Our eventual goal is to save all the seeds needed by our farms, for several reasons. It will lower our expenses, and allow us to adapt varieties to our own climate, soil, and growing preferences. It will free us from dependence on the corporate world, and help conserve the world’s threatened genetic diversity. However, the standard methods of maintaining heirloom or open pollinated varieties are difficult and time consuming. (If you are not sure what heirlooms, hybrids, etc. are, please see my last post.) To get around this, we will be raising landrace crops. Before I explain landraces, here is what is entailed in conventional seed saving.
To maintain an open pollinated variety, two dangers must be avoided; cross pollination, and inbreeding. Cross pollination occurs when plants from different varieties in the same species share pollen. Inbreeding occurs when seed is saved from too few plants in one generation.
To prevent cross pollination, plants of a given variety must be isolated from other plants in the same species. The distance necessary to do this varies. Corn pollen blows for miles on the wind, and squash plants can be crossed by bees with other plants miles away. Tomatoes, on the other hand, can be isolated by about ten feet or so. Also, plants that seem very different are sometimes in the same species, and can cross pollinate. Cabbage, broccoli, cauliflower, Brussels sprouts, kohlrabi and most kales are all in the same species. Pumpkins, some winter squash, zucchini, summer squash and many gourds are also all in the same species as one another. So for some plants, isolation is difficult or impossible, especially in the city. Hand pollination, with cages or bags to exclude unwanted pollen, is possible but time consuming and difficult.
The need to prevent inbreeding further complicates this issue. Some plants will not suffer any damage even if seed is saved from one plant. But some, such as corn, have a minimum population size of a hundred plants. This makes hand pollination even more difficult.
And for most vegetables, it is best to grow several varieties. This hedges a gardener’s bets against the weather. It also makes a garden more interesting. But it certainly makes conventional seed saving even more difficult.
However, there is a way to avoid all this work, and gain some additional benefits. One can abandon the idea of saving pure varieties and save landraces. Most traditional societies saved landraces, not pure varieties. A landrace is a locally adapted population of plants, which is more diverse then a pure variety. Fruit size and color, pest and weather resistance, and days to maturity may vary from plant to plant. This provides the community of gardeners with insurance against bad weather and other problems. The genetics of the landrace slowly change over the years; new mutations or gene introductions persist if they have value in the local area, or fade away if they do not.
To start a modern landrace, many open pollinated or hybrid varieties are planted together and the seeds saved from each plant. If neighbor’s gardens contribute pollen, that is a benefit, not a problem. Then, each year seed is saved from any plant that does well enough to produce seed. (If only the highest yielding plants were selected, genetics that might be valuable in a year with different conditions would be eliminated.) Over time, genetics that yield no benefit to a given area will be eliminated. If one wishes, separate land races can be created for different traits; for instance, an early tomato landrace and a main season landrace, or landraces based on different colors of produce. A small amount of crossing between these landraces will not be detrimental so long as one selects for the desired trait every year. And a landrace can be as diverse (or not) as one wishes.
This approach gives several benefits.
- Maintaining a landrace is far easier than maintaining five or six varieties of a given vegetable.
- A landrace will adapt to a given set of conditions, whereas a bunch of pure varieties will stay much the same. Just because a plant is an heirloom does not mean it will do well in any garden; much more likely it means that it does well only in one particular area of the country.
- Landraces will also adapt to a given set of cultural practices. If seeds are planted early year after year, there will be a natural selection for fast emergence in cool soils. If plants are left un-staked, sturdier plants will have the advantage. Similarly, if the best tasting plants are selected, a particular gardeners landrace will reflect that gardener’s tastes.
- Landraces are interesting; a wide diversity of fruit types can be produced, since the genetics are recombined each year.
- Landraces are unique. Nobody else will be growing the exact same landrace. And the individual plants may be different than any heirloom or commercial variety out there.
- With some species, the natural hybrid vigor produced by this method can generate more vigorous plants.
- For those so inclined, landraces can be used to generate new pure varieties. If a particularly good plant shows up through the constant rolling of the genetic dice, it can be stabilized to produce a new open pollinated variety.
- The wide range of maturity dates in a landrace can be useful. For instance, most home gardeners don’t want to deal with 50 broccoli heads all at once. On the other hand, this can be one of the small drawbacks of landraces; some gardeners may want uniform harvest dates.
- For those worried about genetic diversity or food security, landraces make it easier to preserve genetics and produce food, even in difficult climates. In fact, landraces really shine in marginal climates. Most seeds are grown and varieties bred for mild, wet climates, and will not perform optimally in high, dry, cold, or harsh climates.
- Landraces give gardeners control. All plant breeding reflects the values and ideas of a particular plant breeder or institution. Landraces make it easy for a gardener to become a plant breeder, so that their plants reflect their goals and values.
Of course, standard seed saving practices still have much value. I’m very thankful that seed savers have worked to preserve our heritage, the thousands of diverse varieties passed down from previous generations. We will still isolate some varieties, particularly pepo summer squash to avoid pumpkin genetics, and some tomatoes to generate more varieties for sale. But landraces will make it far easier for us to become self sufficient in seed and maintain high genetic diversity.
Eventually, we hope to start a landrace seed bank in the local area, so that gardeners can work together to maintain and trade a large pool of Denver adapted landraces, with our farms providing the space for larger grow-outs.
For more information on landrace vegetable breeding, check out the Home Grown Goodness forums. There are a lot of folks there who are working on landrace projects. Of course, I don’t agree with everything said on that forum about this or any other topic, but by and large it is a community of friendly and knowledgeable people. I have learned a lot from them.