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Cation‐stimulated H + efflux by intact roots of barley
Author(s) -
GLASS ANTHONY D. M.,
SIDDIQI M. YAEESH
Publication year - 1982
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1982.tb00938.x
Subject(s) - hordeum vulgare , potassium , chemistry , context (archaeology) , efflux , stoichiometry , sodium , hordeum , flux (metallurgy) , analytical chemistry (journal) , nuclear chemistry , poaceae , botany , environmental chemistry , biochemistry , biology , paleontology , organic chemistry
. Rates of proton extrusion and potassium ( 86 Rb) influx by intact roots of barley ( Hordeum vulgare cvs . Fergus, Conquest and Betzes) plants were simultaneously measured in short‐term (15min) experiments. The nature and extent of apparent coupling between these ion fluxes was explored by manipulating conditions of temperature, pH and cation composition and concentration during flux determinations. In addition, the influence of salt status upon these fluxes was examined. At low K + concentrations (0.01 to 1 mol m −3 ), H + efflux and K + influx were strongly correlated in both low‐ and high‐K + roots, although K + : H + exchange stoichiometries were almost consistently greater than 2:1. At higher concentrations (1 to 5 mol m −3 ), H + efflux was either reduced or remained unchanged while K + influxes increased. In the presence of Na 2 SO 4 , rates of H + extrusion demonstrated similar cation dependence, although below 10 mol m −3 Na 2 SO 4 , H + fluxes were generally 50% lower than in equivalent concentrations of K 2 SO 4 . These observations are considered in the context of current hypotheses regarding the mechanisms of k + /H + exchange.