4种金色叶树木对SO2胁迫的生理响应

近年来SO2污染比较严重,它对植物有着多方面的影响。因此,越来越多的学者开始关注这方面的问题。彩叶植物在丰富园林景观及降低环境污染方面占用重要的地位,它们也被认为是净化城市空气最有效的途径之一。旨在阐明4种彩叶树种耐SO2污染机制,对丰富植物耐SO2研究的理论、科学评价植物抗SO2污染能力以及指导园林绿化科学选择树种等具有重要理论和现实意义。研究采用人工模拟熏气的方法对金叶女贞、金叶莸、金叶风箱果和金叶红瑞木4种金色叶树种的2年生苗木进行不同浓度的SO2胁迫,研究了参试树种的外观受害症状及膜脂过氧化、渗透调节物质、保护酶活性等生理指标对SO2的反应,并采用模糊数学隶属函数法和灰色关联度法对其抗SO2能力进行了综合评价。结果表明:4种金色叶植物对SO2均具有一定的净化能力,表现为随着SO2浓度的增加膜透性增大,丙二醛、脯氨酸、可溶性糖和硫含量增加,超氧化物歧化酶、过氧化物酶以及过氧化氢酶活性上升,叶绿素含量先增后降,叶液pH值下降。但4种金色叶树木对SO2的净化能力有差别,其中金叶红瑞木的净化能力强最大,金叶女贞和金叶风箱果的净化能力为中等,而金叶莸的净化能力最差。这与其含硫量的顺序一致,却与其对SO2的抗性大小即金叶女贞>金叶莸>金叶红瑞木>金叶风箱果完全不同,说明这四种植物对SO2的吸收能力与其对该气体的抗性不完全一致。但这不能表明抗性差的树种在兰州地区不能应用,因为,兰州市空气中的SO2实际污染程度与研究所设置的最低浓度相比仍属安全浓度。在所选的10个指标中,丙二醛含量、细胞膜透性、超氧化物歧化酶活性、过氧化氢酶活性、脯氨酸、过氧化物酶活性、叶绿素和可溶性糖等指标均可作为金色叶植物对SO2抗性的重要鉴定指标,而S含量和叶液pH值在评价植物对SO2抗性能力时并不具有重要性。4种植物的受害程度与其SO2抗性相反,说明受害症状可以作为判断其对SO2抗性大小依据。

Physiological responses of four golden-leaf trees to SO2 stress

Nowadays the pollution of SO₂ becomes more and more serious, it has a wide range of effects on plants, for example, it can affect the photosynthesis, physiological characters and tissue structure of many plants. Therefore, more and more researchers began to study these problerm. Leaf-colored plants have the impotant place to enrich the landscape and reduce the polution on environment, and they are considered one of the effective ways to purify the air of city. In order to provide seientific evaluation of SO₂ resistance and seientific references for selecting proper species as ornamental trees in landscape, the resistance of four golden-leaf tress species to sulfur dioxide its mechanism to adapt to sulfur dioxide stress were studied in this paper,. An artificial simulation method was employed to treat two-year-old saplings of four golden-leaf tress species, i.g. Ligustrum vicaryi, Caryopteris clandonensis, Physocarpus opulifolius var. lutein and Cornus alba with different concentration, such as 5.71, 11.43, 17.14, 22.86 mg/m³ of sulfur dioxide. The acute injury symptoms were observed, membrane lipid peroxidation, osmose gulatory molecules and protective enzyme activity were measured, and the methods of subordination function and grey correlation analysis were used to evaluate the resistance to sulfur comprehensively. The results showed that all four tree species had purification ability to SO₂, the membrane permeability, contents of malondialdehyde (MAD), proline (Pro), soluble sugur (SS), sulfur content and the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) were increased, while the contents of chlorophyll (Chl a b) and pH value were decreased with the increment of sulur dioxide concentration. The purification ability to SO₂ of four tree species were different, i.e.: C. alba was maximum, L. vicaryi and P. opulifolius var. lutein were medium,and C. clandonensis was minimum, it was the same as the order of the sulfur contents of the four tree species. However, the resistance of the four tree species to sulfur dioxide ranked from L. vicaryi>C. clandonensis>C. alba>P. opulifolius var. lutein. These demonstrated that the purification ability to SO₂ was different with the resistance to sulfur of these plants. But these couldn't indicate that the four golden-leaf tress species, i.g. L. vicaryi, C. clandonensis, P. opulifolius var. lutein and C. alba couldn't be used in Lanzhou region. Beacause the minimum concentration of SO₂ (5.71 mg/m³) that was set up in this experiment was higher than the practical maximum polution concentration of SO₂ (0.277 mg/m³) which once appeared in Lanzhou, this means that these plants can all be used in safety in Lanzhou region. From the ten criteria tested, eight (membrane permeability, MAD, SOD, CAT, Pro, POD, chl a b and SS) can be considered as main criteria for evaluating the resistance of these four trees to SO₂, but sulfur contents and pH value were not. Injury degree of the four tree species was adverse to the resistance to sulfur dioxide, it indicated that injury symptoms also can be regarded as the basis to judge the resistance to sulfur dioxide of the four tree species.