Reflective mulch enhances ripening and health compounds in apple fruit

The objective of the study was to improve fruit quality, including health compounds, by improving light utilization for fruit crops under hail net. Four reflective mulches including plastics such as Extenday® and a bio-degradable paper were spread in the alleyways of a cv. 'Gala Mondial' apple orchard on 10 August 2010 5 weeks before anticipated harvest.

Reflective mulch affected neither fruit firmness nor sugar, but accelerated starch breakdown, indicative of riper fruits (smaller Streif index), compared with the uncovered grass alleyway (control). Reflective mulches also improved fruit quality such as red coloration of cv. 'Gala Mondial' apples. This was due to significantly enhanced flavonoids and anthocyanins. Flavonoids increased up to 52.4% in the Extenday® treatment (29.2 nmol cm(-2) in the grass control versus 44.5 nmol cm(-2) fruit peel with reflective mulch). Similarly, reflective mulch improved anthocyanin content in cv. 'Gala Mondial' peel up to 66% compared to grass control (14.5 nmol cm(-2) in control fruit versus 24.1 nmol cm(-2) with reflective mulch). The reflective mulch did not affect chlorophyll and carotenoid content in the 'Gala' fruit peel.

Overall, the application of reflective mulches improved fruit quality in terms of better coloration and health compounds and accelerated ripening, leading to higher market value.