冷敏橄榄果实成熟度与抗冷性的关系及其机理研究

Low temperature storage was the most effective method for prolonging the shelf-life of Chinese olive（Canarium album (Lour.) Raeusch）fruits, but Chinese olives were chilling-sensitive fruits, it was easy to produce chilling injury during cold storage, which seriously affected appearance quality and commodity value of Chinese olive fruits. Our previous research showed that fruit harvest maturities of Chinese olives were related to the chilling tolerance and the extent of chilling injury, while the physiological mechanism was not identified at present. Therefore, this research started with the response characteristics of different harvested maturities on chilling injury, energy metabolism, active oxygen metabolism, fatty acid constituents and degrading enzymes of membrane lipids variation of Chinese olive fruits in low temperature stress. By comparing the sensitive disparity of chilling injury on different harvested maturities of Chinese olive fruits, the relationship between fruit maturity and chilling tolerance of Chinese olives and its mechanism were elucidated. This property will be found new scientific basis by elucidating the possible mechanism of the relationship between fruit maturity and chilling tolerance of Chinese olives, and provide the theoretical guidance for determining the optimum harvest maturity of Chinese olive fruits in low temperature storage.

低温贮藏是延缓橄榄[Canarium album (Lour.) Raeusch]果实成熟衰老、延长其贮藏保鲜期最为有效的保鲜方式，但橄榄是冷敏型果实，低温贮藏时容易产生冷害，严重影响橄榄果实的外观品质和商品价值。我们前期研究认为，橄榄果实采收成熟度与抗冷性及冷害发生程度有关，但目前对其生理机制尚不清楚。本课题拟从低温胁迫对不同采收成熟度橄榄果实的冷害发生、组织能量代谢、活性氧代谢、膜脂脂肪酸组分及膜脂降解相关酶活性变化的响应特点入手，通过比较不同采收成熟度橄榄果实对冷害发生的敏感差异性来阐明橄榄果实成熟度与抗冷性的关系及其作用机理。研究成果可望在阐明橄榄果实成熟度与抗冷性的可能机制方面获得新的科学依据，为橄榄果实低温贮藏确定适宜采收成熟度提供理论指导。

本项目以‘檀香’橄榄果实为试材，研究冷敏橄榄果实采收成熟度与抗冷性的关系及其作用机理。结果如下：.1、探讨7个采收成熟度（Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ、Ⅵ、Ⅶ）对（2±1）℃、90%相对湿度下冷藏橄榄果实品质和冷害的影响。结果表明：与第Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅵ、Ⅶ采收成熟度相比，第Ⅴ采收成熟度能保持(2±1)℃冷藏橄榄果实较低的果实冷害指数、果皮褐变指数、果实失重率和较高的好果率，降低果实呼吸强度和呼吸峰值，延缓果实细胞膜相对渗透率的升高，在冷藏中后期（60~100 d）保持较高的果实表面色度角H、较高的果皮叶绿素含量、较高的果肉可溶性固形物、可滴定酸、可溶性总糖和还原糖含量。.2、在此基础上进一步研究（2±1）℃冷藏条件下，第Ⅰ、Ⅲ、Ⅴ、Ⅶ采收成熟度橄榄果实抗冷性与活性氧代谢、膜脂代谢、能量代谢以及酚类物质代谢的关系：与第Ⅰ、Ⅲ、Ⅶ采收成熟度果实相比，第Ⅴ采收成熟度橄榄果实（果皮、果肉）提高SOD、CAT、APX等活性氧清除酶活性和AsA、GSH等内源抗氧化物质含量，降低O2-.产生速率和膜脂过氧化产物MDA含量；第Ⅴ采收成熟度橄榄果实（果皮、果肉）降低PLD、脂酶和LOX等膜脂降解相关酶活性，延缓油酸、亚油酸、亚麻酸等不饱和脂肪酸相对含量下降，维持较高的脂肪酸不饱和指数（IUFA）和脂肪酸不饱和度（U/S），有效维持果实细胞膜结构的完整性；第Ⅴ采收成熟度橄榄果实（果皮、果肉）延缓ATP、ADP含量和能荷下降，抑制AMP含量上升，保持较高的Ca2+-ATPase、Mg2+-ATPase、H+-ATPase和NADK活性及NADPH、NADP含量，延缓果实细胞膜结构完整性的破坏；第Ⅴ采收成熟度橄榄果实（果皮、果肉）降低PPO和POD活性，延缓PAL活性、总酚和类黄酮含量下降，推迟褐变等冷害症状的出现。.因此认为，第Ⅴ采收成熟度可作为减轻（2±1）℃、90%相对湿度下冷藏橄榄果实冷害发生的适宜采收成熟度。