Physiological and morphological responses of locally grown Malaysian rice cultivars (Oryza sativa L.) to different ozone concentrations

• Published in: Water, air, and soil pollution air, and soil pollution, 2004-06, Vol.155 (1-4), p.205-221
• Main Authors: Ishii, S, Marshall, F.M, Bell, J.N.B
• Format: Article
• Language: English
• Subjects: air pollution; Animal, plant and microbial ecology; Applied ecology; Atmospheric pollution; Biological and medical sciences; chemical concentration; chlorophyll; closed fumigation chambers; Crop yield; Cultivars; Developmental stages; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on plants and fungi; Emission measurements; Environmental monitoring; fluorescence; Fundamental and applied biological sciences. Psychology; gas exchange; genotype-environment interaction; grain yield; growth chambers; leaves; Morphology; Oryza sativa; Ozone; photosynthesis; Physiology; phytotoxicity; plant adaptation; plant damage; plant growth; plant morphology; Rice; Senescence; stress tolerance; Urban areas; Yellowing
• ISSN: 0049-6979; 1573-2932
• DOI: 10.1023/b:wate.0000026528.86641.5b

Malaysian rice (Oryza sativa L.) cultivars MR84 and MR185 were grown in greenhouse chambers and exposed to four different levels of ozone from 28th August, 2001 to 22nd January, 2002. Four ozone levels were selected in close relation to the Malaysian peri-urban ambient level (approximately 30 ppb, 8 hr mean), the Malaysian guideline level (approximately 60 ppb) and possible future higher ozone levels (approximately 90 ppb). Both morphological and physiological parameters showed distinctive impacts of ozone treatments. The plants treated with the highest ozone concentration showed different morphological development, probably induced by severe foliar injury and physiological adaptation of the plants to the ozone stress. The physiological measurements revealed a high sensitivity at the early and late vegetative stages. It was concluded that MR84, which was found to be physiologically sensitive, responded to ozone relatively quickly and altered its morphology to compensate for effects on growth and yield, while MR185, found to be physiologically insensitive, responded to ozone stress slowly which resulted in more severe impacts on growth and yield parameters. Slight growth stimulation was observed at the lowest (30 ppb) ozone level for MR185, whilst negative impacts on growth occurred at both of the higher ozone levels. The study provided useful insights into the earlier findings of an open-top chamber filtration study on the same cultivars in the field at a peri-urban site in Malaysia. The present study proved that yield could be reduced substantially when other parameters associated with grain yield were affected, which was accompanied by increasing yellowing of leaves and premature senescence.