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market-farming - Re: [Market-farming] hybrid vs. selection

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  • From: "Wiediger, Alison" <alison.wiediger AT hart.kyschools.us>
  • To: 'Market Farming' <market-farming AT lists.ibiblio.org>
  • Subject: Re: [Market-farming] hybrid vs. selection
  • Date: Mon, 7 Feb 2011 14:24:20 +0000

Excellent, easy to understand explanation.  Thank you for taking the time. 

 

Alison Wiediger, Au Naturel Farm

 

From: market-farming-bounces AT lists.ibiblio.org [mailto:market-farming-bounces AT lists.ibiblio.org] On Behalf Of William H Shoemaker
Sent: Monday, February 07, 2011 8:19 AM
To: 'Market Farming'
Subject: Re: [Market-farming] hybrid vs. selection

 

That is a pretty good set of definitions but I’d like to add some details in case anyone is interested, especially if they save seed.

 

If you save seeds of heirloom varieties, it’s very important that they not be crossed with other varieties of the same crop which may be nearby. That can happen quite naturally, which is why they say in the open-pollinated definition that there should be isolation, or distance, between varieties if the variety is to be maintained accurately. The reason is that pollen from a different variety reaching a flower of an heirloom or open-pollinated variety will change the genetic profile of the seed, meaning the seed won’t be the same variety any more. Like children, they’ll be similar, but will have characteristics of the pollen source as well as the maternal plant (the original variety). The rule of thumb with self-pollinating crops like tomatoes, peppers, snap beans, etc., is that there will be at least 5% “outcrossing” or natural movement of pollen from plant-to-plant if they are nearby. This is facilitated by air movement, but even more-so by bees. If you watch insects visiting tomatoes or snap beans you’ll see lots of native pollinators, even honeybees, visiting the flowers. While they do that they move pollen from plant to plant, facilitating the crossing of varieties. If you are saving seed you can diminish the risk by simply covering the flowers with a paper bag or something similar before they open and securing them from “wild” pollen. Let them self-pollinate under cover, then after several days have passed and the flower naturally drops its petals, the cover can be removed, the baby fruit tagged and allowed to mature before seed harvest. The resulting seed will be true to the maternal parent genetics. Do this on multiple plants to maintain the diversity within the genetics of the variety and mix the seed from different heirloom or open-pollinated parents. You can also cover a whole block of plants with reemay or another fine-textured fabric and it will do a pretty good job too. Isolating your plants, perhaps in a greenhouse, will effectively do the same thing.

 

Its important to know that hybrids are not the same as GMOs but they are much more manipulated as varieties by breeders. With most hybrids their parents have gone through a number of generations of “inbreeding”, where the plants that are selected for specific traits are crossed with themselves. This refines the set of genes to a smaller, more controlled and defined set of genes in each subsequent generation. After about 10 generations these individual inbreds are very unique, often with some poor traits but each having a very concentrated set of valuable traits that are based on specific genes, such as verticillium wilt resistance, or yellow fruit color. When these finished inbreds are crossed, hybrids result. These hybrids have the full complement of positive traits of each inbred parent. Like the High Mowing definitions page said, when you save seed from these hybrids, the offspring begin to “revert”, or become less like the hybrid parent and often exhibit traits similar to the inbred parents of the hybrid. Some of those traits can be poor. And some of the “recessive” genes that are valuable in the hybrid disappear, making those plants less valuable than the hybrid parent. Seed companies like hybrids because they control the production of the hybrid seed because they are the only ones who have the inbred parents.

 

GMO’s are totally different than standard hybrids, though many GMO’s are created with hybrids. GMOs could be created with open-pollinated and heirloom varieties as well. What makes the GMOs different is that they were created by mechanically inserting a gene into the plant that could not be inserted naturally. There are many versions of this technique but essentially they all involve the placement of a gene, or manipulation of a gene, such that the result would not be found in nature. I really believe, like Stewart Brand, that this technique can be incredibly valuable and do much good. The problem is that the potential for selfish gain or other irresponsible behavior drives some of those who use the technique. There is a real moral dilemma involved in the power of this technique and until we have thoroughly vetted the issue and placed reasonable limitations on the use of this technique, there will be public backlash against it. Like many areas of science, we have put tools in the hands of people who care less about their impact on society than on their ability to accumulate wealth at others’ expense.

 

Bill

William H. Shoemaker

Sr. Research Specialist, Food Crops

University of Illinois - Crop Sciences

St Charles Horticulture Research Center

535 Randall Road, St Charles, IL, 60174

630-584-7254, FAX-584-4610

wshoemak AT illinois.edu


 

The following link to the "definitions" page at High Mowing Organic Seeds might be helpful for folks wanting simple definitions of hybrid, heirloom, OP, etc.

http://www.highmowingseeds.com/organic-seed-definitions.html

-John

On Sun, Feb 6, 2011 at 9:38 AM, Vern and Amy <vaspencer AT sisna.com> wrote:

Don,
  I have been struggling with understanding hybrid vs. heirloom/selection for a while.  I find it important so I can educate my customers.  They are concerned about what goes into their bodies, but sometimes don't understand that hybrids aren't necessarily going to kill them.  Sometimes they confuse hybrid with GM.

 




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