2019 ASHS Annual Conference

With the prospect of labor shortages and mechanical harvesting in the tomato industry future, there is a need for compact growth habit (CGH) varieties and corresponding fertilizer recommendations to be developed for large-green fresh-market tomatoes. The University of Florida breeding program developed Fla. 8924 as a new CGH inbred line with determinate vines and short branches that do not require pruning, staking, or tying. Two experiments were conducted in west central Florida in the spring and fall seasons of 2018 to determine the optimal fertilization program to maximize yield of Fla. 8924 as compared to the commercial standard cultivar, Florida 47. Treatments included four nitrogen (N) fertilization programs and staking vs. no staking. Fertilization treatments were different pre-plant band N (BN) rates (0, 67, 135, and 202 kg/ha) combined with post-planting drip fertigation N (DN) rates (202, 135, 67, and 0 kg/ha). In addition, all treatments received pre-plant incorporation N at 56 kg/ha, providing a total of 258 kg/ha. Fruits on the bed top were harvested one time at the mature green stage in each season. Elimination of staking reduced marketable yield by 38% to 43% for ‘Florida 47’ but only by 0% to 23% for Fla. 8924. Unstaked Fla. 8924 had 82% to 89% of marketable yield of staked ‘Florida 47’, which are above the criteria (equal or greater than 80%) for breeding a tomato line for mechanical harvest. Yield responses to fertilization treatments were different in the two seasons. In both seasons, neither fertilization nor staking treatment had cultivar-specific effects. Marketable yield of unstaked tomatoes was maximized with BN at 202 kg/ha and no DN in the spring season, whereas it was maximized with two fertilization programs that included both BN and DN in the fall season. Our results suggest that Fla. 8924 can achieve, even without staking, high marketable yield competitive to a commercial standard cultivar under the staked production system. Yield of Fla. 8924 can be improved by adopting the optimal fertilization program in each season. More DN with minimal pre-plant N is beneficial in spring, whereas a combination of BN and DN is ideal in fall.