Douglas A. Cox Associate Professor of
Floriculture Education Ph.D. (Floriculture),
Cornell University, 1981 Outreach Leader, UMass Extension
Commercial Floriculture Team. Instructional Activity Horticulture Program
Coordinator, Stockbridge School of Agriculture Research Interests Phosphorus nutrition of greenhouse crops It is generally believed that the amount of phosphorus being applied to greenhouse crops is in excess of actual requirements. Too much phosphorus may result in too tall plants and the potential exists for pollution through effluent release to the environment. This work focuses on the role of phosphorus in determining plant size and understanding phosphorus leaching from soilless growth media. Fertilizer use and nutrient leaching from containerized plants The importance of nutrient loss by leaching from containerized greenhouse crops as a source of groundwater pollution is being evaluated. The total nutrient requirement and pattern of uptake by plants and methods of reducing nutrient leaching while providing adequate nutrition are being sought. Subirrigation effects on greenhouse crops The response of several
containerized greenhouse crops to subirrigation versus conventional
surface irrigation is being studied as a method of reducing
fertilizer runoff. Research emphasis is on plant response to the
salt accumulation and stratification effects resulting from
subirrigation. Also, the response of plants subirrigated with plant
growth retardants is under study. Recent Publications Cox, D.A. 2001. Response of poinsettia to late season drench application of paclobutrazol to the growth medium. PGRSA Quarterly. 29(1):15-21. Cox, D.A. 2001. Using phosphorus starvation to regulate growth. Grnhse. Prod News. 11(1):22, 24-25. Cox, D.A. 2001. Growth, nutrient content, and growth medium electrical conductivity of poinsettia irrigated by subirrigation or from overhead. J. Plant Nutr. 24(3):523-533. Cox, D.A. 1999. Growth and nutrient content of poinsettia (Euphorbia pulcherrima Willd. ex Klotz) in a soilless growth medium amended with sewage sludge pellets. J. Plant Nutr. 22(2): 291-301. El-Jaoual, T. and D.A. Cox .1998. Effects of plant age on nitrogen uptake and distribution by greenhouse plants. J. Plant Nutr. 21(5): 1055-1066. El-Jaoual, T. and D.A. Cox .1998. Manganese toxicity in plants: A review. J. Plant Nutr. 21(2): 353-386.
Doug Cox is Team Leader for the UMass Extension Floriculture program.
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