Friday, January 13, 2012

Seed Time, A Series: Part 1: What is a Hybrid and why should I care? Pine Mountain, Kathleen Powers

     As we enter the New Year, the time for preparing our Grow Appalachia seed order has come. While compiling our order we have tried to provide varieties based on ease of growing, disease resistance, and popularity with our past Grow Appalachia participants. We are also trying to buy seed that aligns with our ideals of growing healthy and organic food that is locally produced and supported. This means trying to ensure that the majority of the seed which we order is open-pollinated (non-hybrid), organic, heirloom, untreated, and non-GMO. I know that is a somewhat long list, and to many people all those requirements are completely futile unless you know what they mean and why they are important. So, being a new gardener myself, I thought I would share a little bit of what I am learning about choosing the best seed possible and the reasons why. However because I seem to be extremely long-winded this will be a three part blog series about seed  as I attempt to educate myself as much as possible!

     First, an explanation of hybrid vs. open pollinated seed:

Hybrid: hybrids result from the deliberate crossing of two distinct parent varieties from the same species. Plant breeders began producing hybrids as a way of combining the best traits of separate varieties into one. Hybrids are valued for their better yield, greater uniformity, improved color, disease resistance, etc. However because hybrids are a controlled combination of two different varieties you can’t save the seed from a hybrid crop. For a simplified example, you would take a blue corn variety and pollinate it with a red corn variety to obtain a purple corn variety. The purple corn variety is then your first generation hybrid (usually denoted F1). If you save seed from this purple corn and plant it you may not get the same purple corn variety because that saved seed had genes from both the blue and red parent varieties. This means you could end up with red corn, blue corn, purple corn, or corn that completely fails to produce. So in order to produce new seed from hybrid seed the parent plants must be deliberately crossed each time, meaning that farmers become reliant on seed companies because they need to buy new seed every season. Hybrid seed is produced to increase commercial profit, it is bred to look good (bright, large, and uniform in shape), and to store and ship well. However hybrid seeds usually result in produce that has a decreased nutritional value and less distinct flavor than that produced from open pollinated seed. While we are biased against planting hybrid seeds, please do not think of them as unnatural, lab rat type seeds. Hybridization has been going on since the 1860s (Gregor Mendell’s pea experiments; high school biology anyone?). Hybridization depends on human management of pollination, but is not akin to GMOs (which will be discussed later).

Open Pollinated: This refers to seeds that will reproduce true to type. If you keep different varieties separate from each other (don’t plant two different kinds of corn in the same patch or near one another) they will pollinate within their own variety and will result in a plant like the parent. Continuing with the blue and red corn example; if you plant all blue corn in one patch and keep your red corn patch at a good distance then the blue corn will pollinate within the blue corn patch and you will be able to save seed that will reliably produce more blue corn. When saving seed, growers will choose the best ears of corn to save seed from and in that way can produce varieties that are the most disease resistant and regionally adapted. Using open pollinated seed allows growers to save seed (and in turn save money), conserve genetic diversity, and grow seeds that will be successful in their unique environmental conditions. This conservation of genetic diversity and regional adaptations is very important in protecting our seed (and food!) supply from being wiped out during major disease outbreaks.

Interesting tid bits…. And why I am continuing with the corn example
  • The United States is the largest producer of corn in the world
  • In 2010 the United States produced 12.1 billion bushels of corn, 39% of the world’s total corn production
  • Corn is grown on over 400,000 farms in the U.S.

Corn damaged by the Southern Corn Leaf Blight
So how does corn play a role in the development of hybrid seeds? Well at least as far back as the early 20th century corn has been the dominant field crop in U.S. agriculture. In those days farmers saved seed from the largest ears of corn with the best physical appearance to plant their crop for the next season. Around 1910 several scientists came up with the hybrid production of corn and began conducting studies to test the yield of these hybrid crops. By the late 1920’s hybrid crops were showing consistently higher and more reliable yield than open pollinated crops. Hybrid corn seed offered great benefits to farmers and to the seed companies and when it became commercially available it was quickly adopted as the standard crop for many American farmers who were frustrated by the stagnant yield of open pollinated crops during that time. By the 1960s almost all open pollinated crops had been replaced by hybrid crops, which accounted for 95% of the corn acreage grown in the United States. However one of the dangers of such large scale acceptance of hybrid seed was discovered in the early 1970s, when Southern Corn Leaf Blight dealt a devastating blow to corn crops throughout the United States.  The Southern Corn Leaf Blight began effecting farms as early as the summer of 1968, but not until two years later when it began to spread rapidly throughout the southern states and parts of the Corn Belt, was it considered a real danger. The blight was able to spread rapidly to many crops because 80% of corn crops at that time were planted with hybrid corn that contained T-cytoplasm. T-Cytoplasm was a man-made change to corn that allowed farmers to grow corn with sterile pollen (allowing farmers to better control pollination to produce hybrid seed); effectively skipping the time consuming work of detasseling corn plants. Unfortunately this T-cytoplasm carried a gene that was susceptible to the Southern Corn Blight fungus. Since the majority of corn plants were so genetically similar (containing T-cytoplasm) the fungus was able to spread quickly from one crop to the next. The Southern Corn Blight Epidemic eventually destroyed 15% of the country’s corn crop.

So the basic take away from this history Genetic uniformity = Extreme vulnerability

More detailed information on the 70’s corn blight:

For a good explanation of hybrid vs. open pollinated seed:

Thanks for sticking with me through a long blog post, I hope some of you out there find it helpful,
Next week: GMOs, untreated vs. treated seed, and heirloom varieties!

1 comment:

  1. Awesome post Kathleen. You ladies are such a great resource. Thanks KC