title: Ecophysiological responses of young mangrove species Rhizophora apiculata (Blume) to different chromium contaminated environments.
abstract: Many mangrove forests have suffered from the contaminated environments near industrial areas. This study addresses the question how these environments influence the renewal of mangrove forests. To this end ecophysiological responses of the young mangrove species Rhizophora apiculata (Blume) grown under combinations of the factors heavy metals (here chromium), nutrition and soil/water environment were analyzed. We tested the hypothesis that soil/water conditions and nutrient status of the soil strongly influence the toxic effect of chromium. Seedlings of R. apiculata were grown in three different soil/water environments (natural saline soil with brackish water, salt-leached soil with fresh water and salt-leached-sterilized soil with fresh water) treated with different levels of chromium and NPK fertilizer. The system was inundated twice a day as similar to natural tidal condition in the mangrove wetland in the south of Vietnam. The experiments were carried out for 6months. Growth data of root, leaf and stem, root cell number and stomata number were recorded and analyzed. Results showed that growth of R. apiculata is slower in natural saline soil/water condition. The effect of chromium and of nutrients respectively depends on the soil/water condition. Under high concentrations of chromium, NPK fertilizer amplifies the toxic effect of chromium. Stomata density increases under chromium stress and is largest under the combination of chromium and salty soil/water condition. From the data a nonlinear multivariate regression model was derived capturing the toxicity threshold of R. apiculata under different treatment combinations.
authors.affiliation: Nong Lam University, Ho Chi Minh City, Vietnam; National University Ho Chi Minh City, Institute for Environment and Resources, Vietnam.
authors.forename: Kim Linh
authors.initials: KL
authors.lastname: Nguyen
authors.affiliation: National University Ho Chi Minh City, Institute for Environment and Resources, Vietnam; Braunschweig University of Technology, Institute of Geoecology, Germany.
authors.forename: Hoang Anh
authors.initials: HA
authors.lastname: Nguyen
authors.affiliation: Braunschweig University of Technology, Institute of Geoecology, Germany. Electronic address: o.richter@tu-bs.de.
authors.forename: Otto
authors.initials: O
authors.lastname: Richter
authors.affiliation: Nong Lam University, Ho Chi Minh City, Vietnam.
authors.forename: Minh Thinh
authors.initials: MT
authors.lastname: Pham
authors.affiliation: National University Ho Chi Minh City, Institute for Environment and Resources, Vietnam.
authors.forename: Van Phuoc
authors.initials: VP
authors.lastname: Nguyen
mesh_terms: D002857:Chromium / Q000032:analysis*; D054046:Plant Stomata; D043982:Rhizophoraceae / Q000187:drug effects* / Q000254:growth & development; D054712:Salinity; D012987:Soil; D014744:Vietnam; D014874:Water Pollutants, Chemical / Q000032:analysis*; D053833:Wetlands
chemical_list: D012987:Soil; D014874:Water Pollutants, Chemical; D002857:Chromium
keywords: Chromium; Mangrove; Microorganism; Nutrient; Plant growth modelling; Rhizophora apiculata