离体条件下苹果摘袋日烧发生过程中果皮细胞超微结构的变化

 对套双层纸袋的富士苹果采收后摘袋，探讨全除袋与先摘外袋3 d后摘除内袋对果实日烧发生的影响。结果表明，套袋果实一次性除袋后，当日即呈现日烧症状，表皮细胞结构破坏，叶绿体解体；先摘外袋3 d后摘除内袋，果实无日烧发生，且着色，着色部位部分叶绿体向有色体转化；不摘袋处理的果实表现正常，细胞结构完整。结果说明果实长期套袋后，摘袋时先除外袋而保留数日内袋，可防止因突然性强光对果皮细胞膜的伤害而导致日烧发生。

Effects of Bag-removing on the Cell Ultra-microstructure of Apple Fruit Peel during the Sunburn Development in Vitro

Apple fruits（Malus domestica‘Fuji’）bagged for three months were removed bags in vitro. Bag-removing included two ways, both outer bag and inner bag removed at a time, and outer bag removed, after 3 d then inner bag removed. The fruits were exposed to sunlight and the sunburn development was studied. The results showed that the fruits removed outer and inner bags, appeared the symptom of sunburn on the first day exposed to sunlight, and their epidemic cells were disorganized and chloroplasts were disaggregated. The fruits removed outer bag then inner bag after 3 d became red without sunburn, and some chloroplasts in epidemic cell were converted chromoplasts. The no-bag-removed fruits were heath, and their cells kept intact. It is suggested that retaining red bag could avoid sunburn from sudden strong sunlight which resulted in cell membrane injured.