International Baccalaureate Extended Essay in Biology
Research title: The relationship between various electric current voltage levels
and the germination and post-germination growth of radish (Raphanus sativus L.)
Research question: How do different electric current voltage levels (0V, 3V, 6V, 9V, 12V)
influence germination and post-germination growth of Raphanus sativus L.?
Word count: 3939
I declare this work is my own work and is the final version. I have acknowledged each use of
the words or ideas of another person, whether written, oral or visual.
,Contents page
1. Introduction ......................................................................................................................... 4
2. Research question................................................................................................................ 4
3. Background information ..................................................................................................... 5
3.1 Germination and post-germination plant growth. ............................................................... 5
3.2 Effect of electric current on plant growth ............................................................................ 5
3.3 Characteristics of radish (Raphanus sativus L.) .................................................................. 6
4 Preliminary experiment ....................................................................................................... 7
5 Variables ............................................................................................................................. 7
6 Hypothesis ........................................................................................................................... 8
7 Methodology ....................................................................................................................... 9
7.1 Equipment ........................................................................................................................... 9
7.2 Procedure ............................................................................................................................ 10
8 Results ............................................................................................................................... 11
8.1 Numerical data ................................................................................................................... 11
8.2 Observations ....................................................................................................................... 12
9 Statistical analysis ............................................................................................................. 12
10 Data analysis ..................................................................................................................... 14
11 Evaluation ......................................................................................................................... 19
12 Conclusion......................................................................................................................... 20
13 Ideas for further improvement of the experiment ............................................................. 21
References ................................................................................................................................ 22
2
, Abstract
The aim of the following investigation was to determine the effect the electric current has on
post-germination growth of Raphanus sativus L. seedlings. The hypothesis was: application
of electric current to seeds and seedlings of Raphanus sativus L. will result in accelerated
growth (in optimum voltage) or in decelerated growth (in too low or high voltage) of roots and
shoots. Specific voltages (0V, 3V, 6V, 9V, 12V) were chosen in order to provide wide spectrum
of data and facilitate localization of voltage for which the change in growth was the greatest.
The experiment involved 40 samples (8 per trial) and lasted 10 days, after that time the roots,
shoots, and total lengths of samples were measured. There turned out to be no correlation
between length of shoots or total length and the voltage applied to seeds. However, in case
of root length the post-hoc Tukey test showed significant difference between 0V and 3V trials.
The difference corresponded to root length increase of 40%. Nevertheless the research is
inconclusive and further experiments need to be conducted in order to refute or support
the hypothesis.
Word count: 183
3
Research title: The relationship between various electric current voltage levels
and the germination and post-germination growth of radish (Raphanus sativus L.)
Research question: How do different electric current voltage levels (0V, 3V, 6V, 9V, 12V)
influence germination and post-germination growth of Raphanus sativus L.?
Word count: 3939
I declare this work is my own work and is the final version. I have acknowledged each use of
the words or ideas of another person, whether written, oral or visual.
,Contents page
1. Introduction ......................................................................................................................... 4
2. Research question................................................................................................................ 4
3. Background information ..................................................................................................... 5
3.1 Germination and post-germination plant growth. ............................................................... 5
3.2 Effect of electric current on plant growth ............................................................................ 5
3.3 Characteristics of radish (Raphanus sativus L.) .................................................................. 6
4 Preliminary experiment ....................................................................................................... 7
5 Variables ............................................................................................................................. 7
6 Hypothesis ........................................................................................................................... 8
7 Methodology ....................................................................................................................... 9
7.1 Equipment ........................................................................................................................... 9
7.2 Procedure ............................................................................................................................ 10
8 Results ............................................................................................................................... 11
8.1 Numerical data ................................................................................................................... 11
8.2 Observations ....................................................................................................................... 12
9 Statistical analysis ............................................................................................................. 12
10 Data analysis ..................................................................................................................... 14
11 Evaluation ......................................................................................................................... 19
12 Conclusion......................................................................................................................... 20
13 Ideas for further improvement of the experiment ............................................................. 21
References ................................................................................................................................ 22
2
, Abstract
The aim of the following investigation was to determine the effect the electric current has on
post-germination growth of Raphanus sativus L. seedlings. The hypothesis was: application
of electric current to seeds and seedlings of Raphanus sativus L. will result in accelerated
growth (in optimum voltage) or in decelerated growth (in too low or high voltage) of roots and
shoots. Specific voltages (0V, 3V, 6V, 9V, 12V) were chosen in order to provide wide spectrum
of data and facilitate localization of voltage for which the change in growth was the greatest.
The experiment involved 40 samples (8 per trial) and lasted 10 days, after that time the roots,
shoots, and total lengths of samples were measured. There turned out to be no correlation
between length of shoots or total length and the voltage applied to seeds. However, in case
of root length the post-hoc Tukey test showed significant difference between 0V and 3V trials.
The difference corresponded to root length increase of 40%. Nevertheless the research is
inconclusive and further experiments need to be conducted in order to refute or support
the hypothesis.
Word count: 183
3
