不同荔枝品种采后果实衰老的比较

A Comparative Study of Postharvest Fruit Senescence in Different Lit- chi Cultivars

比较了5个荔枝(LitchichinensisSonn.)品种“(怀枝”、“糯米糍”、“桂味”、“红蜜荔”和“水晶球”)果实采后在常温下的衰老表现。其中,“糯米糍”果实衰老褐变快,而“桂味”衰老最为缓慢。果实褐变过程伴随失水,但品种间脱水速度与果实衰老的速度无显著相关性。果皮的褐变潜力、果皮细胞壁糖醛酸含量、果胶甲酯化程度、果皮和果肉总钙含量、果皮水溶性钙含量与果实衰老均无显著的相关性,但膜透性与坏果率呈显著的正相关,而果皮结构钙与之有显著的负相关性。

Among the 5 tested litchi （Litchi chinensis Sonn.） cultivars （“Huaizhi”, “Guiwei”, “Nuomici”, “Hongmili” and “Shuijingqiu”）, “Nuomici” became deteriorated much faster than other cultivars while “Guiwei” fruit was the slowest in the rotting process （Fig.1A）. Fruit deterioration was accompanied by fruit desiccation （Fig.2B）, but the speed of water loss was not significantly correlated to fruit deterioration rate, indicating that it was not the key factor causing the difference in postharvest performance among cultivars. Fruit deterioration rate was significantly positively correlated to membrane leakage （Fig.2A）, suggesting the capacity to maintain membrane integrity is closely related to the shelflife of litchi. Skin browning potential, uronic acid concentration, degree of methylation of pectin and soluble Ca content in pericarp as well as total Ca content in the pulp were not significantly correlated with fruit deterioration. Content of structural Ca （water-insoluble but acetic acid-soluble calcium, membrane or wallbound Ca）, the major form of Ca in the pericarp, was negatively correlated to fruit deterioration rate （Fig.2E）. The results proved that differences in fruit desiccation rate, browning potential, Ca other than structural form were not the major cause leading to difference in postharvest performance among different cultivars. “Guiwei” being more tolerant to desiccation than other cultivars is likely associated its higher structural Ca concentration in the pericarp.