The Late Season Decline in Strawberry Fruit Soluble Solid Content Observed in Florida Is Caused by Rising Temperatures

The strawberry (Fragaria x ananassa) production season in central Florida runs from the beginning of December to the end of March. The season culminates with a wave of fruit production from lateral crowns. Primary fruit are more common at the beginning of the wave and smaller, lower order fruit more common later. Also, as the wave progresses, mean temperatures typically rise and the soluble solid content (SSC) of fruit typically declines. It is not clear whether or not the development stage of the plant or temperature is responsible for the decline in SSC. Beginning on 26 January of the 2006-2007 season, recently open flowers from 12 'Strawberry Festival' plants were tagged on four dates separated by one week. Flowers from the 26 January date correspond to those producing ripe fruit at the beginning of the final wave. Three days after flowers were tagged the plants were transplanted from the field to growth rooms at 15 degrees C or 22 degrees C with a 12-h day/night cycle. The weight (g) and SSC((o)Brix) of fruit from tagged flowers and the time it took for fruit to ripen (days) was recorded when fruit matured. There was a linear decrease in the size of fruit from plants transplanted early in the experiment relative to plants transplanted later and fruit development period (FDP) was 11.3 days shorter for fruit developing at 22 degrees C (24.4 vs. 35.7). The SSC was lower in fruit grown at 22 degrees C (5.4 vs. 6.6), but there was no effect of transplant date. These results indicate that rising temperatures are responsible for the decline in SSC of fruit at the end of the growing season in Florida.