Mechanism of energy metabolism on cold acclimation treatment for alleviating chilling injury of peach fruit during low temperature storage

To investigate the effective ways of reducing the chilling injury of peach fruits by maintaining energy metabolism level at low temperature storage, the 'Okubo' peach fruits were pre-stored at 8℃ for 5 d and then stored at 0℃ for 60 d (cold acclimation treatment, CAT), and 24℃, 5℃, 0℃ storage were as CKs. All of fruits were packed (6×40/bag) with polyethylene plastic(0.04 mm, 10 holes) and the pocket felled with no tying to ensure gas exchange. Samples were measured every day for 24℃, 5 d for 5℃, 10 d for 0℃and CAT. Each time 40 fruits (4×10/bag) were taken completely random and divided into two parts, 20 fruits were measured directly and the other 20 fruits were placed for 3 d shelf-life under 24℃. The effect of CAT on mitochondria respiratory metabolism-related enzymes and ATP contents during storage and shelf-life were investigated. The results showed that the H+-ATPase, Ca2+-ATPase, SDH and CCO activities of peach fruits appeared active peaks at 2-3 d during 24℃ storage, then significantly decreased with the softening of fruit. The activities of H+-ATPase, Ca2+-ATPase, SDH,CCO and ATP contents of 5℃ treatment are lowest, and their decrease speed are the fastest under this condition. 0℃ storage has better effect than 5℃, while CAT storage can effectively inhibit the reduction of H+-ATPase, SDH and CCO activities, and maintain higher contents of ATP. With the storage duration, the H+-ATPase, Ca2+-ATPase, SDH and CCO activities and ATP contents all decreased during shelf-life, but CAT treatment was significantly better than 5℃ and 0℃ processing. These results suggest that CAT treatment may maintain high energy level by regulating the activities of mitochondria respiratory metabolism-related enzymes, thereby prevent the development of chilling injury of cold-stored peach fruit and prolong storage period.