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The effect of mineral deficiencies on plants Free essay! Download now

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The effect of mineral deficiencies on plants

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Downloads to date: N/A | Words: 3000 | Submitted: 06-Jun-2010
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The effect of mineral deficiencies on plants

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Introduction:
Lemna
Lemna are small, free-floating aquatic water plants found in ponds.
Lemna has been used for testing toxicity of certain chemicals.
Lemna can be transformed by molecular biologist to express proteins of pharmaceutical interest.

Chlorosis (break down of chlorophyll) happens when a plant deprived of certain nutrients such as nitrogen, magnesium, and iron. Chlorosis can be noted by yellowing and decolourising of the leaves. This is because the breakdown of chlorophyll a and chlorophyll b (both green in colour) may reveal other photosynthetic pigments. They are xanthophylls (yellow) and carotene (orange).

Necrosis happens due to chlorosis. The leaves may have brownish or blackish patches. Some examples of deficiencies that lead to necrosis include Boron deficiency, and Calcium deficiency. Some other symptoms involve other mineral deficiencies include dark green leaves, short and brown roots, brittle petioles and mottled leaves (spots on the leaves). Plant symptoms may appear in leaves, stems, roots, flowers, fruits, and seeds.
For deficiency in manganese, a mild chlorosis can be developed along the veins and young leaves. At the early stage, these symptoms are very similar to iron deficiency. Manganese is an important component of enzyme Z in light dependent reactions. The lacking of phosphorus show can show necrosis. However, the major visual symptom is that the plant is stunted or dwarfed. The lacking of sulphur shows a general overall chlorosis while still retaining some green colour. The lacking of potassium can show marginal necrosis where necrosis is happened around the tip of leaves.

Photosynthesis
Photosynthesis is a metabolic pathway that utilise the carbon dioxide into organic compounds especially sugars using the energy from sunlight. The sugars are transported in the form of sucrose plants and stored as starch. Furthermore, sugars can be modified to form other substances including amino acids and lipids. Photosynthesis occurs in plants, algae, and many species of bacteria. Photosynthesis is crucially important for life on Earth, as well as maintaining the normal oxygen level in the atmosphere. Photosynthesis takes place in the organelle chloroplasts where chlorophyll is found there. Photosynthetic organisms are called photoautotroph which means they are able to synthesis food from inorganic substances.

The process of photosynthesis can be divided into light dependent reaction and light independent reaction (Calvin cycle). Chlorophyll a pigment molecules are also known as P700 in Photosystem I and P680 in Photosystem II. Fixation of carbon dioxide and photolysis of water occurred in photosynthesis. The overall general equation of photosynthesis is shown below:
6CO2 + 12H2O + light energy → C6H12O6 + 6O2 + 6H2O

Hypothesis:
The Lemna plant will thrive in the complete culture solution to produce the greatest number of leaves while significant poor growth will be shown in the cultures that are lacking of nitrogen, calcium, and magnesium. This is because nitrogen, calcium, and magnesium are macronutrients which are required by plants in large amount while the remaining nutrients are needed in small amounts only for the growth of the plant.

Variables:
Manipulated variable: The deficiencies of different types of minerals
Responding variable: Growth of Lemna leaves
Fixed variable: Light intensity, Surrounding temperature and humidity, concentration of carbon dioxide in the air, volume of culture solution, initial concentration of minerals present in each culture solution, initial number of Lemna leaves in each culture solution, types of Lemna plants, pH of the solution

Apparatus and materials:
8 Petri dishes with a range of nutrient solutions, including solutions with:
all nutrients present
lacking nitrogen
lacking potassium
lacking magnesium
lacking calcium
lacking iron
lacking phosphorus
lacking sulphur
Distilled water
a dropper, a measuring cylinder, forceps, stereo microscope, stickers for labelling, Petri dish covers

Procedure:
The Petri dishes are rinsed with water and wiped dry.
20cm3 of each nutrient solution is added into each Petri dish.
5 Lemna plants are then scattered into each Petri dish.
The Petri dishes are then covered.
All the Petri dishes are arranged in a tray and put it under a shed along the corridor.
Observations regarding the colour of the leaves and the size of roots are taken. The number of healthy leaves are counted and recorded.
The observations are repeated every 2 subsequent days for 14 days.
The results are recorded in a table for a comparison to be made between different conditions of plants.

Risk assessment:
Ensure that the Lemna plants do not adhere to the wall of the cover. If it is stick to the wall of the cover, use a sterilised forceps to transfer it back to the nutrient solution.
Use sterilised forceps to transfer the plants and avoid your finger from touching the nutrient solution and the plant to prevent contamination.
After a few days of observations, some water droplets may be found condensed on the cover. Wipe the cover dry to give a clearer observation.

Result:
Day of observation
Type of
culture solution
Day 1
Day 4
Day 7
Day 9
Day 11
Day 14
All nutrients present 5 8 11 15 19 37
Lacking Calcium 5 10 10 10 9 9
Lacking Iron 5 7 14 16 23 41
Lacking Potassium 5 5 7 8 15 24
Lacking Magnesium 5 5 6 6 10 12
Lacking Nitrogen 5 4 4 4 4 7
Lacking Phosphorus 5 5 5 5 7 11
Lacking Sulphur 5 6 9 12 19 27
Lacking of nutrients 5 5 0 0 0 0
Number of leaves
...

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