水黃皮、木賊葉木麻黃和繖楊苗木於NaCl及等同滲透勢PEG6000下之光合作用及生長表現

本試驗為探討台灣海岸林常見樹種在鹽份逆境下之適應能力，以水黃皮(Pongamia pinnata)、木賊葉木麻黃(Casuarina equisetifolia) 、繖楊(Thespesia populnea)盆缽苗木為材料，施灌不同濃度NaCl溶液(S1：0.7 %、S2：1.4 %、S3：2.8 %)及等同滲透勢之PEG6000溶液(P1：-0.555 MPa、P2：-1.109 MPa、P3：-2.248 MPa)於生長介質，以充分灌水為對照組(C)，6週後量測光合作用能力、葉綠素螢光參數及生長表現。 3樹種木質枝條水勢(Ψxyl)趨勢皆為C > S1≒P1> S2≒P2> S3≒P3；大致上隨澆灌水勢愈低，全株總葉面積減少，淨光合作用速率也有類似趨勢。PEG處理之苗木則隨濃度加重，光合作用能力明顯下降，且低於相同滲透勢NaCl處理者。3種苗木氣孔導度隨處理程度加重而下降，且PEG處理苗木比相同滲透勢NaCl處理更低；除P3之外，其餘處理Fv/Fm值與C無顯著差異。PEG及NaCl處理後光合作用速率的降低主要導因於氣孔因素。惟除了P3外，其餘處理之苗木光合系統PSII並未受到顯著傷害，顯示這3種樹種光合系統PSII有其耐鹽性。值得注意的是PEG或NaCl處理後都出現類似缺水的反應，但在介質水勢相同的狀況下，PEG處理的傷害明顯比NaCl嚴重。

關鍵字

水黃皮；繖楊；木賊葉木麻黃； PEG ； NaCl ；光合作用；葉綠素螢光

並列摘要

Seedlings of Pongamia pinnata, Casuarina equisetifolia and Thespesia populnea grown in plastic pots were subjected to (1) NaCl (S1:0.7 %, S2:1.4 %, S3:2.8 %),(2) PEG6000, iso-osmotic to NaCl solution(P1:-0.555 MPa, P2:-1.109 MPa, P3:-2.248 MPa) and (3) well-watered treatment “C”, respectively. After 6 weeks, the photosynthetic rate (Pn), stomatal conductance (gs), cholorophyll fluorescence, content of pigments and growth were measured. The trend of xylem water potential(Ψxyl) in treatments is C > S1≒P1> S2≒P2> S3≒P3 in the three species. Leaf area decreased with decreasing water potential, and the photosynthetic rate also showed this trend. In PEG treatment, Pn decreased with decreasing solution osmotic potential and was lower than iso-osmotic NaCl treatments. The gs of the three species decreased by decreasing water potential, and the decreasing gs in PEG treatments was more severe than iso-osmotic NaCl. Fv/Fm did not differ significantly among treatments except P3 treatment. After PEG and NaCl treatments, the decrease in Pn largely resulted from the decrease in gs. Except P3, photosystem II (PSII) did not differ significantly among other treatments. The damages caused by PEG and NaCl were due to osmotic stress similiar to water stress. It should be noted that seedlings irrigated with iso-osmotic PEG were damaged than those treated with NaCl.

並列關鍵字

Pongamia pinnata ； Casuarina equisetifolia ； Thespesia populnea ； PEG ； NaCl ； Net photosynthetic rate ； Chlorophyll fluorescence

參考文獻

陳財輝、呂錦明 (1987 ) 海岸沙丘植物生理特性及生長關係之研究(I)-海岸木麻黃防風林之生長及林分生物量。海岸林研究報告。第1號。

張上鎮、王升陽、葉汀峰、吳季玲 (1997) 超音波法快速粹取及定量葉綠素。台灣林業科學。12(3):329∼334。

范貴珠、陳儀真(2003) 土壤鹽度對苦檻藍扦插苗生長、水分狀態及葉綠素濃度的影響。臺大實驗林研究報告。17(3):159-169。

陳燕章 (1981) 三種木麻黃耐鹽性之比較硏究。台灣大學森林學研究所。碩士論文。

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水黃皮、木賊葉木麻黃和繖楊苗木於NaCl及等同滲透勢PEG6000下之光合作用及生長表現

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