Antioxidants production is amongst the physiological responses of plants to protect their tissues from oxidative damages caused by chilling and freezing stresses. Indeed, cold tolerance of plants is related to production of reactive oxygen species (ROS) scavengers to combat oxidative stress. In this study, two citrus cultivars including Citrus sinensis 'Siavaraz' and Citrus limon 'Lisbon' grown at the north of Iran were examined to compare antioxidants changes including total flavonoid, total phenol and total antioxidant capacities (TAC) in the flavedo tissue of the fruits under various low temperature treatments of control (15 ºC), 3, 0, -3 and -6 ºC. The results indicated that total flavonoid content and TAC in Citrus limon 'Lisbon' was significantly higher than in Citrus sinensis 'Siavaraz'. During the treatments, both cultivars showed a significant increase in the flavonoid content. Meanwhile, total phenol content significantly increased from 15 to -6 ºC in Citrus limon 'Lisbon' and from 15 to 0 ºC in Citrus sinensis 'Siavaraz'. These results suggest that the biosynthesis of phenolics and flavonoids in flavedo of citrus fruit in response to low temperature might be correlated with environmental adaptation rather than antioxidant response.
Antioxidant capacity; citrus; low temperature treatment
