The effect of growth medium on duckweed growth Essay Example Essay Example

The effect of growth medium on duckweed growth Essay Example Paper The effect of growth medium on duckweed growth Essay Introduction Duckweed (Lemna minor) is a common plant that floats in water and is common to stagnant water such as ponds. According to Texas AM University Duckweed is the smallest flowering plant on earth. It is thought duckweed helps to reduce pollution levels. Duckweed is quick growing new leaves. The plant undergoes asexual reproduction by splitting into two (or more) new plants.CharacteristicsDuckweed plants consist of between two or three leaves known as fronds; these fronds are commonly between 1/6th and 1/8th of an inch in length.HabitatDuckweeds grow in large colonies on the surface of calm water, and more than one species can grow in the same body of water.WarningDuckweed grows rapidly and can aggressively invade pods and bodies of water. It can disrupt marine ecosystems. If the Duckweed grows rapidly and covers the body of water it can prevent light from reaching plants that live on the bottom of the pond. This can then cause fish that feed on the plants to die. It can also reduce the l evels of oxygen in the pond water.BenefitsDuckweed plants do provide a habitat for micro invertebrates. Duckweed plants grow best in nitrogen rich environments. This is especially high in polluted ponds. This means the plant is especially good in cleaning polluted ponds.Factors that affect the growth of plantsThe major difference between distilled water and that obtained from the tap; is that distillation removes the minerals that are found in tap water. Distilled water does not have the fluoride, chloride or trace amounts of sodium found in tap water.Soil contains a complex mixture array of minerals; it is this in combination with water, carbon, hydrogen, nitrogen and oxygen that forms the soil solution. Plants are thought to use sixteen elements in order to grow successfully. Of the sixteen, twelve are found primarily in the soil.Plants are presently recognized to utilize sixteen elements in order to sustain growth. Of these sixteen elements twelve are minerals found primarily in the soil. This is the part of this particular chapter where we could easily go into a litany of items on the periodic table of elements, but we’ll stick to the basics.Carbon, hydrogen, oxygen, and nitrogen are said to be non mineral. Carbon forms the organic skeleton of the plant. This is taken up from the atmosphere with the absorption of carbon dioxide. This is fixed to make sugars during photosynthesis.Oxygen is needed for respiration to take place in the plant. In this process energy is created by the breakdown of the sugars that are made during photosynthesis. Oxygen combines with hydrogen to form water. Water makes up a large proportion of the mass of any plant. Water is used to transport minerals and sugars produced during photosynthesis.Magnesium – is essential for many of the functions inside of the plant. It is an essential element of the chlorophyll molecule. It is an enzyme activator and constituent of many of the enzymes in a plant. Magnesium deficiency sy mptoms in tomato (Epstein and Bloom 2004). Leaves are often a pale green colour (due to the effect on chlorophyll). Some of the leaf margins will curl upwards or turn red-brown to a purple colour.Manganese -The leaves will show a light interveinal chlorosis developed under a limited supply of Mn. The early stages of the chlorosis induced by manganese deficiency are somewhat similar to iron deficiency. Manganese deficiency symptoms in tomato (Epstein and Bloom 2004)Nitrogen – deficiency will affect the rate at which the plant will grow. The older leaves at the bottom of the plant will first turn a yellow-greenish colour, then yellow, red or even purple. The newer leaves at the top of the plant will turn slightly yellowish-green. The colour change is due to the destruction of chloroplasts.Phosphorus deficient plants are often stunted and short in stature. The stalks that develop are weak and thin and appear spindly. Purple veins may appear on the leaves or the leaves may turn p urplish. Older leaves may appear bluish-green.Sulphur deficiency resembles that of Nitrogen, but it appears first in younger leaves with them pale-yellow or light green.Iron deficient leaves show strong chlorosis at the top of the plant and then moves down to the bottom. Leaves turn a yellow colour but keep there green veins.Potassium deficient leaves show marginal tip burn. As the deficiency progresses death occurs in the interveinal spaces between the main veins along with interveinal chlorosis.Biological AimThe aim of this experiment is to determine what effect the lack on minerals has on the growth of a plant.HypothesisAs fertiliser contains all of the necessary minerals that a plant will need to grow, the duckweed grown in fertiliser will produce the most leaflets. As tap water contains some minerals (chloride etc), duckweed will grow better in this than in distilled water that contains no minerals.Null HypothesisThe duckweed will not be affected by the absence of minerals and therefore there will be no difference between the number of leaflets in the three experiments.EquipmentThe equipment used was a described in the NEC handoutMethodThe method was conducted as described in the NEC handoutVariablesIndependent variable = the conditions in which the duckweed is grownConstant variablesNeed to make sure that the volume of liquid added to each of the containers is the same amount. This ensures that any effect of growth rate is not as a result of the amount of water added.The duckweed is taken from the same area of the pond this should ensure that the pond weed has gown in the same nutrients and environmental conditions.The duckweed taken from the pond is of a proportionate size. That the samples have the same amount of leaflets.Risk assessmentThere is a risk of infectious diseases such as weil’s disease from contaminated water supplies. It is therefore essential that precautions are taken when placing hands into the water. All open wounds on the hands should be covered and vinyl gloves warn when coming into contact. Also care must be taken when around ponds, ensure that no risks are taken to get hold of the duckweed.ResultsDayTreatmentDistilled WaterTap WaterWith fertiliserNumber of leafletsNumber of leafletsNumber of leaflets12Mean12Mean12mean133333333343334447887344576131213104447881815171345591110252123164551113123229311955512151444424322566131715585758Table 1 shows the number of leaflets on each duckweed plant grown under different conditionsDayTreatmentDistilled WaterNumber of leaflets121Leaves are normalLeaves are normal4Leaves are normalLeaves are normal7New leaflets a light interveinal chlorosisNew leaflets a light interveinal chlorosis10New leaflets a light interveinal chlorosisNew leaflets a light interveinal chlorosis13More â€Å"newer† of the leaf is turning yellowishMore â€Å"newer† of the leaf is turning yellowish16All of the leaves including older leaves turning yellowAll of the leaves including old er leaves turning yellow19All of the leaves including older leaves turning yellowAll of the leaves including older leaves turning yellow22Most leaves are now yellowMost leaves are now yellowTap WaterNumber of leaflets12Leaves are normalLeaves are normalLeaves are normalLeaves are normalLeaves are normalLeaves are normalLeaves are normalLeaves are normalLeaves are normalLeaves are normalLeaves are normalLeaves are normalNewer leaflets are much smaller and growing less rapidlyNewer leaflets are much smaller and growing less rapidlyNewer leaflets are much smaller and growing less rapidlyNewer leaflets are much smaller and growing less rapidlyWith fertiliserNumber of leaflets12Leaves are normalLeaves are normalLeaves are normalLeaves are normalLeaves are normalLeaves are normalLeaves are normalLeaves are normalLeaves are normalLeaves are normalLeaves are normalLeaves are normalLeaves are normalLeaves are normalLeaves are normalLeaves are normalGraph 1 shows the effect of minerals on the growth of leaflets on DuckweedThe plants grown in distilled water show very little difference in the amount of leaflets that grew on the duckweed plant. It also showed the smallest amount of growth in overall size. The growth of the duckweed is due to the minerals held in the plant, those minerals absorbed from the pond. As the duckweed ages the minerals are used up, there are no new minerals being replaced and the plant starts to show deficiencies in many of the minerals by the loss of chlorophyll and turn yellow.The duckweed grown in the tap water like the one grown in the distilled water retains minerals from the pond. There are some minerals in the tap water that aid grow this is shown by more leaflets growing in the later stages of the experiment. However if this experiment was elongated the amount of new leaflets would decrease that the plant would plateau as in the distilled water. This is due toany nutrients in the tap water being used up by the plant. The plant would also begin to exhibit phenotypic symptoms of nutrient deficieny such as yellow leaves.Plants grown in the fertiliser have the greatest rate of growth. The rate at which new leaves is not slowing and all leaves are a healthy green colour. This is because the nutrients that were in the plants from the pond are being replaced by excess minerals in the fertilisers. The longer the experiment proceeds the greater the rate of leaflet growth. This is shown by an increase in the gradient of the graph.ANOVA: Single FactorSUMMARYGroupsCountSumAverageVarianceColumn 18334.1250.839286Column 28718.87519.76786Column 38193.524.1875346.8527ANOVASource of VariationSSdfMSFP-valueF critBetween Groups1758.7712879.38547.1794410.0042083.4668Within Groups2572.21921122.4866Total4330.9923With a p value of 0.01 we can reject the null hypothesis and accept the hypothesis with a confidence of 99%. This means that there is a significant difference in the growth of leaflets in plants grown in different mediums. It sugg ests that minerals have a significant difference in the growth of plants.EvaluationAlthough this experiment shows the effect that minerals and the lack of minerals have on plant growth. This is all that it tells use. It makes no advancement to our knowledge of the effect of individual minerals to plants. This would have been overcome by the use of Sachs solutions which are specifically designed to have a single nutrient deficiency. This would then show how the effect of removing one nutrient would have on the phenotype of a plants growth.There was also a problem with water loss from the containers probably due to evaporation from the container and the leaves of the plant. No attempt was made to replace the loss fluid. This could then have had an effect on the growth of the plants. Before the experiment started I should have marked the meniscus of the water and then topped up the volume with distilled water.The health of the duckweed plants used was not investigated at the beginning of the experiment. Even though the duckweed was taken from the same area of the pond, some of the samples could have been diseased. If I would have had time I could of investigated this by growing all of the duckweed in nutrient rich water for a few weeks before replacing them in the new mediums. This would have meant all of the samples would have been healthy and disease free.I also noticed that to the end of the experiment algae was growing in the tap water and fertiliser samples. This could have some effect on the rate of plant growth. To prevent this, the water could have been boiled and cooled before adding in the plant. The effect of growth medium on duckweed growth Essay Thank you for reading this Sample!