Practical 2: Effect of Low Temperature on Barley Seed Germination
Principle
Germination of seeds depends on temperature, as it influences metabolic and enzymatic processes
that convert stored food into energy needed for growth. Barley seeds, like most seeds, have an
optimal temperature range for germination. Below this optimal range, metabolic processes
slowdown, which delays or reduces germination rates. This experiment is designed to assess how
low temperatures affect barley seed germination by comparing germination rates at different
temperatures.
Materials
Barley seeds (Healthy)
Petri dishes or small trays
Filter paper or paper towels
Thermometers
Distilled water
Incubator (with temperature control)
Cold environment (e.g., a refrigerator for lower temperature treatments)
Room-temperature environment for control
Ruler (for measuring seedling growth)
Labels and markers
Notebook for recording observations
Procedure
o Select 100 viable barley seeds and divide them into 2 equal groups (e.g., 2 sets of 15
seeds).
o Line petri dishes with filter paper or paper towels.
o Saturate the paper with distilled water, making sure it's moist but not waterlogged.
o Place the seeds evenly on the paper in the dishes.
o Label each petri plate according to the temperature treatment (e.g., 5°C and 25-34°C for
control).
o Place one dish in a refrigerator (approx. 4-5°C).
o Keep the other petri plate at room temperature (25-34°C) as a control group.
o Check the moisture level in each petri plate daily and add distilled water as needed to
keep the filter paper moist.
o Record the temperature in each environment daily to ensure stability.
o Monitor seed germination for 7-10 days. Germination is typically defined as the
emergence of the radicle (root tip).
o Record the number of seeds germinated in each dish every 24 hours.
o Measure the length of seedlings (radicles and shoots) to assess growth.
o After the observation period, calculate the percentage germination for each temperature
condition.
o Measure and record the average length of seedlings in each group.
Results (Hypothetical Example):
Germination Rates: As seen in the results, the lowest temperature (5°C) had the least germination
(16.6%), indicating that this temperature severely affects the seed's ability to germinate. At 10°C,
the seeds showed moderate germination (50%), while the control group at 20°C had the highest
germination rate (93.3%).
Seedling Growth: Similarly, seedlings grown at higher temperatures exhibited greater growth.
Those at 5°C were stunted, with shorter root and shoot lengths, reflecting the slow metabolic
activity at this low temperature.
Conclusion: Low temperatures delay germination and reduce seedling growth in barley seeds,
confirming that temperature plays a critical role in seed germination by influencing enzyme
activity and metabolic rates. Optimal germination occurs at moderate temperatures (34°C), while
lower temperatures (5°C) hinder the process significantly.
