Goran Fruk, Mladen Fruk, Marko Vuković, Josip Buhin, Mushtaque Ahmed Jatoi and Tomislav Jemrić
Four anti-hail and anti-insect nets (red, white and yellow anti-hail and Stop Drosophila Normal) were used on apple cv. ‘Braeburn’ grown in northern Croatia in order to evaluate their effect on fruit colouration that was measured with the colorimeter (expressed as: L* – lightness, a* – yellow/blue b* – green/red) on two sides of fruit (“green” side and “red” side), and also they were used in order to evaluate their effect on the coloured surface percentage, apart from their anti-hail and pest damage protection properties. The fruits were harvested on 12th October 2015. Most differences were found between the fruit grown under the white anti-hail net and the fruit grown without the anti-hail net. Colour value “a*” was lower on the red side of the fruit under the white net in comparison with the red net. On the green side, “a*” value was lower and “L*” value was higher under the white net in comparison with control fruit. Different net colour had no influence on total colour difference. Regarding to the colouration, differences among the nets are found in classes 0–25% and 50–75% of skin coloured fruit. The fruit grown under the white nets had the higher percentage of fruit in class 0–25% than those grown without the net. The lower share of fruit in class 50–75% of skin colouration was recorded under the white net than under the red net or in the control fruit. Colouration index was lower in the fruit grown under the white net than in the control fruit. It can be concluded that the white anti-hail net promotes ripening, but at the same time it decreases red colouration. No significant differences in fruit colour have been found in the fruit grown under the red, yellow and Stop Drosophila Normal nets. Some accepted colour parameters such as a*/b* ratio are not appropriate for describing colour changes in ‘Braeburn’ apple in this study.