光強度與苯濃度對‘娃娃’朱蕉移除苯與二氧化碳之影響

Effect of Light lntensity and Benzene Concentrationon on Removal of Benzene and Carbon Dioxide by Cordyline terminalis 'Baby Doll'

許多室內植物能移除苯等具致癌性之揮發性有機物質；但移除效率受光強度與初始氣體濃度等環境因子影響。‘娃娃’朱蕉[Cordyline terminalis（L.）Kunth‘BabyDoll’]是朱蕉屬植物單位面積取穗量最高的品種，可耐低光應用於室內綠化布置。本研究將‘娃娃’朱蕉盆栽置於含有初始5μL．L^(-1)苯之薰氣箱內，並以20、40、60、80及100μmol．m^(-2)．s^(-1)等五種不同光強度（photosynthetic photon flux, PPF）處理，結果顯示：不論光度為何，處理4天期間，薰氣箱內之苯濃度均下降。低光（20或40μmol．m^(-2)．s^(-1)PPF）處理淨光合作用速率與移除苯之速率較低，於80或100μmol．m^(-2)．s^(-1)PPF處理之植株葉片淨光合作用速率與單位葉面積苯移除速率最高。光強度提高使各處理盆栽首日明期CO_2移除速率增加，自第二日起，薰氣箱內平均CO_2濃度隨處理光強度增高而遞減。另於80μmol．m^(-2)．s^(-1)PPF下，將‘娃娃’朱蕉置於含5、10、15、20及25μL．L^(-1)初始濃度苯之薰氣箱內，結果顯示植栽對苯之移除速率隨苯初始濃度提高而增加。5-25μL．L^(-1)初始苯濃度不影響‘娃娃’朱蕉的二氧化碳吸收及釋放，且各處理之葉片Fv/Fm值均維持在0.79-0.81。 Many indoor plants can remove benzene, a common volatile organic compound that has been classified as a human carcinogen. Light intensity and initial benzene concentration may affect the removal efficacy of the plants. Cordyline terminalis (L.) Kunth 'Baby Doll' is widely used for indoor decorations as this delicate potted plant can tolerate a wide range of irradiances and generates prolific branches when pinched. Potted plants of 'Baby Doll', with root-zone wrapped, were placed under light intensity of 20, 40, 60, 80, and 100 μmol．m^(-2)．s^(-1) photosynthetic photon flux (PPF) in chambers containing an initial 5 μL．L^(-1) benzene for four days. In all treatments, benzene concentration in the chambers declined as analyzed with gas chromatography. Plants under 20 or 40 μmol．m^(-2)．s^(-1) PPF had lower stomatal conductance, net photosynthetic rate, and benzene removal rate per leaf area than those under 80 or 100 μmol．m^(-2)．s^(-1) PPF. Carbon dioxide removal rate during lighting period of day 1 increased linearly as light intensity increased. Potted plants of 'Baby Doll' were placed within chambers containing various initial concentrations of benzene under 80 μmol．m^(-2)．s^(-1) PPF. Results showed that benzene removal rate of the plant increased linearly with the initial benzene concentration increased from 5 to 25 μL．L^(-1). Initial benzene concentration did not affect the CO_2 uptake and evolution of the plants. Benzene concentration did not alter leaf Fv/Fm, ranged between 0.79 and 0.81, after all treatments for five days.