Growth of plants in different nutrient solutions
Plants suffer from deficiency diseaseA disease that develops because an organism (plant or animal) does not have enough vitamins or mineral ions. when they do not have enough mineralsNaturally occurring, inorganic chemical substances. Minerals are necessary for both plant and animal health. ions. This can be investigated in science experiments by measuring the growth of barley seedlings.
Method
- Sow ten barley seeds onto cotton wool in a Petri dish. Add 10 cm3 of distilled water, seal using tape to avoid water loss through evaporation and place on a sunny windowsill to germinate. Repeat with three other Petri dishes.
- About one week after germination, open the each Petri dish, pour out any distilled water and add 10 cm3 of the following solutions:
- Petri dish 1 - Distilled water
- Petri dish 2 - Culture solution containing magnesium sulfate and potassium nitrate
- Petri dish 3 - Culture solution containing magnesium sulfate (deficient in nitrogen)
- Petri dish 4 - Culture solution containing potassium nitrate (deficient in magnesium)
- Replace all Petri dishes on the window sill and leave for two weeks.
- Open each Petri dish and carefully remove each seedlingsA young plant developing from a seed. from the cotton wool.
- Dry in an oven and record the total dry mass of each set of ten seedlings.
Results
| Petri dish | Solution added | Seedling dry mass |
| 1 | Distilled water | 2.1 g |
| 2 | Culture solution containing magnesium sulfate and potassium nitrate | 3.4 g |
| 3 | Culture solution containing magnesium sulfate (deficient in nitrogen) | 2.3 g |
| 4 | Culture solution containing potassium nitrate (deficient in magnesium) | 2.7 g |
| Petri dish | 1 |
|---|---|
| Solution added | Distilled water |
| Seedling dry mass | 2.1 g |
| Petri dish | 2 |
|---|---|
| Solution added | Culture solution containing magnesium sulfate and potassium nitrate |
| Seedling dry mass | 3.4 g |
| Petri dish | 3 |
|---|---|
| Solution added | Culture solution containing magnesium sulfate (deficient in nitrogen) |
| Seedling dry mass | 2.3 g |
| Petri dish | 4 |
|---|---|
| Solution added | Culture solution containing potassium nitrate (deficient in magnesium) |
| Seedling dry mass | 2.7 g |
Conclusions
Question
What conclusions can you draw from this data? Use numbers in your answer. [3 marks]
The average dry mass of seedlings increases from 2.1 to 3.4 grams when water is replaced by a culture solution (1 mark). When this solution does not have nitrogen the dry mass reduces to 2.3 grams (1 mark). When this solution does not have magnesium the dry mass reduces to 2.6 grams (1 mark).
Observations
Seedlings grown without nitrogen are smaller than others. Nitrogen is used to make proteins, which are used for growth and repair. Seedlings grown without magnesium will appear yellow and will be smaller. Magnesium is used to make chlorophyllThe green chemical inside the chloroplasts of plant cells. It enables photosynthesis to take place., which is essential for photosynthesisA chemical process used by plants to make glucose and oxygen from carbon dioxide and water, using light energy. Oxygen is produced as a by-product of photosynthesis. Algae subsumed within plants and some bacteria are also photosynthetic..