Agricultural Science (AS)·Crop science · NSSCAS 3.1a
Seeds: dormancy, germination & germination percentage
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A farmer in the Omusati region opens a bag of saved mahangu seed. It looks lifeless and dry. Will it grow, and how many of the seeds will actually come up? Why do some healthy seeds refuse to sprout even in perfect soil, and how can a farmer measure whether a batch of seed is worth planting at all? In this lesson we learn how a seed sleeps, how it wakes, and how to calculate exactly how good a bag of seed really is.
What you'll learn in this lesson
By the end you should be able to (NSSCAS Agricultural Science (AS) 3.1a):
- Describe the importance of the seed in crop production: propagation, storage of the next crop, carrying genetic quality, food reserve and plant breeding
- Explain what seed dormancy is and why it is an advantage to the plant
- Describe the different types of seed dormancy: hard seed coat (physical), embryo (physiological), chemical inhibitors and light requirement
- Describe methods of overcoming dormancy: scarification, after-ripening, cold stratification, leaching and shallow sowing
- Discuss the factors affecting germination: water, oxygen, temperature, stratification, vernalisation and viability
- Describe how to carry out a germination test and interpret the result
- Calculate the germination percentage of a seed sample using germination % = (seeds germinated / total seeds sown) x 100
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