馬鈴薯在高溫下的生理反應

Abstract

高溫逆境會造成馬鈴薯(Solanum tuberosum L.)植株形態、生理與生化之改變，而影響馬鈴薯的結球與產量。本研究以葉片細胞膜熱穩定性 (cellular membrane thermostatbility)、脯胺酸含量(proline content)、葉綠素螢光參數(chlorophyll fluorescence parameters)與葉綠素計(Chlorophyll meter, SPAD)讀值四種生理指標之變化，探討馬鈴薯在不同高溫逆境下的反應，並以‘克尼伯’(Kennebec)為對照，比較不同馬鈴薯品系的耐熱程度。由嘉義溪口鄉馬鈴薯田間取樣種植後30-52天的‘克尼伯’其葉片相對熱傷害值介於62-95.8%，有隨時間略降低的趨勢，但差異不顯著。分析農業試驗所夏作馬鈴薯之細胞膜熱穩定性，並與最後收成之塊莖重量比對，結果為有薯球的品系其相對熱傷害值較低。‘克尼伯’沒有結薯，其它27種供試品系中有兩個97.1之實生品系之熱傷害值較‘克尼伯’低。於九月中提早種植之農業試驗所秋作中，22種供試馬鈴薯中有PS3-2與97.1之實生品系兩種較‘克尼伯’之熱傷害值低。以35/30℃熱馴化一天可增加‘克尼伯’、LT-7之熱適應性，它們的熱傷害值均比未馴化株低，其它13種供試品系中，PS3-1、PS3-2兩種之相對熱傷害值較‘克尼伯’低。日、夜溫30/25℃處理7天對四種馬鈴薯‘克尼伯’、LT-7、97.1-28與PS3-2造成脯胺酸含量上升、處理14天結果葉綠素計讀值減少，最後‘克尼伯’薯球鮮重減少79 %，沒有結薯的品系其脯胺酸含量增加最多。種後一個月給予40℃黑暗處理3小時，4種馬鈴薯中以‘克尼伯’之葉綠素螢光參數值(Fv/Fm及ΦPSII)降低幅度較大，‘大西洋’ (Atlantic)的 Fv/Fm 值在處理6小時降到最低，其它各品種(系)的Fv/Fm值及其它螢光參數此時無顯著差異。比較相同四種馬鈴薯在生長箱定溫20℃及30℃處理三週的葉綠素螢光參數變化，在30℃處理7天，四種馬鈴薯Fm值均比20℃處理低；‘克尼伯’之Fo值最低。30℃處理21天有三種馬鈴薯的 Fv/Fm 值顯著降低，其中‘大西洋’及‘克尼伯’的 Fv/Fm 值低於0.8，‘克尼伯’之ΦPSII值且為最低。採收時‘大西洋’及‘克尼伯’ 的地上部鮮重減少70%以上，‘克尼伯’沒有結薯，另兩種馬鈴薯地上部鮮重及薯球鮮重分別維持20℃處理的55%與30%以上。將6種馬鈴薯分別給予20/15℃與30/25℃兩種處理，調查同一葉片在一週內的葉綠素螢光參數變化，97.1-19於高溫處理第一天其Fv/Fm值即顯著低於20/15℃處理，LT-7與‘克尼伯’於高溫處理第4天，97.1-47於第7天Fv/Fm值才明顯較低。採收時97.1-47有最高的地上部鮮重及薯球鮮重，比20/15℃處理減少幅度相對最低，而維持相同的莖葉與薯球鮮重比。在田間初夏測量14個馬鈴薯品系的Fv/Fm值介於0.46-0.70，‘台農一號’維持比‘台農三號’顯著較高的Fv/Fm 值。以97.1與295兩種馬鈴薯比較35/30℃、30/25℃與20/15℃三種溫度處理對植株營養生長的影響，結果顯示栽培於35/30℃處理14天的植株最矮，葉綠素計讀值最低，葉色最早也最快變淺。植株在30/25℃下即生長受抑制，地上部重量為20/15℃處理之70%，薯球生成少，於35/30℃處理下，兩種馬鈴薯皆不能結球。整體而言，馬鈴薯品系07-237選1 (97.1-45)、PS3-2、06-674與97.1-47具有比‘克尼伯’更耐熱之生理性狀。

Heat stress causes a series of morphological, physiological and biochemical changes in potato (Solanum tuberosum L.) plants and results in adverse effect on the tuber production. In this study, the responses of potato to high temperature were monitored by the variation of the cellular membrane thermostability, proline content, chlorophyll fluorescence parameters and chlorophyll meter reading (SPAD values) in leaf. The clonal difference in heat tolerance was evaluated with ‘Kennebec’ as a reference. The relative injury values ranged between 62% and 95.8% with a decreasing tendency along with increasing growth period in ‘Kennebec’ when sampled at 30-52 days after planting from a farmer’s field in Chia-yi. The analyses of cellular membrane thermostability of potatoes at TARI in summer showed that clones with lower relative injury (RI) values had higher tuberization rate. The ‘Kennebec’ failed to produce any tuber and, out of other 27 clones tested only two of 97.1 seed progenies had significantly lower RI value than that of ‘Kennebec’. In 22 clones tested from the fall crop (planted in mid September) of TARI, clone PS3-2 and one clone of 97.1 had RI value significantly lower than that of ‘Kennebec’. The effect of acclimation at 35/30℃(day/night) for 24 hours was revealed by the reduced RI value in both ‘Kennebec’ and LT-7, and among 13 other tested clones, PS-1 and PS-2 were considered more heat tolerant than ‘Kennebec’ for their low RI values. Proline content of four potato varieties increased under 30/25℃ for 7 days , the respective SPAD values taken at 14 days of treatment decreased. At harvest, ‘Kennebec’ had 79% reduction in tuber fresh weight and the clone without tuber production had leaf proline content much increased. The chlorophyll fluorescence responses to high temperature were used to determine heat tolerance of potato plants. At 3 hours of 40℃ in dark, ‘Kennebec’ showed more reduction in Fv/Fm and ΦPSII than other 3 lines examined. The Fv/Fm value of ‘Atlantic’ dropped to the lowest at 6 hr of treatment, and all 4 variety/lines showed similar Fv/Fm and other parameters then. The same 4 potato variety/lines were examined under temperature treatments of 20℃ and 30℃ for 3 weeks. The Fm of all 4 at 30℃ were lower than at 20℃. ‘Kennebec’ had the lowest Fo. At 30℃ for 21 days, three variety/lines showed significant reduction in Fv/Fm and both ‘Atlantic’ and ‘Kennebec’ had a value less than 0.8. ‘Kennebec’ also had the lowest ΦPSII value. At harvest, the shoot fresh weight of both ‘Atlantic’ and ‘Kennebec’ was reduced by more than 70%, and no tuber was produced in ‘Kennebec’. The other two lines at 30℃ produced 55% of shoot and 30% of tuber fresh weight obtained at 20℃. The Fv/Fm of the same leaf was monitored for one week on 6 potato lines grown under 20/15℃ and 30/25℃. The value declined under 30/25℃ treatment at one day in 97.1-19, at 4th day in LT-7 and ‘Kennebec’ and 7th day in 97.1-47, and the latter had the highest shoot and tuber fresh weight at harvest. 97.1-47 kept similar ratio of shoot to tuber fresh weight under both 20/15℃ and 30/25℃. The Fv/Fm values of 14 potato lines examined in field ranged between 0.46 and 0.70. Among them, ‘TN 1’ had higher Fv/Fm value than ‘TN 3’. To evaluate the vegetative growth of potato under heat stress, two clones were grown at 35/30℃, 30/25℃ or 20/15℃. Plants at 35/30℃ for 14 days had the smallest plant height and leaf SPAD values. The temperature of 30/25℃ restricts haulm growth, resulting in 70% of the shoot fresh weight of 20/15℃ treatment and very limited tuberization. Under 35/30℃ treatment, leaf SPAD value rapidly decreased and there was no tuberization. In all, potato clones like 07-237-1 (97.1-45)、PS3-2、06-674 and 97.1-47 showed physiological response related to better heat tolerance than ‘Kennebec’.