Method
We will begin by forming agar jelly that has all the nutrients except for the independent variable we are testing, along with one with all the essential nutrients as our control. We will then place a single pea seed in each of the formed agar jellies at the same depth and distance from the edges of the container it is being held in. We will place them in roughly the same place where they will receive equal sunlight and water them with equal amounts of water. As they continue to grow we will observe their progress noting any oddities that do not compare with our control.
The lacking nutrients of the differently numbered pots is shown below:
1 – Nitrogen
2 – Magnesium
3 – Sulfur
4 – Potassium
5 – Phosphorus
6 – Iron
7 – Calcium
8 – Control (no nutrients missing)
Risk Assessment
One risk to our personal health was the possibility of getting agar jelly on our skin, which could cause irritation. As a result when moving the peas into the jelly we ensured this was done with tweezers and the pots handled with caution whilst being moved to prevent any spillages.
A risk that we should be aware that could affect the reliability of our results is the positioning of the pots throughout the course of the investigation. This could effect the amount of sunlight they receive and therefore affect their potential to grow. As a results we will aim to place them as much in the same position as possible without causing them to block each other’s source of light.
Another risk is the position of the seed within the agar, which we will aim to have as equal as possible, as this would effect the amount of nutrients available the seed gets but also the amount of light that will be able to pass through the agar to react with the seed. This could potentially effect our results and so we will aim to carefully place each seed correctly in an attempt to correct this risk.
Predictions
Our prediction for the plant suffering from nitrogen deficiency is that it will suffer from stunted growth. This is due to nitrogen being an essential element in the synthesizing of new DNA, and without a copy of DNA new cells or proteins can be formed disallowing the plat to grow any further, along with a discoloring in the leaves as chlorophyll would not be present as it requires nitrogen to be made.
In the plant lacking magnesium we would also expect a discoloring in the plant as it is essential in the production of chlorophyll that give the plants their green color. We might also expect stunted growth as magnesium activates a number of enzymes essential for growth.
The plant lacking in sulfur would suffer from a number of symptoms as sulfur is used in the production of proteins, which without would stunt growth, deter chlorophyll production, and prevent the growth of some enzymes, which we would expect to alter the growth of the plant.
Because potassium is often the largest nutrient absorbed by plants we would expect it’s absence to be quite damaging for the plant, and we might expect the overall condition of the plant to be fairly poor after lacking this, for example it might be rendered susceptible to disease, poor leaf colour due to it being used in photosynthesis, and generally poor growth.
Although iron is a micronutrient and therefore not one of the mist essential in the plant’s survival, it is still very important for the production of chlorophyll and therefore a lack of this nutrient would lead to discoloration in the leaves and possibly poor growth due to lack of energy obtained through photosynthesis.
Calcium is another macronutrient that is important for the plant’s survival. A lacking of this we would expect to result in poor transport throughout the plant due to calcium being a main part of the cell wall in plants, and the plant would be unable to grow very tall as the walls would not be strong enough to support the plant’s growth. This may also lead to poor photosynthesis as the plant would not stand very tall and therefore unable to reach more light.
The final pot, in which all the nutrients are present, we would expect to grow as well as any other plant, it would be able to grow tall, with full coloration in the leaves. It would also be resistant to disease that may cripple it, along with being able to support itself to grow to it’s full potential and reach light easily.
Limitations and Improvements
Although there is little more we could have done to make the investigation more reliable, there are always things to improve on. One of these was the number of tests carried out in the investigation, as to get a better idea of the effects of nutrient deficiency on plants, whereas in this practical the data was qualitive not quantative. However we did try and compensate for this with peer review it which increases the reliability of results as they are able to be reproduced if they appear the same. Nonetheless an improvement I would make should I do the practical again would be to have more than one set of tests running at one time, however still ensure conditions were the same for all of the tests.
A limitation to the results was the composition of the agar jellies used in the investigation, as there were bound to be some slight differences in the amount of nutrients found in each pot, compared to the relative need within the plant. However this was combated by using very fine results to calculate the amount of nutrients put in the agar jelly pots. However a more notable limitation was the thickness of the agar jellies, some of which were visibly different, as when placing the pea in and moving it with the tweezers, some were more resistant that others and as a result may effect the growth of the seeds, as the shoots would encounter more resistance when trying to grow in the thicker jellies than in the thinner ones. This also suggests greater water content in some pots more than others that would limit the reliability of the results as if a plant has more access to water, or more dilute access to nutrients this would effect it’s growth. Should we do the investigation again I would aim to make measurements of nutrients and water more precise.
Another potential limitation to the results is the amount of water being added throughout the course of the experiment as a larger amount of water added may dilute the nutrients and make them more difficult for the plant to reach, whereas too little water may stunt the growth of the plant, therefore we will aim to use the same amount of water for each pot when adding any. Another limitation may also be the position of each pot throughout the investigation, as this would cause a variation in the sunlight being available for the pots, even if only slightly, therefore we will aim to place them as close to each other without obstructing the light for the other plants. However this is still a minor limitation to our results. Therefore should we carry out the experiment again we would aim to limit this effect on our results.
Conclusion
Although there were a number of limitations to the investigation, it was nonetheless carried out to a satisfactory standard and as a result our findings can be assumed to be reliable, depending somewhat on the peer review in which we will find out whether our results can be repeated. From these tests we are able to understand the effect of nutrient deficiency on plants as they grow, and highlights the importance of the presence of these nutrients in plant growth, and their effects within the plant.
