The Study On Formaldehyde Absorption Capacity In 18 Ornamental Plants

The 18 ornamental plants were selected as materials to conduct the experiments for evaluating their formaldehyde (HCHO)-absorption capacity by using the model plant tobacco(Nicotiana tabacum cv. Xanth) as a contol. The selected 18 plants are as follows: Kalanchoe blossfeldiana, Pilea peperomioides, Cafathea makoyana, Begonia semperflorens, Oncidium, Pelargonium X Citrenella, Crassula perforate, Syngonium podophyllum, Philodendron selloum, Rohdea japonica, Philodendron pandurifor, Cymbidium grandifiorium, Pelargonium, Pteris multifida Poir, Peperomia sandersii, Tradescantia flurnuensis cv.Variegata, Eustoma grandiflorum, and Acapulco.Seven kinds of experiments were carried out in this study:①The preliminary investigation on the HCHO-absorption capacity in 18 ornamental plants. The leaf disks of the ornamental plants were immersed in a 4mM HCHO solution (pH 6). 1mL HCHO solution was taken for each treatment in a 16 h interval for determination of the remained formaldehyde concentration in the solution, respectively, to evaluate the formaldehyde-absorption ability of each plant;②Measurements of chlorophyll contents in the leaf discs before and after formaldehyde treatments. The leaf disks of the ornamental plants were treated as described above, after treatment, the chlorophyll contents in the leaf discs were measured. The damage extents caused by formaldehyde on the plant leaves were determined by comparing the chlorophyll contents in the treated leaf discs with that in the fresh leaf discs;③Examination of the HCHO-absorption capacity of different plants to various concentrations of formaldehyde solution. The experiment procedure is similar to experiment①. The same fresh weight (0.5g) of different plant leaf discs was treated in 7 mM,10 mM and 13 mM formaldehyde (pH 6) solution for 96 h, respectively. The remained formaldehyde concentration in the solution was measured to determine the formaldehyde-absorption ability of different plant to different concentrations of formaldehyde;④Measurements of the changes in leaf disc chlorophyll contents before and after the treatment in different concentrations of formaldehyde solutions. The same fresh weight of different plant leaf discs were treated in 7mM, lOmM and 13mM concentration of formaldehyde solution (pH 6) for 96 h, respectively. The chlorophyll contents in leaf discs were determined to evaluate the formaldehyde-tolerance of different ornamental plant leaves;⑤Examination of the HCHO-absorption capacity of different fresh weight of the same species.0.2g,0.5g, 1.0g,1.5g,2.0g of leaf discs of the same species was treated with 7mM formaldehyde (pH 6) solution, respectively. The remained formaldehyde concentration in the solution was measured to determine the relativity between the fresh weight of plant leaf discs and ability to absorb formaldehyde;⑥The investigation on the HCHO-absorption capacity of plant leaf discs under different conditions (including ambient temperature and pH) The same fresh weight (0.5g) of plant leaf discs were soaked in 7mM formaldehyde solutions with different pH (5,7 and 9) and incubated at 25℃in a growth chamber. The amount of formaldehyde absorbed by the plant leaf discs was determined to investigate the effects of environmental pH on the absorption capacity of formaldehyde by the plants.0.5g fresh weight of plant leaf disks were soaked in 7mM formaldehyde solution (pH 6) and then incubated at different temperatures (15℃,20℃,28℃and 37℃) in a growth chamber. The amount of formaldehyde absorbed by the plant leaf discs was determined to investigate the effects of the ambient temperature on the absorption capacity of formaldehyde by the plants;⑦Determination of the amount of formaldehyde absorbed by the plant leaf discs before and after sterilization The sterilized and no sterilized plant leaf disks (0.2g) were soaked in 7mM formaldehyde solution (pH 6) at 25℃in a growth chamber. The amount of formaldehyde absorbed by the plant leaf discs was measure to determine whether micro-organisms on the leaves contributed to the formaldehyde-absorption capacity of the plant and the formaldehyde-absorption ability of the plant leaves excluding micro-organism effects.The results from the above experiments are summarized as follows:First, the 18 selected ornamental plants could absorb formaldehyde not excluding microorganism effects. For the formaldehyde absorption capacity, the strongest plants are Cymbidium grandifiorium, Philodendron selloum, Pelargonium X Citrenella, Eustoma grandiflorum, Pelargonium, Pteris multifida Poir and Nicotiana tabacum cv. Xanth; the second ones are Philodendron pandurifor, Syngonium podophyllum, Rohdea japonica, Crassula perforate, Kalanchoe blossfeldiana, Acapulco, Oncidium and Cafathea makoyana, and the weakest plants are Tradescantia flurnuensis cv.Variegata, Pilea peperomioides, Begonia semperflorens and Peperomia sandersii.Second, formaldehyde has different toxic effects on all selected ornamental plants after treatment, which suggests that the HCHO-tolerance of these plants is different. For the formaldehyde-tolerance, the strongest plants are Crassula perforate, Cafathea makoyana, Pilea peperomioides, Pelargonium, Oncidium and Eustoma grandiflorum; the second ones are Syngonium podophyllum, Cymbidium grandifiorium, Philodendron selloum, Philodendron pandurifor, Tradescantia flurnuensis cv.Variegata, Peperomia sandersii, Kalanchoe blossfeldiana and Rohdea japonica, and the worst plants are Acapulco, Begonia semperflorens, Pelargonium X Citrenella, Pteris multifida Poir and Nicotiana tabacum cv. Xanth. However, the formaldehyde absorption capacity of each plant is not related with its HCHO-tolerance.Third, the best environmental conditions of formaldehyde absorption for the ornamental plants are different. The best environmental temperature is 20℃or 28℃, and pH is neutral or acidic. Low temperature (15℃), high temperature (37℃) or alkaline pH will inhibit the HCHO absorption of the majority plants.Fourth, the micro-organisms on leaves contribute on the absorption of formaldehyde by the plant, but they functioned after a period of incubation time (such as 24h or 48h in this study). In addition, by comparing the HCHO-absorption capacity of the sterilized and no sterilized Cymbidium grandifiorium, Philodendron pandurifor and Nicotiana tabacum cv. Xanth, we found that from strong to weak are as follows:Nicotiana tabacum cv. Xanth, Cymbidium grandifiorium, Philodendron pandurifor.The results of the present study indicate that the majority of ornamental plants can absorb formaldehyde but their absorption capacity is different. Environmental conditions also affect the absorption of formaldehyde. The data of the present study provides evidences on how to select the plants with good formaldehyde absorption capacity and how to exert their functions.