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The effect of growth medium on duckweed growth

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Introduction

The effect of growth medium on duckweed growth Duckweed (Lemna minor) is a common plant that floats in water and is common to stagnant water such as ponds. According to Texas A&M 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. Characteristics Duckweed 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. Habitat Duckweeds grow in large colonies on the surface of calm water, and more than one species can grow in the same body of water. Warning Duckweed 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 levels of oxygen in the pond water. Benefits Duckweed plants do provide a habitat for micro invertebrates. Duckweed plants grow best in nitrogen rich environments. This is especially high in polluted ponds. ...read more.

Middle

The duckweed taken from the pond is of a proportionate size. That the samples have the same amount of leaflets. Risk assessment There 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. Results Day Treatment Distilled Water Tap Water With fertiliser Number of leaflets Number of leaflets Number of leaflets 1 2 Mean 1 2 Mean 1 2 mean 1 3 3 3 3 3 3 3 3 3 4 3 3 3 4 4 4 7 8 8 7 3 4 4 5 7 6 13 12 13 10 4 4 4 7 8 8 18 15 17 13 4 5 5 9 11 10 25 21 23 16 4 5 5 11 13 12 32 29 31 19 5 5 5 12 15 14 44 42 43 22 5 6 6 13 17 15 58 57 58 Table 1 shows the number of leaflets on each duckweed plant grown under different conditions Day Treatment Distilled Water ...read more.

Conclusion

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. ?? ?? ?? ?? This document was downloaded from Coursework.Info - The UK's Coursework Database - http://www.coursework.info/ This document was downloaded from Coursework.Info - The UK's Coursework Database - http://www.coursework.info/ This document was downloaded from Coursework.Info - The UK's Coursework Database - http://www.coursework.info/ This document was downloaded from Coursework.Info - The UK's Coursework Database - http://www.coursework.info/ ...read more.

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