Abstract: Fruit of pear cultivar Dangshansu were used as materials for investigating the relationship a
mong sclereids, related enzymes and fruit quality. The results showed that fruit had the similar developmental
course either bagged or not, the density of sclereid group was high at the early stage, then decreased with the
fruit development, and became stable two months before ripeness. The size of sclereid group increased gradu
ally during early stage, then decreased and increased again with fruit development, while the quantity of scle
reid increased also during early stage and decreased, but reached to max 49 d after anthesis, in accordance
with the activities decline of POD ( Peroxidase) , PAL ( Phenylalanine ammonia2lyase) , and PPO ( Polyphe
nol oxidase) enzymes. In control and bagging treatments, the content of titratable acid in bagged fruit was
higher, but TSS ( total soluble solid) , total soluble sugars and fruit mass were lower than that in unbagged
fruit. Especially the quantity of sclereid in bagged fruits were markedly decreased than that in unbagged fruit
at all stages. Meanwhile, compared with that of bagged fruit, activities of all the three enzymes were more
lower in bagged fruit, indicating that the activities of POD, PAL and PPO were positively related to the forma
tion of sclereids.

Key words: Pear, Bagging, Fruit quality, Sclereid, Enzyme