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The chlorophyll fluorescence and leaf reflectance spectra characteristics amorg different Chinese kale (Brassica oleracea L.var.alboglabra) with Various Leaf Colors
|關鍵字:||chlorophyll fluorescence;葉綠素螢光;reflectance spectra;photoinhibition;反射光譜;光抑制||出版社:||生命科學院碩士在職專班||摘要:||
結果顯示黃芥藍之葉綠素及類胡蘿蔔素含量均較低，Caro/Chl值較高，而三種葉色芥藍之葉綠素變化雖大，但其Chl a/b差異不顯著。將三種葉色之芥藍施以不同強度的人工光照（即以 200、400、800、1200 及2000 μmol m-2 s-1 PPFD 及不同照射時間）處理，結果顯示無論照光前或後，Fo( 最小螢光放射量 )、Fm( 最大螢光放射量 )及Fv/Fm( PSII最大光化學潛能 )與葉綠素及類胡蘿蔔素含量均呈曲線正相關，而與Caro/Chl呈直線負相關，其中黃芥藍之Fo、Fm及Fv/Fm均較低。三種芥藍合併分析之結果亦顯示，隨著光度增加，P ( 光化學消散佔吸收光能的比例 ) 會逐漸變小，D (熱消散佔所有吸收光能之比例 )及NPQ（非光化學消散）則逐漸增加，而E (過多的能量佔所有吸收能量的比例 )略升，惟比例較P及D小且上升趨勢較不規則，至於PRI則逐漸下降。在相同光度下，葉綠素含量較高的葉片，其Pn（光合作用）及P均較高，而D、E及NPQ則較低，且PRI下降程度較小。三種不同葉色芥藍在未照光前之Fv/Fm均為0.8左右，但照以高光 (2000μmolm-2s-1 PPFD ) 2小時後暗適應20 min， Fm及Fv/Fm之降幅均以黃芥藍較高，黑芥藍及綠芥藍較低，顯示黃芥藍對高光敏感，光抑制較嚴重。
此外，從秋季（10月）至早春（2月），在自然條件下的測定結果顯示，三種葉色芥藍的黎明Fv/Fm值會隨測定當日最低溫之下降而稍減，但其值多在0.80〜0.86之間。而中午之Fv/Fm及Fv'/Fm' 均會隨測定當日PPFD增加而降低，三種芥藍Fv'/Fm'之降幅均大致相近，而Fv/Fm之降幅則是黃芥藍較大，尤以高PPFD下為甚，此外NPQ亦隨PPFD上升而增加，而黃芥藍之增幅均較黑芥藍及綠芥藍大，唯黃芥藍之NPQf與其他兩種芥藍大致相近，但是NPQS（亦即qI，慢速光抑制）之增幅較黑芥藍及綠芥藍高，導致黃芥藍光抑制較嚴重，即在強光下Fv/Fm降幅較大。比較中午測得之螢光參數（∆Fv/Fm、Fv'/Fm'及Φ與NPQ 、NPQf及NPQs）與黎明PRI－中午PRI（∆PRI）間之相關係數均較PRI為高。因此，藉由 ∆PRI之測定，可做為推估PSII效能之良好指標。
In order to understand the chlorophyll fluorescence and leaf reflectance spectral of leaves with different leaf color, 3 varieties of Brassica oleracea ( dark-green, green and light-green ) were used to study.
The results showed that the ‘light-green’ leaves had lower both chlorophyll (Chl) and carotenoid (Caro) content, but their Caro/Chl ratio were higher than that of other varieties, and the Chl a/b was no significant difference among varieties. When merged together the results measured from 3 varieties of B. oleracea to statistical analysis, it was found that Fo ( minimum chlorophyll fluorescence ), Fm ( maximum chlorophyll fluorescence ) and Fv/Fm ( maximum photosystem II photochemical efficiency, Fv=Fm-Fo ) showed curvilinear relationships with the increasing of both chlorophyll and carotenoid content, but negative linear relationships was observed between the fluorescence parameters and Caro/Chl ratio. As well, the ‘light-green’ leaves had lower Fo , Fm and Fv/Fm.
Comparison of the relationships between fluorescence parameters and photochemical reflectance index ( PRI, PRI=(R531-R570)/(R531+R570) ) . It was found that P ( fraction of light absorbed in PSⅡ antennae that is utilized in photosynthetic electron transport ) decreased gradually with photosynthetic photon flux density（PPFD）increasing, on the contrary, both D (fraction of light absorbed in PSⅡantennae that is dissipated via thermal energy dissipation in the antennae ) and NPQ (non-photochemical quenching) increased gradually with PPFD increasing. While E (fraction of excess absorbed in PSⅡantennae) increased slightly with PPFD increasing, PRI decreased gradually with light increasing. Under the same PPFD condition, the leaves with higher chlorophyll content showed higher photosynthetic capacity and P, less D , E , NPQ and PRI. Three B. oleracea studied, maintained their Fv/Fm about 0.8 at predawn, however, Fv/Fm decreased to 0.2 when leaves treaded with after 2000 μmolm-2s-1 PPFD for 2 h, and ‘light-green’ leaves showed more decreased than that of other varieties. This result indicated that the ‘light-green’ leaves might sensitive to high light.
From autumn (October ) to early spring (February ), predawn Fv/Fm value of 3 B. oleracea reduced slightly（0.86-0.80）with minimum temperature decreasing. However, under higher PPFD , ‘light-green’ leaves showed higher degree of photoinhibition (lower Fv/Fm), and higher ΔFv/Fm, NPQ, NPQs. Compared both fluorescence parameters（∆Fv/Fm、Fv'/Fm'、Φ and NPQ 、NPQf、NPQs）and PRI, much better relationships tend to exist at the ΔPRI. Thus ΔPRI is suit to indicate the actual dissipation of the excess energy as well as PSⅡefficiency during illumination.
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