The Effect of Nutrient Concentration on Duckweed Growth
The effect of nutrient concentration on duckweed growth
Gina Neonakis
Biology 203L:11
Biology 203:10
November 14, 2011
Abstract Lemna minor, or duckweed, is a small plant that floats on the surface of stagnant water that is usually rich in nutrients. Phosphorus is an important macronutrient in the growth of aquatic plants. We tested the effect of phosphorus on duckweed population growth using a control medium rich in nutrients and compared it to the population growth in a medium that lacked phosphorus. Each treatment had 5 replicates that began in beakers with 40 duckweed thalli, grown in a laboratory setting for 14 days under 140-W lights at room temperature. A regression showed that there was significant growth in each of the populations (P<0.05), and a t-test resulted in a significant difference between the growth rates of each condition on day 3 (t=1.37, P>0.05) and day 14 (t=5.86, P<0.05). The intrinsic growth rate, r, for the nutrient rich treatment was 0.11 and 0.08 for the nutrient lacking treatment, therefore the medium containing phosphorus had a faster growth rate than that without phosphorus. Phosphorus is a limiting factor in the growth of duckweed, and thus affects the population growth rate.
Introduction
Lemna minor, more commonly known as duckweed, is a member of the Lemnaceae family (Monette et al. 2006). It is a small aquatic plant found floating on the surface of stagnant, nutrient rich waters. Each plant, known as a thallus, is comprised of a small leaf attached to a single rootlet, which resides below the surface of the water. In order for duckweed to multiply, new thalli develop around the edges of the initial leaf, resulting in clumps. The plant population increases geometrically to rapidly cover the surface of still water in a brief period of time. However, this is only apparent if environmental conditions such as light, nutrients and temperature are not limited (Taylor, 2011). The nutrient concentration of the water
Gina Neonakis
Biology 203L:11
Biology 203:10
November 14, 2011
Abstract Lemna minor, or duckweed, is a small plant that floats on the surface of stagnant water that is usually rich in nutrients. Phosphorus is an important macronutrient in the growth of aquatic plants. We tested the effect of phosphorus on duckweed population growth using a control medium rich in nutrients and compared it to the population growth in a medium that lacked phosphorus. Each treatment had 5 replicates that began in beakers with 40 duckweed thalli, grown in a laboratory setting for 14 days under 140-W lights at room temperature. A regression showed that there was significant growth in each of the populations (P<0.05), and a t-test resulted in a significant difference between the growth rates of each condition on day 3 (t=1.37, P>0.05) and day 14 (t=5.86, P<0.05). The intrinsic growth rate, r, for the nutrient rich treatment was 0.11 and 0.08 for the nutrient lacking treatment, therefore the medium containing phosphorus had a faster growth rate than that without phosphorus. Phosphorus is a limiting factor in the growth of duckweed, and thus affects the population growth rate.
Introduction
Lemna minor, more commonly known as duckweed, is a member of the Lemnaceae family (Monette et al. 2006). It is a small aquatic plant found floating on the surface of stagnant, nutrient rich waters. Each plant, known as a thallus, is comprised of a small leaf attached to a single rootlet, which resides below the surface of the water. In order for duckweed to multiply, new thalli develop around the edges of the initial leaf, resulting in clumps. The plant population increases geometrically to rapidly cover the surface of still water in a brief period of time. However, this is only apparent if environmental conditions such as light, nutrients and temperature are not limited (Taylor, 2011). The nutrient concentration of the water
Cited: Dickinson, Matthew B., and Thomas E. Miller (1998). Competition among Small, Free-floating, Aquatic Plants. American Midland Naturalist 140.1: 55-67. JSTOR. Web. 10 Nov. 2011. <http://www.jstor.org/stable/2426988?seq=1>. Driever, Steven M., Egbert H. Nes, and Rudi M.M Roijackers. (2005). Growth limitation of Lemna minor due to high plant density. Aquatic Botany 81: 245-51. Fogg, G. E. (2003). Phosphorus in primary aquatic plants. Water Research 7.1-2: 77-91. 1 Apr. 2003. Web. 9 Nov. 2011. <http://www.sciencedirect.com/science/article/pii/0043135473901541>. Lacoul, Paresh, and Bill Freedman. (2006). Enviromental influences on aquatic plants in freshwater ecosystems. Envionmental Reviews 14: 89-136. Monette, Frederic, Samir Lasfar, Lousie Millettem and Abdelkrim Azzouz. (2006). Comprehensive Modeling of Mat Density Effect on Duckweed (Lemna Minor) Growth Under Controlled Eutrophication. Water Research 40.15: 2901-910. Onaindia, M., B.G Bikuna, and I. Benito. (1995). Aquatic Plants in Relation to Environmental Factors in Northern Spain. Journal of Environmental Management 47: 123-37. Scheffer, Martin, Sandor Szabo, Alessandra Gragani, Egbert H. Van Nes, Sergio Rinaldi, Nils Kautsky, Jon Norberg, Rudi M.M Roijackers, and Rob J.M Franken. (2003). Floating Plant Dominance as a Stable State. 100.7: 4040-045. <http://www.pnas.org/cgi/doi/10.1073/pnas.0737918100>. Taylor, Barry R. (2011) Introductory Ecology: Bio 203 Laboratory Manual 2011. Antigonish: St. Francis Xavier University.