Abstract of Thesis Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Master of Science
Hydroponic greenhouse pepper in Florida: practices of plant trellising, population, transplant depth, soilless media, and irrigation
Chairman: Dr. Daniel J. Cantliffe
Major Department: Horticultural Sciences
Production of mature ripened bell pepper fruits (Capsicum annuum L.) was evaluated in northcentral Florida in passive-ventilated greenhouses. Plants were grown in containers with soilless media and irrigated with a complete nutrient solution. Planting at the end of December led to flat-shaped seedless fruits in the first fruits that set during low winter temperatures. The total extra large fruit yield of five harvests during spring and summer (April to July) was higher in plants trellised to the "Spanish" system (vertical canopy support with no shoot pruning) compared to plants pruned and trained to the "V" system (vertical support of individual-pruned stems) (7.3 vs. 4.5 kg·m-2 at 3.8 plant·m-2, respectively). Marketable fruit yields in plants under both trellis systems grown in pots or flat bags increased linearly from 3.5 to 7.4 kg·m-2 in response to increased plant densities (from 1.5 to 3.8 plant·m-2). The percentage of fruits with blossom-end rot and the amount of labor used in trellising the plants were reduced in plants under the "Spanish" trellis system.
"Elephant's foot" disorder in pepper plants was referred to a basal stem swelling with damaged epidermis below the cotyledonary node. Factors that could lead to the disorder were investigated. Salt deposition at the base of the stem was correlated with the percentage of plants with epidermal wounds. Pine bark, coconut coir, coarse perlite, and peat mix irrigated with volumes from 2 to 4 liters per plant per day did not affect the percentage of plants with the disorder. Transplanting pepper seedlings to the depth of the first or second leaf node was a simple management practice found to help reduce the appearance of this disorder.
In a 250-day crop (October to June), irrigation was managed with different frequencies of events (62, 26, 16, 12, and 9 events per day based on solar radiation integrals) and volumes per irrigation event (36.7 and 73.5 mL) in plants grown in a passive-ventilated greenhouse with occasional use of heating. It was suggested that under these climate conditions, water and not nutrients limited fruit yield in plants under a low number of irrigation events per day. A high frequency of irrigation (62 and 26 events per day) increased fruit cracking. With mean numbers of irrigation events of 12 and 16, and a volume per event of 73.5 mL, marketable fruit yields of 9 kg·m-2 were obtained from plants grown in coarse perlite, pine bark or peat mix, with a low incidence of fruit cracking and low amounts of water and fertilizer. Fruit yields and fruit disorders were comparable and similar, respectively, to those obtained under simple protection structures in Mediterranean countries. Increasing night temperatures to a minimum during the winter, decreasing high temperatures during the late spring and summer, and using germplasm with low susceptibility to fruit disorders were suggested as means to increase fruit yields. Low-cost management practices such as using the “Spanish” trellis system, deep transplanting, and irrigation management could be used to improve fruit yield and quality in a high-roof passive ventilated greenhouse for pepper production in Florida. Further research should evaluate the economical feasibility of these practices.