采前氯吡脲处理对‘秦美’猕猴桃贮藏期间果实硬度及细胞壁降解的影响

以‘秦美’猕猴桃果实为试材,于盛花期后28 d分别采用0(对照,清水)、5、10、20 mg/L 4个质量浓度的氯吡脲(1-(2-chloropyridin-4-yl)-3-phenylurea,CPPU)溶液进行蘸果处理,蘸果时间3～5 s,研究采前CPPU处理对‘秦美’猕猴桃贮藏期间果实硬度及细胞壁降解酶活力的影响。结果表明:CPPU处理加速了果实硬度、原果胶和纤维素质量分数的下降,提高了可溶性果胶质量分数及多聚半乳糖醛酸酶(polygalacturonase,PG)、果胶甲酯酶(pectin methylesterase,PME)、纤维素酶(cellulase,Cx)和β-半乳糖苷酶(β-D-galaetosidase,β-Gal)细胞壁降解活力。各处理组果实硬度与可溶性果胶质量分数和PG、Cx活力呈极显著负相关(P0.01),与原果胶、纤维素质量分数呈极显著正相关(P0.01);20 mg/L CPPU处理组果实的β-Gal活力与硬度呈显著负相关(P0.05)。CPPU处理提高了果实细胞壁降解酶的活力,促进了细胞壁的降解,加速了贮藏期间果实的软化,降低了果实的耐贮藏性。为维持猕猴桃采后果实硬度,延长贮藏期,生产中不宜使用CPPU处理,或使用的质量浓度不宜超过5 mg/L。

Effect of Preharvest 1-(2-Chloropyridin-4-yl)-3-phenylurea Treatment on Fruit Firmness and Cell Wall Degradation of ‘Qinmei’ Kiwifruit during Cold Storage

The effect of preharvest forchlorfenuron (1-(2-chloropyridin-4-yl)-3-phenylurea, CPPU) treatment on fruit firmness and cell wall degrading enzyme activities in ‘Qinmei’ kiwifruit during cold storage was studied by dipping young fruits with 0, 5, 10 or 20 mg/L CPPU solution 28 days after flowering. Control fruits were dipped in water. All fruits were dipped for 3–5 s. The results showed that CPPU treatment accelerated the decline in fruit firmness and the contents of protopectin and cellulose and increased the content of soluble pectin and cell wall degrading enzyme activities, including polygalacturonase (PG), pectin methylesterase (PME), cellulase (Cx) and beta galactosidase (β-Gal). For all treatment groups, fruit firmness was significantly negatively correlated with soluble pectin content and PG and Cx activity (P < 0.01), and was significantly positively correlated with protopectin and cellulose contents (P < 0.01). The firmness of 20 mg/L CPPU treated fruits was significantly negatively correlated with β-Gal activity (P < 0.05). CPPU treatment enhanced the activity of cell wall degrading enzymes, sped up the degradation of cell wall components, accelerated fruit softening during storage, and reduced storability. In order to maintain the firmness of post-harvest kiwifruit and prolong the storage period, CPPU should not be used or used at a concentration at a concentration not exceeding 5 mg/L.