In the RAR experiment , this analysis was restricted to the data taken over the period from day 9 to day 24 (i.e. In treatment-1 ponds were supplied with duckweed as supplementary fish feed and in treatment-2 ponds were kept as control (without supply of duckweed). Gently raise the strainer and allow … We also learned that duckweed needs nutrients to survive, not only sunlight and water. This tiny organism is ideal for population growth experiments because it reproduces quickly, requires minimal space to grow, and requires no maintenance. Duckweed can tolerate a wide range of pH (3.0–10.0), but displays optimum growth in a medium of 5.0–7.0. �9;�B�S�;%e3 �"�`LQ� The purpose of this research was to investigate the ef- fect of wastewater dissolved salt content on the growth of duckweeds (Spirodela) when a duckweed system is em- ployed for municipal wastewater treatment. These plants are very useful for investigations on population growth. The plant reproduces by vegetative budding, although it may flower. 2 mg/L was considered as the threshold toxicity in Lemna … This organism was used because it can reproduce asexually and rapidly. In other … The Effect of Fertilizer on Duckweed Growth by: Bri Benardin and Darien Ellis Discussion The control group steadily grew until it leveled out at and average of 65 fronds in the three cups. One of the many environmental factors that affect duckweed growth is the wavelength of the light that strikes the fronds. The control group did not have any drops of nitrate solution, so it stopped growing after the seventh day. Slight agitation, such as where an outlet flows, seems to increase the asexual reproductive process. You will find the best micro-climate for production this way. Our group has selected to look at how light affects the growth. For Cu concentration of 0. In this lab we will be testing how it grows in different environments. A dense cover of duckweed inhibits competing submerged aquatic plants, which require solar energy for growth and they can also often exclude algae from bodies of water. Do not grow in the same area as you are … The average of 0.001 g/mL cups, the duckweed grew in the first couple of days, but leveled "Sunlight is broken up into a prism of light, … Measure the surface area of your aquarium or pond. AQ꓅��� ߆ �5�J�9�>q�c)�A1a��@�1H�����X����]�� In doing this experiment we kept in mind the study of population growth and were interested in observing the different ways a population responds to different environments. In this case phosphate was taken away from the nourishment given to the plant; this was to see how it might affect the plants growth rate after a few weeks. 3. 1. h�22W0P���w�/�+Q0���L)�66 Olah.V et al., conducted studies on two species of Duckweed and observed that the physiological responses of the different species to same ambient concentration of a toxic chemical (hexavalent Cr VI) is in different manner. Measuring Duckweed Begin by deciding how many samples of duckweed you will take from your aquarium or pond. We hypothesized that the carrying capacity would reach the peak when the duckweed was being exposed to natural light over the red and blue light because natural light incorporates all the colors. Growth characteristics—We measured the response of the duckweed to light in terms of the number of fronds as a function of time. W��:�B�\3����5� Cup D was shown to have the highest growth rate, which was expected, as it has the highest concentration of fertilizer thus providing the most nutrition. However, current plant models face some limitations, e.g., plant and pathogen cannot co-culture in a contained environment. Population Growth 1 Lab 2. Lower the tea strainer carefully into the pond. DOCX, PDF, TXT or read online from Scribd, 0% found this document useful, Mark this document as useful, 0% found this document not useful, Mark this document as not useful, Duckweed is an aquatic plant used often in removing some nitrates, left in natural light for a week will yield, natural light which was near the window, high light on a, * There could be a confounding variable with the s, counted out twenty-five duckweed frons and put that amount in each, natural light, low light). Introduction Duckweed is an aquatic plant used often in removing some nitrates from water. h޼Zmo�8�+�K��Z|9,�M�f��;4���>��� ?�4�y�0'Q�Qh2a'�l�4 Aquatic habitats have, in general, degenerated throughout the world because of pollution by both industry and other activities. It is predicted that a lower light intensity will lower the rate of growth in duckweed. 1), 2 mg/L, the growth index was optimal. �K�6y��c��ǚ:L0y�\r��y�R�9G �X�q��o�4����ۥϕ�Va�J�@�����'E3R�`O … Duckweed are useful plants for students to use to develop investigations. %PDF-1.5 %���� The hypothesis that was tested was that sunlight is a limiting factor for duckweed growth. Duckweed is the perfect space food: small, fast-growing and nutritious. The lack of dissolved oxygen in water bodies, through its uptake by microbes for decomposition of organic compounds, produces degrees of anaerobiosis that results in m… POPULATION GROWTH IN Lemna (Duckweed) A. It is predicted that a lower light intensity will lower the rate of growth in duckweed. )@H� B���X��ʂT�����b;;� �� As the weeks went by a significant difference between the duckweed samples without phosphate and the samples with phosphate was noticeable, … In our experiment of duckweed population growth, we learned that greater levels of nitrate solution increase the growth rate of duckweed. An experiment on duckweed (Lemna minor) as supplementary feed in monoculture of nile tilapia (Oreochromis niloticus) was conducted for a period of 90 days. Based on these results, Cu concentration of 0. The duckweed was placed in stagnant water which contributes to the growth of the duckweed as this is a more favourable condition for duckweed growth (John W. Cross, 1998-2002). For Lab 7, the duckweed lab, the purpose is to test what factors might affect the growth of duckweed. Early growth should be exponential, or in other words it should occur at an increasing rate. Below 17 °C some duckweeds show a decreasing rate of growth. #! Also, if one spot fails, you have several others producing. This is particularly true for wildlife and fisheries biologists and plant and animal ecologists interested in protecting endangered species (plants and … Ponds were stocked at a … Experiment # Lemna minor(Duckweed) Population Growth Introduction– Students will grow duckweed (Lemna minor) over a two to three week period to observe what happens to a population of organisms when allowed to grow without predation or competition. To be able to model this growth at these temperatures, an experiment is conducted with as goal; determining the death rate of duckweed at temperatures above 35°C. Previous workers (Smith et al., 2004) established a linear relationship between frond count and fresh weight (Eqn. Introduction An understanding of the dynamics of population growth and the factors that may influence changes in population size is important in many ecological settings. In Part B the magnitude of interaction is explored by growing monocultures and mixed … On the other hand, at concentration ranging from ~ 0 (control) to 0. This experiment investigates the growth of duckweed in response to sunlight exposure. Duckweed growth is optimum at temperatures between 20 and 30 °C, but serious effects will occur at temperatures between 35 and 40 °C. On average, fronds live for four to five … We will study how wavelength affects the duckweed’s growth over several weeks. Measure the surface area of your tea strainer. Experiment 3, "Population growth and resource competition in Lemna minor and Spirodela polyrhiza", studies the population growth and competition of two species of floating aquatic plants. Discover everything Scribd has to offer, including books and audiobooks from major publishers. Although there was only a small, margin of increase between the natural light and high light, both f. those environments dominated the amounts of fronds in the low light. the population no longer grows). endstream endobj 176 0 obj <>stream Conclusion Literature In conclusion, the results of the experiment were pretty close to what was hypothesized: If duckweed is exposed to various levels of pH, its growth will be closely correlated with how close the pH level is to 6 Although the duckweed living in the petri dish All cups placed in the environment began with 25 fronds. changed from counting the number of duckweed at day 0 and day 14 to counting them every day changed from testing duckweed growth in beakers to testing duckweed growth in large outdoor tanks changed from testing the effect of pH on duckweed growth to testing the effect of light levels on duckweed … Spirodela polyrhiza (greater duckweed) grown on filtered wastewater from Princeton Meadows Wastewater Treatment Plant. However, as time passes, the rate of growth s hould slow and approach zero (i.e. Finally, we placed two, high light cups were placed under a high light, the, a window, and the low light cups were placed. Lemna minor has variable growth rates under varying climatic conditions. Student Project: Investigations with Lemna Minor. Populations may even decline if the experiment runs long enough. Duckweed prefers slow moving water however, you will notice fastest growth with areas of agitation. It is hypothesized that altering the amount of light received by duckweed will alter its photosynthetic rate. z�I�Ǩ�����̳��������Reg�ݻ����4���n�������Y��d�����t�W����`�/(F��W�Ȇ]�������ӳ7o�����ԋ�O�7K����L+)�.6弾:Y��+B��_ LY�]n���٧8�\�w��*�w��+�JiK�N&�1s:L:��@�B�� Xy[�^|�o�5���/���-/;}4���9vI����C�^׋��lAD�SBi���\W�e|淋��5��>׋�źn��׫���[����@dA��/C�xk?�V�+�V�[��^��� Duckweed is a small aquatic plant that is able to grow rapidly, making it the ideal specimen for our experiment. After observing the, from: natural light, high light, as well as, the amount of fronds supported our hypothesis. This model, and the literature, lack essential information on the growth/death rate of duckweed at temperatures above 35°C. 2. The free-floating, freshwater plant consists of a green elliptical frond with one root and is found in still waters, from temperate to tropical zones. The experiment had two treatments each with three replications. Materials Duckweed fronds, 16 Dissecting needle or forceps Fertilizer, liquid Graduated cylinder, 25-mL Potting soil Marker or wax … Yes, duckweed makes good fertilizer as it absorbs the nutrients from the pond water. In Part A the growth of lab populations of Lemna minor and Sprirodela polyrhiza grown alone and in mixed cultures are monitored. 2. It was predicted that the duckweed exposed to more sunlight will have a higher population. Also, the effect of plant growth on the removal efficiencies of cer- tain pollutants was investigated. In synthetic leachate a maximum growth rate of 7.03 ± 1.25 g m -2 day -1 was recorded during all tests whereas, at dumpsite leachate maximum growth rate of duckweed was 4.87 g m -2 day -1. Anong Phewnil et al., concluded that the growth rate ofLemna Perpusilla Torr. Wait while the duckweed floats back over the strainer. 2�K�O�;�:����䕭uk,iB^��Q��`&�l��Ohi�i�Ҏ�)�9�R(O�p�"�r ^������m�U��U��jS_����}U"���v ^�:�[��f=�xs��"��K��a�� c�yx g�M�ެ^�\/�T/�����-.�E 175 0 obj <>stream ���]��P�eq�6X�>��e��_Ns��B�e��yB*$�aR�aOJ䍵�|��SS�6z�.Aа��l���#���u( ?p|,�X�Щ"R{AZ��g����:���a��p�F���H��йg1f���s��^�{��`-p�d-[3>�Ѩ}�-�����-+�GX���8�Д��%����l �z��3�7�ˇ�/�����A����0�3)��t�J�4���8�R�;\ՊN���sN2� ��|��U]�����\{��{9�������q���Q�d{^Eg���AB��6�w��8K��d�� �6aL����{f��=5t@�/xFX]v�#8.�kDž��������%u㱦�nt��MWF����M�D/9����P���7W���ھ�̓'ٹ� a_�}���x68��V_�t�y��d�i1"2y0r����S��n{�J{�]��� �SsWӣ�Q�i3MC���DZ. The relationship between duckweed growth and the total nitrogen concentration in the mediium follows the Mitscherlich Function and is similar to that of other plants. Different wavelengths of visible light appear as different colors. It will disturb the duckweed. By studying how light levels changed the production of radiation-fighting antioxidants, researchers made it even better. After a week had passed the results were as follows: Before we conducted our experiment, we hypothesized that the natural light, environment would be the best place for fond growth. Grow in several places. We will use the tiny aquatic plant Duckweed (Lemna minor) in this investigation because it undergoes continuous growth. The best nutritional situations for duckweed growth are in waters with decaying organic material, providing it with a steady supply of nutrients. In order to verify duckweed tolerance to Cu, photosynthesis was measured at the maximal concentration which caused no effect on the plant growth. ��9��m���P�Dɒc;�|�I�e8�>�$�D)b,Q�0H�.$Q�Ɖ�V #F[�9a�)��9�%�\I���F� W� 4T�n-%�A�%����aD�1�SI��qF�� �Aav$E��S+��'@�(��e�*���Xc��8��N��V���✀Ζ0*��uPP0��X a���� y(H�X��_~�Np%����Z���";'2�X]mrCg�K9,��Q����"���e�pWe��ş�_{j�ٌC33Xx&܌�\�,��vQcL�`ᬛIzb In this study, the impact of copper (Cu) on the growth of the duckweed Lemna minor, followed by its removal, was studied with 0.1–1.0 mg/L of Cu in a quarter Coïc and Lesaint solution at pH=6.1. Human activities have, in general, resulted in much higher flows of minerals and organic materials through aquatic systems, often leading to eutrophication and a huge drop in the biomass produced in such systems. It is hypothesized that altering the amount of light received by duckweed will alter its photosynthetic rate. In which situation has the independent variable for the experiment been changed? Duckweed is a small aquatic plant that is able to grow rapidly, making it the ideal specimen for our experiment. Duckweed’s fast growth rate allowed us to conduct a two week long experiment to test if these factors manipulate duckweed growth rate. Duckweed (Lemna minor) as a Model Plant System for the Study of Human Microbial Pathogenesis Background Plant infection models provide certain advantages over animal models in the study of pathogenesis. The duckweed divide quicker. Check all that apply. Growth rates were four-fold higher for Tilapia supplemented with duckweed compared with Taro leaves or no supplement; and were 22% higher in ponds fertilized with biodigester effluent compared with no fertilizer . A model or mathematical expression derived from duckweed growth data was used to fit data from experiments conducted in a greenhouse in Lubbock, Texas. 5 mg/L, duckweed growth was inhibited by 70% (indicated on the figure by the broken line) representing the minimal growth index attained under our experimental conditions.