A. Gazula, E.H. Simonne, R.C. Hochmuth, J.H. Chandler, and D.W. Studstill
University of Florida, IFAS,
Horticultural Sciences Department, Gainesville, FL 32611-0690

Abstract. Grape tomatoes (Solanum lycopersicon L. var. cerasiforme) have sparked consumer demand because of their intense flavor, potential health benefits, and ease of use as a snack or in salads. A nitrogen (N) fertigation schedule developed in 2005 and 2006 and focusing on daily N rates rather than seasonal rate, was tested in 2007. ‘Tami G’ plants were transplanted on a sandy soil at the North Florida Research and Education Center – Suwannee Valley, near Live Oak, FL on 20 Mar., using standard plasticulture practices under six different N fertigation programs. Treatments with 50 lbs/A preplant N included fertigated N rates (50%, 100% and 150% of the target program), a 100% target program with delayed first injection, a 100% target program with reduced rate once plants reached the top of the stake, and an all-N injected program. Tomatoes were harvested eight times. Seasonal cumulative yields (8 harvests) were 24,650a, 25,181a, 12,441b, 16,540ab, 22,418a, and 19,943ab lbs/A for the all N injected, 50% target, 100% target, 150% target, 100% target with delayed injection and 100% target with reduced maintenance rate fertigation programs, respectively. Fruit pulp soluble solid concentrations (SSC) measured at five harvests ranged from 5.5 to 7.9oBrix and were not significantly affected by fertigation program. These encouraging results alone did not allow the formal validation of the target fertigation schedule because of the unexpectedly low yields for the 100% and 150% target rates. These results suggest that grape tomato grown could be grown with plasticulture without a pre-plant N fertilizer application in the bed and injections beginning at transplant when the drip-irrigation schedule maintains soil moisture between 8 and 12 cbar in the root zone. This experiment will be repeated in 2008 with larger plots.

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