| Summary: | 碩士 === 中國文化大學 === 生物科技研究所 === 90 === Sweet potato is an important food crop. Temperatures below 10℃ cause chilling injury of sweet potato. In Experiment 1, the appearance of 22 varieties at 5℃ for 14 days was observed. Leaf chlorophyll (CHL) and malondialdehyde contents, leakiness, chlorophyll fluorescence and relative water content (RWC), of 24 varieties were measured during 5 days of chilling (7/ 7℃) and the following 3 days of recovery (24/20℃). Taiwan cultivated chilling-tolerant variety ‘Tainung 71’ and chilling-sensitive ‘Tainung 65’ were selected as experimental materials of Experiment 2 and 3.
In Experiment 2, based on the mentioned six parameters during 5-days chilling (7/ 7℃) and the following 3-days recovery (24/20℃), PBZ pretreatment concentration of ‘Tainung 65’ was measured. The optimal concentration was 300μg/5mL/plant by leaf spray.
In Experiment 3, turgor pressure (TP), RWC, CHL, chlorophyll fluorescence, leakiness, ascorbate peroxidase (APX) and glutathione reductase (GR) activity, ascorbate (ASA) and glutathione contents of ‘Tainung 71’ and ‘Tainung 65’ leaves during 5 days chilling and 3 days recovery were measured after 300μg/5mL /plant PBZ or 5mL/plant d H2O of leaf spray at 24hr before chilling. ‘Tainung 65’ possessed higher CHL content, APX and GR activity, and GSH/GSSG during chilling and recovery. While ‘Tainung 71’ exhibited better RWC, Leakiness, Fv/Fm, Fo, ΦPSⅡ than ‘Tainung 65’. ‘Tainung 71’ was more chilling-tolerant.
Pre-spray of PBZ 300μg/5mL/plant only promoted ASA content of chilling -tolerant ‘Tainung 71’ during chilling and recovery; but increased TP, CHL and reducing agents GSH and ASA, also inhibited Leakiness and Fo of ‘Tainung 65’. While APX and GR activity of ‘Tainung 65’ were lowered.
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