title: Osmotic and specific ion effects on the germination of Prosopis strombulifera.
abstract: OBJECTIVE
  Salinity can affect germination of seeds either by creating osmotic potentials that prevent water uptake or by toxic effects of specific ions. Most studies have only used monosaline solutions, although these limit the extent to which one can interpret the results or relate them to field conditions. The aim of this work was to evaluate the germination of Prosopis strombulifera seeds under increasing salinity by using the most abundant salts in central Argentina in monosaline or bisaline iso-osmotic solutions, or in solutions of mannitol and polyethylene glycol.
  
  
  METHODS
  Seeds were allowed to germinate under controlled conditions in a germination chamber at 30 +/- 1 degrees C and at 80 % r.h. Salinizing agents were KCl, NaCl, Na(2)SO(4), K(2)SO(4), NaCl + Na(2)SO(4) and KCl + K(2)SO(4) and osmotic agents were polyethylene glycol 6000 and mannitol. Treatments for all osmotica consisted of 0.0, -0.4, -0.8, -1.2, -1.5, -1.9 and -2.2 MPa solutions.
  
  
  RESULTS
  The percentage of germination decreased as salinity increased. SO(4)(2-) in monosaline solutions, with osmotic potentials -1.2 MPa and lower, was more inhibitory than Cl(-) at iso-osmotic concentrations. This SO(4)(2-) toxicity was alleviated in salt mixtures and was more noticeable in higher concentrations. K(+) was more inhibitory than Na(+) independently of the accompanying anion.
  
  
  CONCLUSIONS
  Different responses to different compositions of iso-osmotic salt solutions and to both osmotic agents indicate specific ionic effects. This study demonstrates that the germination of P. strombulifera is strongly influenced by the nature of the ions in the salt solutions and their interactions. Comparative studies of Cl(-) and SO(4)(2-) effects and the interaction between SO(4)(2-) and Cl(-) in salt mixtures indicate that extrapolation of results obtained with monosaline solutions in the laboratory to field conditions can be speculative.
authors.affiliation: Laboratorio de Fisiología Vegetal, Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis, 5700 San Luis, Argentina.
authors.forename: Laura
authors.initials: L
authors.lastname: Sosa
authors.forename: Analía
authors.initials: A
authors.lastname: Llanes
authors.forename: Herminda
authors.initials: H
authors.lastname: Reinoso
authors.forename: Mariana
authors.initials: M
authors.lastname: Reginato
authors.forename: Virginia
authors.initials: V
authors.lastname: Luna
mesh_terms: D002712:Chlorides / Q000494:pharmacology*; D018525:Germination / Q000187:drug effects* / Q000502:physiology; D008353:Mannitol / Q000494:pharmacology; D009994:Osmolar Concentration; D009997:Osmotic Pressure; D011092:Polyethylene Glycols / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D029862:Prosopis / Q000187:drug effects* / Q000254:growth & development; D012639:Seeds / Q000187:drug effects / Q000254:growth & development; D012965:Sodium Chloride / Q000494:pharmacology; D013431:Sulfates / Q000494:pharmacology*
chemical_list: D002712:Chlorides; D013431:Sulfates; C012036:sodium sulfate; C031512:potassium sulfate; D008353:Mannitol; D011092:Polyethylene Glycols; D012965:Sodium Chloride; D011189:Potassium Chloride