Effects of chloride and sulfate salts on seed germination of halophytes from dry alpine climate

Abstract

A soil’s ionic profile along with other climatic factors influences seed germination in natural habitats. This study evaluates the role of different chloride and sulfate salts during germination of three halophytes (Halogeton glomeratus, Lepidium latifolium, and Peganum harmala) distributed in temperate salt playa habitats of Pakistan. Seeds were germinated in six salts concentrations (0 to 500 mM) under five temperature regimes (5/15 to 25/35 °C) and two photoperiods (12 h photoperiod and 24 h-dark). Germination percentage and germination velocity decreased with an increase in salt concentration and corresponding osmotic potentials. Germination of H. glomeratus and L. latifolium in iso-osmotic solutions of various salts was faster in K+ salts compared to Na+ and Mg2+ while in P. harmala germination was higher in Mg2+ and Na+ salts. H. glomeratus and L. latifolium were more tolerant to SO42− than Cl− salts, however, P. harmala was unaffected by anion. Optimal temperature was 20/30 °C for germination of all species irrespective of salt type. Sulfate seems to be less inhibitory only during germination of H. glomeratus in complete dark. The climatic condition of dry alpine habitat allows selected species to germinate at moderate temperature regimes (April–May) in the presence of light. High ionic concentration in soil may inhibit germination of all species but P. harmala appears to be more adapted in comparison to others. High sulfate soil content may favor seedling recruitment of H. glomeratus (annual plant) under mountain cracks.