Building Digital Education of Heirloom Crops
for the Resilience of African Food Systems in the Climate Crisis
Lecture 6
Other Propagation Goals - Seed Improvement and Selection
Selection of plants for propagation
Recap from the previous lecture
To successfully select the plants from which to take seeds, you must consider the purpose of your seed saving.
You should never take seeds from sick or weakened plants. These specimens should be removed from the garden bed before flowering. This way, they cannot participate in fertilization and can spread their pollen to strong and healthy plants.
Since late in the Stone Age, farmers and gardeners have worked to improve the quality of their crops. Perhaps they sought larger fruits, more robust plants, or an earlier harvest. If this process is done using modern methods, it is called selection or plant breeding. To improve a particular variety, select the plants with the desired properties.
Seed savers' primary activity is selecting plants with desirable traits. They do this by crossing different plants and picking the offspring exhibiting the most favorable characteristics. This process of selection and simple crossing is a fundamental method of plant breeding and improvement.
In essence, seed savers are nature's gardeners, carefully choosing which plants will contribute to the next generation and enhancing specific traits over time.
Propagation goals (without conservation) [1]
Selection
Create a selection suitable for your farm from a mixture of several plants, carefully selecting plants according to your defined principles.
For example, you have more than 10 different colors of beans. They are all bush beans, ripen and harvested at a similar time, and have similar cooking times. You sow all these beans in one field for many years in a row and select the most productive and resistant to drought, temperature fluctuations, and diseases. This way, you will create unique seeds best suited for your specific farm.
Key points:
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Starting with a diverse population: Begin with a mix of different plants, such as various varieties of beans.
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Defining selection criteria: Identify the traits you want to improve, like yield, disease resistance, or taste.
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Repeated selection: Consistently select plants exhibiting the desired traits over generations.
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Adaptation to specific conditions: This process allows you to develop plants that are well-adapted to your unique farm environment.
Heterogeneous material
Heterogeneous material can consist of both self-pollinating and cross-pollinating plants. In one field, different varieties suitable for the region are sown together. Usually, 3-7 varieties are mixed, grown, and harvested for seeds for at least 3-5 seasons. Cross-pollinating plants will cross-pollinate while self-pollinating plants will cross-pollinate less or not at all. It will be a "patchwork," each variety contributing its genetic material.
If the heterogeneous material has been grown in the same place for more than 30 years, it can be considered a landrace.
Key points:
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Mixing different varieties: Growing multiple varieties together increases genetic diversity and promotes cross-pollination.
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Creating a unique population: Over time, a distinct population will emerge with characteristics adapted to the local environment.
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Landrace development: If this process continues for many generations, a landrace, a locally adapted variety, can develop.
Landrace
Landrace means a race of that place, that land. A landrace is a genotype cultivated in one place for a long time. It is a locally adapted variety that has evolved over generations through natural and human selection.
A landrace can be cucumbers or garlic (meaning it can also be propagated vegetatively).
The plant has adapted and evolved. It will be more uniform and not as diverse as heterogeneous material.
Even heirloom varieties grown in one place for 30 years could be considered a "landrace". The longer they are grown, the more uniform they usually become.
Key points:
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Local adaptation: Landraces are well-suited to the specific environmental conditions of their region.
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Genetic diversity: While landraces are more uniform than heterogeneous populations, they still retain some genetic diversity.
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Long-term adaptation: Developing a landrace takes many generations, as plants adapt to their environment over time.
Improvement
You decide that you want to improve a particular plant variety. You choose which plant traits to focus on and propagate only those plants.
For example, you collect seeds from the lettuce plants that flower last. This propagates the plant's trait of producing leaves for a more extended period rather than quickly flowering.
How the process is done:
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Choosing a trait: You identify a specific trait you want to improve in a plant, such as longer leaf production or disease resistance.
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Selecting plants: You carefully choose plants that exhibit this desired trait to a greater degree than others.
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Propagation: You collect seeds or cuttings from these selected plants and grow new ones.
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Repeating the process: You continue to select and propagate plants with the desired trait over many generations, gradually enhancing it.
Let us look at three examples:
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If you grow peas, you want pods to develop earlier and a more extended harvest season. Consequently, you take seeds from the plants that produce the first pea pods and the plants that keep producing for the longest time. To keep track of which plants and which pods you have selected for seed saving, you mark them clearly. When the chosen pods are ripe, you have seeds with the best properties of your variety.
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On the other hand, for lettuce you want it to stay crisp and tender for as long as possible. Therefore, you take seeds from the heads which are the largest and last to bolt ("run to seed").
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Carrots are biennial. In the first year, you harvest for eating; the following year, the remaining plants will bolt, flower, and set seeds. However, some carrots may bolt the first year, and the seed saver might think this is an excellent way to harvest seeds without waiting another year. But if you do, you increase the possibility that all your future carrots will bolt the first year and will not be worth eating.
What should you look for when selecting seeds and plants for propagation?
Open-pollinated varieties [2]
To begin producing your seeds, the seeds should be from open-pollinated varieties and, if possible, from organic, biodynamic, or agroecological agriculture or inherited from your family or local gardeners and farmers.
Open-pollinated varieties are all plants that produce offspring with the same appearance and properties as the parent plant. They can all be used to save your own seed.
Seeds of open-pollinated varieties do not have any special labeling on the seed packet, but "Heirloom" is a guarantee.
Breeders in scientific institutions and seed industry companies apply many and varied methods to improve seeds and crossbreed purposefully.
You should avoid using varieties that the big seed industry has developed. So do not use F1 or F2 hybrid seeds, GMOs, or any seed developed through biotechnology. To begin producing your own seeds, the seeds should be from open-pollinated varieties and, if possible, from organic, biodynamic, or agroecological agriculture.
Nature is very generous and will provide far more seeds than you need for your own use. The surplus can be given to others or exchanged.
More information and videos on www.diyseeds.org
Hybrid seeds: A double-edged sword [1]
Hybrids are the offspring of two different varieties or species. While they often offer benefits like increased yield and disease resistance, they also have limitations.
F1 hybrids, commonly found in commercial seed production, are created by crossing two inbred lines. This results in plants with desirable traits from both parents. However, F1 hybrids often produce inferior offspring in subsequent generations, known as F2. This is because the genetic diversity lost in the inbreeding process is not restored in the F1 generation.
To maintain the desired traits of F1 hybrids, gardeners must purchase new seeds each year. This dependency on seed companies can limit the availability of heirloom varieties and reduce genetic diversity.
Commercial growers prioritize traits like uniform ripening, resistance to damage, and long shelf life. These traits may not be as crucial for home gardeners who value taste, variety, and freshness.
The high cost of developing and registering new hybrid varieties has reduced the available options, particularly for heirloom varieties. This concerns those who value genetic diversity and the preservation of traditional agricultural practices.
Understanding seed selection
Seed selection is a critical process in gardening, where the goal is to choose plants that will produce the best next generation of crops. By carefully selecting seeds, gardeners can improve the health, productivity, and adaptability of their plants over time.
Key Considerations:
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First, focus on plant health and productivity. Select seeds from plants that have shown strong disease resistance and high yield. If you have a shorter growing season, prioritize early-maturing varieties.
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Next, consider quality and appearance. Taste is a key factor—choose plants that consistently produce flavorful fruits or vegetables. Also, select seeds from plants with appealing visual traits, such as uniform size or vibrant colors.
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Environmental adaptation is essential. Choose plants that are well-suited to your local climate and soil conditions to ensure they thrive. Not every plant grows well in every environment, so this step helps increase your chances of success.
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Maintaining genetic diversity is also important. Diversity in your seed selection helps plants adapt to changing environmental conditions and prevents genetic bottlenecking.
Practical Tips:
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Clear labeling is essential—those tiny seedlings will all look alike, but their futures are very different. Marking seed plants early on saves confusion later.
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And then there is garden planning. Setting aside a dedicated space for seed production is like having a nursery within your garden—a space where plants can fully mature, focusing all their energy on producing the best possible seeds.
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As you move through the seasons, there is another important detail to remember: the life cycles of plants. Some, like beans and lettuce, will flower and produce seeds in a single season. But others—biennials like carrots and onions—require patience. These plants live for two years, focusing their energy on root development the first year, and flowering for seed production in the second. Understanding this cycle helps you plan ahead, ensuring that your seed-saving efforts align with the natural rhythm of the plants.
Conclusion
Gardeners play a crucial role in the preservation and improvement of plant varieties through careful seed selection. By actively choosing seeds from healthy, productive, and well-adapted plants, you become part of a long tradition of enhancing crops to meet the needs of your specific environment.
Through repeated selection and crossing of plants with desired traits, seed savers can develop plants uniquely suited to their environment. Heterogeneous populations and landraces, which evolve over time, offer genetic diversity and local adaptation, while the use of open-pollinated varieties supports long-term sustainability. Avoiding hybrids like F1 ensures that future crops retain valuable traits without dependence on commercial seed companies.
By focusing on factors such as plant health, quality, environmental adaptation, and genetic diversity, you ensure that your garden will continue to produce thriving and resilient plants. Your thoughtful choices today not only support immediate success but also contribute to the sustainability and evolution of future generations of crops.
References:
[1] - Growing Seed Savers. (2019). A Guide To Seed Saving [Brochure].
https://growingseedsavers.org/content/pdfs/GSS_Guide_to_Seed_Saving_ENG_Spreads.pdf
[2] - Diyseeds (2022), https://www.diyseeds.org/en/films/ [Movies]
The content of this page was created as part of the project 'Building Digital Education of Indigenous Inherited Crops for the Resilience of African Food Systems in the Climate Crisis Development.' The project was funded by the Ministry of Foreign Affairs in 2024 from the development cooperation budget. This content reflects only the views of the project partners.
