Growth and Nutrient Composition of Platycodon Grown in Media Amended with Pellets Processed with Poultry Feathers

Growth and flowering of Platycodon grandiflorus (Jacq.) A. DC. 'Sentimental Blue' was evaluated in growing media amended with pellets (P) processed with poultry feather keratins with and without application of slow-release fertilizer. Macro- and micro-nutrients in the media were analyzed in pellets before and after mixing them with peatmoss (PM) during plant growth and flowering. Peatmoss was mixed with pellets at the ratio of 4 to 1 by volume. Leachates and leaf tissues were analyzed during plant culture. Pellets were grouped into treatments of (a) pellets with shredded or powdered forms of poultry feather keratin, (b) pellets containing polyactide as a substitution for perlite, and (c) pellets enriched with urea to evaluate if these pellets function as a slow-release fertilizer when mixed with PM. The number of days to anthesis was shorter in PM medium supplemented with P45-1, P45-2, and P84 than in other media. The number of branches, flowers, and fresh weight was greater in the media with P45-2 mixed in with PM and Osmocote (OS) application. Pellet45-2 is recommended as an inert material to prepare a new soilless growing medium. Pellets made from long fiber or long fiber plus powder forms of feather keratin did not affect growth and flowering. Low levels of soluble salts (EC) in the media and leachates 60 days after seedling transplantation suggested that additional fertilizer is required during culture. Inferior plant growth and flowering in the medium containing polylactide was not observed with Osmocote application during 60 days of growth. The feasibility of testing pellets enriched with urea (P73 Urea) as a source of slow release nitrogen should be considered carefully due to the high concentration of NH4-N in the media. Based on the growth and flowering responses and on the concentrations of macro- and micro-nutrients in the media, leachates, and leaf tissue, P45-2 can be used to prepare a growing medium with PM. The suggested ranges compiled for general ornamental plants can be recommended for platycodon 'Sentimental Blue' based on concentrations of macro- and micro-nutrients in growing media, leachates, and leaf tissue.