Plant Growth and Nutrient Uptake of Encore Azalea in Response to Nitrogen Availability and Container Type

An efficient nutrient management program is crucial to maximize success (high quality finished product as well as profitability) in the nursery production of ornamental crops. Generally, the goal of nutrient management is to identify a rate of fertilizer high enough to satisfy the nutrient requirements for the target crop while avoiding excessive plant growth, or leaching of nutrients to the environment. However, the nutrient requirements of a crop does not remain constant during a growing season. Therefore, the objective of this study was to investigate on a biweekly interval the nutrient uptake of Encore azalea ‘Chiffon’ through one growing season. The results will serve as a guide for the timing of fertilizer application at rates according to plant requirements at a given stage of production. One-year-old azalea liners were potted in April 2013 to two types of one-gallon containers: a conventional black plastic container or a biodegradable container made from recycled paper. Plants were fertilized twice per week with 250 mL of modified Hoagland’s solution containing either 0 or 15 mM nitrogen (N). From May to December 2013, five plants from each treatment combination were harvested every two weeks for nutrient analysis. Plant height, width, and leaf SPAD were measured before each harvest. The higher N rate (15 mM) increased tissue N concentration (leaf, stem, and root), tissue and total plant dry weight, plant growth index, and leaf SPAD readings at most harvest dates. Container type did not influence N concentration in the leaves. Plants grown in plastic containers started to show higher N concentration in stems and roots in September compared to those in biocontainers. Biocontainers didn’t influence plant dry weight from May to August, but increased tissue and total plant dry weight from September to December.