苦瓜采后某些生理生化变化与其衰败的关系

Relationships between some physio-biochemical changes and senescence during storage in bitter gourd

对采后常温贮藏的蓝山大白苦瓜的呼吸速率、乙烯释放速率及SOD、POD、CAT活性和AsA、GSH的含量进行了测定.结果表明,适期采收的食用苦瓜呼吸速率呈下降趋势,第8天叶绿素消失、瓜皮转黄前后转为上升,一直延续至苦瓜衰败,其呼吸类型属晚峰型;苦瓜采后乙烯释放呈上升趋势,初期乙烯释放微弱,增加缓慢,从第6天开始急剧增加.乙烯释放速率上升早于呼吸上升,二者在采收6d后迅速同步上升.苦瓜采后1～4d,保护酶系统的SOD、POD、CAT活性出现适应性上升,非保护酶系统的AsA、GSH含量也上升;在4～8d,除POD活性迅速下降后又急剧上升及AsA含量在6d后下降外,SOD、CAT活性和GSH含量均稳中有降,保持相对稳定;在叶绿素消失、瓜皮转黄的第8天后,AsA、GSH含量急剧减少,而SOD、POD、CAT活性急剧增强,视为衰老迅速恶化的结果.

The respiration pattern of bitter gourd should belong to the late peak type.Ethylene production was very little at the primary stage after harvest and at the 4th day the obvious increment was detected and this increment tendency went on until breakdown of bitter gourd arrived.The other changes were classified as three stages:physiological adjustment stage (1~4 days),relative stable stage (4~8 days) and senecence stage (8~12 days).It was supposed that ethylene played an important role and lipid peroxidation did little in ripening and senescence of bitter gourd.It was suggested that the increment of respiratory rate,POD activity and the decrease of AsA content after 6th day should be considered as physiological implications of ripening,and that the rapid decrease of soluble protein and GSH content,the rapid increment of SOD and CAT activity after 8th day should be thought to be physiological indexes of senescence.