Résumé
Postharvest storage duration is one of the key parameters to reduce food waste. Links between plant preharvest conditions and postharvest parameters variation are poorly studied. Furthermore, preharvest growing conditions are drivers for plants quality, including antioxidant capacity, phenolic compounds, and vitamins content, which might have a major role on shelf-life. The standard preharvest photoperiod condition (16 h of light and 8 h of dark, 16/8) allows plants to express their circadian rhythm, an endogenous rhythm naturally based on 24 h that regulates metabolic processes of living organisms. Circadian rhythm disturbances have already been studied due to the changes of plants competitiveness and growth. Controlled environment agriculture allows photoperiods to be changed, and circadian rhythm has proven to be a new tool to optimize plant yield and quality while reducing energy cost. In this work, we studied two preharvest light conditions (16/8 – control; 16/8-16/8-16/12 – modified) and their effect on postharvest of butterhead lettuce. After harvest the lettuce was packaged in macroperforated film and stored at 4°C for 14 days. The visual aspect, browning and gas content were analyzed after 7 and 14 days. The respiratory rate was determined after 14 days. No differences were observed on visual aspect, browning or fresh weight loss. On the other hand, significant differences were observed for gas composition. Lettuces grown under circadian rhythm perturbations released significantly more carbon dioxide (CO2) than control. Furthermore, the respiratory quotient (RQ) was significantly higher than the control, illustrating that the substrates were preferentially organic acid for lettuces under circadian rhythm perturbations compared to sugars for control ones. Preharvest light conditions have a major impact on postharvest lettuces respiration metabolism and, consequently on freshness duration.