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- Author or Editor: Juan Zhou x
The aim of this research was to assess how fruit tree age influences nutrient partitioning patterns in aboveground organs. We selected 6-year-old (mature) and 20-year-old (old) ‘Cresthaven’ peach trees and measured the macronutrient concentrations in organs removed during pruning, thinning, harvesting, and leaf fall for 3 years. Then, we calculated the total amount of nutrients removed at each event and studied the partitioning patterns between mature and old peach trees. The results showed that mature peach trees had higher phosphorus (P) and potassium (K) concentrations in fruit mesocarp and fallen leaves than old trees. When we estimated the total nutrient content, mature peach trees allocated more nitrogen (N), P, K, and calcium (Ca) to pruned wood and harvested fruit but had less N and Ca in senescing leaves compared with old peach trees. The results of this study suggest that the different proportion of organs removed through orchard management practices from trees of different ages as well as the concentration of nutrients in these organs must be considered when estimating nutrient restitution needs and tree nutritional requirements.
Cold storage is used to delay the senescence of peaches, but it can also lead to internal browning and aroma loss. Modified atmosphere packaging (MAP) has been reported to inhibit the internal browning and prolong the storage time. Four MAP treatments in the present study were set as follows: I: O2 1% to 3%, CO2 3% to 5%, and N2 92% to 96%; II: O2 3% to 5%, CO2 3% to 5%, and N2 90% to 94%; III: O2 6% to 8%, CO2 3% to 5%, and N2 87% to 91%; and control (CK): O2 21%, CO2 0.03%, and N2 79%. The concentration of sugars, acids, aroma compounds, superoxide radical (O2 −), hydrogen peroxide (H2O2), and malondialdehyde (MDA), as well as the activities of enzymes, such as superoxide dismutase (SOD), peroxidase (POD), lipoxygenase (LOX), hydroperoxide lyase (HPL), alcohol dehydrogenase, and alcohol O-acyltransferase (AAT) activities, were investigated. The results revealed that MAP, especially for treatment II, could inhibit the loss of flavors such as sugars, acids, and aroma compounds; maintain higher SOD and POD activities; and inhibit the accumulation of O2 −, H2O2, and MDA during shelf life after storage at low temperature for 30 days. It could also inhibit the LOX and HPL activities at low temperature, but maintain higher LOX and HPL activities during shelf life. These findings indicated that treatment II could prolong the storage time to 30 days and shelf life for 3 days; maintain the higher content of sugars, acids, and aroma compounds; protect the cell membrane from oxidative injury; and inhibit internal browning during cold storage and shelf life.
Heat treatment induces resistance to low temperature in horticultural crops. Changes in soluble protein and heat-stable protein (HSP) contents, the total soluble solids (TSS), titratable acidity (TA), reducing sugar, weight loss and firmness of honey peach (cv. Hujingmilu) during heat treatment and refrigerated storage were investigated. Low-temperature storage alone led to decreasing of TA and reducing sugar and caused severe fresh mealiness. The hot-air treatment before low temperature combined with the use of a plastic bag (thickness of 0.03 mm) could counteract this effect. Heat treatment before refrigerated storage increased both soluble protein and HSP contents, and the ratio of heat-stable to soluble protein. The most favorable effect was obtained with 46 °C for 30 minutes. In addition, heat treatment before storage retarded the increase in fruit firmness, maintained the highest contents of the TSS and reducing sugar and inhibited the decline of TA during refrigerated storage. Treatment for 30 minutes at 46 °C before low-temperature storage in combination with a 0.03-mm plastic bag might be a useful technique to alleviate chilling injury (CI) and maintain honey peach fruit quality during cold storage.