High temperature effects on strawberry fruit quality and antioxidant contents

Abstract

Strawberry (Fragaria × ananassa Duch.) is a demanded edible fruit with exceptional nutritional qualities. Nowadays, strawberries are commercially cultivated across a wide range of climatic and geographical regions in the world. However, it is anticipated that quality and quantity of strawberry might be affected by the recent trend in climate changes. This research evaluates the effects of anticipated increase in temperature of the growth environment on fruit development, yield, and antioxidant contents and bioavailability of strawberries. Strawberry cultivars, 'Albion' and 'San Andreas' were grown at 25/20 and 30/20°C day/night temperatures under ambient CO2 levels in controlled environment chambers. Ripe fruits were harvested and analysed for their physical and nutritional qualities. Increase in temperature by 5°C significantly (p<0.05) reduced fruit growth and yield of both cultivars. Average individual fruit weight and total fruit weight plant-1 were declined by 70 and 80%, respectively at 30/20°C compared to plants grown at 25/20°C. Fruits produced by plants grown at higher temperature were irregular in shape, smaller in size and lower intensity in red colour; however, those fruits had significantly (P<0.05) higher total polyphenols (171.1±29 mg 100 g-1) content and antioxidant capacity (10.32±1.9 μmol g-1), compared to the fruits grown at 25/20°C (93.9±10 mg 100 g-1 and 6.42±1.22 μmol g-1, respectively). Additionally, at 30/20°C, fruit surface colour became darker (decreased lightness). HPLC results revealed remarkably higher amounts (15.2±5.5 mg 100 g-1) of pelargonidin-3-glucoside, the main phenolic compound in strawberry in comparison with 11.3±3.4 mg 100 g-1 at 25°C.