Egyptian plant species as new ozone biomonitors | ||
| Journal of Pest Control and Environmental Sciences | ||
| Volume 7, Issue 1, April 1999, Pages 1-36 PDF (2.52 M) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/jpces.1999.462089 | ||
| Authors | ||
| Samia A. Madkour* ; J. A. Laurence | ||
| Boyce Thomson Institute for Plant Research at Cornell University, Ithaca, NY, USA | ||
| Abstract | ||
| The aim of this study was to test and select one or more highly sensitive, specific and environmentally successful Egyptian bioindicators for ozone (O3). For that purpose, more than thirty Egyptian species and cultivars were subjected between 1993 and 1995 to extensive screening studies under controlled environmental and pollutant exposure conditions to mimic the Egyptian environmental conditions and O3 levels in urban and rural sites. Four plant species were found to be more sensitive to O3 than the universally used O3-bioindicator, tobacco Bel W3, under the Egyptian environmental conditions used. These plant species, Jew's mallow (Corchorus ohtorius C.v. local) white clover (Trifolium repens L c.v. Masty), garden rocket (Eruca sativa C.V. local) and alfalfa (Medicago sativa L. C.V. local), ranked in order of decreasing sensitivity exhibits typical O3 injury symptoms faster and at lower O3 concentrations than tobacco Bel W3. Three parameters were tested in search of a reliable tool for the diagnosis and prediction of O3 hidden damage prior to the appearance of visual foliar symptoms. pigments degradation, stomatal conductance (G3) and net photosynthetic CO2 assimilation (Pnet) Pigment degradation was found to be unreliable in predicting species sensitivity to O3. Evidence supporting stomatal conductance involvement in O3 tolerance were found only in tolerant species. A good correlation was found between G3 restriction of O3 and CO2 influx into the mesophyll tissues, and Pnet Changes in Pnet seemed to depend largely on fluctuation in G3. | ||
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