Effects of high oxygen on postharvest physiology of banana fruit

Chinese. 研究高氧处理对香蕉果实采后腺苷酸库、能荷的影响及探讨高氧对其成熟、衰老的作用机制。在100%、60% 、40% 和21% O2 4种不同氧浓度条件下，检测香蕉果实采后色泽、硬度、呼吸速率、乙烯释放量、细胞膜透性、腺苷酸库和能荷的变化。高氧促进了采后香蕉果皮的转黄、果实的软化、呼吸高峰和乙烯释放高峰的提前出现、呼吸作用的增强和细胞膜的渗透性增大。另外，采后香蕉在贮藏过程中，ATP、ADP的含量和能荷出现最高峰值，而AMP含量则出现最低峰值。经100%、60% O2处理后果实的ATP含量和能荷在第4天达到最高峰值（分别约25、15 nmol•g-1 FW和0.48、0.35），在第8天迅速下降，果实的AMP含量在第4天则达到最低峰值；而40% O2处理后果实的ATP含量和能荷在第8天达到最高峰值（11.5 nmol•g-1 FW和0.42），在第16天迅速下降，果实的AMP含量在第12天达到最低峰值。高氧处理显著降低了采后香蕉果实组织的腺苷酸库的量和能荷值，增强了呼吸作用，并促进果实成熟、衰老。因此, 该处理不适合采后香蕉果实的贮运保鲜。

English. The effect of high oxygen on the adenylate-related pool and energy charge in havested banana fruits was investigated to understand better the role of high oxygen in maturation and senescence of the fruits. The color and firmness, rates of respiration and ethylene evolution, cellular membrane permeability, adenylate-related pool, and energy charge of banana fruits were determined when 100%, 60%, 40% or 21% oxygen was used. Application of high oxygen promoted change in skin colour and softening, enhanced respiration, accelerated the time of the peaks of respiration and ethylene evolution rate, and increased cellular membrane permeability of banana fruit. During the storage, ATP and ADP contents, and energy charge appeared the highest peaks, while AMP content exhibited the lowest value. When exposed to 100 or 60% oxygen, ATP content and energy charge of banana fruit on day 4 had the highest values (about 25 and 15 nmol•g-1 FW, and 0.48 and 0.35, respectively), and then decreased rapidly on day 8, whereas AMP content exhibited the lowest value on day 4. Furthermore, when 40% oxygen was used, the highest peaks of ATP content and energy charge (11.5 nmol•g-1 FW and 0.42) appeared on day 8, and then declined rapidly on day 16, whereas the lowest AMP content was observed on day 12. Exposure of harvested banana fruit to high oxygen significantly reduces ATP and ADP contents in the adenylate-related pool and energy charge values. It appeares that high oxygen is unsuitable for storage and transportation of harvested banana fruit because it increases respiration and accelerates ripening and senescence of the fruit.