salts on the seed germination and radicle survival of this halophytic shrub, seeds were incubated in various salt (NaCl, Na₂SO₄, MgCl₂, or MgSO₄ with or without CaCl₂) or polyethylene glycol-6000 solutions. The germination percentage and the percentage of emerging radicles surviving to a length of at least 4 mm were examined. The survival of K. caspicum radicles depended mainly on the cation composition of the media: both Na⁺ and Mg²⁺ had toxic effects on the radicles, while Ca²⁺ alleviated the toxicity of these cations. Mg²⁺ was more toxic than Na⁺ and a higher concentration of Ca²⁺ was needed to alleviate its toxicity. It was suggested that the establishment of seedlings of K. caspicum in the field is facilitated by the marked alleviation of salt toxicity by Ca²⁺ and that the proportion of soluble Na, Mg and Ca ions in the soil determines the distribution of K. caspicum in the field.