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Title: Fertilizer effects on annual growth in sweetgum, hickory, and cedar substrates

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

Submitted to: Southern Nursery Association Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 1/19/2011
Publication Date: 8/15/2011
Citation: Murphy, A.M., Gilliam, C.H., Fain, G.B., Gallagher, T.V., Torbert III, H.A., Sibley, J.L. 2011. Fertilizer effects on annual growth in sweetgum, hickory, and cedar substrates. Southern Nursery Association Proceedings. 56:283-287.

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. 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. Data from this study shows 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.

Technical Abstract: 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 indicated that increasing fertility rate had no effect on plant production. Data showed that 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.