Essentiality of Ammonium for Cranberry Nutrition1

Abstract

Abstract Cranberry plants, Vaccinium macrocarpon Ait. ‘Stevens’ were grown in nutrient solutions with several levels of NH 4 -N and NO 3 -N alone and in combination. The nutrient solutions were sampled weekly and analyzed for concn of NO 3 -N and NH 4 -N. It was found that the plants absorbed NH 4 -N preferentially to NO 3 -N. Dry wt and number of new shoots produced were strongly favored by the NH 4 form of N. Tissue N concn was low and the plants were N-deficient when the NH 4 -N was depleted from the nutrient solutions before termination of the experiment, and concn was high with a sustained NH 4 -N supply. Plants grown in NO 3 -N solutions were N-deficient and had tissue N concn interm ediate to those for the extreme levels of NH 4 -N. No NO 3 -N was detected in the plant tissues. Nitrate reductase activity was absent from the aboveground portions of the plants when the possible effect of microorganisms were removed. It is concluded that NH 4 -N is essential for cranberry growth.