Nitrate and Ammonium Uptake in Vaccinium Species Differing in Tolerance to High Soil pH

in HortScience
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  • 1 Univ. of Wisconsin, Madison, Horticulture, Madison, WI 53706
  • | 2 Univ. of Florida, Horticultural Sciences, Gainesville, FL 32611

Cultivated Vaccinium species (e.g. highbush blueberry, Vaccinium corymbosum, or cranberry, V. macrocarpon) commonly require acidic soil (pH 4.5 to 5.5) for optimum growth. Under these conditions, ammonium (NH4+) is the dominant form of inorganic N. In contrast, V. arboreum, the sparkleberry can tolerate higher-pH mineral soils, where nitrate (NO3-) is typically the predominant inorganic N form. This tolerance may be related to increased ability to acquire and utilize NO3—N. Measurements of 15NO3- and 15NH4+ influx kinetics in excised roots of V. arboreum, V. corymbosum, and V. macrocarpon did not support this hypothesis. NO3- influx kinetics measured from 10 micromolar to 200 micromolar NO3- were similar among all three species. NO3- influx was consistently lower than NH4+ influx at all concentrations for all three species.