The effects of different levels of minerals on plant
growth
Technical & Teaching Notes
Type and purpose of activity
This experiment can be used to:
 provide evidence for assessment of Outcome 3
 develop knowledge and understanding of the importance of macro elements in plants
 develop problem solving skills and in particular Outcome 2 PC:
(b) Information is accurately processed, using calculations where appropriate
(d) Experimental procedures are planned, designed and evaluated appropriately.
Background Information
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This experiment is inexpensive, easy to set up, reliable and generates plenty of
quantitative results, suitable for analysis.
However, it does require a light bank and the radish seed take 2-3 weeks to grow to a
suitable size followed by 2-3 days to dry to a constant dry mass.
The theory background to the experiment is straightforward and included in the
Student Activity Guide.
Reference
Hewitson, J. and Price, R. (1994) Plant mineral nutrition in the classroom: the radish, Raphanus
sativus L is a good plant for such studies. School Science Review, 76 (274), 45-55.
Classroom management
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To obtain meaningful results, at least five radishes will have to be grown at each level
of minerals chosen e.g. 0, 3, 6, 9 and 12 fertiliser pellets per container - black film
cans are ideal. (i.e. 25 radishes in total).
As cost is not a major factor in this experiment, students could either work in small
groups (2-4) or as one large group and the class results pooled.
The experiment should take about 30 minutes to set up initially. Using a light bank
the radish should be ready to harvest 18-21 days later, having required the minimum
of maintenance during this time. Harvesting should take about another 30 minutes.
After 2-3 days drying to constant weight the plants will be weighed and the results
pooled.
Supply of Materials
In order to satisfy the core skill in problem solving, students will be required to 'identify and obtain
resources' required for themselves. It is therefore not appropriate to provide all equipment and
materials in e.g. a tray system for each student/group. Normal laboratory apparatus should not be
made available in kits but should generally be available in the laboratory. Trays could be provided
containing one type of specialist equipment or materials.
Science & Plants for Schools: www.saps.org.uk
The effects of different levels of minerals on plant growth: p. 1
This document may be photocopied for educational use in any institution taking part in the SAPS programme.
It may not be photocopied for any other purpose. Revised 2012.
Extension work
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Try fertiliser pellets with different ratios of N, P and K.
Replace fertiliser pellets with mineral deficient solutions.
Investigate the application of plant growth substances e.g. gibberellic acid.
Vary the variety of radish grown.
Density of radish could be measured instead of dry mass.
Technical guide
Materials required
Materials required by each group:
 25 black film cans with a 4-5 mm hole in the base
 25 wicks
 50 radish seed
 NPK fertiliser pellets (slow release 14:14:14) (at least 150)
 25 labels
 marker pen
 dropping bottle distilled water
Materials to be shared:
 light bank
 growing mix (equal parts peat and fine vermiculite mixed)
 water containers with lid and capillary matting
Preparation of materials
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Radish plants of a suitable size can be grown in film cans with a 4-5 mm hole in the
bottom made with a sharp pair of scissors. Empty film cans can be obtained free of
charge from a chemists/film processors.
It is important the peat/vermiculite mix that the radish seed is sown in is low in
nutrients. e.g. Philip Harris Growing Mix, Catalogue number H56720/0, 2 litres cost
about £2. The most suitable slow release fertiliser pellets can also be obtained from
Philip Harris, NPK slow-release fertiliser pellets, Catalogue number H56740/6, about
£1.
Radish seed, labels and capillary matting can all be obtained from a garden centre.
To make wicks, cut pieces of capillary matting approximately 50x5 mm and taper at
both ends.
Science & Plants for Schools: www.saps.org.uk
The effects of different levels of minerals on plant growth: p. 2
This document may be photocopied for educational use in any institution taking part in the SAPS programme.
It may not be photocopied for any other purpose. Revised 2012.
The water containers can be empty ice cream or margarine containers with a couple of slits about
30x10 mm cut at one end of the lid. A piece of capillary matting is then cut to fit the lid. However
the matting must have a couple of ‘tails’ to fit through the holes in the lid and reach the water in
the container.
Alternatively, a tray (e.g. 300x100x40 mm) can have a piece of glass/perspex supported above it
by two dowelling rods. The capillary matting can then sit on the glass/perspex with either end
dipping in the water in the tray.
In all set ups the plant containers will be placed on the capillary matting.
Supply of materials
It is not appropriate to provide all equipment and materials in e.g. a tray system for each
student/group. Equipment and materials should be supplied in a way that students have to
identify and obtain resources. Normal laboratory apparatus should not be made available in kits
but should generally be available in the laboratory. Trays could be provided containing
one type of specialist equipment or materials.
Science & Plants for Schools: www.saps.org.uk
The effects of different levels of minerals on plant growth: p. 3
This document may be photocopied for educational use in any institution taking part in the SAPS programme.
It may not be photocopied for any other purpose. Revised 2012.