EVALUATION OF SOME JAPANESE'S GARDEN PLANT SPECIES FOR ITS TOLERANCE TO AIR POLLUTION A. COMPARISON OF DIFFERENT SPECIES GROWN IN A SPECIFIC PART OF THE GARDEN

Abstract

Because the different plant species showed a different behaviour against air pollution in the different sites and even in the same site, the present study was conducted on some selected ornamental plants grown together in different parts of Japanese garden, industrial Helwan City, the greatest Cairo, Egypt during the summer season 2017 to determine the relative tolerance of these plants to air pollution prevailing in this city using the air pollution tolerance index (APTI), which estimated by the use of four physio-biochemical parameters of the leaves, i.e. ascorbic acid content, relative water content (RWC %), leaf extract pH and total chlorophyll content as a practical tool for determining tolerance level of the plants and comparing among themselves. Mature leaf samples were monthly collected for 3 times during the morning hours from the selected ornamental plants grown in the North, Middle, South, East and West parts of the garden for analyzing. The APTI scale was used for determination of sensitivity/tolerance degree for every plant species.The obtained results indicated that a considerable variation in the means of ascorbic acid content, RWC %, pH of the leaf extract, total chlorophyll content and APTI values were observed among the different plant species selected from each part. Thus, every species exhibited a sole behaviour than the other ones under air pollution conditions of the same place. Based on the APTI values of various species in every individual place of the garden and the corresponding tolerance degree, it can be advised to plant Yucca elephantipes, Ficus benjamina, Bauhinia variegata and Lantana camara species in the North part; Yucca elephantipes, Cassia nodosa, C. fistula and F. benjamina species in the Middle part; C. fistula, Delonix regia (Poinciana), Ficus cycomorus (Gemez), Lantana camara and Washingtonia filifera palm in the South part; Ficus benghalensis, Codiaeum variegata (Croton), Duranta erecta and Lantana camara species in the East part, while for the West part, it is prefer to plant Delonix regia (Pionciana), Pinus halepensis, Bauhinia variegata, Ficus retusa (F. nitida), F. microcarpa Hawii, Lantana camara and Brachychiton porpulenum species as the most suitable ornamental plants for air pollution load prevailing in every part of Japanese garden.