Mary Johnalynn S. Caigoy, Andrea Isabel T. Contreras (March 2011)
For a plant to be considered an active bioindicator, its response to a pollutant after exposure for a defined period of time should be investigated. This study determined the reproductive response of Ixora chinensis exposed to different exposure periods of nitrogen dioxide in terms of mean pollen viability. A group of plants were exposed to 0.062 ppm NO2 inside a chamber for 1 hour, twice a day, for 17 days. Pollen samples were obtained every time there were newly-dehisced flowers. Pollen samples were also obtained from the control group which was not exposed to NO2. Pollen viability was determined using TTC stain. Pollen viability of the exposed plants increased over the span of exposure of 17 days while that of the non-exposed plants increased. The decreasing pollen viability could be attributed to alterations in the pollen’s development due to the pollutant NO2. The results could further strengthen the potential of Ixora as a bioindicator of NO2. Exposure of Ixora to varying concentrations of NO2 may be done in future studies. This is to investigate the effect of pollutant concentration variation on the pollen viability of Ixora.
Keywords: nitrogen dioxide, pollen viability, bio monitoring, Ixora chinensis, exposure length