GROUND-LEVEL OZONE: A THREAT TO RICE CROP IN MUDAIRRIGATION AREA OF PENINSULAR MALAYSIA
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Date
2008
Journal Title
Journal ISSN
Volume Title
Publisher
Journal of Sustainability Science and Management
Abstract
It has long been recognized that pollutant gases cause significant impacts on crops and
forests in both developed and developing countries. Ground-level ozone (03) or better known as
tropospheric ozone is recognised as the pollutant most likely to cause widespread crop damage. For
this pollutant anAOT40 (accumulative 0 3 concentration above a threshold of40 ppb) value causing
5% yield loss for all agricultural crops has been established as 3000 ppbĀ·h, which is applicable during
daylight hours over a growing season (UN-ECE, 1996). In order to have a complete estimate ofair
pollution damage i.e., 0 3 to paddy plantation area, a dose-response, or yield-loss function have to be
developed. In this study, data was gathered from tests in open-top chambers (OTCs), whereby four
OTCs were fabricated; two of which were exposed to ambient air pollution (NF) of which ozone
is the major perpetrator whilst the remaining were provided with clean air i.e. charcoal filtered air
treatment (F). The response ofa popular local rice cultivar, MR.-219 to current ambient air pollution
of which 0
3 is the overwhelming dominant pollutant was investigated for five successive seasons
in Muda Irrigation Scheme Area (MADA); the largest rice growing area in Malaysia. The results
ofthe study clearly indicate that at ozone concentrations even lower than the Malaysian air quality
guidelines (60 ppb 8 hr mean) level, there exist a significant impact on the growth and yield ofthe
popular rice cultivar MR-219. Even though weeds, diseases, and insect pests were absent, water and
nutrients were in abundance, no adverse soil conditions, and that no extreme weather event such as
typhoons occurs; the physiological, growth and development performances of rice plants exposed
to ambient ozone were found to be significantly (P< 0.05) reduced by AOT40 compared to control
rice plants infiltered chamber. This study discovered that the root was the most significantly affected
component ofMR-219 rice plant. Meanwhile, reproductive stage is the most vulnerable period of
growth to ozone impact followed by grain filling and vegetative stages, respectively.
Description
Keywords
Air Pollution, Ground-level ozone, Open Top Chamber, Rice yield, MADA