Kirsten Ashley Q. Arroyo, Ma. Thea P. Gadong, Johannes M. Magpusao (March 2002)
Philippine Science High School Western Visayas Campus – Department of Science and Technology (DOST-PSHS WVC), Brgy. Bito-on, Jaro, Iloilo City 5000, Philippines
ABSTRACT
This One-Spot Case Study in a Completely Randomized Design determined the air pollution tolerance index (APTI) of some common plant species in Iloilo City. The study hypothesized that there is no significant difference in the APTI of these plant species among the test areas in the city. Leaf samples were taken from three areas, namely, Jaro Plaza, Bonifacio Drive-Gen. Luna Street, and Philippine Science High School Western Visayas Campus, which was considered as the control test area, having relatively minimal pollutants. These sites had four plant species in common, specifically, talisay (Terminalia catappa), papaya (Carica papaya), Indian tree (Polyathia longifolia), and mahogany (Swietenia macrophylla). The APTI value was calculated by the determination of ascorbic acid, relative water content, total chlorophyll, and pH level of mature plant leaf samples. The test solution, standard solution, and blank solution of leaf extract was titrated against the standard dye solution in order to determine the ascorbic acid content: the fresh, turgid, and dry weights of plants leaf samples were determined as a measure of the relative water content; the spectrophotometric readings of the different leaf extracts at 645 nm and 663 nm against 80% acetone estimated the total chlorophyll content; and the pH of the leaf extracts was measured using a pH meter. The APTI was then calculated from these measurements. Triplicate trials were performed on each plant sample from each test area. The mean and the standard deviation were utilized as descriptive statistical tools. The One-Way Analysis of Variance (ANOVA), both set at 0.05 alpha level of significance, were utilized as inferential statistical tool.
The results of this study showed that mahogany was the best bioindicator since it had the lowest mean APTI value 5.709422 among the group, followed by Indian tree (5.849522) and talisay (6.470933). Papaya was the least potent bioindicator as it had the highest mean APTI value of 6.895633. This established that mahogany was most sensitive or the plant, which can best tolerate an immense degree of air pollution. The results further showed that the most polluted area among the three sites was Bonifacio Drive-Gen. Luna St. having the lowest APTI values, while the least polluted area was PSHSWVC having the highest APTI values.