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Title: Low-value trees as alternative substrates in greenhouse production of three annual species

Author
item MURPHY, A - Auburn University
item GILLIAM, C - Auburn University
item FAIN, G - Auburn University
item Torbert, Henry - Allen
item GALLAGHER, T - Auburn University
item SIBLEY, J - Auburn University
item BOYER, C - Auburn University

Submitted to: Journal of Environmental Horticulture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/21/2011
Publication Date: 9/1/2011
Citation: Murphy, A.M., Gilliam, C.H., Fain, G.B., Torbert III, H.A., Gallagher, T.V., Sibley, J.L., Boyer, C.R. 2011. Low-value trees as alternative substrates in greenhouse production of three annual species. Journal of Environmental Horticulture. 29:152-161.

Interpretive Summary: With potential shortages of peat for horticultural use, recent research has focused on identifying and evaluating potential alternatives to peat for use in the greenhouse production of annual crops. Growers would also find it beneficial to find a perlite replacement due to the overall dusty nature of perlite. This study showed that greenhouse producers could amend their standard greenhouse substrate with up to 50% freshly cut eastern redcedar with little to no differences in plant growth and overall aesthetic quality. Data from this study also showed the potential for using hardwood alternatives such as sweetgum and hickory, although standard greenhouse practices concerning fertilization, watering practices, etc. would need to be adjusted.

Technical Abstract: Peat and perlite have served as industry standards in greenhouse substrates for over 50 years. Expanded perlite has long been used as an amendment in container mediums because of its ability to add air space to container substrates without adding to bulk density or affecting substrate pH and EC. However, due to increased restrictions on the harvesting of peat, as well as fluctuations in fuel prices necessary for shipping, the future availability of peat is a largely unknown factor in greenhouse production. Additionally, growers consider perlite to be a general nuisance due to the lung and eye irritation problems. These studies evaluated three possible substrate alternatives for use in greenhouse products, including fresh sweetgum (SG), hickory (H), and eastern redcedar (RC). Three greenhouse annual crops (petunia, impatiens, and vinca) were planted in varying ratios of these three wood species mixed with peat. Plants grown with SG and H as amendments did not perform as well as a traditional peat:perlite mix with respect to flower number, growth indices, SPAD values, and PDW. However, plants grown in RC tended to be equivalent to those grown in a traditional mix. Data showed that 2 greenhouse producers could amend their standard greenhouse substrate with up to 50% eastern redcedar with little to no differences in plant growth and overall aesthetic quality.