International Research Journal of Plant Science (ISSN: 2141-5447) Vol. 2(4) pp. 099-106, April, 2011 Available online http://www.interesjournals.org/IRJPS Copyright © 2011 International Research Journals Full length Research Paper Anticipated performance index of some tree species considered for green belt development in an urban area Dali Mondal a, Srimanta Gupta a* and Jayanta Kumar Datta a a Department of Environmental Science,University of Burdwan, Golapbag, Burdwan-713104, West Bengal, India Accepted 4 April, 2011 In the present study, the Air Pollution Tolerance Index (APTI) of ten plant species collected from an urban area has been evaluated by analyzing important biochemical parameters. High values of APTI were recorded in Psidium guajava (31.75%); Swietenia mahoganii(28.08%); Mangifera indica (27.97%); Polyanthia longifolia (25.58%) and Ficus benghalensis (25.02%). The Anticipated Performance Index (API) of these plant species was also calculated by considering their APTI values together with other socio-economic and biological parameters. According to API most tolerant plant species for green belt development were Ficus benghalensis (87%); Mangifera indica (87%); Swietenia mahoganii (87%) and Saraca indica (81%). Keyword : Air Pollution Tolerance Index; API; Suitability for green belt development; Burdwan; West Bengal. INTRODUCTION Air pollution control is more complex than most other environmental challenges. No physical or chemical method is known to ameliorate aerial pollutants. A suitable alternative may be to develop a biological method by growing green plants in and around industrial and urban areas ( Agarwal, 1988; Santra, 1995; Thakre, 1995; Shannigrahi et al.,2003; Sivasamy and Srinivasan, 1996; Fukuoka, 1997; Ghosh and Majee, 2001). Plants, the main green belt (GB) component, act as a sink and as living filters to minimize air pollution by absorption, adsorption, detoxification, accumulation and/or metabolization without sustaining serious foliar damage or decline in growth, thus improving air quality by providing oxygen to the atmosphere (Sharma et al., 1994; Rawat and Banerjee, 1996; Beckett et al., 1998). Plants differ markedly in their responses to pollutants, some being highly sensitive and others hardy and tolerant (Singh and Rao, 1983; Shannigrahi et al.,2003). Parameters used in defining sensitivity or resistance of plants towards different air pollutant concentrations are ascorbic acid content (Keller and Schwager, 1977), relative water content (RWC) (Sen and Bhandari, 1978), *Corresponding author: Email: srimantagupta@yahoo.co.in chlorophyll content (Bell and Mudd, 1976), and leaf extract pH (Chaudhary and Rao, 1977). Categorization of plants as sensitive or tolerant is determined by the level of these parameters in plants, and thus plants show different susceptibility to different pollutants. Sensitive species are early indicators of pollution, and the tolerant species help in reducing the overall pollution load (Rao, 1983). Singh and Rao (1983) have developed the Air Pollution Tolarence Index (APTI), which is based on four biochemical properties of leaves: ascorbic acid, total chlorophyll, relative water content and leaf extract pH. Plant sensitivity and tolerance to air pollutants varies with these parameters. Chlorophyll content decreases due to production of reactive oxygen species (ROS) in the chloroplast under water stress (ROSs are very small reactive molecules that can cause damage to cell structures during environmental stress). Higher ascorbic acid content of leaves might be an effective strategy to protect thylakoid membranes from oxidative damage under such water stress (Tambussi et al., 2000), as ascorbic acid is critically involved in the defense against ROS produced by the photosynthetic apparatus (Smirnoff, 1996). The present study the selection of plant species which can be grown around industrial/urban areas in India. Plants differ considerably with reference to their respons- 100 Int. Res. J. Plant Sci. es towards pollutants, some being highly sensitive and others hardy and tolerant. On the basis of the APTI and some relevant biological and socioeconomic characters, the anticipated performance index (API), from best to not recommended, of various plant species was determined for GB development. Statistical analysis MATERIALS AND METHODS RESULTS AND DISCUSSION Selection of sampling area and sampling details The research work was mainly confined in Burdwan town, West Bengal. As per Gupta et al., (2009) ambient air quality status of this town i.e. the average concentration (µg/m3) of SO2, NO2 and RSPM (Respirable Suspended Particulate Matter) are 8.59, 176.06 and 59.94 respectively. Ten plant species were selected during the summer season of 2010 from Golapbag campus of Burdwan University. The screening and selection of the plant species was partly based on literature survey of similar work and guidelines of Central Pollution Control Board (1999 - 2000). The ten plant leaf samples were collected at the lower most position of canopy at a height of 6-7ft from the ground surface. Samples were cleaned with distilled water and then refrigerated (22ºC)under suitable condition for further biochemical analysis. Method for biochemical parameters Various biochemical parameters such as leaf extracts pH (Sing and Rao, 1983), relative water content (Sen and Bhandari, 1978), total chlorophyll (Arnon, 1949), ascorbic acid (Keller and Schwager, 1977), soluble sugar (Sadasivam and Manikam, 1996) and protein (Lowry et al., 1951) were done from the collected leaf samples. Calculation of Air Pollution Tolerance Index (APTI) of plants Air pollution tolerance index (APTI) was proposed by Singh and Rao, (1983) to assess the tolerant/resistance power of plants against air pollution. The air pollution tolerance index was calculated using the formula: APTI = A (T + P ) + R 10 Where: A =Ascorbic Acid (mg/g) T =Total Chlorophyll (mg/g -f.w) P = pH of the leaf extract R = Relative water content of leaf (%). Based on the development and evaluation of APTI values among the samples they were categorized into three groups, namely <10 is sensitive species, >10-16 is intermediate species and >17 is tolerant species. Calculation of Anticipated Pollution Index (API) By combining the resultant APTI values with some relevant biological and socio-economic characters (plant habit, canopy structure, type of plant, laminar structure and economic value), the API was calculated for different species. Based on these characters, different grades (+ or _) are allotted to plants. Different plants are scored according to their grades. The criteria used for calculating the API of different plant species are given in Table 1 and 2. Linear regression analysis was performed between independent variables viz. Chlorophyll, pH, RWC, ascorbic acid and dependent variable such as APTI by using XL STAT (Version 10) software. These scatter plots illustrated the degree of correlation (R2) between the said variables. Discussion on experimental results of biochemical parameters Plants have been categorized into groups according to their degree of sensitivity toward and tolerance of various air pollutants on the basis of experiment and available data ( Kagamimori et al., 1978; Bhattacharya, 1983; Khan and Abbasi, 2002). Levels of tolerance to air pollution vary from species to species, depending on the capacity of plants to withstand the effect of pollutants without showing any external damage. APTI is a unique index because it incorporates four different biochemical parameters: total chlorophyll, pH of leaf extract, ascorbic acid, and relative water content. The APTI has been determined for 10 plant species (Table 3). As shown in Table 3, the highest mean total chlorophyll content (in mg/g fresh wt) was recorded in Saraca indica (2.47) followed by Psidium guajava (2.19), Fiscus religiosa (2.17) respectively. Higher chlorophyll content in plants might favour tolerance to pollutants (Joshi et al., 1993). Whereas a considerable loss in total chlorophyll, in the leaves of plants exposed air pollution stress supports the argument that the chloroplast is the primary site of attack by air pollutants such as SPM, SO2 and NOX (Tripathi and Gautam,2007). Air pollutants make their entrance into the tissues through the stomata and cause partial denaturation of the chloroplast and decrease pigment contents in the cells of polluted leaves (Rao and Leblanc, 1966). High amount of gaseous SO2 causes destruction of chlorophyll and that might be due to the replacement of 2+ Mg by two hydrogen atoms and degradation of chlorophyll molecules to phaeophytin (Rao and Leblanc, 1966). The mean value of leaf extract pH ranged from that of Swietenia mahoganii recorded at 5.83 to that of Ficus benghalensis at around 6.81 (Table 3). The low pH of the leaf extract showed a relationship with the type of air pollution. The more acidic nature demonstrates that the air pollutants, mostly gaseous types, namely SO2, NOX diffuse and form acid radicals in the leaf matrix by reacting with cellular water. This further effect the chlorophyll molecules (Turk and Wirth, 1975). A pH on the higher side improves tolerance against air pollution (Agarwal, 1986). Mean values of ascorbic acid content of ten plants are depicted in Table 3. The mean relative water content (RWC) was lowest in Ficus hispida (69.96%) and highest in Mangifera indica (84.66%) (Table 3). The Relative Water Content(RWC) indicates Mondal et al. 101 Table 1. Gradation of plant species on the basis of air pollution tolerance indexn(APTI ) and other biological and socioeconomic characters. Pattern of assessment Grade allotted 12.0-16.0 + 16.1-20.0 20.1-24.0 24.1-28.0 28.1-32.0 32.1-36.0 ++ +++ ++++ +++++ ++++++ Small Medium Large + ++ Sparse/Irregular/Globular Spreading crown/Open/Semi dense Spreading dense - ++ Deciduous Evergreen + Size Small Medium Large + ++ Texture Smooth Coriaceous + Hardiness Delineate Hardy + Less than three uses Three or four uses Five or more uses + ++ Grading Character (a) Tolerance (b) Biological and Socio-Economic Air Pollution Index(APTI) Tolerance (i) Plant Habit (ii) Canopy Structure (iii)Type of Plant (iv)Laminar structure (v)Economic Value + Maximum grades that can be scored by a plant = 16 change in leaf matrix hydration condition and will generate higher acidity condition when RWC is low. The RWC also helps to maintain physiological balance under stress condition higher relative water content is advantageous for drought resistance in plants (Dedio, 1975).The highest content of ascorbic acid (in mg/gm fresh wt) was found in Swietenia mahoganii (29.50), followed by Psidium guajava (28.90), Polyanthia longifolia (25.10), Mangifera indica (24.50) respectively. The lowest mean value was recorded in Ficus hispida (8.04). Ascorbic acid is regarded as an antioxidant. It is found in large amounts in all growing plant parts and influences 102 Int. Res. J. Plant Sci. Table 2. Anticipated Performance Index (API) of plant species. Grade 0 1 2 3 4 5 6 7 Score (%) Up to 30 31 – 40 41 – 50 51 – 60 61 – 70 71 – 80 81 – 90 91 – 100 Assessment category Not recommended Very poor Poor Moderate Good Very good Excellent Best Table 3. Mean value of biochemical parameters along with APTI of the leaf samples. (Units are expressed as mg/g-f.w. except pH and Relative Water Content which is expressed in units and percentage respectively). Sl No Local Name 1 Asoke 2 Debdaru 3 Banyan 4 Dumur 5 Guava 6 Sisoo 7 Mango 8 Chattim 9 Mahagunii 10 Asattha Scientific Name Saraca indica Polyanthia longifolia Ficus benghalensis Ficus hispida Psidium guajava Dalbergia sisoo Mangifera indica Alstonia scholaris Swietenia mahoganii Ficus religiosa Chlorophyll pH Mean ± SD Mean ± SD 2.47 ± 0.97 6.49 ± 0.28 0.77 ± 0.22 6.31 ± 0.27 1.17 ± 0.49 6.81 ± 0.43 1.60 ± 0.64 6.58 ± 0.62 2.19 ± 0.75 6.36 ± 0.42 1.84 ± 0.78 6.27 ± 0.60 2.13 ± 0.76 6.33 ± 0.63 1.49 ± 0.56 5.94 ± 0.69 1.52 ± 0.72 5.83 ± 0.55 2.17 ± 0.16 6.30 ± 0.18 RWC Mean SD 80.12 6.56 83.05 4.96 83.45 4.20 69.96 ±10.60 77.69 5.98 73.91 ±15.20 84.66 6.46 79.76 9.88 70.73 ±14.40 73.64 3.24 ± ± ± ± Ascorbic Acid Sugar Protein APTI Mean ± SD Mean ± SD Mean ± SD Mean ± SD 32.90 4.69 25.80 1.83 19.20 10.64 21.90 6.54 36.20 15.68 38.70 5.45 58.20 8.89 18.40 6.46 43.80 8.99 26.20 3.48 23.90 3.31 25.58 6.93 25.02 7.43 13.26 3.65 31.75 5.20 21.04 4.66 27.97 6.90 16.92 3.39 28.08 5.73 15.11 2.88 18.50 ± 5.43 25.10 10.98 21.80 10.87 ± ± 8.04 ± 3.19 ± 28.90± 9.82 17.50 ± 7.25 ± ± 24.50 11.70 ± 13.20 ± 5.94 29.50 ± 8.33 ± 9.06 ± 2.78 59.24 19.69 62.01 28.18 62.48 22.15 35.42 10.53 56.58 14.56 49.19 24.34 79.88 16.21 51.49 15.04 105.40 33.65 37.42 6.589 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± * Standard deviation resistance to adverse environmental conditions, including air pollution (Keller and Schwager, 1977; Lima et al., 2000). Pollution load dependent increase in ascorbic content of all the species may be due to the more rate of production of reactive oxygen species (ROS) such as SO3-, HSO3-, OH-, and O2- during photo-oxidation of SO3- to SO4- where sulphites are generated from SO2 absorbed. The free radical production under SO2 exposure would increase the free radical scavengers, such as ascorbic acid, super oxide dismutase,and peroxidase . (Pierre and Queirz, 1981) based on dosage and physiological status of plant. Increase level of ± ± ± ± ± ± ± ± ± ± Mondal et al. 103 Table 4. Evaluation of plant species on the basis of their APTI value and some biological and socio-economic characters. Assessment Parameter Grade Allotted Laminar Sl No Local Name Scientific Name APTI Tree Habit Canopy Structure Type Tree 1 Asoke Saraca indica ++++ + ++ 2 Debdaru Polyanthia longifolia ++++ + 3 Banyan Ficus benghalensis ++++ 4 Dumur Ficus hispida + 5 Guava Psidium guajava 6 Sisoo 7 Mango 8 9 10 Size Texture Economic Importance Hardness Total Plus %Scoring + ++ + + + 13 81 6 + + + + - + 10 62 4 ++ ++ + + + ++ + 14 87 6 + - - + + + - 5 31 1 ++++++ + - - + + ++ + 12 75 5 Dalbergia sisoo +++ ++ + + - - + + 9 56 3 Mangifera indica +++++ ++ + + + + ++ + 14 87 6 Chattim Alstonia scholaris ++ + ++ + + + + - 9 56 3 Mahagunii Swietenia mahoganii +++++ ++ ++ + - + ++ + 14 87 6 Asattha Ficus religiosa + ++ ++ + + + ++ + 11 69 4 ascorbic acid may be due to the defense mechanism of the plant. Increased levels of ascorbic acid in leaves will increase air pollution tolerance in plants (Chaudhury and Rao, 1977). Soluble sugar is an important constituent and source of energy for all living organisms. Plants manufacture this organic substance during photosynthesis and breakdown during respiration. They exist as free sugar and polysaccharide. Decrease in soluble sugar content in plants with increased in gaseous pollutants level in industrial regions was reported by Tzvetkova and Kolarvo (1996). Among the studied species the mean sugar content (mg/g-f.w.) was lowest in Ficus hispida (35.42) and highest in Swietenia mahoganii (105.40) (Table 3). The concentration of soluble sugars is indicative of the physiological activity of a plant and it determines the sensitivity of plants to air pollution. Reduction in soluble sugar content in industrial area can be attributed to increased respiration and decreased of API Grade CO2 fixation because of chlorophyll deterioration. Pollutants like SO2, NO2 and H2S under hardening conditions can cause more depletion of soluble sugars in leaves of plants grown in polluted area (Davison and Barners, 1986). The reaction of sulfite with aldehydes and ketones of carbohydrates can also cause reduction in carbohydrate content. Protein is one of most essential foliar biochemical constituents of plants and is required for enzymatic activity in plant species. Protein content in plants exhibits both increasing and decreasing trend in response to pollution stress depending on the plant species and its inherent resistance against pollution. The mean protein content (mg/g-f.w.) was lowest in Alstonia scholaris (18.40) and highest in Mangifera indica (58.20) (Table 3). Reduction in protein content might be due to the enhanced rate of protein denaturation which is also supported by the findings of Prasad and Inamdar (1990). Constantinidou and Kozlowski (1979) found enhanced protein denaturation and breakdown of existing protein to amino acid as the main causes of reduction in protein content. As shown in Table 3, plant species with higher APTI values were Psidium guajava (31.75), Swietenia mahoganii (28.08), Mangifera indica (27.97), Polyanthia longifolia (25.58),Ficus benghalensis (25.02), and Saraca indica (23.90). Scatter Plot Interpretations Figure 1 shows the linear regression plots individual variables with APTI. It is observed that a high positive correlation (p<.05 and p<.01) exists between APTI and Relative Water Content and APTI and ascorbic acid. It indicates that ascorbic acid and RWC of leaf are the most significant and determining factors on which the tolerance depends. 104 Int. Res. J. Plant Sci. 90 35 ASCO R BIC A CID ( m g /g ) 80 70 RWC(% ) 60 50 y = 0.4434x + 67.661 R2 = 0.2556 40 30 20 10 0 0.000 10.000 20.000 30.000 40.000 30 25 20 15 10 y = 1.2226x - 8.5106 R2 = 0.9545 5 0 0.000 10.000 20.000 30.000 40.000 APTI APTI (Figure 1a) (Figure 1b) 7 2.5 6.6 1.5 6.4 pH Ch loroph yll (mg /g f.w.) 6.8 2 6.2 1 0.5 y = 0.0134x + 1.3586 R2 = 0.0258 y = -0.0041x + 6.4163 R2 = 0.0081 6 5.8 0 0.000 10.000 20.000 30.000 40.000 APTI (Figure 1c) 5.6 0 .000 10.000 2 0.000 30.000 40.000 APTI (Figure 1d) Figure 1. Scatter plot of various biochemical parameters with APTI values. Anticipated Performance Index (API) of plant species in a Green Belt (GB) plantation Plant species for plantation in industrial urban areas were evaluated for various biological and socio-economic as well as a few biochemical characteristics, viz. APTI, plant habit, canopy structure, type of plant, laminar structure and economic value. These parameters were subjected to a grading scale to determine the anticipated performance of plant species as advocated in reference (Sing and Rao, 1983). The grading pattern of ten plant species evaluated in Table 4, and which fit into the grading pattern with respect to their anticipated performance index (API) were recommended (Table 5) for plantation in an industrial/urban area. A comparison of the assessment parameters with respect to grading characters using a multiplication or summation of the anticipated performance of plant species found those parameters to be quite similar. Table 5 showed that out of 10 species, Ficus benghalensis, Mangifera indica, Swietenia mahoganii and Saraca indica were the most tolerant plant to grow in industrial areas and can be expected to perform well. It has a dense plant canopy of evergreen like foliage, which may afford protection from pollution stress. The economic and aesthetic value of this tree is well known and it may be recommended for extensive planting as a first curtain. Psidium guajava was judged to be very good performers, while Polyanthia longifolia and Ficus religiosa qualified for the good performer category. Besides these 7 good performing species, 3 were found to be unsuitable as a pollution sink because of their lower anticipated performance but have been planted in industrial areas for their aesthetic value and other economic uses. The latter species are attractive plants that certainly enhance the aesthetic value of the industrial/urban areas. Thus, an evaluation of anticipated plant performance might be very useful in the selection of appropriate species. Mondal et al. 105 Table 5. Anticipated Performance Index (API) of studied plant species. Sl No Local Name Scientific Name Grade Allotted API Value Total % Assessment 1 Banyan Ficus benghalensis 14 87 6 Excellent 2 Mango Mangifera indica 14 87 6 Excellent 3 Mahagunii Swietenia mahoganii 14 87 6 Excellent 4 Asoke Saraca indica 13 81 6 Excellent 5 Guava Psidium guajava 12 75 5 Very Good 6 Debdaru Polyanthia longifolia 10 62 4 Good 7 Asattha Ficus religiosa 11 69 4 Good 8 Sisoo Dalbergia sisoo 9 56 3 Moderate 9 Chattim Alstonia scholaris 9 56 3 Moderate 10 Dumur Ficus hispida 5 31 1 Very Poor CONCLUSION The present study reveals that evaluation of anticipated performance of plants might be very useful in the selection of appropriate tree species for urban green belt development. This study indicates Ficus benghalensis, Mangifera indica, Swietenia mahoganii and Saraca indica are the most tolerant plant to grow in industrial areas and can be expected to perform well for the development of green belts. 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