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what are seed banks

Sustainable, Secure Food Blog

Growing food for all, sustainable for our earth.

Why is it important to have seed banks and seed access?

Species extinction due to natural and man-made influences is undeniable and a serious threat to our planet. Once they are gone, we have lost them forever.

For plants, seed banks are a way to combat this threat. They are an important part of a robust seed system for food security. Seed banks protect and save plant genetic diversity, which is important for a number of reasons. These saved and viable seeds contain a treasure trove of useful genes that breeders can use for developing improved varieties of our major food crops. For example:

  1. Improve resistance to current and emerging plant diseases and insects.
  2. Provide drought or flood tolerance.
  3. Improve yields and nutrition to feed a growing global population.

Rare, heritage, indigenous, wild or regionally-specific plants are particularly vulnerable to extinction. Their loss over time also can lead to genetic erosion of our food system. In other words, we lose the genetic diversity of a variety of crops. Adapting to climate change or new pests can be difficult without good genetic diversity. Crop breeders need a variety of genetic resources to help our crops adapt to changing conditions. As modern cultivars gain acreage and sometimes replace these plants, it becomes increasingly important to make sure these historic genetics are preserved in seed banks for future use.

In the United States, our grocery store produce sections are full of “exotic” fruits and vegetables. But, most of these are not grown in the U.S. We benefit from agriculture worldwide. The coffee you drink in the morning is not “made in the USA.” But, worldwide markets do not have the wide variety of produce that we enjoy. In addition, some diets are driven by cultural practice. In the US, we may enjoy going to an ethnic restaurant – remember the food we get there is driven by their unique cultures.

An example of unique adaptation is crop evolution on many of the Caribbean islands. The islands are relatively isolated, so plants have fewer opportunities to naturally cross with other plants. The Caribbean also enjoys a full-year growing season. These island crop varieties are uniquely adapted to the region’s growing conditions. Caribbean cultural practices have value for improving island agriculture and preserving cultural heritage through food. Storing seeds of island varieties in seed banks will help to preserve these unique foods for future generations to enjoy and share.

Seed banks also allow for faster recovery from an environmental or natural disaster that can strike in an instant. It seems as if almost every day we hear about oil spills, wild fires, hurricanes, earthquakes and flooding. These events can lead to huge losses of plant life quickly.

An example of this is the effects of Hurricane Maria. On September 20, 2017, Maria caused severe crop loss in Puerto Rico. The loss of production crops from hurricanes is an immediate problem for food and economic security. Replacing crops quickly – once conditions for growing are safe – is an important goal in island recovery. And, having access to viable seeds ready to cultivate immediately is part of this recovery.

There was a clear need for seeds for Puerto Rican growers following Hurricane Maria. The University of Puerto Rico extension service responded by efficiently distributing an estimated 8,000 pounds of donated seed. The seeds went to small-scale farms, community gardens and individuals across the entire island. From mid-December through the start of the New Year, extension agents distributed seeds. This was despite many extension offices lacking phone and regular electric service! Within weeks of receiving seeds, growers were selling seedlings and microgreens. Home gardeners, retirees and school children, in addition to career growers, all received donated seeds to jump start their produce production on the island.

The large donation was the result of what was supposed to be a small seed drive to help a handful of community gardens. The initiative grew rapidly due to requests from growers on the island and the generosity of donors (individuals, garden clubs and seed companies) from the mainland with easy access to numerous seeds.

As of this writing, it’s only been two months since planting, so it is too soon to tell what effect the wave of donated seeds will have. Initial results of baby lettuce and 6-inch zucchini harvests are promising. If planting had occurred days after the hurricane with regional seed varieties, then harvest would be earlier and yields may be higher. However, on-island seeds were unavailable to growers.

What will be better than donations after the next hurricane season? A seed system in place on islands with backup stocks of common cultivars. This will help get plants back in the ground soon after the storm. Having a seed system where home gardeners and farmers have immediate access to high-quality seed builds security and autonomy into a food system, which is valuable for a community.

Preserving genetic resources takes both an appreciation of the value of the plants and funding to follow through. Raising awareness of the value of genetic diversity is a start.

Answered by Maria Gallo and Sarah Dohle, Delaware Valley University

About us: This blog is sponsored and written by members of the American Society of Agronomy and Crop Science Society of America. Our members are researchers and trained, certified, professionals in the areas of growing our world’s food supply while protecting our environment. We work at universities, government research facilities, and private businesses across the United States and the world.

Species extinction due to natural and man-made influences is undeniable and a serious threat to our planet. Once they are gone, we have lost them forever. For plants, seed banks are a way to combat this threat. They are an important part of a robust seed system for food security. Seed banks protect and save…

Soil seed bank

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Soil seed bank, natural storage of seeds in the leaf litter, on the soil surface, or in the soil of many ecosystems, which serves as a repository for the production of subsequent generations of plants to enable their survival. The term soil seed bank can be used to describe the storage of seeds from a single species or from all the species in a particular area. Given the variety of stresses that ecosystems experience—such as cold, wildfire, drought, and disturbance—seed banks are often a crucial survival mechanism for many plants and maintain the long-term stability of ecosystems.

The role of seed dormancy

Seed dormancy and environmental constraints on germination influence various characteristics of soil seed banks. For example, seed dormancy determines how long a seed can remain viable in the soil. Factors such as embryo immaturity, chemical inhibitors, and physical constraints influence seed dormancy. Light filtered through plant canopies, for example, can inhibit germination in some species, while a long winter chilling may break dormancy in other species. The result is a considerable variety in the patterns of germination of the seed banks by seasons, disturbances, or other environmental shifts.

Variation in the characteristics of seed dormancy determine whether a species’s soil seed bank is transient (temporary) or persistent. Transient seed banks are composed of species that produce seeds with a brief or no period of dormancy. Such seeds generally germinate prior to the next round of seed production, and the seed bank is thus continually depleted and reestablished. Transient seed banks are typical for many plants, especially long-lived perennials such as trees and shrubs. Often, such species rely on other strategies or life-history stages for persistence. For example, species may depend on long-lived adults, “banks” of seedlings in a forest understory, or extensive seed dispersal. In contrast, species with persistent seed banks have seeds that can remain dormant for more than a year, meaning that there is always some viable seed in the soil as a reserve. Persistent seed banks are common in annual plants and some woody plants, in which the failure of seed to establish the next generation would mean the collapse of the population. Scientists sometimes further classify persistent seed banks based on the extent or pattern of dormancy.

The role of disturbance

In addition to dormancy, considerable variation occurs in seed bank germination because of seasonal or other environmental shifts. Disturbances such as fire, flooding, windstorms, plowing, or forest clearing are frequently strong selective forces and may increase the overall germination response of seeds. Ecosystems characterized by wildfire often have extreme cases of persistent seed banks, as is common for many areas with Mediterranean climates, such as Australia, California, and South Africa. In those ecosystems the germination of many species requires signals provided by fire, such as a heat pulse into the soil or chemicals from smoke or charred wood. Germination may not occur until after a wildfire, which then results in mass germination from the seed bank the following spring. Similarly, the seed banks of agricultural weeds are often well adapted to the almost continuous human-made disturbances of their environment. Such weeds frequently have complex dormancy patterns that reflect the agricultural practices under which they evolved.

Seed bank modeling

Researcher Dan Cohen was one of the first scientists to model soil seed banks. In the 1960s, focusing on desert annuals subject to highly irregular rainfall, he developed population-dynamics models that suggested that a reserve of some fraction of seed in the soil was essential for the plants to avoid local extinction. Cohen found that the dynamics of soil seed banks reflect the degree of ecological constraint a species or population faces in establishing the next generation. Although his work focused on annuals, the conceptual framework applies readily to any plant species. Such modeling is important to ecological research and conservation planning, as traditional demographic models and field surveys often fail to consider population reserves in the soil.

Soil seed bank, the natural storage of seeds in or on the soil of many ecosystems, which serves as a repository for subsequent generations of plants.