添加鎘處理對菸草根圈分泌低分子量有機酸的影響

Influence of Cadmium Treatment on Low Molecular Weight Organic Acids Exudation in Tobacco Rhizosphere Soils

周淑艷(Shu-Yen Chou) ； 邱志郁(Chih-Yu Chiu) ； 陳建德(Chien-The Chen) ； 莊舜堯(Shun-Yao Zhuang) ； 王明光(Ming-Kuang Wang)

《土壤與環境》 8卷1期 (2005/06) Pp. 15-21

https://doi.org/10.30058/SE.200506.0002

摘要

為了瞭解植物如何在根圈中對鎘所造成的毒害進行生理調節，本研究透過盆栽試驗以探討菸草生長於鎘處理之土壤中，低分子量有機酸的釋放和鎘之濃度的關係。氯化鎘被添加至未污染的土壤中，使土壤含鎘1，5，10 mg kg^-1，於室溫下維持60%田間容水量孵育30天後，取500g孵育完成之土壤分裝於直徑12cm的栽培盆中，並將苗齡2週之菸草幼苗移植至盆中以進行盆栽試驗，菸草於溫室中栽培50天後取根圈及本體土壤。土壤經去離子水萃取之後，以氣相層析儀進行低分子量有機酸之定量。菸草在添加鎘處理之根圈土壤中存在有大量的醋酸（acetic），乳酸（lactic），乙醇酸（glycolic），反丁烯二酸（maleic）及琥珀酸（succinic），未添加鎘處理之根圈土壤則含量較少，其中以乙醇酸及反丁烯二酸為主要有機酸。二者約佔有機酸總濃度之70%。至於未種植菸草之本體土壤則未測得有機酸。在10 mg Cd kg^(-1) 之處理條件下，根圈土壤中有機酸的含量如下：醋酸：261μmol kg^-1，乳酸：154μmol kg^-1，乙醇酸：797μmol kg^-1，反丁烯二酸：504μmol kg^-1及琥珀酸：174μmol kg^-1，幾乎是未添加鎘處理之根圈土壤中的兩倍。根圈土壤中有機酸濃度和鎘之添加濃度呈高度正相關，醋酸、乳酸、乙醇酸、反丁烯二酸及琥珀酸和鎘濃度的相關係數依次分別為：0.98、0.90、0.97、0.92及0.99。綜合以上結果，菸草根圈土壤中低分子量有機酸之含量會隨著土壤中鎘的濃度增加而提高。

關鍵字

鎘 ； 低分子量有機酸 ； 根圈土壤 ； 菸草

並列摘要

With an attempt to know physiological response of plant to Cd toxicity in rhizosphere, we used pot experiments to investigate how low-molecular-weight organic acids (LMWOAs) released from tobacco root when it grew in Cd treated soil. The CdCl2 was added into uncontaminated soils, giving Cd concentrations ranged from 1, 5 to 10 mg kg^(-1) soil, and incubated with moisture of 60% of field capacity for 30 d. Five hundred grams of soil of each Cd concentration was put into 12 cm (i.d.) pots, and then transplanted 2-week-old tobacco seedlings (Nicotiana benthavamiana) into the pot. Plants were grown for 50 d under greenhouse conditions in summer, 2003. On harvest of plants, rhizosphere and bulk soils were collected and then extracted with distilled water. Acetic, lactic, glycolic, maleic and succinic acids were quantified by gas chromatography. The rhizosphere soils were dominated up to around 70% with glycolic and maleic acids. No LMWOAs were identified in the bulk soils, and the LMWOAs in uncontaminated rhizosphere soils were low. The LMWOAs were with the highest concentrations in rhizosphere soils of the treatment with 10 mg Cd kg^-1 soil. The concentrations are 260.8 μmol kg^-1 (acetic), 154.3 μmol kg^-1 (lactic), 797.3 mol kg^-1 (glycolic), 503.5 μmol kg^-1 (maleic) and 173.7 (succinic) μmol kg^-1 soil. The LMWOAs concentrations were almost two times compared to control rhizosphere soils. The correlation coefficients of LMWOAs and Cd concentration in soils were 0.98 (acetic), 0.90 (lactic), 0.97 (glycolic), 0.92 (maleic), and 0.99 (succinic), respectively. These results suggest that the increasing of Cd concentrations enhance LMWOAs exudates in the rhizosphere of tobacco.

並列關鍵字

Cadmium ； Low molecular weight organic acids ； Rhizosphere soil ； Tobacco