Seed Saving - An Introduction to Seed Saving - Japan - ARI
by the Asian Rural Institute
page developed by Rina Tanaka, ARI Volunteer
submitted January 2021
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Collecting cucumber seeds
Seed Saving at ARI
At ARI, we collect the seeds from some of our crops, save them, and sow them in the following years. In this way, we can be more self-sufficient since we do not need to buy a large amount of expensive seeds every year. Furthermore, most non-organic seeds in Japan are covered with chemical disinfectant which might pollute the soil and harm other living creatures. Also, by selectively saving the seeds of plants that are thriving in our local environment and showing characteristics that are favorable to us (for example, big straight carrots), we can grow healthy plants that satisfy our specific needs. You can find more general information on the importance of saving seeds here. How do we save seeds?
This page focuses on how to save seeds using cucumbers as an example. You will find that the process is not so complicated! Of course, the details of saving cucumber seeds are different from those for saving seeds from other categories of crops and vegetables, like carrots, rice, or potatoes, but the general ideas are still relevant.
1. Selecting the plant to collect seeds from and marking it
You have a lot of freedom in choosing which plant/fruit to save for seeds!
Here are some things to consider when choosing the plant:
Health: It should be growing steadily and not weakened by diseases or pests.
Appearance: It has a good shape, the size is adequate, and the color is beautiful.
Taste: It should taste good.
Others: It has certain characteristics that you like.
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After deciding on which plant/fruit to collect seeds from, mark that plant with a tag or bright-colored cloth to avoid harvesting it.
2. Collecting the seeds
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We allow the seeds to completely develop in the marked plant before harvesting the fruits or flowers. For cucumbers, we should wait until the outside skin has become yellow to ensure that the seeds have matured. The quality of cucumber seeds from the bottom 2/3 (two-thirds) of the fruit tends to be better. To extract the seeds from that part, we remove the top 1/3 (one-third) of the cucumber with a knife.
Note that harvesting for seed collection often happens much later than harvesting for eating. Fruits considered ripe for eating contain seeds that are not yet developed. Therefore, if we want to collect the seeds, we must WAIT until the seeds inside the fruits or flowers have fully matured.
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Then, we cut the remaining cucumber in half vertically to expose the seeds.
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Once the seeds are exposed, we scrape them into a bucket using our hands.
3. Drying the seeds
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If the seeds are dirty, we clean them before drying. For cucumbers, it is hard to remove the jelly-like material coating the seeds with water, so we put the slimy seeds into a jar and leave them until the jelly starts to rot. The rotten jelly will come off the seeds easily when you wash them with water.
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Once the seeds are clean, put them in a net, swing the net to shake off the water, and hang them in a cool dark place until they become dry (about 4 days at ARI). We do not recommend drying the seeds on newspaper since they become stuck to the paper.
4. Storing the seeds
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When the seeds have fully dried, put them in an air-tight container or plastic bag and store them in a cool dark place (about 5-10°C). To make sure that the seeds stay dry, you can put moisture-absorbing materials with the seeds, such as charcoal, powder milk, ash, dry grain, or a silica gel bag.
It is important to keep a clear record of the seeds. We recommend that you put a label on the container with the following information:
The name of the plant
The plant’s variety and where it’s from
The date on which the seeds were collected
Any remarks on the characteristics of the seeds
How long can we store the seeds?
Depending on the type of crop, you can keep the seeds for a few years (~5 years) when preserved properly. However, it is better to use the seeds as soon as you can (1-2 years) since the germination rate and vigor will go down as they become older. Note that certain seeds like carrot seeds need a one-year resting time for the seeds to be effective.
What are things we have to be careful of when saving seeds?
Some seeds are difficult to save because of the way they are created
One such type of seed is hybrid (F1) seeds. When a plant grown from a hybrid seed produces seeds (“children seeds”), the qualities of these seeds will not be stable. This means that when you plant these children seeds, some of them will not have the same traits that the parents had. So, even if you collect (children) seeds from a big hybrid cucumber (parent), some child cucumber plants might produce small cucumbers. Although non-hybrid seeds are easier for seed saving, it is still possible to collect seeds from hybrid seeds. If you repeatedly collect big cucumbers, save them for seeds, plant them, collect big cucumbers, and so on, you can eventually get seeds that are stable.
Contamination due to cross breeding can occur
We can split plants into two groups - self-pollinated and cross-pollinated - based on how they are pollinated. Self-pollinated plants have both the male and female parts in a single flower, so these parts can interact directly. Cross-pollinated plants have separate male and female flowers, so they require insects or wind to carry the pollen from the male to the female flower. This means that cross-breeding can occur, which is when the plant you want to collect seeds from is contaminated by pollen belonging to a different, unknown variety.
Self-pollinated plants: peas, beans, lettuce, rice, wheat, okra, tomatoes (though they require bees to vibrate the male part so that the pollen inside comes out)
Cross-pollinated plants: cucumbers, pumpkins, radishes, carrots, cabbage family (cabbage, Chinese cabbage, broccoli, turnip/radish, komatsuna, kale), onion, corn
Both: eggplants, chilies, bell peppers, coriander
Even though self-pollinated plants also have chances of cross-breeding, cross-pollinated plants are more likely to cross-breed with each other. In particular, certain families of cross-pollinated plants, like the cabbage family and the pepper family, cross-breed easily within the family. For example, if you plant chilies and bell peppers at the same time next to each other, the pollen from a male chili flower could end up in a female bell pepper flower, leaving seeds that produce mysterious fruits like spicy bell peppers.
How can we prevent cross-breeding?
Use a physical barrier
Before the flowers start blooming, cover the male flowers with bags or the entire plant with a bug net/row cover. Then, when the flowers have bloomed, artificially pollinate the flowers by shaking off pollen from a male flower into a female flower.
Use distance
Plant different varieties/breeds far apart from each other. The distance required to prevent cross-breeding depends on the crop. For example, peppers require about 150 meters and squash plants would need about 800 meters.
Use time lag
Plant different varieties at different times.
Plant varieties that flower at different times.
If you can ensure that flowers belonging to just one variety are blooming at a particular time, you will not have to worry about cross-breeding.
Seed quality degrading due to continuous inbreeding
If you continuously collect seeds from the same breed in one area, the quality of seeds decreases over time. To prevent this from happening, you could try to cross plants that are of the same breed but grown in different places.
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