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GLASS B 《American journal of human genetics》1950,2(3):269-278
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Interactive effects of K+ and N (principally NH4+) on plant growth and ion uptake were investigated using hydroponically grown rice (Oryza sativa L. cv. M202) seedlings by varying the availability of NH4+ or NO3? and K+ during an 18d growth period, a 3d pretreatment period and during flux measurements. Plants grew best in media containing 100 mmol m?3 NH4+ and 200mmolm?3 K+ (N100/K200), followed by N2/K200 < N100/K2 < N2/K2. 86Rb+(K+) fluxes were increased by exposure to N during the 18 d growth period and the 3 d of pretreatment, but decreased by the presence of NH4+ during flux measurements. This inhibition was a function of prior N/K provision and the [NH4+]0 present during flux determinations. NH4+ was least inhibitory to 86Rb+(K+) influx in high-N/low-K plants. Pretreatments with K+ failed to stimulate NH4+ uptake, and the presence of K+ in the uptake solutions reduced NH4+ fluxes only in high-N/low-K plants. 相似文献
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Abstract. 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 Na2 SO4 , rates of H+ extrusion demonstrated similar cation dependence, although below 10 mol m−3 Na2 SO4 , H+ fluxes were generally 50% lower than in equivalent concentrations of K2 SO4 . These observations are considered in the context of current hypotheses regarding the mechanisms of k+ /H+ exchange. 相似文献