Chang Lan-Yen, Sargent Steven A, Kim Jeongim, Brecht Jeffrey K
Division of Crop Improvement, Tainan District Agricultural Research and Extension Station, Tainan, Taiwan.
Horticultural Sciences Department, University of Florida, Gainesville, FL, United States.
Front Plant Sci. 2022 Sep 15;13:966789. doi: 10.3389/fpls.2022.966789. eCollection 2022.
Storage at the putative chilling threshold temperature (CTT) to avoid chilling injury still limits postharvest handling of tropical fruit like banana in that ripening may occur at the CTT. To determine whether chilling injury (CI) symptoms would develop in mature green (MG) banana fruit if the CTT exposure was extended by inhibiting ethylene action and thus ripening, 1-methylcyclopropene (1-MCP) was applied. Individual 'fingers' from multiple 'clusters' of MG bananas were either immersed in water or 50 μg L 1-MCP (a.i.) solution and each treatment was divided into three subgroups for storage at 5.0°C (severe CI), 13.0°C (mild CI), or 14.0°C (CTT) ± 0.1°C. 1-MCP delayed ripening in terms of color change for 10 days for fruit stored at the CTT. Ethylene production by fruit at 5.0°C remained around 0.04 ng kg s with no obvious increase during 31-day storage. Ethylene production at 14.0°C (-1-MCP/+1-MCP) increased on Day 33 while increasing on Day 38 for 13.0°C fruit without 1-MCP and on Day 39 for fruit with 1-MCP. Peak climacteric ethylene occurred on Days 44 and 39 for 13.0 and 14.0°C fruit without 1-MCP, respectively, and on Days 59 and 51 for 13.0°C and 14.0°C 1-MCP-treated fruit, respectively. As hypothesized, longer exposure of MG banana fruit to the CTT of 14.0°C without onset of ripening as was allowed by prior 1-MCP treatment allowed CI to develop at that normally non-chilling temperature. Vascular browning was the first visual and most sensitive CI symptom in the experiment and was observed on Day 4 at 5.0°C, Day 10 at 13.0°C, Day 19 at 14.0°C without 1-MCP, and on Day 28 at 14.0°C with 1-MCP. Using a 1-MCP pre-treatment to remove the influence of ethylene from bananas stored at 13°C or 14°C also resulted in slight reduction in vascular browning severity. In conclusion, a putative safe temperature may become a CI temperature if the shelf-life-limiting factor is removed, allowing longer exposure. Chilling at the CTT caused relatively mild injury on fruit, and vascular browning is a sensitive indicator of CI status, while the light-adapted quantum yield of photosystem II [Y(II)] could be a non-destructive indicator of early CI stress in MG banana. Fruit at 13.0/14.0°C developed CI symptoms slightly later with 1-MCP than without 1-MCP. This suggests that ethylene might be involved in early CI symptom development.
将热带水果（如香蕉）贮藏在假定的冷害阈值温度（CTT）以避免冷害，这仍然限制了其采后处理，因为在CTT时可能会发生成熟。为了确定如果通过抑制乙烯作用从而延缓成熟来延长CTT暴露时间，成熟绿色（MG）香蕉果实是否会出现冷害（CI）症状，使用了1-甲基环丙烯（1-MCP）。将MG香蕉多个“果串”上的单个“果指”分别浸入水中或50μg L 1-MCP（有效成分）溶液中，每种处理分为三个亚组，分别贮藏在5.0°C（严重冷害）、13.0°C（轻度冷害）或14.0°C（CTT）±0.1°C。1-MCP处理使贮藏在CTT的果实颜色变化方面的成熟延迟了10天。5.0°C下果实的乙烯产量在31天贮藏期间一直保持在约0.04 ng kg s左右，没有明显增加。14.0°C（-1-MCP/+1-MCP）下果实的乙烯产量在第33天增加，而未用1-MCP处理的13.0°C果实和用1-MCP处理的果实分别在第38天和第39天增加。未用1-MCP处理的13.0°C和14.0°C果实的乙烯跃变高峰分别出现在第44天和第39天，而用1-MCP处理的13.0°C和14.0°C果实的乙烯跃变高峰分别出现在第59天和第51天。如所假设的那样，MG香蕉果实经1-MCP预处理后，在未成熟的情况下更长时间暴露于14.0°C的CTT，使得在该通常不会产生冷害的温度下出现了冷害。在实验中，维管束褐变是最早出现的视觉且最敏感的冷害症状，在5.0°C下第4天、13.0°C下第10天、未用1-MCP处理的14.0°C下第19天以及用1-MCP处理的14.0°C下第28天观察到。使用1-MCP预处理消除乙烯对贮藏在13°C或14°C香蕉的影响，也导致维管束褐变严重程度略有降低。总之，如果去除限制货架期的因素并允许更长时间暴露，假定的安全温度可能会变成冷害温度。在CTT下冷藏对果实造成的伤害相对较轻，维管束褐变是冷害状态的敏感指标，而光适应下的光系统II量子产率[Y(II)]可能是MG香蕉早期冷害胁迫的无损指标。13.0/14.0°C下用1-MCP处理的果实比未用1-MCP处理的果实稍晚出现冷害症状。这表明乙烯可能参与了冷害症状的早期发展。
