采前喷施茉莉酸甲酯对火龙果采后品质和生理特性的影响

【目的】分析采前喷施茉莉酸甲酯（MeJA）对火龙果采收品质、耐贮性及生理特性的影响，为生产上应用MeJA提升火龙果采收品质和耐贮性提供技术支持。【方法】以紫红龙火龙果为试验材料，采用5种质量浓度（0、50、100、200和400μmol/L）的MeJA采前8 d喷施火龙果，调查采收时产量、单果重、一级果率、商品果率和病果率，观察比较采后腐烂时间和腐烂率变化，测定对照（0μmol/L）和最佳处理贮藏过程中品质和生理特性的变化。【结果】采前喷施MeJA对火龙果公顷产量和单果重无显著影响（P>0.05），但采前喷施100μmol/L MeJA处理能明显提升火龙果采收时的商品性，其一级果率和商品果率分别较对照显著提高52.37%和104.38%（P<0.05，下同），病果率较对照降低49.47%。常温贮藏期间采前喷施100μmol/L MeJA处理较对照延迟1 d出现腐烂现象，且腐烂率始终低于对照；维持贮藏期间较高的可溶性固形物、可溶性糖和可滴定酸等内在品质；显著提升贮藏期间果皮多酚含量和总抗氧化能力，以及多酚氧化酶（PPO）、过氧化物酶（POD）、β-1，3-葡聚糖酶（GLU）、几丁质酶（CHT）和苯丙氨酸解氨酶（PAL）活性，酶活性最大差值发生在果实开始腐烂前后，PPO、POD和CHT活性于贮藏第6 d差值最大，其酶活性分别较对照提高33.13%、140.38%和207.16%，PAL和GLU活性于贮藏第9 d差值最大，其酶活性分别较对照提高83.38%和25.29%。【结论】采前喷施适宜浓度的MeJA可减少生育期火龙果的感病率，提升商品果率，维持贮藏品质，提高贮藏期间的抗氧化能力和抗病能力，从而延缓果实衰老和控制贮藏期间腐烂的发生，延长贮藏期，以100μmol/L的处理效果最佳。

Effects of pre-harvest application of methyl jasmonate on quality and physiological characteristics of pitaya

【Objective】 The purpose of this study was to explore the effects of preharvest methyl jasmonate(MeJA) treatment on the harvest quality, storability and physiological characteristics of pitaya, and to provide technical support for the application of MeJA to improve the quality and storability of pitaya fruit.【Method】 Taking Zihonglong pitaya as material, five kinds of MeJA concentration gradients(0, 50, 100, 200, 400 μmol/L) were used to spray pitaya 8 days before harvest. Investigated the harvest yield, single fruit weight, first-class fruit rate, commercial fruit rate and diseased fruit rate.By observing and comparing the changes of decay time and decay rate after harvest, the changes of quality and physiological characteristics during storage of the control(0 μmol/L) and the best treatment was determined.【Result】 Under the experimental conditions, spraying MeJA before harvest had no significant effect on the yield per hectare and single fruit weight of pitaya(P>0.05). But, 100 μmol/L MeJA treatment improved the harvest marketability of pitaya, the first-class fruit rate and commercial fruit rate were significantly increased by 52.37% and 104.38%, respectively(P<0.05, the same below), and the rate of diseased fruit was reduced by 49.47%. During storage at room temperature, decay occurred 1 d later sprayed by 100 μmol/L MeJA before harvest than the control, and the decay rate was always lower than that of the control.Maintained higher intrinsic qualities such as soluble solids, soluble sugars and titratable acid during storage. The contents of polyphenols, total antioxidant capacity and activities of polyphenol oxidase(PPO), peroxidase(POD), β-1, 3-glucanase(GLU), chitinase(CHT) and phenylalnine ammonialyase(PAL) were significantly increased by 100 μmol/L MeJA treatment. The maximum difference of enzyme activity occurred before and after the beginning of decay. PPO, POD and CHT activities had the maximum values at the 6th d of storage, which were increased by 33.13%, 140.38% and 207.16% than the control, respectively. PAL and GLU had the maximum values at 9th d of storage, which were increased by 83.38% and 25.29% than the control, respectively.【Conclusion】 Spraying appropriate concentration of MeJA before harvest can reduce the susceptible rate of pitaya in growth period, improve the commercial fruit rate, maintain the storage quality, improve the antioxidant capacity and disease resistance during storage, so as to delay the fruit aging and control the occurrence of decay during storage, and prolong the storage period. The best treatment was 100 μmol/L.