Seed Saving and Seed Storage: A Guide for Economically Important Foods

Seed saving is a vital skill for ensuring food security and preserving genetic diversity. This guide provides practical techniques for saving and storing seeds from the top 100 economically important food crops, enabling you to cultivate your own resilient food supply. Seed saving involves selecting healthy and mature fruits, proper seed extraction, cleaning, and drying[1]. Each plant species requires specific considerations and techniques for successful seed saving[1].

I. General Principles

1. Select Healthy Plants: Save seeds from the healthiest plants and produce with desirable traits, such as disease resistance, high yield, and good flavor. Seeds from sickly plants may produce weak seedlings, might pass on genetic weakness, or even harbor disease. For best results, save seeds from your best plants[3]. For all leafy and root vegetables, choose the last plant to go to seed, otherwise you’ll be selecting for plants that bolt (set seed early in the season)[7].
2. Choose Open-Pollinated Varieties: Grow open-pollinated varieties for seed saving. Seeds from hybrid varieties may not “breed true”, i.e. might produce plants very different from the parent[3].
3. Know Pollination Habits: Understand whether plants self-pollinate (e.g., tomatoes, beans, peas) or cross-pollinate (e.g., pumpkins)[5]. Seeds from plants that can be easily cross-pollinated by insects or wind may give unexpected results[3].
4. Allow Full Maturity: Let seeds mature on the plant before collecting. For vegetables, this sometimes means leaving them on the plant longer than you would for best eating quality. For flowers, this means letting the seed heads dry on the plant rather than deadheading[3].

II. Detecting Viable Seeds

Detecting viable seeds is crucial for successful planting, and several methods exist to determine seed viability. The most accurate and reliable method is the germination test, which involves planting a sample of seeds in a controlled environment and observing the rate of germination. Other methods include the paper towel method, where seeds are placed on a moist paper towel to check for sprouting, and the float test, where viable seeds typically sink in water. Non-destructive techniques, such as hyperspectral imaging (HSI) and micro-optrode techniques, are also being developed for rapid and large-scale seed viability detection.

Several methods exist to determine seed viability. One common method involves placing the seeds in water, where it’s often believed that viable seeds sink while non-viable ones float. However, while some sunken seeds will germinate and some floating seeds will fail to sprout, there isn’t a strong correlation between buoyancy and viability. Larger seeds are better for this test, but you shouldn’t rely on the sink/float test to determine which seeds to discard and which to plant. The buoyancy of a seed is related to its density; denser seeds are more likely to sink. Viable seeds tend to be denser because they contain a fully developed embryo and sufficient food reserves. Seeds may float due to air pockets or lightweight structures, but the seed coat still allows water to permeate through to the embryo, allowing germination to occur even while floating.

III. Seed Saving Techniques

Seed saving involves several key steps, including selecting healthy and mature fruits, proper seed extraction, cleaning, and drying[1]. Each plant species requires specific considerations and techniques for successful seed saving[1]. How you go about saving seeds will depend on the plant species in question[9].

* Dry Seeded Crops: Dry seeded crops have seeds enclosed in pods or husks[9]. Several vegetable plant families are dry-seeded[9]. For example, beans and peas are dry seeded crops[5]. Cut entire seed heads and invert over a tub or newspaper in a dry place, or in a paper bag[7]. Shake seeds off immediately, or let them fall later[7].

* Wet Seeded Crops: Wet seeded crops have seeds embedded in the flesh of fruits. The Solanaceae family includes tomatoes, peppers, and eggplants. The Cucurbitaceae family includes melons, squashes, and cucumbers. For pumpkins, ensure 400m from any other varieties in your neighborhood. Pick the pumpkin and allow it to ripen further for a couple of weeks. Scoop the seeds out. Rinse with cold water in a colander. Rub off any fleshy bits holding on to seed as this could cause mold later. Remove any damaged or split seeds. Spread the seeds onto baking paper on a tray, making sure the seeds aren’t touching. Place in a protected, cool area away from vermin, for 2-3 weeks, turning the seed occasionally.

IV. Seed Cleaning and Drying

1. Cleaning: Remove any pulp, chaff, or debris from the seeds.
2. Drying: Spread seeds in a single layer on a screen or paper towel in a cool, dry, and well-ventilated place. The drying material should take up about one-fourth of the container space[6].
3. Drying time Drying time varies depending on the seed type and humidity, but generally takes 1-2 weeks.

V. Seed Storage

Proper storage is essential to ensure the longevity and viability of saved seeds[1]. By following appropriate storage techniques, market gardeners can preserve the genetic integrity of their seeds for future use[1].

1. Cool and Dry Environment: Store seeds in a cool, dry place to extend their viability[1][6]. A cool, dry environment is key[1].
2. Airtight Containers: Keep seeds in airtight containers like tins, cans, or glass jars with tight fittings[6].
3. Moisture Absorbents: Put in some moisture absorbing material. Dry wood ash, dry charcoal, or small pieces of newspaper[6].
4. Labeling: Label the containers with the type of seed, place, and date of collection[6].
5. Long-Term Storage: In most national seed banks, the preferred method for long-term storage is freezing to near 0º F, which is the temperature in a home freezer or in the freezing compartment of a home refrigera- tor[2].

VI. Special Considerations

* Seed Viability: From species to species there are great differences in capability to survive storage some species may survive for long periods under all conditions[6]. Store only new, mature, healthy and well-dried seeds[6].

Seed Storage Types:

Orthodox seeds can be dried to low moisture levels and stored for long periods[4].
Intermediate seeds can be stored for a longer period, but cannot withstand low temperatures[4].
Recalcitrant seeds can only be stored for a short time, as they cannot be dried to low moisture levels[4].

Monitoring: If you store the seeds for a long time, germinate a sample from time to time to make sure that they are still good[2].

VII. Storage Structure

This method includes storing seeds inside pockets or pots made of natural materials like cob, cow dung, cane and more[8]. There are different sealing and plastering techniques, from making whole pots out of the soil and cow dung on a cane or straw skeleton to sealing the mouths of terracotta pots with soil and dung[8]. It is preferred mostly for seeds of legumes, millets and grains[8].

VIII. Seed Saving and Extraction Techniques

This guide provides a general overview of seed saving and extraction methods for some of the most economically important food crops.

1. Cereals (Grains)

Wheat: Harvest when stalks are dry and golden. Thresh by beating the stalks. Winnow to separate grain from chaff.
Rice: Harvest when grains are mature and straw is golden. Thresh and winnow like wheat.
Corn (Maize): Allow ears to dry on the stalk. Remove kernels by hand or with a corn sheller.
Barley: Harvest and process like wheat.
Sorghum: Harvest and process like wheat.
Oats: Harvest and process like wheat.
Rye: Harvest and process like wheat.
Millet: Harvest and process like wheat.

Extraction Method: Dry extraction is done either manually or mechanically. Manual extraction is by beating. Threshers are used for mechanical extraction. Take care to avoid mechanical injury.

2. Vegetables

Tomatoes: Ferment seeds by squeezing the pulp and seeds into a jar with some water. Let sit until a white mold forms. Rinse and dry.
Peppers: Allow peppers to fully ripen on the plant. Remove seeds by hand and dry.
Eggplant: Extract by crushing.
Pumpkins & Squash: Scoop out seeds, rinse, and dry.
Cucumbers: Ferment like tomatoes, or scrape out seeds, wash and dry.
Onions: Harvest seed heads when dry. Rub to release seeds.
Carrots: Allow seed heads to dry. Rub to release seeds.
Cabbage: Allow seed pods to dry. Crush pods to release seeds.
Lettuce: Allow plants to bolt and form seed heads. Harvest when dry and fluffy.
Spinach: Harvest seeds from dry seed stalks.
Beans: Allow pods to dry completely on the plant. Shell the beans and dry them further.
Peas: Harvest and dry like beans.
Okra: Dry Method, The fully matured and dried fruits are harvested and dried in the sun for 2-3 days. After extraction of seed, the seed are dried in the sun between 8.00-11.00 Am and 2.00-5.00 Pm to bring out the original moisture content.
Artichokes: Dry Method.
Asparagus: Extract from the berry.
Caulifower and Broccoli Harvest seeds from dry seed stalks.
Chillies and Peppers Harvest seeds from dry seed stalks.
String Beans Shell the beans and dry them further.

Extraction Methods: Manual Method (a) Maceration e.g., watermelon, (b) Crushing e.g., brinjal, (c) Scraping e.g., cucumber (d) Separated e.g., muskmelon, (e) Scooping e.g., pumpkins and (f) Extraction e.g., squashes.

3. Fruits & Oilseed Crops

Oil Palm Fruit: Soya beans are usually processed through extraction methods using hexane or other solvents.
Soya Beans: Soya beans are usually processed through extraction methods using hexane or other solvents.
Rape (or Colza) Seed: Oilseed crops recorded the largest growth over the period, with an increase of 121 percent between 2000 and 2022.
Seed Cotton: China and India are the leading producers of seed cotton (unginned).
Coconut (in shell): the main oil crops produced in the world in 2022.

Extraction Methods: A lot of oil seed extraction is done with machines.

4. Roots and Tubers

Potatoes: Potatoes were the most produced commodity in the group, with 375 million tonnes in 2022. Potatoes are typically grown from “seed potatoes” (small potatoes or cut pieces with “eyes”). True potato seed (TPS) can be extracted from berries, though less common. Growing from Seed Potatoes: Plant in well-drained soil, 4 inches deep and 12 inches apart. Hill soil as plants grow. Extracting True Potato Seed (TPS): Harvest berries when soft. Blend with water to create a pulp. Strain through a fine-mesh strainer. Clean and dry seeds.
Cassava: Cassava with 330 million tonnes in 2022. Cassava is typically propagated from stem cuttings. Growing from Stem Cuttings: Select disease-free cuttings (2 cm diameter, 20-25 cm long). Plant at an angle, two-thirds below soil. Space 1 meter apart. Soil Tillage: Cassava needs a sufficiently loose-textured soil to facilitate initial root penetration and to allow for root thickening.
Yams: Yams volumes grew by 123 percent in recent years. Yams are commonly propagated from small tubers or pieces of larger tubers. Growing from Tubers: Plant small whole tubers or cut pieces in mounds or ridges. Ensure well-drained soil.
Sweet Potatoes: Sweet potatoes declined by 38 percent between 2000 and 2022. Sweet potatoes are typically grown from “slips” (sprouts grown from mature sweet potatoes). Growing from Slips: Place sweet potatoes in a warm, well-lit area until sprouts emerge. Remove slips (6-8 inches long) and plant in prepared beds or containers. Plant slips 2-4 inches deep, spacing 12-18 inches apart in rows 3-4 feet apart. Soil Preparation: Sweet potatoes produce best in a well-drained, light, sandy loam or silt loam soil. Rich, heavy soils produce high yields of low-quality roots. Fertilizing: Apply fertilizer, such as 12-12-12, prior to planting, mixing it with the bed soil. Ridges: Sweet potatoes grow best on a ridge about 12 in. high.

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News i8

Seed Saving and Seed Storage for Economically Important Foods

I. General Principles

II. Detecting Viable Seeds

III. Seed Saving Techniques

IV. Seed Cleaning and Drying

V. Seed Storage

VI. Special Considerations

Seed Storage Types:

VII. Storage Structure

VIII. Seed Saving and Extraction Techniques

1. Cereals (Grains)

2. Vegetables

3. Fruits & Oilseed Crops

4. Roots and Tubers

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I. General Principles

II. Detecting Viable Seeds

III. Seed Saving Techniques

IV. Seed Cleaning and Drying

V. Seed Storage

VI. Special Considerations

Seed Storage Types:

VII. Storage Structure

VIII. Seed Saving and Extraction Techniques

1. Cereals (Grains)

2. Vegetables

3. Fruits & Oilseed Crops

4. Roots and Tubers

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