Effect of Temperature on Soluble Solids Content in Strawberry in Queensland, Australia

Abstract

Warmer conditions under climate change will alter plant, flower and fruit development in strawberry (Fragaria × ananassa Duch.). Most of the studies examining the relationship between soluble solids content (SSC) and temperature have been conducted in areas with a temperate or Mediterranean climate. I investigated the link between SSC and temperature in Queensland, Australia. Potted plants of ‘Festival’, ‘Fortuna’, ‘Brilliance’, ‘Beauty’ and ‘Red Rhapsody’ were planted on 19 April 2021 and information collected on productivity, SSC and titratable acidity (TA) from 14 July to 6 October. Additional data were collected on the concentrations of the main soluble sugars in the fruit from 4 August to 6 October. Nights were 2 to 4 °C warmer than the long-term average conditions from 1965 to 1990. Marketable yield was lower in ‘Beauty’ and higher in the other cultivars. Fruit were smaller in ‘Festival’, ‘Fortuna’ and ‘Beauty’ and larger in ‘Brilliance’ and ‘Red Rhapsody’. Mean (±SE or standard error) SSC pooled across the cultivars was 7.6 ± 0.05%, and mean TA was 0.59 ± 0.005%. Fructose (30.2 ± 0.2 mg/g FW) and glucose (27.1 ± 0.3 mg/g FW) were the main sugars in the fruit, with lower concentrations of sucrose (0.05 ± 0.02 mg/g FW) and maltose (less than 1 mg/g FW). The mean concentration of all the sugars was 57.4 ± 0.5 mg/g FW. Soluble solids content decreased from 8.6 to 6.8% as the average daily mean temperature in the eight days before harvest increased from 14.5 to 19.5 °C (p < 0.001, R2 = 0.72). These results are consistent with similar studies in Florida and suggest that higher temperatures in the future will decrease fruit quality in subtropical locations.