Theses and Dissertations


Tongyin Li

Issuing Body

Mississippi State University


Bi, Guihong

Committee Member

Harkess, Richard L.

Committee Member

Blythe, Eugene K.

Committee Member

Denny, Geoffrey C.

Committee Member

Reddy, K. Raja

Date of Degree


Document Type

Dissertation - Open Access



Degree Name

Doctor of Philosophy


College of Agriculture and Life Sciences


Department of Plant and Soil Sciences


Encore azaleas are popular ornamental plants for their full sun tolerance, coldhardiness, low maintenance requirements, and reblooming habit in spring, summer, and fall. With their varying growth rates and multiple blooms during a growing season, there is limited information on the nutrient and irrigation requirements of Encore azalea cultivars. The objectives of this study were to investigate the optimum nitrogen (N) requirement of Encore azalea ‘Chiffon’ during a growing season and determine how irrigation frequency and fertilization practices (rates, methods, and timing) affect plant growth and nutrient uptake using both a traditional plastic container and a paper biocontainer. One-year-old liners of Encore azalea ‘Chiffon’ were treated with different N fertigation rates, irrigation frequencies, and sprayed with 3% urea or water in late fall. Plants were investigated for their growth responses and flower production, and analyzed for nutrient and carbohydrate status in different studies when they were grown in both a traditional plastic container and a biodegradable container made from a mix of recycled paper. The biocontainers increased plant growth index, plant dry weight, leaf area, root growth, and uptake of both macro- and micronutrients using N rates of 10, 15, and 20 mM. During a growing season, the biocontainer-grown plants had three flushes of growth while the plastic container-grown plants had only two. The third flush of growth on the biocontainer-grown plants occurred in mid-September, resulting in greater dry weight and N uptake than with plants grown in plastic containers. One irrigation per day resulted in higher flower count and greater root length and surface area. Foliar urea application in late fall was effective in improving plant N status by increasing plant N concentration and content without affecting plant dry weight, but decreased tissue concentrations of glucose, fructose, sucrose, and starch to varying degrees.



carbohydrate status||urea spray||irrigation frequency||alternative container||sustainable production||rhododendron