Abstract: To investigate the regulatory effect and underlying mechanism of low temperature conditioning (LTC) on chilling injury in kiwifruits during controlled freezing-point storage, ‘Hayward’ kiwifruits were subjected to LTC treatments for 48, 72, and 96 h, followed by storage for 150 days under controlled freezing-point conditions ((−0.5 ± 0.2) ℃). Physiological changes during the conditioning period and quality parameters during subsequent storage were measured, along with variations in physiological and biochemical indicators such as malondialdehyde (MDA) content, relative electrical conductivity (REC), superoxide dismutase (SOD), catalase (CAT), and lipoxygenase (LOX) activity. The results showed that during the conditioning stage, LTC treatment increased the activities of SOD and CAT, significantly inhibited LOX activity, and delayed the accumulation of MDA and the increase in REC compared with the control group. During the controlled freezing-point storage, LTC treatment effectively suppressed chilling injury, softening, and decay in kiwifruits, delayed the decline in firmness, and titratable acid (TA) content, and reduced the increase in mass loss rate, the peaks of respiration rate and ethylene release. LTC treatment for 96 h showed the most pronounced effects: after 8 days of shelf life, the chilling injury rate of kiwifruits was reduced by 45.43% when compared with the control group. During storage, the peak activities of SOD and CAT were 42.94% and 44.30% higher than those in the control group, respectively. In summary, LTC treatment can activate the reactive oxygen species (ROS) scavenging system in kiwifruits, alleviate membrane lipid peroxidation, and enhance the adaptability to low-temperature environments, thereby mitigating chilling injury during subsequent controlled freezing-point storage and maintaining fruit quality.

Key words: low temperature conditioning; kiwifruit; ice temperature storage; chilling injury