Effect Of Ornamental Plants On Removing Formaldehyde And Preliminary Studies On The The Mechanism

Most ornamental plants can remove formaldehyde effectively from indoor air. However, different plants have different ability of removing formaldehyde. So far previous studies have rarely involved in the mechanism. In this paper eleven ornamental plants were placed in a glass box to simulate the indoor air pollution. It was found that there were many differences between Melissa officinalis and Hedera helix cv.aureovariegata in removing formaldehyde. Comparing the change of leaf ultrastructures and physiological characteristics caused by formaldehyde,we drawed the following conclutions:(1) According to general analysis of the potted plants including the cases and the soil,the sequence of the decontamination ability was Podocarpus nagi (Thunb.)Zoll.et Mor.ex Zoll. > Syngonium podophyllum > Alocasia macrorrhiza (Linn.) Schott > Hedera helix cv.aureovariegata > Melissa officinalis > Aglaonema modestum Schott ex Engl. > Cymbidium goeringii (Rchb. f.) Rchb. F. > Crassula argentea > Rhapis excelsa(Thunb.)Henry ex Rehd., > Chlorophytum comosum (Thunb.) Jacq.cv.Vittatum > Aloe vera (Linn.) N. L. Burman var. chinensis (Haw.) Berg..(2) After substracting the effects of pots and soil from the total removing effects,the decontamination ability of experimental plant leaves was sorted out again: Melissa officinalis > Podocarpus nagi (Thunb.)Zoll.et Mor.ex Zoll .> Alocasia macrorrhiza (Linn.) Schott > Aloe vera (Linn.) N. L. Burman var. chinensis (Haw.) Berg. > Rhapis excelsa(Thunb.)Henry ex Rehd. > Aglaonema modestum Schott ex Engl. > Cymbidium goeringii (Rchb. f.) Rchb. F. > Crassula argentea > Chlorophytum comosum (Thunb.) Jacq.cv.Vittatum > Syngonium podophyllum > Hedera helix cv.aureovariegata.(3) The cases and the soil also absorbed formaldehyde . When they were put in the glass box,the temperature in the box was little changed,but the relative humidity was influenced.(4) With the increased concentration of formaldehyde, chlorophyll content in leaves of Melissa officinalis first increased and then decreased and the value was lower than the control. The chlorophyll a/b value and the catalase activity were higher than the control and also exhibit the tendency of first increase and then decrease. Relative electrolyte leakage rate decreased with the increased concentration of formaldehyde,but the value was higher than the control. Respiratory rate increased when formaldehyde concentration increased,but the value was lower than the control.To Hedera helix cv.aureovariegata, chlorophyll content in leaves increased with the increase of formaldehyde concentration and the value was higher than the control. The chlorophyll a/b value also higher than the control and presented a decrease tendency with the formaldehyde concentration. Relative electrolyte leakage rate first increased and then decreased and the value was higher than the control. Respiratory rate increased, but the value was lower. The catalase activity decreased and were lower.(5) Melissa officinalis and Hedera helix cv.aureovariegata had strong self-repair capacity after formaldehyde stress.(6) Stomatal density was one of the main factors on removing formaldehyde. Melissa officinalis and Hedera helix cv. aureovariegata could remove formaldehyde by stomatal and non-stomatal ways. Melissa officinalis removed more formaldehyde by non-stomatal ways,while Hedera helix cv. aureovariegata removed more by stomatal ways.(7) Formaldehyde absorbed or accumulated on the leaf surface of Melissa officinalis and Hedera helix cv. aureovariegata was difficult to be re-released into the environment.