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Saving Seeds for a Food-Secure Future
- 1. Saving Seeds for a Food-Secure Future Heidi Kratsch Area Horticulture Specialist
- 2. What is a Seed? OProduct of sexual reproduction OMaximizes genetic diversity
- 3. Genetic diversity is decreasing O95% of human food needs now provided by just 4 crops: rice, wheat, corn, potatoes. OIndustrial agriculture focuses on only a handful of cultivars. O75% of agricultural genetic diversity disappeared in the last century.
- 5. Wheat Stem Rust (Ug99) OFirst identified in Uganda in 1999. OHas spread through Africa into the Middle East. O~90% of world’s wheat is defenseless against this virulent strain. Puccinia graminis
- 6. The Irish Potato Famine
- 7. Panama Disease O1950s – ‘Gros Michel’ – wiped out! OToday – ‘Cavendish’- it’s dying! OFuture – do we need a new cultivar?
- 11. Step 1: Avoid growing F1 hybrids OAlmost all corn seed OMany varieties of cross-pollinated species OMust buy new seeds every year
- 12. Choose open-pollinated OCome true to type OThe easiest are self-pollinated: beans, peas, tomatoes, peppers OHeirloom varieties – saved through generations of families and neighbors OHistory goes back 12,000 years!
- 13. Step 2: Protect varietal purity
- 14. Flower Structure
- 15. Definition of Terms OAnnual, biennial, perennial OPerfect flower OImperfect flowers OVernalization OMonoecious (single house) plants ODioecious (two houses) plants
- 16. Self-Pollination
- 17. Bagging self-pollinators Bagging flowers on pepper plants
- 18. Plants self-pollinate in the bag Reemay bags Treated paper bags
- 22. Isolate plants that readily cross-pollinate ODistance OTime OBagging OCaging
- 23. Pollination Cages OFrame: OWood OWire OPlastic pipe OMetal tubing OCovered with: OSpun polyester cloth (Reemay) OWindow screen
- 24. Alternate Day Caging ONeed a minimum of two cages. OAlternate days open to pollinators. Kale and cabbage will readily cross pollinate.
- 26. 1 4 2 3
- 27. Step 3: Rogue plants for trueness to type
- 28. Select desirable characteristics OVigor OEarliness ODrought resistance OInsect resistance OFlavor OLate bolting in cool-season crops
- 29. Ample population size OEspecially important for cross-pollinating plants. OSelect a minimum of 6 plants for seed saving. OMore plants = more genetic diversity
- 30. Questions?
- 31. Step 4: Harvest Seeds
- 32. Overwintering Biennials OSeed-to-seed method vs. OSeed-to-root-to-seed method OBiennials include: O Carrot, celery, parsley O Beet, chard O Leek, onion O Rutabaga, turnip, parsnip O Broccoli, kale, brussels sprouts
- 33. Root Cellaring
- 34. Onions (Allium cepa) Cepa group OBiennial, cross- pollinating (insect) OOverwinter in ground or lift bulbs. OBulbs – harvest seed first season OSeed – harvest seed second season. Don’t wait too long to harvest seed or the seed heads will shatter!
- 35. Broccoli (Brassica oleracea) OBiennial, cross- pollinating (insect) OWill cross with all other plants of this species. ODo not eat plants grown for seed. OUse cold frame, small hoop house to overwinter.
- 36. Beets and Chards (Beta vulgaris) Biennial, cross-pollinated (wind) – bag or cage Up to 4 feet tall!
- 37. Spinach (Spinacia oleracea) Male plant with flowers Female plant with seeds Dioecious, annual, cross-pollinating (wind)
- 38. Lettuce (Lactuca sativa) OSelf-pollinating annual OBolts in response to lengthening days OHead-lettuce types need to be slit to allow seed stalk to emerge. O Seeds ripen 12-24 days after flowering
- 39. Squash (Cucurbita pepo) Acorn, yellow crookneck, scallop, zucchini OMonoecious, cross- pollinating (insect) annual OCut fruit from vine and let sit for 3 weeks or longer before harvesting seed. Male flower Female flower
- 40. Pea (Pisum sativum) OSelf-pollinating annual OAllow pods to dry on the vine. OFreeze pods in airtight container for 3-5 days to kill weevil eggs. Peas and beans are easy for beginning seed savers.
- 41. Carrot (Daucus carota) OBiennial, cross- pollinated (insect) OUse seed-to-root-to- seed method OUmbels can be left to dry on the plant, or OCut and air-dry. ODe-bearding is unnecessary.
- 42. Corn (Zea mays) OCross-pollinated (wind) annual OTassels vs. silks OGrow in blocks OSusceptible to inbreeding depression ODry ears on the stalk, or remove and dry under shelter
- 43. Step 5: Clean seeds ODry processing OWet processing OFermenting ORinsing ODecanting
- 44. Dry processing – threshing, winnowing
- 45. Wet processing ORemove seeds from fruit OWash and rinse OAir-dry OFerment – tomato, cucumber Tomato seeds must be fermented to remove gelatinous coating.
- 46. Fermentation
- 47. Step 6: Store seeds OExcellent storage produces vigorous seeds. OTwo enemies: OHigh temperature OHigh moisture
- 48. Long-term storage OCool, dry conditions OEnvelopes OMoisture-proof container or freezer OMust be “very dry.”
- 49. Getting to “very dry” OFan/air conditioner OFood dehydrator OSilica gel OCheck daily until between 5-7% moisture
- 50. Testing for Dryness OWeigh before and after drying slowly in an oven at low temperature. OSeed moisture content (%) = fresh seed weight – dry seed weight ÷ dry seed weight × 100%
- 51. Long-term storage OFrozen seeds last up to 10 times longer OStore in paper envelopes with silica gel “dessicant” for one week. OAllow frozen sealed jar to reach room Supplies: OSeed Savers Exchange – www.seedsavers.org
- 52. Keep good records OKeep a card for each variety. O Plant and variety O Source, date obtained O Germination % O Date stored O Accession number O Last year grown
- 53. Veggies generally not grown from seed OPotato OGarlic OArtichoke OAsparagus OSweet potato ORhubarb
- 54. Questions?
Editor's Notes
- Why is this a problem? Because if disease or future climate change decimates one of the handful of plants and animals we've come to depend on to feed our growing planet, we might desperately need one of those varieties we've let go extinct. The precipitous loss of the world's wheat diversity is a particular cause for concern. One of wheat's oldest adversaries, Puccinia graminis, a fungus known as stem rust, is spreading across the globe. The pestilence's current incarnation is a virulent and fast-mutating strain dubbed Ug99 because it was first identified in Uganda in 1999. It then spread to Kenya, Ethiopia, Sudan, and Yemen. By 2007 it had jumped the Persian Gulf into Iran. Scientists predict that Ug99 will soon make its way into the breadbaskets of India and Pakistan, then infiltrate Russia, China, and—with a mere hitch of a spore on an airplane passenger's shoe—our hemisphere as well. Roughly 90 percent of the world's wheat is defenseless against Ug99. Were the fungus to come to the U.S., an estimated one billion dollars' worth of wheat would be at risk. Scientists project that in Asia and Africa alone the portion of wheat in imminent danger would leave one billion people without their primary food source. A significant humanitarian crisis is inevitable, according to Rick Ward of the Durable Rust Resistance in Wheat project at Cornell University.
- ‘Lumpers’ Phytophthora infestans Lack of genetic variation in Irish potatoes contributed to the severity of the Irish potato famine, which devastated Ireland's population and economy. Today, evolutionary theory tells us that relying on crops with low genetic variation can lead to disaster. Heeding the warnings of scientists and history may help us prevent wide-scale crop devastation due to changing environmental conditions. Lumpers In the 1800s, the Irish solved their problem of feeding a growing population by planting potatoes. Specifically, they planted the "lumper" potato variety. And since potatoes can be propagated vegetatively, all of these lumpers were clones, genetically identical to one another. The lumper fed Ireland for a time, but it also set the stage for human and economic ruin. Evolutionary theory suggests that populations with low genetic variation are more vulnerable to changing environmental conditions than are diverse populations. The Irish potato clones were certainly low on genetic variation, so when the environment changed and a potato disease swept through the country in the 1840s, the potatoes (and the people who depended upon them) were devastated. The importance of diversity The genetically identical lumpers were all susceptible to a rot caused by Phytophthora infestans, which turns non-resistant potatoes to inedible slime. Because Ireland was so dependent on the potato, one in eight Irish people died of starvation in three years during the Irish potato famine of the 1840s. Although the famine ultimately had many causes, the disaster would likely not have been so terrible had more genetically variable potatoes been planted. Some potatoes would have carried the right genes to make it through the epidemic, and more of the resistant varieties could have been planted in the years following the first epidemic. Later, scientists identified resistance genes in a potato from South America, where farmers have preserved the genetic variation of potatoes by growing many cultivated varieties alongside the potato's wild cousins.
- Fusarium wilt Panama disease impacts the production of a wide range of banana cultivars (8). However, it is most widely known for damage it caused on a single cultivar in the early export plantations (6,11). Prior to 1960, the export trade was based almost entirely on the susceptible cultivar ‘Gros Michel.’ This reliance on Gros Michel and the common practice of using infected rhizomes to establish new plantations resulted in widespread and severe losses, especially in the western tropics (Fig. 2). In the Ulua Valley of Honduras alone, 30,000 hectares were lost between 1940 and 1960. Damage occurred more rapidly in areas such as Suriname, where an entire operation of 4,000 hectares was out of production within 8 years, and the Quepos area in Costa Rica, where it took 12 years for 6,000 hectares to be destroyed. Because it cost between $2,000 and $5,000 to establish a hectare of plantation at the time, direct losses during the Gros Michel era reached many millions of dollars. By the mid-1900s, the export trade was forced to convert to resistant cultivars in the Cavendish subgroup (8). These cultivars continue to perform well in the western tropics and remain the clones on which the trades are based (Fig. 3). However, in several areas in the Eastern Hemisphere these cultivars are now damaged by Panama disease (Fig. 4). These losses are significant, and signal a serious threat to production in the Western Hemisphere because there is currently no acceptable replacement for the Cavendish cultivars. Furthermore, because the variant of the pathogen that is responsible for these outbreaks also affects plantain, this important staple food is threatened as well.
- 1970s – southern corn leaf blight – 15% of nation’s crop wiped out. Currently, 43% corn acreage planted to varieties derived from 6 inbred lines. Ignoring history Despite the warnings of evolution and history, much agriculture continues to depend on genetically uniform crops. The widespread planting of a single corn variety contributed to the loss of over a billion dollars worth of corn in 1970, when the U.S. crop was overwhelmed by a fungus. And in the 1980s, dependence upon a single type of grapevine root forced California grape growers to replant approximately two million acres of vines when a new race of the pest insect, grape phylloxera (Daktulosphaira vitifoliae, shown at right) attacked in the 1980s. Although planting a single, genetically uniform crop might increase short term yields, evolutionary theory and the lessons of history highlight an undesirable side effect. Planting genetically uniform crops increases the risk of "losing it all" when environmental variables change: for example, if a new pest is introduced or rainfall levels drop.
- Mexico is considered the center of corn biodiversity. Olga Toro Maldonado was short on corn seed and slightly curious. In the spring of 1998, alongside the corn she had always raised on her hillside plot, she planted 60 kernels purchased from the government store. "The corn looked good," she recalls, so the next year she planted a cross between the two species. The harvest was smaller than the year before--one ear per stalk rather than the usual two--but the corn was tasty enough. She ground it into flour for tortillas and fed the kernels to her chickens. A few scientists stopped by in fall 2000 and took away samples from her most recent harvest. They returned a week later with some disturbing news. Toro's corn contained transgenes--genes from bacteria and other organisms artificially introduced into the corn to make it resistant to herbicides or insects. Toro, 40, heard the word "contamination" and began worrying about her six children, her chickens and whether the pollen from her corn had spread. "I feel guilty," she says. "But another woman told me she planted it, too. I'm not the only ignorant one. We don't know the damage we can do." The head scientist was Ignacio Chapela, a 42-year-old Mexican and a microbial ecologist at the University of California, Berkeley. His team collected corn from the mountains of Oaxaca, in southern Mexico, and found that several samples contained transgenes. The finding was startling because the Mexican government bans the planting of genetically modified (GM) corn. And the agriculture industry has long contended that contamination from GM crops was extremely unlikely. "I was dumbfounded," Chapela says. "I knew it was a difficult political fray we were getting ourselves into."
- Tomatoes, beans, peas, lettuces, peppers
- Insects sometimes cross-pollinate self-pollinating plants. Except for corn, bagging is used to prevent cross-pollination of self-pollinating plants. Does not work for spinach – wind pollinated and pollen fine enough to pass through the bag.
- Treated paper bags available from the Lawson Bag Company. Do not use glassine envelopes or plastic bags! Reemay is spun polyester cloth.
- Annual varieties can be isolated by time. When the first crop is beginning to flower, sow the second variety. (corn, sunflowers, lettuce). Works best with varieties that have different maturity dates – otherwise, season may be too short to allow both to produce.
- Need at least 2 cages – one for cabbage, one for kale crop. Remove cage from one group in the morning, replace at night. Remove cage from the 2nd group the next morning, replace at night. The process can be stopped when a sufficient number of seed pods have formed. To ensure seed purity, leave cages on both plant groups until all flowering has stopped.
- The mechanics of plant breeding are not difficult. For cross-pollination, flowers are bagged before they open to prevent uncontrolled pollination or selfing. For perfect flowers, the petals and anthers of the flower to be pollinated should be removed before bagging. Next pollen from the male parent is gently brushed over the stigma of the female. The female is then rebagged to prevent further uncontrolled pollination. The seeds produced from the cross can be collected from the bag. Mature seeds must be cleaned and stored after they are harvested. Cleaning involves removing the ovary tissue surrounding the seed. Seeds from fruit with a fleshy ovary must be allowed to dry before storage. Generally, seeds must be stored to maintain a constant relative humidity – glass jars or ziplock bags work well. Low humidity and refrigeration slows respiration and keeps the seed viable for a long time.
- Exposure to temps below 50 for 8 to 12 weeks - vernalization
- 90-95% relative humidity and 35-38F
- Flowers are perfect – but unable to self pollinate. Insect pollinated. Inspect flowers – rogue for bolting or flowering in first season. Harvest as soon as heads are dry. Bend over a sack and cut from stalk to avoid losing seeds.
- Isolation distance of one mile. Beginners should allow only one variety of oleracea to flower in a season. Some short-season broccolis will flower and produce seed in one season, when planted early. Self-incompatible – insect pollinated. Hold no longer than 4 to 6 weeks before replanting. Store at 32 to 40 F and 80 to 90% humidity.
- Can plant as is or break apart with a rolling pin. Pollen can travel up to 5 miles. Can bag or cage. Dig root before the first killing frost.
- Cross-pollinating by wind. Pollen carried up to 10 miles! Fine – penetrates mesh screens. Maintain a ratio of one male to two females. Prickly and smooth seeded varieties – wear gloves. When dry, strip stems in an upward motion, allowing seed to fall into a bag.
- Heads of 10 to 25 florets. Bees and other hairy insects. All flowers on a head open in one day, close and never re-open.
- Squashes belong to one of six species. Pepo is most common. Must be bagged and hand-pollinated to ensure purity. C. maxima (banana, buttercup, hubbard), C. mixta, C. moschata (butternut, crookneck), C. agyrosperma (cushaw).
- Food dehydrator – 85F