Chapter 4: Seed Reproduction
4.10 Summary
We have now completed our discussions on basic weed biology and reproduction. Last chapter covered vegetative propagation and this chapter focused on reproduction via seed production. The terms seed bank, seed viability, and seed dormancy were introduced. We compared different types of dormancy that weed seeds utilize and explored the role of phytochrome in starting seed germination. We also discussed how a weed population migrates or spreads, comparing those that reproduce via seeds with those that reproduce vegetatively. Finally, we took a broad view of how annuals and perennials differ in their general modes of reproduction.
Key Takeaways
Key takeaways from this chapter include:
- The weed seed bank (soil seed bank) contains both viable and dormant seeds present in the top eight inches of soil.
- Types of dormancy include: morphological, physical, and physiological dormancy.
- Phytochrome is a group of pigment-proteins involved in maintaining dormancy and triggering germination.
- Seed dispersal mechanisms include: shattering, windborne, water dispersal, mucilaginous (sticky) seed coats, self burial, and symbiosis.
- The seedling recruitment effect is the term for how weeds move in waves. These waves occur based on the number of seeds at a certain distance from the mother plant, and the increased likelihood of germination as distance from the mother plant increases.
- Annuals establish faster as seedlings, are more competitive as seedlings, and have longer living seeds than perennials.
- Perennials are more competitive as adults than annuals, and can dominate an ecosystem rather than co-exist with other plants such as crops.