乾旱逆境下甘藷生育初期之逆境指標研究

本研究以甘藷（Ipomoea batatas L.）台農57號為材料，於溫室進行30天之乾旱逆境處理（CK組累積供水量為9,500 mL、輕度乾旱組4,500 mL，重度乾旱組0 mL），於處理期間調查甘藷生育初期之性狀變化，包含葉溫、莖蔓長、鮮乾重等外表型性狀及葉片光合色素（葉綠素、類胡蘿蔔素）、丙二醛（MDA）等生理反應，並建立甘藷耐旱性之評估指標及適期。試驗結果顯示，甘藷葉溫於20-30 DAT（days after treatment）呈顯著差異，重度乾旱組之葉溫顯著較高，CK組較低；甘藷莖蔓長、鮮（乾）重皆於25-30 DAT呈顯著差異，以CK之莖蔓長、鮮乾重顯著高於輕度乾旱組，而重度乾旱組顯著最低。葉綠素a、總葉綠素及類胡蘿蔔素含量皆於15-30 DAT呈顯著差異，以重度乾旱組顯著較低，CK與輕度乾旱組之間多無顯著差異；而葉綠素b則於30 DAT方有明顯差異。甘藷葉片MDA含量於10 DAT即出現顯著差異，以重度乾旱組顯著較高，而CK與輕度乾旱組較低且兩者間無顯著差異。綜合本試驗結果，重度乾旱顯著抑制甘藷生育初期之生長，與CK相比，30 DAT之甘藷莖蔓長降低20.9%、莖及根部重量分別下降63.8%（莖鮮重）、43.0%（莖乾重）、84.0%（根鮮重）及78.6%（根乾重），光合色素含量分別減少40.0%（葉綠素a）、30.7%（葉綠素b）、35.5%（總葉綠素）及23.7%（類胡蘿蔔素），而葉溫上升1.4°C、葉片MDA含量增加201.7%。其中，葉溫為便利、有效且非破壞性之指標，可於20 DAT後進行調查；葉片MDA指標穩定、可靠且效率較快，於10 DAT即可進行分析，可供未來甘藷耐旱品系篩選及節水栽培等相關研究之參考。

關鍵字

甘藷；乾旱逆境指標；葉溫；光合色素；丙二醛

並列摘要

In this study, the sweetpotatos (Ipomoea batatas L. cv. TN57) were treated with 30 days of drought treatment in the greenhouse (the cumulative water supplies were 9,500 mL (CK), 4,500 mL (mild drought), and 0 mL (severe drought) in the pot experiment). The phenotypic traits during the early growth stage of sweetpotato were investigated, including leaf temperature, shoot length, fresh and dry weight of shoot and root, as well as the physiological responses of photosynthetic pigments (chlorophyll and carotenoids) and MDA contents. The results showed that there was a significant difference in sweetpotato leaf temperature at 20-30 DAT (days after treatment). The leaf temperature was higher in the severe drought treatment and lower in the CK group. At 25-30 DAT, there were significant differences in shoot length, weight of sweetpotato shoot and root. The shoot length, fresh and dry weight were significantly higher in the CK group than in the mild drought treatment, while the lowest shoot length, fresh and dry weight were found in the severe drought treatment. The chlorophyll a, total chlorophyll and carotenoid contents of sweetpotato leaf were significantly different at 15-30 DAT. The severe drought treatment group was significantly lower, and there was no significant difference between the CK and mild drought treatment. The changes in leaf MDA content showed significant differences after 10 DAT. The MDA content was significantly higher in the severe drought treatment, and there was no significant difference between the CK and mild drought treatment. In summary, the severe drought inhibited the growth of sweetpotato. Compared with the CK group at 30 DAT, the shoot length decreased by 20.9%, shoot FW, shoot DW, root FW and root DW decreased by 63.8%, 43.0%, 84.0% and 78.6%, respectively. For the photosynthetic pigment contents, the chlorophyll a, chlorophyll b, total chlorophyll and carotenoids decreased by 40.0%, 30.7%, 35.5% and 23.7%, respectively. The leaf temperature increased by 1.4°C and the MDA content increased by 201.7%. Among these traits, the leaf temperature was a convenient, effective and non–destructive method that could be investigated after 20 DAT; the leaf MDA was a stable, reliable and valid indicator that could be analyzed at 10 DAT. The results of the present study could be used as reference for future research on drought-tolerant lines selection or water-saving cultivation of sweetpotato.

並列關鍵字

Sweetpotato ； Drought stress index ； Leaf temperature ； Photosynthetic pigments ； Malondialdehyde

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