The role of low temperatures in the development of the red blush on apple fruit ('Granny Smith')

Combinations of low and high temperatures with light were applied to detach ed 'Granny Smith' apples to assess their role in the reported effect of col d nights and warm days on blush formation in apple skin. Of the temperature combinations tried, 4 degrees C for 16 h in the dark followed by UVB-Visib le light at 20 degrees C for 75 h was the most effective in increasing anth ocyanin concentrations in green fruit skin. UVB-Visible light was essential for anthocyanin accumulation, regardless of the temperature combination. W E-Visible light appeared to induce quercetin accumulation without an effect of temperature. It was concluded that cool nights followed by warm days wh en UVB and light is incident on the fruit skin will bring about blush forma tion in apple fruit. (C) 1999 Elsevier Science B.V. All rights reserved.