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Participatory Plant Breeding Part 2

Creating a stable food supply for an unstable climate
By Rebekah L. Fraser


Genotype x Environment = Phenotype. This simple equation represents a highly complex system that farmers need to understand. A plant's phenotype, or physical appearance, is affected by its genotype, the genetic constitution of the plant. The genotype determines how the genes react to the environment. Environmental factors include climate, soil, water supply, wind level, temperature, pest pressure and seasonal variation. In an unstable climate, understanding both genotype and the effects of environment on genotype is crucial to success in farming.

Participatory plant breeding (PPB) offers growers the opportunity to explore the above equation as it pertains to their farm. Run by the Organic Seed Alliance, participatory plant breeding is a program in which breeding experts and organic farmers collaborate in designing and conducting on-farm research to develop new varieties.



PHOTO COURTESY OF JANICE1334/MORGUEFILE.COM

Candidates for PPB

The best plant breeders are those who know how their breeding efforts will work under the environment of intended use. Successful PPB projects start with farmers who really know what they need, based on the needs of the businesses they supply and the needs of the end user - the person putting that crop on the table at a restaurant or at home.

Successful PPB farmers also know how each plant responds to environmental conditions. Farmers who can extrapolate that information to anticipate what the plant will actually look like under different environmental conditions have an even greater chance of success with PPB. These growers can say, "With the kind of year we're having, the carrots won't size up as well as in typical years," or "With the wind as it's been, the leaves on that plant won't be as robust as they normally would," etc.

John Navazio is the senior scientist for the Organic Seed Alliance and a plant breeding and seed specialist for Washington State University Extension. Navazio says even farmers without this knowledge and level of experience are candidates for PPB. He encourages new growers to do PPB right from the start, but says they must be absolutely fascinated and have a true economic reason for getting involved in plant breeding and adapting something for their area. The program involves coursework as well as on-farm germplasm research. "The procedural steps we teach for on-farm plant breeding are kind of like getting a crash course in learning how to interpret the environmental effects on your crops," he says.

Methodology

With the need identified, the next step is to introduce a plant breeder with knowledge of genetics, family structure and breeding methodology to the farmer. Together, the farmer and breeder screen through material, some of which the farmer may have already bred on the farm. "We get a lot of farmers who have done some breeding, but can't quite get it to prime time," notes Navazio. "The first step in the process, before worrying about selection intensity, is to find the material that satisfies those needs. Does it have the right color, the right flavor, the right 'ship-ability,' etc.? That's a crucial step in the process."

Sometimes the farmer and breeder don't even need to make a cross, but can just select from what the farmer already has. From the initial collection of plants, the farmer-breeder team grows a large population. The breeder trusts the farmer to chart the course toward the ideal physical characteristics, or phenotype, of the crop. The farmer steers the breeder in laying everything out on the farm, so the farmer won't have to do a lot of hand pollination or hand labor and will be able to manage the data collection.

Next, the farmer-breeder team creates a system to examine the maximum amount of material in the segregating population and pick out the winners. They slowly narrow the cultivars to close in on the desired phenotype. While the farmer will envision an ideal phenotype, the best plant breeders and farmers know the final result won't necessarily be perfect.

Modern plant breeding often involves separating single plants and forming individual families via inbreeding and pedigree maintenance. In order to crystallize desired traits, lab breeders maintain numerous samples of seed and utilize hand pollination and other labor and time-intensive methods that are unfeasible for farmers.

Using methodologies of recurrent selection, including half and full-sibling family selection, PPB breeders slowly weed out the undesirable plant families. Instead of concentrating on perfect families, PPB breeders do negative selection to eliminate the inferior families. In this way, they slowly weed the population down to the plants with many highly desirable traits. Instead of inbreeding, PPB breeders allow all of the best plants to mate with the best. Navazio says it's much easier to do on the farm, because it requires less effort from the farmer and the breeder to maintain what would normally be hundreds of little pedigreed families.

Benefits

It may take a little longer, but negative selection allows farmer-breeder teams to maintain a wider genetic breadth within the population. This makes the resultant varieties more genetically resilient, stronger, more vigorous and more adaptive to the environment over time. Ultimately, this is the key to having a more stable, environmentally sustainable food supply, even in an unstable climate.

PPB in action

After screening more than 50 varieties over a three-year period, Navazio and one group of farmers he works with via the PPB program are selecting varieties of chicory and radicchio to be cold-hardy enough to withstand 15-degree temperatures. This success is a very small piece in this very large puzzle. However, if farmers on the East Coast take one of the newly developed varieties of chicory or radicchio and adapt it to their unique environmental needs, then another piece of the puzzle will be in place.

"There are a heck of a lot of places in the eastern U.S. where it never gets below 15 degrees," says Navazio. "We're going to have live winter food that didn't need to be shipped from Yuma, Ariz., or El Centro, Calif."

The author is a freelance writer based in Massachusetts and a monthly contributor to Growing.