Evaluating Bearberry Nitrogen Nutrition Using Hydroponic Cultures: Establishing Preliminary DRIS Norms

Abstract

This study was designed to explore nitrogen (N) nutrition in bearberry plants (Arctostaphylos uva‐ursi L.) using a hydroponic culture system. Two experiments were performed in which the total N concentration (34, 52, and 73 mg L^?1) and N‐NO₃ ^?:N‐NH₄ ⁺ ratio (50/50, 60/40, and 70/30 in %) in the nutrient solution were varied and effects on nutrient uptake [N, phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg)] and foliar composition determined. Highest‐quality plants were yielded using a N level of 73 mg L^?1 and a N‐NO₃ ^?:N‐NH₄ ⁺ ratio of 50/50. Standard nutrient values for foliar tissue were obtained for bearberry plants growing in these hydroponic cultures for their use as preliminary norms in the diagnosis and recommendation integrated system (DRIS). In a subsequent complementary experiment, these norms were used in the DRIS procedure and applied to plants growing in solutions of varying K concentrations. It was found that the DRIS norms established in the hydroponic experiments were able to account for changes in nutrient limiting factors produced in response to the varying K concentrations in the nutrient solution. The results obtained will be useful for the nutritional diagnosis of bearberry plants.