光質對桃葉斑鳩菊(Vernonia amygdalina)之光生理與抗氧化能力影響

Abstract

桃葉斑鳩菊(Vernonia Amygdalina)為一種非洲常見的灌木植物，在當地除作蔬菜之外亦有許多民俗醫療用途，近代醫學亦對其進行許多藥用研究，發現桃葉斑鳩菊具有高抗氧化力，且有治療癌症、糖尿病、肝受損、肥胖等疾病的功能，為一極具發展潛力之作物。空氣、水、光為植物的生長必要條件，已知不同光質對於植物的生理反應與代謝產物會有不同的影響，在溫或植物工廠中為易於控制的生長條件，可利用其創造作物更高的利用價值。本研究利用紅、藍、綠、紅藍混光之 LED燈與螢光燈等，對桃葉斑鳩菊進行處理，以探討不同光質對其產量、抗氧化能力、色素含量與葉綠素螢光反應的影響，也期望利用葉片反射光譜建立非破壞性檢測色素與抗氧化能力的系統，並建立其微體繁殖系統以供未來生產之使用。研究結果顯示，在藍光處理下的株高、地上部與地下部之乾重最高，綠光處理則為最低。呼應葉綠素螢光指數中光系統Ⅱ的量子產能 Y(Ⅱ)與光系統Ⅱ開放程度 qP 一樣是藍光最高而綠光最低，可知藍光的光合效能較高而綠光較低，故有不同的生物累積量。色素方面，藍光會促進葉綠素與類胡蘿蔔素的生合成，而紅光與紅藍混光處理的色素含量最低。葉綠素螢光數據最大光合潛能 Fv/Fm 中顯示各處理下的植株都未遭遇逆境，但紅光與紅藍混光處理的植株健康程度相對較低。在抗氧化力方面，清除DPPH 的能力以綠光與紅藍混光處理最高，還原力則是紅藍混光處理最高；抗氧化物質含量的部分，總酚在處理之間無顯著差異，而紅光與紅藍混光處理下的植株類黃酮含量較其他處理為低。本研究中發現葉綠素代謝途徑也會受光質影響，在紅光處理下，Chl→Chlide→Pho 為主要途徑而Chl→Phe→Pho 為次要途徑，其他處理則相反，顯示紅光可能會影響葉綠素代謝途徑中的酵素活性而改變途徑。反射光譜檢測部分，NDVI 對 Car/Chl、NPQ、還原力，PRI 對單一色素、DPPH 清除能力的相關性都有達顯著水準，可做非破壞性檢測之應用。最後，在微體繁殖系統立中，發現在0.5 mg L-1 BA + 0.5 mg L-1 NAA 之下會誘導最多的地上部生成，而若提高NAA 的比例則會促進地下部發育，且利用側芽先培養無菌苗，後續再利用無菌苗來培養成株會有更高的效率。總結而言，在藍光處理下可以得到最多的生物量，且植株健康狀態最佳；紅光與紅藍混光處理的健康程度相對較低，但紅藍混光處理下的植株可能會有較高的抗氧化能力。紅光處理也會顯著影響葉綠素代謝途徑，且不同光照處理可能會對葉片結構造成影響，進而影響其葉面反射率。因此可知桃葉斑鳩菊具有很強的抗氧化力，且藉由不同光質處理確實會對其生長及生理代謝等造成影響，使光質成為可以利用的調控因子，應用於培養高品質的植株。

Vernonia amygdalina is a shrub or small tree that grow through tropical Africa. Beside of being used as green vegetable, it has been found pharmacologically use. In recent years, lots of study about Vernonia amygdalina ‘s medical usage have been done. Studies found that this plant has a tremendous antioxidant ability, and it also has efficacy on disease such as cancer, diabetes, liver damage and obesity, which is valuable for development. Air, water and light are necessary factors for plant growth, and light quality has different influence to plant’s physiology and biosynthesis metabolites, which is a factor that is easy to control in greenhouse or plant factory, and could be used to produce higher value than normal plants. In our study, we used red(R), blue(B), green(G), red + blue(RB) as treatments and fluorescence light(FL), to investigate the influences of different qualities of light on Vernonia amygdalina’s biomass, antioxidant ability, pigment content and chlorophyll fluorescence parameters. We also want to find if reflectance spectra and vegetation indices could be used for antioxidant ability or pigments’ prediction. Finally, to produce higher quality plant, build up the micropropagation method of Vernonia amygdalina is our target, too. The results showed that shoot elongation and biomass were induced under blue fluorescence light(B) and were the smallest under green fluorescence light(G). Respond to the highest quantum yield for photochemical energy conversion in PSII (Y(Ⅱ)) and photochemical quenching (qP) under blue fluorescence light, make the highest photosynthetic efficiency and green fluorescence light was the lowest. B could induce pigments synthesis, while R and RB were in contrast. Maximum quantum efficiency(Fv/Fm)showed that all treatment did not experienced stress, but R and R+B were lower than other treatments, showed that these two were relatively unhealthy than others. As the effect to antioxidant efficiency, DPPH scavenging ability were higher under G and RB, while the reducing power was the highest under RB. Total phenolic content has no significant difference between treatments, and flavonoids contents were the lowest under R and RB. Different wavelengths mediated the chlorophyll (Chl) degradation pathway of the leaves. Chl→Chlide→Pho was the major route and Chl→Phe→Pho was the minor route under R. Calculated vegetation indices NDVI correlated well with Car/Chl, NPQ, and reducing power; PRI correlated well with pigments and DPPH scavenging ability. Finally, we found that under 0.5 mg L-1 BA + 0.5 mg L-1 NAA could induce the most shoots, and if higher the NAA ratio could induced more roots. Use nodal as explant to induced antibacterial shoot, and use the antibacterial shoots as explants to induced more shoots and roots would be a more efficiency method. In general, we can get not only the most biomass but also the healthiest plant under B. The plant under R and RB are relatively unhealthy, but could get the highest antioxidant ability. R could significantly influence the degradation pathway of chlorophyll. Different light quality may make the structure of the leaves change, and also the reflectance. We know that Vernonia amygdalina has strong antioxidant ability, and it physiology and metabolite would be influence under different light quality, which make it become a controlling factor, to use to grow high quality plant.