耐熱矮牽牛之耐熱性與耐熱指標

Heat tolerance and heat-tolerance indicators of heat tolerant petunias

林嘉洋(Chia-Yang Lin)

指導教授 ： 葉德銘

共同指導教授 ： 張育森

國立臺灣大學/生物資源暨農學院/園藝學研究所/碩士(2006年)

https://doi.org/10.6342/NTU.2006.01868

摘要

為了發展矮牽牛的耐熱指標，本研究比較七個耐熱矮牽牛或不耐熱的矮牽牛品種之形態與生理作用的相異之處。與16℃相比，矮牽牛耐熱品種‘Wave Blue’與‘Tidal Wave Silver’在27℃下地上部乾重增加，且比不耐熱品種維持較多的分枝數及根系。隨溫度由16℃升高至33℃，各品種的相對傷害值(relative injury, RI)有顯著降低，且耐熱品種降低的程度較大。27℃之下，品種間的RI值區別性最大，且RI值與各品種由16℃升高至27℃所減少的分枝數呈二次正相關(R2 = 0.79, P < 0.001)，故平均溫度27℃為篩選耐熱矮牽牛的適合環境，較低的RI植與較多的分枝為耐熱矮牽牛的指標。
在三個根溫下栽培四週後，以50℃、30分鐘的水浴處理最能區分品種間RI值的差異。耐熱矮牽牛‘Happy Dream Blue’與‘Tidal Wave Silver’栽培在根溫30℃的環境下，其RI值有顯著的降低，而不耐熱品種則否。
不同於傳統矮牽牛品種對光週期的反應，耐熱品種‘Wave Blue’與‘Tidal Wave Silver’在日長14-17小時下的分枝數與花朵數較多。耐熱矮牽牛‘Tidal Wave Silver’在長日之下地上部乾重增加，不耐熱品種‘Fantasy Ivory’則顯著減少。長日之下參試品種的根系均減少，耐熱矮牽牛在長日下維持較多的根系。矮牽牛的營養生長對光週期的反應依品種而不同，但參試品種的開花均受到長日的誘導，顯示無論耐熱與否，參試品種仍皆為非絕對性的長日植物。
耐熱品種‘Tidal Wave Silver’及不耐熱品種‘Fantasy Ivory’矮牽牛花粉在經過45℃加熱0、1或2小時之後，觀察熱處理對矮牽牛花粉活力及萌發率的影響以及花粉耐熱性的品種間差異。加熱1或2小時後，花粉活力及發芽率顯著較不加熱處理降低，但不耐熱矮牽牛‘Fantasy Ivory’下降程度顯著較‘Tidal Wave Silver’劇烈。花粉活力與花粉發芽率之間具有顯著的線性關係(R2 = 0.87, P < 0.0001)，表示花粉的活力對於花芽的萌發能力具有代表性。以45℃預處理花粉1小時，其花粉活力的下降程度可作為辨別矮牽牛耐熱性的指標。
矮牽牛種子播於21℃、25℃、30℃及35℃之下，種子發芽率、子葉展開率、種子或子葉展開的T50與T90均不能有效區別品種間的差異。在30℃之下，耐熱品種在子葉展開後隨即有本葉發生，而不耐熱品種幾乎無本葉發生。因此在30℃之下是否有本葉發生，可能為篩選耐熱矮牽牛的有效指標。

關鍵字

矮牽牛 ； 耐熱 ； 分枝數 ； 細胞膜熱穩定性 ； 根系

並列摘要

Summary
To develop the heat-tolerance indicators of petunia (Petunia ×hybrida Hort.), differential morphological and physiological responses to four temperatures regimes between seven heat-tolerant (HT) or heat-sensitive (HS) petunia cultivars were investigated. While grown at 27℃, the shoot dry weights of HT cultivars Wave Blue and Tidal Wave Silver increased as compared with grown at 16℃. HT cultivars maintained more branches and root dry weight than the HS cultivars did. The relative injury (RI) values of all cultivars tested decreased significantly as growing mean temperature increased from 16℃ to 33℃, and the reduction of RI values was more obvious in HT cultivars. While grown at 27℃, RI values of the tested cultivars were the most distinct, and were positively related to the reduction of branches (R2 = 0.79, P < 0.001). Thus, a mean of 27℃ was a suitable growing temperature to screen the heat-tolerant petunias, which had lower RI values and more branches.
The most effective treatment to distinguish RI values between HT and HS petunia cultivars was 50℃ water bath for 30 minutes. The RI values of HT cultivars Happy Dream Blue and Tidal Wave Silver grown at 29℃ root temperature were smaller than those at 21℃ or 26℃, while RI values of HS cultivars grown at all root temperatures were constant.
Unlike the traditional cultivars, HT cultivars Wave Blue and Tidal Wave Silver produced similar or more branches and flowers under LD treatments. The LD treatments increased shoot dry weight in HT cultivar Tidal Wave Silver, but decreased dry weight in HS cultivar Fantasy Ivory. All cultivars had less root dry weight under LD than SD, but Tidal Wave Silver maintained more root dry weight than HS cultivars. Despite of the differential vegetative growth responses, flowering was all promoted under LD in three cultivars tested
The pollens of ‘Tidal Wave Silver’ and ‘Fantasy Ivory’ petunia were subjected to 45℃ for 0, 1, or 2 hours to determine the effects of heat treatment on pollen viability and germination percentage. After heated for 1 or 2 hours, both pollen viability and germination percentage of both cultivars declined significantly. However, ‘Fantasy Ivory’ exhibited more decline in pollen viability and germination percentage than ‘Tidal Wave Silver’. A linear relationship existed between pollen viability and germination percentage (R2 = 0.87, P < 0.0001), indicating that pollen viability could be used to measure germination. The pollen viability after treated with 45℃ for 1 hour could also be used for screening heat-tolerant petunias.
Neither the percentage of seed germination, the percentage of cotyledon expansion, the time to 50% or 90% of seed germination or cotyledon expansion could be used to distinguish heat-tolerance in four petunia cultivars. At 30℃, the first leaves of HT cultivars Tidal Wave Silver and Wave Blue emerged, while those of HS cultivars did not. Thus, the first leaf emergence at 30℃ could be used for screening heat-tolerant petunias.

並列關鍵字

petunia ； heat tolerance ； branch ； cell membrane thermostability ； root

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