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The chlorophyll fluorescence and reflectance spectra characteristics of Coleus blumei under different light condition
藉由測定三種不同色素含量的彩葉草（Coleus blumei，Blumei Benth、Wiazrd Rose與Solenostemon Scutellaroides）葉片之螢光參數及反射光譜指數，探討以反射光譜推估其紅色（含花青素）與綠色部位之花青素及葉綠素含量，及兩葉色部位對不同強度的可見光與UV-B（280-320 nm）之因應策略。結果顯示反射光譜指數 [（R750-800/ R695-740）-1] 及 [（R750–R705）/（R750﹢R705）]，兼具推估兩葉色部位之Chla+b含量之功能，而花青素含量的推估則以反射光譜指數 [（R700-710/R550-570）-1] 為佳。低葉綠素含量的三種彩葉草葉片，其在400-700 nm波段的反射與穿透率均較高葉綠素含量的葉片者為高，且綠色部位又高於紅色部位。在不同強度（200、400、800、1200及2000 μmol m-2s-1PPFD）的人工光照下，三種彩葉草之高葉綠素含量葉片的兩葉色部位，其PSⅡ效能（Fv/Fm）、光化學效率（P）與非光化學消散（NPQ）均未較低葉綠素含量的葉片者為高，熱消散（D）也未較低，僅過剩吸收光能（E）有隨葉綠素含量增加而呈下降的趨勢。顯示兩葉色部位之低葉綠素含量的葉片在可見光照下，均以較高的反射與穿透率來避免吸收過多的光能，且以較高的光化學效率來因應。兩葉色部位在光照後移至暗處，在20-120分鐘內其Fv/Fm均可快速回復，顯示兩葉色部位均以熱消散伴隨著葉黃素循環及可逆失活（reversible inactive）的PSⅡ來消散過剩光能。但紅色部位的P及D與暗處理的Fv/Fm均較綠色部位為佳，唯NPQ值未有差異。這可能是紅色部位的葉綠素含量稍高及表面花青素對可見光的遮蔽效應（masking effect），而非其提供了更旺盛的葉黃素循環所致。但在不同劑量（17.39、34.78、20.21與40.42 KJ m-2）的UV-B照射下，兩葉色部位在UV-B波段的反射及穿透率，與葉綠素含量或葉色部位間均無顯著相關，且以反射光譜指數推估花青素含量，顯示花青素含量減少，但紅色部位的Fv/Fm仍較綠色部位高。故紅色部位的高PSⅡ效能，可能是因其表面花青素的崩解而非其遮蔽效應。|
Abstract: In order to estimate the chlorophyll and anthocyanin concentration by non-invasive technique and to elucidate the responses of leaves with different pigments under visible light and ultraviolet-B(280~320 nm)illumination. Three Coleus blumei varieties(Blumei Benth, Wiazrd Rose and Solenostemon Scutellaroides )were selected as materials and their reflectance spectra and chlorophyll fluorescence in both red portion(high anthocyanin concentration) and green portion(no anthocyanin)of leaves were measured. Results indicate that the reflectance indices [(R750-800/ R695-740)-1] and [(R750-R705)/(R750﹢R705)] were close related to total chlorophyll concentration in both red and green portion of C. blumei leaves, and the assessment of total anthocyanin concentration was more related to the index of [(R700-710/R550-570)-1]. Almost the green portion of leaves with higher chlorophyll concentration showed the same level of the maximum efficiency of PSⅡ (Fv/Fm), the fraction of light absorbed that is utilized in photosynthetic electron transport(P), and non-photochemical fluorescence quenching(NPQ) as the lower chlorophyll concentration ones, when treated with different light intensities (200, 400, 800, 1200 and 2000 μmol m-2s-1PPFD) for 20 mininutes. However the excess absorption energy(E)of both portion of leaves decreased with increasing chlorophyll concentration. It could be considered that the leaves with lower chlorophyll concentration could avoid absorbing excess energy by higher reflectance and transmittance between 400-700 nm, on the contrary the leaves with higher chlorophyll concentration have higher efficiency of PSⅡ to minimize excess energy. For red portion, which P was higher and D and E were lower than the green portion. But there was no significant difference in NPQ between two portions. It seems due to the higher PSⅡ efficiency by higher chlorophyll concentration, and the masking effect of anthocyanin in epidermis in red portion rather than inducing more efficiency of xanthophyll cycle. The reflectance and transmittance between 280-320 nm of both leaf portions were not related to the chlorophyll and anthocyanin concentrations, when both the two portions of leaves were treated with different UV-B doses (17.39, 34.78, 20.21 and 40.42 KJ m-2). It also showed that the anthocyanin concentration in red portion decreased with increasing UV-B dose, but which Fv/Fm was still higher than that of green portion. Indicating the PSⅡ of red portion showed better performance under UV-B illumination was due to the degradation of anthocyanin in epidermis rather than its masking effect.
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