EFFECT OF SYNTHETIC WASTE-WATER ON YOUNG KANDELIA CANDEL PLANTS GROWING UNDER GREENHOUSE CONDITIONS

A greenhouse experiment was performed to evaluate the effects of synth etic wastewater in three different strengths, NW, MW and CW, on the gr owth of the one-year old Kandelia candel (L.) Druce plants. NW had the characteristics and strength similar to natural municipal wastewater while MW and CW contained five and ten times of the nutrients and heav y metals in NW, respectively. Artificial seawater was used as the cont rol. During one year wastewater treatment experiment, Kandelia were fo und to withstand wastewater of high strength and toxic symptoms were n ot detected in all plants. Synthetic wastewater with strength similar to the natural municipal sewage (NW) stimulated plant growth. The plan ts treated with NW had significantly higher aerial and root biomass, t aller stem than those found in the CW, MW and the control. Maximum gro wth, in terms of both stem height and total biomass, of all plants occ urred in summer months, from June to September. With respect to the ph ysiological and biochemical activities, CW and MW treated plants had s ignificantly lower levels of chlorophyll a, total chlorophyll and cata lase activity than those found in NW and control groups. In contrast, the proline content of plants treated with wastewater was similar to t hat of the control. These results suggest that normal wastewater (NW), attributed to its nutrients and trace elements, enhanced plant growth . The medium (MW) and concentrated wastewater (CW) supported similar a mount of plant growth as the control but the physiological and biochem ical parameters indicate that these treated plants might have been exp osed to some kind of stress, probably due to the excess heavy metals p resent in MW and CW.