Poinsettia and Easter Lily Growth and Development Responses to Root Substrate Containing Biochar

Greenhouse production of Poinsettia (Euphorbia pulcherrima) and Easter lily (Lilium longiflorum) mainly uses peat-based root substrates. The decrease of peatland has increased the need for alternative root substrate components in the horticulture industry. Biochar, a byproduct of bio-energy production, has the potential to be an alternative root substrate component to reduce the use of peatmoss in greenhouse production. The objectives of the present studies were to determine the effects of different percentages of biochar and fertigation regimes on the growth and development of ?Prestige Red? poinsettia and Easter lily ?Nellie White? in greenhouse production.

Two experiments were conducted to evaluate different percentages of one type of biochar added to a commercial peat-based root substrate for poinsettia and Easter lily greenhouse production. In experiment one, rooted poinsettia cuttings were potted in one of the six root substrates mixes including Sunshine Mix #1 replaced by 0%, 20%, 40%, 60%, 80%, or 100% biochar (by volume) and irrigated under four fertigation regimes (100 to 200 mg?L-1 N, 200 to 300 mg?L^-1 N, 300 to 400 mg?L^-1 N, or 400 to 500 mg?L^-1 N). Root rot and red bract necrosis were only observed in the highest fertigation regime (400-500 mg?L^-1 N) combined with the highest biochar percentage (100%). At 100 to 400 mg?L^-1 N fertilization rate, up to 80% of the commercial peat-based root substrate could be replaced by biochar without a significant change in poinsettia growth and quality.

In experiment two, Easter lily bulbs were potted in one of the five root substrates mixes (Sunshine Mix #1 amended with 0%, 20%, 40%, 60%, and 80% biochar) and irrigated under four fertigation regimes (constant liquid feed at 200 mg?L^-1 N or 300 mg?L^-1 N, and fertilization at every third watering with 200 mg?L^-1 N or 300 mg?L^-1 N). Neither fertigation regimes nor biochar percentages significantly affected the Easter lily growth and development. Under the four fertigation regimes used in this experiment, up to 80% peat-based root substrate could be replaced by biochar without a significant difference on the growth and development of Easter lily.