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Effect pH on radish growth and germination

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Aretha Chan

on 26 November 2014

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Transcript of Effect pH on radish growth and germination

Acid Rain
Radishes ("Raphanus sativus")
- None of the alternative pHs germinated
- Basic plants showed signs of germination
- Perhaps, baking soda caused aeration of soil, peat pellet puffed up
- Acidic rain plants exhibited mold growth on pellets
- Shows certain pHs levels were ideal for fungal growth
- Highly acidic plants' soil shriveled away
ndependent Variable
: Whether or not germination happens. If it grows, we will measure the length of the leaves, as well as the diameter and flavour of the radishes for our final observation.
Dependent Variable
: Varying levels of pH of watering solutions.
- Control Variable: Neutral (7.0)
- Treatment Variables: Basic (9.0)
Acid Rain (4.3)
Highly Acidic (2.4)
The Effect of pH on Radish Growth and Germination
"Any form of precipitation that has elevated levels of nitric and sulfuric acid, resulting in a low pH".
- pH of acid rain is 4.2-4.4 (5)
- Effects:
- Kills microorganisms
- Limits availability & accessibility of nutrients to plants
- Releases toxins (including aluminum) into soil
- Strips essential nutrients from plant leaves, making the plant susceptible to disease & drying out (1)

- Fast-growing plant species
- Ideal growth environment is moist, fertile, sandy or loamy soils with pH ranging from 5.8-6.8
- Ideal growth conditions is at a constant temperature between 40-85 degrees Fahrenheit (6)
- Radish seed commonly germinates within 3-4 days in ideal conditions
- Moisture of soil will affect flavour of the radishes (4)

- As air pollution worsens, acid rain & acid deposition are becoming significantly more common
- Harmful to vegetation
- Can be detrimental to food production (i.e. Radishes)

1. The lower the pH, the weaker the plants will be in terms of germination and plant height.
2. If we lower the pH of the watering solution to acid rain, then plant growth will be delayed, or inhibited altogether.
3. If we increase the pH of the watering solution to basic, plant growth will be delayed, but not inhibited altogether.
Timeline of Germination
Similar Experiments
Comparative Results
Experiment #1: Germination
(pH 9) - did not germinate
(pH 3)- seeds slowly germinated, 3 seeds germinated within 5 days
(pH 7) - 10 seeds germinated within 5 days (2)

Experiment #2: Growth
(pH 5.6) - Recorded every 3 days 5 times, the plant grew 2.5cm, then stopped growing.
Highly Acidic
(pH 4.5) - Recorded every 3 days 5 times, the plant grew 0.35cm, 0.50cm, 0.20cm and 0.35cm.
(pH 7) - Recorded every 3 days 5 times, the plant grew 2.7cm, 1.1cm, 0.4cm and 0.5cm. (3)
Why did we get our results?
Improvements in Experimental Design
Could we have achieved better results if we conducted the experiment differently?
- Use smaller increments of pH change to actual monitor the effects
- Started earlier
- Periodic acid rain to simulate what would realistically occur in nature
- Place in even more ideal conditions (i.e. direct sunlight, regulated temperatures)
- Consistently monitor the moisture of the soil to attend to the needs of the radishes instead of using a set schedule for watering
- Use a large planting location for more soil depth
Real World Significance
- Plants are crucial to our environment & human survival, providing us with both sources of oxygen & food.
- This experiment has proven that consistent acid rain could be detrimental to our food sources

A greater effort should be made to stop pollution before something as drastic as this happens in the actual world.
- It is
that acidic rain indeed prevents radish growth and germination
- The effects of pH change were even greater than expected: No germination instead of poor growth.
- Radishes have a confined range of ideal pH: Even small deviations prevented germination
- If acid rain came consistently, the earth would become devoid of radishes, and vegetation generally.

Absolute Growth
Qualitative Observations
8 peat pellets in trays
Diluted vinegar and saturated baking soda solutions
4 solutions:
pH 9, basic
pH 7, neutral (control)
pH 4, acid rain
ph 2, very acidic
2 plants per treatment
8 hours of sunlight
constant cool temperature
Watered a few mL every day
Recorded for germination
Monitored and recorded plant growth every 2 days
Healthy radish after 24 days

Two leaves, two more leaf buds started branching during the last two days.
Continuous growth

Grew to certain height, and slowed growth while leaves increased
Very thin taproot growth

No presence of edible radish yet
1 Acid Rain. (2014, September 10). US EPA. Retrieved October 11, 2014, from http://www.epa.gov/acidrain/index.html

2 Bensalem, R. (Director) (2013, March 20). Radish Seed Germination Experiment: Observing the Effects of Different pH Levels. Lecture conducted from Prezi.

3 Magahan, K., Styles, F., & Dinges, S. (2011, October). Effects of Acidity on Radishes. Retrieved November 25, 2014, from http://www.plantingscience.org/index.php?module=pagesetter&type=file&func=get&tid=2&fid=presentation2&pid=4677

4 Maier, C. (n.d.). What Factors Affect a Radish's Growth?. Home Guides. Retrieved October 14, 2014, from http://homeguides.sfgate.com/factors-affect-radishs-growth-66951.html

5 pH Scale. (n.d.). EPA. Retrieved October 14, 2014, from http://www.epa.gov/acidrain/education/site_students/phscale.html#chart

6 Westover, J. (n.d.). How Long Does it Take for Radishes to Germinate?. Home Guides. Retrieved October 13, 2014, from http://homeguides.sfgate.com/long-radishes-germinate-68498.html

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