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What are the tolerance limits of plants to a particular stimuli - Coggle…

- - - - Mint
        
        Spearmint
        
        While other species of mint such as peppermint generally require cooler temperatures to thrive, spearmint can more comfortably grow in warmer temperatures and as the lab is likely to lean towards warmer temperatures spearmint is chosen to minimize the risk of any plants dying due to external factors.
        
        Mint generally takes only two weeks to grow to full height and has a fast growth rate ensuring that a clear impact should be clearly visible in the data. Mint also thrives when grown hydroponically, is cheap and easily accessible.
      - Legumes
        
        Plant cannot have nitrogen fixing bacteria or else the independent variable will change (e.g. peas, beans and other legumes which are commonly contain these bacteria)
  - - - Pros: nutrients are completely controlled, plants grow quickly, roots can be measured easily, water availability is not a factor.
      - Cons: Harder to set up (equipment must be water proof), water can evaporate creating possible inconsistencies for different trials, still water may attract bacteria and insects changing variables, any necessary nutrients must be sourced externally which requires more time
    - - Pros: Easy to buy soils already containing all necessary nutrients, bacterial, microbes, etc., increasing the likelihood of successful growth. A wider range of plants can grow in soil even after germination and until maturity.
      - Cons: Nutrients are hard to isolate if using soil as a growing medium. Roots are visually obscured and soil type and quality can vary greatly depending on brand introducing potential for random error. This is because depending on the attributes of the soil it may absorb water, nutrients, toxins, etc., differently.
    - - Pros: Many seeds can be tested at once/many trials can be completed in the experiment very easily, improving the reliability of results. By testing so many seeds the impact of random error is reduced as results are not as relent on the behavior of one or two plants. Seeds also only require minimal maintenance and
        tend to germinate quickly increasing the chance of a successful experiment unaffected by human error.
      - Cons: To test how tolerance limits impact plant growth is difficult if only the germination period is considered. While it is an important part of plant growth, seed germination often has slightly different parameters to actual plant growth such as --. This means that determining the tolerance limits of certain plant species would not be as accurate.
  - - - Without the addition of other necessary nutrients like phosphorus and potassium the mint seedlings cannot access these necessary nutrients as they are being grown hydroponically. These nutrients also cannot be substituted with more nitrogen as each nutrient is used for different but still crucial functions in the plant. If there is no available phosphorus and potassium each plant would be limited by this factor and die out rather than being effected by the concentration of ammonia available to it and the experiment would not work.
    - - Refreshing the water that the mint is grown in regularly is important because the still water becomes a hotspot for algae and bacteria . By refreshing the water this insures sterility of the plant and . Leaving water for too long can also affect its pH which if too high or low will denature enzymes in plant cells leading to less efficient reactions, slower growth and eventual death.
    - - To be able to photosynthesize to have energy for cell function some form of light is required. Without this, cells cannot sustain themselves and undergo cell division, leading to a slower growth rate. To avoid this an equal amount of sunlight is provided to all plants in the experiment.
    - - Depending on the temperature of its environment, plants will react in various ways due to different rates of reactions, activity levels of enzymes, denaturing etc. As such, unless all the plants are kept under the same consistent temperatures, unaccounted variation may occur leading to errors in the data.
    - - Water is required for photosynthesis but also required for the transport of nutrients to cells. Without ample water this limits the plant's growth and would result in a decrease in mass regardless of the concentration of ammonia sulfate.
- - - - While mint does grow primarily vertically depending on variables such as light location (plant leaves and stems will generally grow towards the closest light and unless this light is directly above the plant this will cause a perceived decrease in the vertical height of the stem.,
    - - While discoloration is a clear sign of nutrient deficiencies similarly to difficulties when measuring the surface area of leaves, measuring the amount of plant impacted by discoloration can be hard due to the unusual shape of leaves and the fragility of dead leaves. Some amount of personal say may also go into what would be considered discoloration, leading to potential differences each time the experiment is repeated.
    - - Root length may decrease or increase based on the availability of necessities as the plant searches for water or nutrients as opposed to the health of the plant. Not only this but the length and width of roots is very hard to measure and has a high risk of error.
    - - To test how tolerance limits impact plant growth is difficult if only the germination period is considered. While it is an important part of plant growth, seed germination often has slightly different parameters to actual plant growth such as --. This means that determining the tolerance limits of certain plant species would not be as accurate.
    - - Measuring the mass of the plant includes growth of the roots, stem and leaves and takes into consideration growth through height but also width as well. This ensures to a better ability that any growth, even if not visible to the eye, is measured. And therefore, a more accurate image of the impact the ID has on the plant can be formed.
      - % Rate of Growth
        
        Measuring the rate at which each plant is growing ensures that initial differences in mass do not influence results and all plants have a level playing field. It also provides some flexibility
      - Rate of Growth
        
        While looking at the rate of growth does eliminate discrepancies in the initial masses of the plants, it fails to take into consideration the fact that smaller plants with smaller leaves and roots would
    - - While a healthy plant will have a higher number of larger leaves when compared to an unhealthy plant of the same species, surface area of a biological organism can be very hard to accurately calculate because of its unique shape, and other simpler measurements can be just as insightful.
    - - Simply counting the number of leaves, etc., does not take into account the size and health of these parts of the plant. It also may not be very specific as all the plants may only grow one or two flowers each, providing little data to analyze. Fruits, flowers and vegetables can also be very dependent on the season or the fertilization of the plant's gametes restricting the experiment quite significantly.
- - - - Plants cannot accept nitrogen that is in the air because they cannot break down the strong triple covalent bond and instead use nitrogen in the form of nitrate (NO3) and ammonium (NH4). If too much of these compounds are present in the soil or water, it can be toxic causing leaves to discolor and veins in leaves to collapse. Excess nitrogen past the plant's tolerance limit
      - Nitrogen is chosen as the nutrient that will be used as the independent variable because of its larger impact on plant growth. Outside of nutrients plants obtain through photosynthesis nitrogen is the nutrient taken up by plants in the largest quantities and therefore should have the largest impact on a plant's mass. This means that the impact of this IV should be easier to observe and measure which may lead to more accurate data.
      - Without nitrogen plants have reduced stalk growth and ability to grow fruit. Nitrogen is also required in the synthesis of amino acids, proteins, and in the formation of nitrogenous bases, making it crucial in the growth of any plant.
    - - Macronutrients like potassium, phosphorus, sulfur, calcium or magnesium and micronutrients like iron or zinc, etc., all are crucial for the growth of plants. For example, potassium and phosphorus are used in plants in their vascular systems and in vegetables and fruits, as well as for root and seed growth and nucleotide production.
      - While important, micronutrients are used by plants in such small quantities that performing different trials with varying levels of these nutrients would be difficult to complete accurately. And, while macro nutrients like potassium and phosphorus are used in larger quantities and necessary for plant survival are not quite as impactful on a plant's biomass as nitrogen is.
- - - - The trials will consist of a control with none, too little (0.8 g/L), too much (2.4 g/L) and the optimal amount of ammonia sulfate to get a wide spread of data and hopefully illustrate the nitrogen tolerance limits of the seedlings.
  - - - Urea/ Organic Fertilizers
        
        Although natural and easy to dispose of safely, urea contains many other nutrients and even disregarding this can have varying amounts of ammonia/nitrogen depending on the source leading to a less accurate experiment
      - Ammonia Sulfate
        
        Ammonia sulfate is made of only ammonia and sulfate and so ensures that no other unaccounted for nutrients are being provided potentially changing the plant's growth rate. Sulfate is also non-toxic to plants and has little impact on its growth provided an excess amount is not provided.
        
        When disposing of ammonia sulfate care must be taken so it does not end up in water ways. This is because as a concentrated fertilizer it can cause many negative impacts such as eutrophication, ruining ecosystems and the environment.