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Investigating the Effects of Salt on Seed Germination

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Introduction

Seed Germination Investigation PROBLEM/RESEARCH QUESTION In this investigation, we are researching and investigating whether the concentration/percentage of NaCl (salt) in water affects the germination rate of seeds and if so, which concentration germinates the most seeds. We will formulate our research by conducting an experiment in which we will observe the germination of seeds in various concentrations of salt water and evaluate the results gathered. In particular, we will measure the percentage of seeds germinated in one week and formulate our conclusions from there. HYPOTHESIS I hypothesise that the highest percentage of seeds will germinate in the petri dish that contains the lowest percentage of NaCl in water- 0.5% salt salinity and the percentage will decrease as the percentage of salt in the solution increases. I predict this because I know from prior knowledge that seeds need to be able to absorb H2O to germinate and salt prevents this. So if we increase the amount of salt and therefore, decrease the amount of H2O in the solution, germination of seeds will occur less than those in lower percentages of salt, thus allowing for the 0.5% solution to germinate the most seeds as it contains the least amount of salt out of our five different samples. VARIABLES The independent variable (the variable being changed): The independent variable is going to be the concentration/percentage of salt in water (%). This variable will be changed and a different percentage of NaCl will be used in every petri dish. We will measure and change the concentration of NaCl with water for each petri dish by measuring and pouring 5mL of solution from a particular solution bottle and into a petri dish, using a different solution bottle-which contain different concentration of salt-for each dish. ...read more.

Middle

2. Place the five petri dishes next to each other with their lids and make sure that they are the same size and make. 3. Label with the marker a different NaCl percentage on each lid (0.5%, 1%, 1.5%, 2%, 2.5%). Ensure that lids do not get mixed up with each other. 4. Divide the 30 cotton wool balls into groups of six so that there are five groups. 5. Place each group of cotton wool balls inside a different petri dish and space them out evenly in the dish, ensuring that there is very little gap between them. Macintosh HD:Users:160161:Desktop:Screen Shot 2013-08-26 at 7.53.24 PM.png 6. Divide the 50 cress seeds into groups of ten and place each group into a different petri dish. Place them gently on the surface of the cotton wool balls, spreading them evenly around the edge with a 1cm gap between them. 7. Measure out 5mL of the 0.5% NaCl solution in a measuring tube and carefully drop the solution on the seeds in the respective petri dish with the label: 0.5%. Ensure that all of the solution is dropped on the seeds and not on the side. 8. Repeat the step 7 with the 1% solution; ensuring the measuring tube is washed before. Remember to pour the solution on the seeds in the petri dish with the label 1%. 9. Repeat step 7 again with the 1.5%, 2% and 2.5% NaCl solutions, remembering to wash the measuring tube each time and pouring the solutions to their respective labeled petri dishes. ...read more.

Conclusion

is used. Our method was fairly clear, concise and allowed us collect our data in a fairly orderly way, doing so for most tests. It allowed us to complete the experiment with accuracy excluding the human errors present. Although our method is quite accurate, there are many improvements that could be made to it. These include: * Reducing the chance of human interference affecting the results (different amounts of solution poured on each seed.) Using a fixed amount for each seed (e.g. 1mL)-instead of just trying to divide 5mL across ten seeds- could solve this problem. * Using a wider range of concentrations so that the trend can become more evident and more precise conclusions can be drawn on the increase/decrease of seed germination rate. * We could test each concentration of NaCl three or four times and develop an average, excluding results that stand out so that our data becomes more reliable. * We could leave the seeds for a longer period of time (e.g. one month) in natural conditions such as a pot or flower bed and water them daily with the various concentrations of NaCl and see which seed has grown the most after the one-month. * We could extend this experiment by investigating whether using a different type of seed effects the germination rate and if so, which species of seeds germinates the quickest and most consistently. * We could also investigate how long it takes for every seed to germinate for each concentration and whether using soil instead of cotton wool affects the results. ...read more.

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