by Susan LeBlanc, Master Gardener
I was recently asked to give a talk in Swan River, Manitoba on behalf of the Manitoba Master Gardener Association. The following is a recount of the power point presentation.
Millions of years ago neither plant life nor their methods of reproduction were as we know them today. Fast forward through the evolutionary development of flowering plants. Some flowers developed fragrance and many displayed bold, bright eye-catching colours. Insects and other creatures (bats, birds, lizards and lemurs) evolved alongside the flowers and were drawn to these new food sources. Flowers also developed in ways that ensured pollen grains (male) landed on the female area known as the stigma. Migration of pollen down the pollen tube through both the stigma and style into the ovary results in fertilization and the production of seeds. The movement of pollen across flower surfaces by pollinators, or in some plants by wind, inadvertently deposits pollen onto the stigma initiating the process of fertilization. Modern humans can trace their dependence on food production to the evolution of flowering plants and their pollinators. Seventy-five percent of food crops worldwide depend at least partly on pollination.
Do you prefer to purchase packages of new hybrid seeds to try new varieties every year? This is a fine decision but not for seed saving. Seeds saved from hybrid plants will never grow true to the type of parent plants that produced them. Hybrid seed or F1 hybrid plants (F1=first filial generation) result from a crossing of two deliberately chosen parent lines. F1 hybrid plants are often more vigorous, more uniform and may produce a higher yield, but their seeds produce plants of unpredictable characteristics. The unpredictable characteristics of later crossings of F1 hybrids are the result of the various re-combination possibilities from the genes in the parent lines. If you grow hybrid varieties you have to purchase new seeds every year. Only plants grown from open-pollinated heirloom seeds remain true to type year after year as long as no pollen from other plants (with which cross-pollination can occur) is introduced.
The seed saver has learned: 1) Heirloom varieties are good value for the money. 2) Vegetables grown from heirloom seeds may be more flavourful. 3) You know what additives and conditions the seeds have been subjected to if you have saved them yourself. 4) By growing open-pollinated and heirloom plants you are offering a diversity of pollen that maintains healthy immune systems in pollinators.
According to the FAO (Food and Agriculture Organization of the United Nations) 75% of genetic diversity of agricultural crops has been lost worldwide in the past 100 years. In modern agriculture, corn, rice, potatoes, and wheat have become corporate commodities causing small seed companies to close. People worldwide are relying increasingly on these four plant species as their basic food source. Of the 10,000 species of food plants that could be grown around the world, we work with only about 150-200.
It is genetic uniformity that tends to leave crops more susceptible to pest attacks and disease. A memorable example of a deleterious effect of genetic uniformity is the Irish Potato Famine of 1845-1849. Several years in a row potato blight destroyed the crops of the only one or two high yielding potato varieties grown in Ireland at that time resulting in the loss of about 1 million Irish lives. Heritage seeds are often well adapted to regional specifics like climate and soil. This is why seed diversity is so important. By choosing to grow heirloom seeds, you are actively helping to maintain genetic diversity.
• Pollen transfer by insects, birds, wind, humans
• No restriction of pollen flow between individual plants of the same variety • Plants from open pollinated seeds grow true to type if no pollen is transferred from varieties with which cross pollination can occur
Heirloom varieties/heirloom seeds
• Are always open pollinated
• Have a history of being grown in a family, region or community over many years • Seed companies may call a variety “heirloom” if it is over 50 years old.
Hybrid varieties/hybrid seeds
• Deliberate crossing of two distinct parent plants (varieties or species) to breed plants with specific traits • The seeds/plants of these crossings are called F1 (first filial generation) hybrids • The seeds of F1 hybrids do not grow true to type due to a lot of genetic recombination resulting in plants with different characteristics
• Hybrids also result if open pollination between two varieties or closely related species (cross pollination) occurs naturally