Sanchez, Lemuell Karla A.  4  0   <br/><br/>
Effect of cadmium on growth and morphology of duckweed (lemma perpisilla).        6 
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<br/><br/>   Thesis: (B.S. Biology) -  Pamantasan ng Lungsod ng Maynila, 2006. 
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<br/><br/> ABSTRACT:  	The study focused on the effect of cadmium on growth and morphology of duckweed (Lemna perpusilla).  	Duckweed samples were exposed to varying cadmium  concentrations (0.05ppm, 0.1ppm, 0.5ppm, 1 ppm, and 5ppm) for four days. Set-ups of four plants having three fronds each were placed in 180 ml  different cadmium solutions in triplicates. Growth, was  measured by the increase in number of fronds and changes in dry weight, while morphological observations focused on the leaf coloration, size and shape of stomatal opening, and chlorophyll content of the test plant. Emergence of new fronds were recorded daily while cpmparisons between the experimental groups and the control group in terms of leaf coloration, dry mass, and chlorophyll content, were done after treatment. Metal uptake was determined by subjecting the heavy metal solutions to Atomic Absorption Spectroscopy at the end of the experiment.  	Lemna perpusilla exhibited changes in leaf coloration from rich green to light green during the exposure to cadmium. Alterations in shape of stomata from ovoid to round and a significant enlargement of stomatal opening were also observed in the plants exposed to 5ppm solution. The number of fronds decreased significantly on the 0.5 ppm. 1ppm, and 5ppm experimental groups whike no significant difference was observed on the number of fronds on the 0.05ppm and 0.1ppm experimental groups. Moreover, no significant difference was seen on the dry weight, chlorophyll concentration, and metal uptake of the test plants.       
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