Vol 117 (2004): Proceedings of the Florida State Horticultural Society

The influence of calcium thiosulfate on yield and postharvest quality of 'sweet charlie' strawberry

Camille E. Esmel
University of Florida
Published December 1, 2004
  • fragaria &times,
  • ananassa,
  • fruit yield,
  • strawberry post harvest


Strawberries (Fragaria × ananassa Duch.) are a highvalue crop with a short postharvest life. Florida is a producer of fresh winter strawberries in the United States with 2,874 hectares of production. Supplemental calcium (Ca) is applied to various fruit crops to maintain or increase commodity quality. Many Florida strawberry growers apply supplemental Ca to their crop despite lack of conclusive evidence of an increase in berry quality or yield. Supplemental Ca applied to 'Sweet Charlie' as calcium thiosulfate during production may help increase its shelf life. The objectives of this study were to determine the effects of Ca supplied as calcium thiosulfate on yield, growth, and postharvest quality when applied supplemental to a grower's standard fertilization regime and as the sole source of calcium through fertigation. 'Sweet Charlie' strawberry plants were grown at the University of Florida, on Seffner fine sand at the Gulf Coast Research Education Center (GCREC) in Dover, Florida. Experimental design was a randomized complete block design with four replications. Treatments consisted of the Florida strawberry grower's standard fertilization [Ca(NO[sub3])[sub2]] with and without calcium thiosulfate supplement, and no Ca (NO[sub3])[sub2] with and without calcium thiosulfate supplement. Yield data were collected twice weekly throughout the growing season. Fruit were graded for quality based upon size, disease incidence, frost/water damage, and misshapen form. Calcium content was determined for fruit during January, February, and March. Postharvest quality evaluations of pH, total titratable acidity, soluble solids content, and firmness were determined in March. For all measured variables, no significant interaction occurred between fertilizer and calcium thiosulfate supplementation. Total culls for November was significantly reduced by calcium thiosulfate supplementation. All other variables were not significantly affected by calcium thiosulfate application or fertilization regime.