Effect of Nutrient Application Rate on Plant Growth Indices and Biomass of Fennel (Foeniculum vulgare cv. Grosfruchtiger) Produced Within a Protected Agricultural Greenhouse System

Fennel (Foeniculum vulgare cv. Grosfruchtiger), a member of the Apiaceae family, is a perennial crop cultivated for its culinary and nutraceutical use. All parts of the plant are aromatic and edible, and seeds are used for extracting essential oil which is known to be a potent and powerful aid for digestive health. As a result, there is an increased demand for this unique crop. Traditionally, fennel has been cultivated in soil; soilless production within protected agricultural systems has been limited. This study investigated the effect of fertilizer rates on the growth of ‘Grosfruchtiger’ in a protected agricultural environment. Fennel seeds purchased from Johnny’s Selected Seeds (Winslow, MA) were germinated in a soilless substrate in a greenhouse at the Mid-Florida Research and Education Center located in Apopka, FL. Four weeks after germination, seedlings were transplanted into 7.6-L containers filled with soilless substrate (Fafard 4 Mix, Sun Gro Horticulture, Agawam, MA) and watered through a drip irrigation system. A slow release fertilizer (Osmocote Exact Standard, Everris International, The Netherlands) was applied at a rate of 2, 4, and 4 g/L after transplanting. Plant growth indices (width1 x width2 x height) were recorded weekly. Eight weeks after transplanting, plants were destructively harvested and dried in an oven at 65 °C until a constant dry weight was obtained to quantify shoot biomass. Differences in plant growth indices and biomass among nutrient application rates will be discussed. Results from this work will assist in selection of fertilizer application rates for fennel production in a protected production environment.