| 摘要: | 甘藷‘臺農57號’、‘臺農66號’及‘桃園2號’種植於生長箱中，設定日/夜溫24/20℃、光強度500μmol•-2•s-1、每日光週期16h、相對濕度80%，30天後分別進行高溫試驗（38/35℃處理13天）、乾旱試驗（不給水22天）及淹水試驗（水位維持至栽培介質表面45天）。每次取樣選成熟葉片遮光40 min做暗適應後，使用葉綠素螢光儀測定暗適應葉片之最小螢光值（Fo）、光適應葉片之最小螢光值（Fo’）、暗適應葉片之最大螢光值（Fm）、光適應葉片之最大螢光值（Fm’）、暗適應葉片之螢光變量（Fv）、暗適應葉片光系統II光化學的最高量子效率（Fv/Fm）、閃光前穩定狀態之螢光值（Fs）、光適應葉片之光化學淬熄（qP）、葉片從暗適應到光適應之非光化學淬熄（qN）、葉片從Fm至Fm’之非光化學淬熄（NPQ）、光適應葉片PSII之電子傳遞速率（ETR）、光適應葉片PSII的有效光量子產量（ФPSII）。結果顯示三品種葉綠素螢光對不同逆境之敏感性，自高至低依序為高溫、乾旱、淹水。高溫處理13天期間，‘桃園2號’6h之NPQ比另兩品種高，最快受高溫影響；而‘臺農66號’在高溫11與13天Fv/Fm為三品種中最低、13天之qN亦為三品種中最高，長期而言‘臺農66號’葉綠素螢光表現最不耐高溫。乾旱22天期間，‘臺農66號’於乾旱2-3與7天之ETR皆比另兩品種低，最早受乾旱影響，但14與22天之qN為三品種中最低；‘臺農57號’乾旱13天之NPQ、19天之Fv/Fm比其他兩品種高，其葉綠素螢光表現較耐旱。淹水45天期間，‘臺農66號’於15-16與26天之ФPSII比其他兩品種低，14與23天之qN、以及5-6、14與23天之NPQ亦比其他兩品種高，於淹水中早期‘臺農66號’葉綠素螢光表現最敏感；但‘桃園2號’於淹水42與44天Fv/Fm為三品種中最低，故淹水晚期‘桃園2號’葉綠素螢光表現最不耐淹水。甘藷三品種於高溫逆境下Fv/Fm於6h即顯著降低，可做為高溫耐受性篩選之參考。
The cuttings of sweetpotato 'Tainung No. 57', 'Tainung No. 66', and 'Taoyuan No. 2' were planted in a growth chamber under 80% relative humidity, 500 μmol‧m^(-2)‧s^(-1) photostnthetic photon flux, day 24℃/night 20 ℃, and 16-h photoperiod conditions for 30 days. Plants were then received three treatments: high temperature (38/35℃ for 13 days), drought (water withholding for 22 days), and waterlogging (above medium level for 46 days), respectively. At each sampling, mature leaves were dark-adapted for 40 min followed by the measurements of minimal fluorescence from dark-adapted leaf (Fo), minimal fluorescence from light-adapted leaf (Fo'), maximum fluorescence from dark-adapted leaf (Fm), maximum fluorescence from light-adapted leaf (Fm'), variable fluorescence from dark-adapted leaf (Fv), maximum quantum efficiency of PSII photochemistry from dark-adapted leaf (Fv/Fm), the steady-state value of fluorescence immediately prior to the flash (Fs), photochemical quenching of PSII (qP), nonphotochemical quenching of leaf from dark- to light-adaption (qN), nonphotochemical quenching of leaf from Fm to Fm' (NPQ), electron transport rate through PSII (ETR), effective quantum yield of PSII (ФPSII) with a mini-Pam. The results showed that the sensitivity from high to low of chlorophyll fluorescence in three sweetpotato cultivars followed the order of high temperature, drought, and waterlogging. During 13 days of 38/35℃ treatment, 'Taoyuan No. 2' showed higher NPQ at 6 h than the other two cultivars. 'Taoyuan No. 2' was affected earliest by high temperature. Among three cultivars, 'Tainung No. 66' showed the lowest Fv/Fm on days 11 and 13, and the highest qN on day 13 after treatments. Chlorophyll fluorescence of 'Tainung No. 66' exhibited the lowest tolerance to high temperature in long term. During 22 days of drought, ETR of 'Tainung No. 66' was lower than other two cultivars on days 2-3 and 7. 'Tainung No. 66' was affected earliest by drought, while showed the lowest qN on days 14 and 22. In 'Tainung No. 57', NPQ on day 13 and Fv/Fm on day 19 were higher than other two cultivars. 'Tainung No. 57' was the most drought-tolerant cultivar, as shown by chlorophyll fluorescence. During 45 days of waterlogging, ΦPS II on days 15-16 and 26 of 'Tainung No. 66' were lower, while qN on days 14 and 23, and NPQ on days 5-6, 14 and 23 were higher than other two cultivars. In the early-mid stage of waterlogging, chlorophyll fluorescence of 'Tainung No. 66' was the most sensitive. However, 'Taoyuan No. 2' showed the lowest Fv/Fm among three cultivars on days 42 and 44, indicating 'Taoyuan No. 2' the least tolerance to waterlogging in the late stage of waterlogging. After 6 h under high temperature, the three sweetpotato cultivars exhibited reduced Fv/Fm, which might be a good indicator for tolerance screening. |
