Strawberries (Fragaria ×ananassa Duch.) were grown in two seasons at Dover, Fla., with polyethylene mulch and drip irrigation. Nitrogen was injected weekly at 0.28 (50), 0.56 (100), 0.84 (150), 1.12 (200), and 1.40 (250) kg N/ha per day (kg·ha-1 for season) for `Oso Grande' and `Sweet Charlie' in 1991-92 season and for `Oso Grande' and `Seascape' in 1992-1993 season. Nitrogen fertilization in 1991-1992, over the range of 0.28 to 1.40 kg N/ha per day, had no significant effect on early (November to January) strawberry yields. March (the largest production month) yield and total-season yield increased with increasing N fertilization to 0.76 and 0.54 kg N/ha per day, respectively. Nitrogen fertilization did not affect yields of strawberry in 1992-93. Fruit firmness and average fruit weight were not affected by N fertilization from 0.28 to 1.40 kg N/ha per day. Nitrogen fertilization increased whole leaf N, leaf blade N, and petiole sap nitrate-N concentrations linearly for most sampling dates in both years. Early yields were greater for `Sweet Charlie' than `Oso Grande'. Yields were greater for `Oso Grande' during March, and total-season yields were similar for both cultivars in 1991-92. `Oso Grande' had greater early, March, and total yields than `Seascape' in 1992-93.
George J. Hochmuth, Earl E. Albregts, Craig C. Chandler, John Cornell, and Jay Harrison
Earl E. Albregts, George J. Hochnmth, Craig K. Chandler, John Cornell, and Jay Harrison
`Oso Grande' and `Sweet Charlie' strawberries (Fragaria × ananassa Duch.) in 1991-92 and `Oso Grande' and `Seascape' in 1992-93 were grown in a K fertilization study using polyethylene-mulched and fumigated beds. Potassium was injected weekly into the drip irrigation system at 0.28,0.56,0.84, 1.12, and 1.40 kg K/ha per day. Early, March, and total-season marketable fruit yields were not affected by K rate during either season. The average fruit weight of `Oso Grande' for the early, March, and total-season harvest periods in the 1992-93 season decreased with increased K rate. For the same harvest periods, `Seascape' average fruit weight increased, decreased, and did not change, respectively, with increased K rate. Cull fruit yield during both seasons and fruit firmness during the 1992-93 season were not affected by K rate. Petiole sap, whole leaf, and leaf blade K concentrations increased with increasing K rates on most sampling dates during both seasons. `Oso Grande' and `Sweet Charlie' produced similar total marketable fruit yields the first season, but `Oso Grande' produced higher total yields than `Seascape' during all harvest periods of the second season.
Ernesto A. Brovelli, Jeffrey K. Brecht, Wayne B. Sherman, and Jay M. Harrison
Potential maturity indices were determined for two melting-flesh (FL 90-20 and Tropic Beauty) and two nonmelting-flesh (Oro A and Fl 86-28 C) peach cultivars. A range of developmental stages was obtained by conducting two harvests and separating fruit based on their diameter. Fruit in each category were divided into two groups. One group was used for determining potential maturity indices: soluble solids, titratable acidity, soluble solids: titratable acidity, peel and flesh color on the cheeks (CH) and blossom end (BE), CH and BE texture, ethylene production, and respiration rate. The other group was stored at 0°C for 1 week and ripened at 20°C for 2 days to simulate actual handling conditions, and were presented to a trained sensory panel, which rated the fruit for three textural (hardness, rubberiness, and juiciness) and three flavor aspects (sweetness; sourness; bitterness; and green, peachy, and overripe character). Principal component (PC) analysis was used to consolidate the results of the descriptive sensory evaluation into a single variable that could be correlated with the objective measurements at harvest. The first overall PC explained 40% of the total variation. Following are the attributes that best correlated with PC 1 and, thus, are promising maturity indices: for FL 90-20, peel hue, peel L, and CH texture; for Tropic Beauty, peel L, CH texture, and BE texture; for Oro A, CH texture, BE texture, and CH chroma; for 86-28C, BE texture, CH hue, and CH texture.