自由基清除剂对延缓青花菜花蕾衰老的效应

青花菜采后花蕾迅速衰老，叶绿素和蛋白质含量明显下降，超氧物歧化酶（ＳＯＤ）和过氧化氢酶（ＣＡＴ）活性随衰老进程先升高而后下降，丙二醛（ＭＤＡ）持续增加，细胞膜透性迅速增大。２０ｍｇ／Ｌ６－苄基腺嘌呤（６－ＢＡ）处理明显延缓叶绿素和蛋白质的降解，提高ＳＯＤ活性，对ＣＡＴ激活尤为明显，抑制了Ｈａｂｅｒ－Ｗｅｉｓｓ反应，降低过氧化氢（Ｈ２Ｏ２）和羟基自由基（ＯＨ）含量，延缓膜脂过氧化作用，降低子ＭＤＡ含量，减小膜渗漏，延缓花蕾衰老。２０ｍｇ／Ｌ６－ＢＡ中加入０２％苯甲酸钠（ＳＢＮ），对６－ＢＡ产生的各种延衰效应均有增效作用，进一步推迟花蕾衰老。２００ｍｇ／Ｌ抗坏血酸（ＡｓＡ）促进叶绿素和蛋白质降解，在提高ＳＯＤ和ＣＡＴ活性的同时，ＭＤＡ反而明显增加，膜透性迅速增大，加速衰老。

Effects of Free Radical Scavengers on Delaying the Senescence in Flower Buds of Broccoli

The flower buds of broccoli senesced quickly after harvesting. The contents of chlorophyll and protein decreased obviously. During the process of the senescence, the activities of SOD an CAT increased and then decreased, MDA content increased steadily,and the permeability of cell membrane augmented rapidly.With 20mg/L6-BA,the decompositions of chlorophyll and protein were delayed significantly, SOD activity was raised, CAT activity was activated especially, the reaction of Haber-Weiss was inhibited, both contents of H 2O 2 and OH.were reduced, the lipid peroxidation was deferred, MDA content was reduced, and the seepage of cell membrane was decreased. All these changes delayed the senescence of the flower buds. With 20mg/L 6-BA 0 2% SBN, the effects on delaying the senescence were greater. But with 200mg/L AsA, the decomposition of chlorophyll and protein was promoted, while the activities of SOD and CAT were enhanced, MDA content was increased significantly, the permeability of cell membrane was augmented rapidly, and thus accelerated the senescence.