Investigating the effect of using coffee on germinability of Raphanus
sativus (Radish)
Introduction
Coffee is a form of beverage used by people all around the world. It contains caffeine
which increases the activity of the brain and nervous system. Coffee helps to increase mental
alertness, energy, and ability to concentrate. However, high doses lead to insomnia, increased
heartrate, and anxiety. Based on the type of plant and the environment it grows in, the effect of
coffee is different. Coffee is acidic meaning that it can have positive effects on plants which
grow in acidic soil. I predicted that using coffee on plants will lead to healthy plant growth.
However, I had no evidence for this claim and after doing some research, I understood that
coffee can be used as a fertilizer for some plants. Brewed coffee is a source of nitrogen for
plants, producing healthy green growth (Vanderlinden, C, planet green, Crowder, T, 2022).
Coffee is a member of the plant family rubiaceae. The coffee plant is a small tree with glossy
green leaves. It takes about 3 to 5 years for the plant to give flowers and fruits. Moreover,
coffee contains caffeine which can have both positive and negative effects, depending on the
concentration. Fertilizing plants with caffeine can affect plant growth, but not necessarily
positively. Coffee plants contain caffeine-building enzymes that are members of Nmethyltransferase which are found in build various compounds and are found in all plants.
When caffeine is being discussed, the N-methyltransferase mutate. Coffee also contains
calcium and magnesium, both of which are beneficial to plant health (Vanderlinden, C, planet
green, Crowder, T, 2022). For using coffee as, a plant fertilizer, it needs to be diluted. Which
is why I wanted to investigate if coffee did, in fact, affect plant growth and germination. It is
crucial to know the conclusion of this research because it leads to learning about an ecofriendlier way of handling organic waste instead of using chemical fertilizers which leads to
the release of harmful greenhouse gases into the atmosphere.
Research question
How does different concentration of diluted coffee () used to water Raphanus sativus seeds
affect the success rate of germination over 96 hours?
Hypothesis
Increase in concentration of coffee () will cause an increase in the germination rate of Raphanus
Sativus until an optimum concentration is reached.
Methodology
Independent variable: different concentrations of diluted coffee used to water Raphanus
Sativus
Dependent variable: the success of Raphanus Sativus germination (%) over 96 hours.
Variable
How it is kept constant
Why it is kept constant
The temperature
All the dishes will be kept in Enzyme
activity
of
the same room, with the Raphanus Sativus depends
windows closed, and to make on the temperature levels. If
sure that the temperature the temperature is higher
stays the same during all then
the
optimum
trials, a thermometer will be temperature,
used
to
check
temperature every day.
the become
optimum
enzymes
denatured.
temperature
The
for
Raphanus Sativus is 55-75˚F.
The time (96 hours)
This will be maintained by The time will be limited to 4
using a chronometer.
days (96 hours) to calculated
the
rate
of
germination
equally.
Humidity
A hygrometer will be used to Humidity
monitor the humidity.
has
to
be
maintained throughout the
investigation,
influences
because
the
rate
it
of
germination. if humidity is
low, the seed will have
trouble germinating, and if
humidity is high, it can lead
to damping off which occurs
when pathogens affect the
seeds.
The volume of coffee and This will be maintained by The volume of water in cm3
water used to water the measuring the water and is kept constant to prevent
coffee
Raphanus Sativus
volume
using
measuring cylinder.
a different levels of nutrient
from being absorbed by the
Raphanus Sativus.
Infusion
time
when A chronometer will be used The infusion time must be
preparing
the
diluted to make sure that the infusion kept constant, because the
coffee (1 hour)
time stays constant.
longer the coffee is infused,
the more acidic it gets which
can negatively affect the
germination process.
Material list
During the investigation, the number of materials being used are the total number of materials
needed for all trials of the experiment.

6 petri dishes

30 qualitative filter paper

25.0+0.5cm3 measuring cylinder

5×800cm3 Beaker

5×800cm3 Erlenmeyer flask

Raphanus sativus seeds

Coffee

Water

Digital thermometer

Hygrometer

Chronometer
Risk assessments, and environmental issues

It is necessary to wear gloves during the experiment

If any glassware is broken, all pieces need to be removed and cleaned using a brush and
dustpan.

If boiled water is spilled on the body, place it under lukewarm or cool water for 20 to
30 minutes and then cover it (burns and scalds, nhs.uk).
Procedure for data collection
Preparing the diluted coffee
1. One scoop of coffee was poured into each labelled flask
2. Then water was boiled for each beaker using a kettle and poured into 4 beakers with
low to high amounts.
3. As soon as the water was poured into the beakers, a chronometer was started and set to
one hour
4. After an hour, the coffee was filtered out int their labelled Erlenmeyer flask to make
sure that no excess coffee was left to affect the concentration of coffee.
5. The coffees were left in the fried overnight to avoid any mold or bacteria growth.
Setting up the germination experiment
1. 6 pieces of filter paper were cut to fit the petri dishes, and then placed at the bottom of
the dish.
2. 40 Raphanus Sativus were placed on each petri dish and then covered with a lid.
3. Then a hygrometer and a digital thermometer were placed next to the dishes for
regulating the internal conditions. (The temperature and humidity were checked every
24 hours)
4. Mixture of coffee and water were then measured by 25.0+0.5cm3 measuring cylinder
and poured into the petri dishes.
5. After initially watering the Raphanus Sativus, a chronometer was set for 96 hours.
6. After 96 hours was over, the final number of germinated Raphanus Sativus was
recorded and used to calculate the percentage of successful germination.
7. Steps 1-6 were repeated for 5 trials for having sufficient data. (Before each trial, the
material was completely cleaned)
Bibliography:
Vanderlinden, C, planet green, Crowder, T. (2022). Don't Toss That Joe! Use Diluted Coffee
to Fertilize Plants. Retrieved from, https://home.howstuffworks.com/green-living/usediluted-coffee-to-fertilize
plants.htm#:~:text=Coffee%20grounds%20(and%20brewed%20coffee,should%20look%20lik
e%20weak%20tea.