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The influence of NO<-uptake and reduction on ionic balance in barley seedlings (Hordeumn vulgare, cv. Compana) was studied. KNO3 and KCI treatment solutions were used for comparison of cation and anion uptake. The rate of Cl-uptake was more rapid than the rate of NO3-uptake during the first 2 to 4 hours of treatment. There was an acceleration in rate of NO-uptake after 4 hours resulting in a sustained rate of NO3-uptake which exceeded the rate of Cl-uptake. The initial (2 to 4 hours) rate of K+ uptake appeared to be independent of the rate of anion uptake. sorption by roots was balanced by organic acid anion changes, illustrated the intimate involvement of organic acid metabolism in ion accumulation by tissues of higher plants. Subsequently, several investigations have further characterized the nature of the relationship of inorganic ion uptake and organic acid metabolism (4-9, 13-15).The ability of cells to regulate their organic acid anion levels in response to ion uptake imbalances makes it necessary to include organic ion status in any consideration of inorganic ion accumulation. This is particularly pertinent since many organic ions do not readily diffuse through membranes and thus may retain inorganic counterions within a limiting membrane.Under normal physiological conditions, plants absorb similar quantities of inorganic cations and anions, with NO:-being the predominant anion absorbed. Nevertheless, the inorganic cation content in plants is three to six times that of the inorganic anion content (3) because of the reduction and utilization of NO,-.

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