柚果实采后组织含水量、保护酶活性与汁胞粒化的关系

Water content of tissues, protective enzyme activity and their relationship to juicy sac granulation in pummelo at postharvest stage

柚果实在贮藏期间，果皮中的超氧化物歧化酶（ＳＯＤ）活性前期呈缓慢下降趋势， ６０ ｄ 后逐渐上升；果肉中的ＳＯＤ活性则相反．果皮中的过氧化物酶（ＰＯＤ）活性迅速上升， ６０～７５ ｄ 后下降；果肉中的ＰＯＤ活性变化与果皮相似，只是９０ ｄ 后又缓慢上升，但果肉中的ＰＯＤ活性较小．自交和杂交王官溪蜜柚果皮中的过氧化氢酶（ＣＡＴ）活性呈下降的趋势，四季柚前期上升，后期下降；而果肉中的ＣＡＴ活性变化是自交王官溪蜜柚呈下降趋势，杂交王官溪蜜柚和四季柚前期上升，后期下降．果皮、果肉中的丙二醛（ＭＤＡ）质量摩尔浓度前期上升，后期下降，但峰值出现的时间和前期增幅都不同，自交王官溪蜜柚的峰值来得早，增幅也大．果皮、果肉的组织含水量、束缚水含量变化与ＭＤＡ相似．四季柚果实汁胞粒化指数几乎为零，杂交王官溪蜜柚果实汁胞粒化指数从１．３７％ 上升到２．２９％ ，自交王官溪蜜柚果实汁胞粒化指数从３７．４７％ 上升到９４．６７％ ．

During storage, the activity of superoxide dismutase (SOD) in rind of pummelo showed the trend of decreasing slowly in early period, and increased gradually 60 days later, but contrary in pulp. The activity of peroxidase (POD) in rind increased rapidly, and decreased 60-75 days later, while in pulp the activity of POD was low, changed similarly and increased slowly 90 days later. The activity of catalase (CAT) in rind of both hybrid and inbreed showed the trend of decreasing, but increased in early period and decreased later in four season pummelo, while in inbreed pummelo pulp it showed the trend of decreasing, but increased in early period and decreased later in hybrid and four season pummelo. The molality of malondialdehyde (MDA) in rind and pulp increased in early period and decreased later, but the time of peak appearing and range of increasing in early period were different in varieties: the peak appearing was earlier and range of increasing was larger in inbreed than those in hybrid and four season pummelo. The change of content of free water and band water in rind and pulp were similar as MDA. The index of juicy sac granulation in four season pummelo was almost 0, but that in hybrid increased from 1.374% to 2.29%, and that in inbreed increased from 37.47% to 94.67%.