The effects of bagging on fruit characteristics and its role in physical fruit protection were investigated in three pitaya cultivars: Vietnam White (VN-White) and Chuchi Liu (Hylocereus undatus), and Chaozou 5 (Hylocereus sp.). The experiment comprised four treatments: paper-white bag (P-WB), net screen-black bag, polyethylene plasticblack bag (PP-BB), polyethylene plastic-white bag (PP-WB) and non-bagged control. Fruit bagging did not change the fruit lightness but significantly affected other peel colorimetric parameters. VN-White fruits bagged with P-WB became redder (a* ¼ 27.6), less yellow (b* ¼ 4.4) and had higher colour purity (h8 ¼ 10.7) than non-bagged fruits. Fruits with P-WB in Chuchi Liu also showed significant difference in b* and h8 values as compared with control. Bagging with PP-BB or PP-WB in Chaozou 5 also produced redder fruits (a* ¼ 31.7 and 30.3) with more colour intensity (C* 5 32.4 and 31.3) than non-bagged fruits. There were no significant differences in fruit size and weight, total soluble solids content and fruit ripening duration among treatments in all three cultivars. Fruit firmness also exhibited no significant differences among most treatments except for PP-BB, which gave a lower value than other treatments. In general, fruit bagging could reduce the peel thickness but could not increase the edible fruit rate. The most important role of fruit bagging was to effectively protect fruits from physiological factors such as cracking, bird damage and blemish, which led to the significant decrease of the total damaged and defective fruits (13.7-33.3%), as compared with non-bagged control (66.7-72.6%).

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