Organic Farming...Organic Varieties?
Organic Agriculture Centre of Canada
Can varieties developed for conventional farming, with its use of herbicides, synthetic fertilizers and pesticides, really do well in organic settings? It's a question that has been asked in organic circles for decades. And it's gaining in importance as more and more farmers make the switch to organic.
Plant breeding is carried out in controlled conditions, which usually resemble the conditions of conventional farming. Various inputs (fertilizers, herbicides and pest control) are used to create a uniform environment for all the plants. The highest yielding plants are then selected and multiplied.
But, organic systems are often more variable. For example, organic farmers can't use herbicides to control weeds. Instead, they use crop rotations and mechanical weeding to control weeds, and sometimes even the crop itself. Organic crops should grow quickly and shade out the weeds. Far more than under conventional management, organic crops have to help take care of themselves.
And so the question arises – how will varieties developed in conventional settings fare in organic settings? Will they produce good yields, both in quality and quantity? A group of researchers at the University of Alberta has been looking at this question. The results of this work were published in the 2009 study “Should spring wheat breeding for organically managed systems be conducted on organically managed land?” in the journal Euphytica.
The researchers, led by Dean Spaner, conducted an experiment using two cultivars of spring wheat, AC Barrie, the most commonly grown spring wheat cultivar on the prairies in the 1990s, and Attila, developed by CIMMYT, a non-profit research and training center headquartered in Mexico .
Now for a quick biology lesson! Wheat normally self-pollinates. This means that the pollen from one plant fertilizes the ovary of the same plant – neighbouring plants generally don't 'mingle' to create offspring. So, in order to cross two varieties, the plant breeder has to remove the male parts of a plant of one variety. Then, the breeder can pollinate the female parts by hand, with the pollen of the other variety. When these seeds are grown, this creates a population of offspring that are a cross of the two parent varieties, containing a mixture of genes from each parent . Each offspring then continues to self-pollinate and is called a line. The researchers can select individual lines and multiply them to become a variety.
Using this technique, the researchers crossed AC Barrie and Attila. Then they grew the parent varieties, along with their offspring, for three years. Half of each variety or line was grown under organic management, the other half under conventional management in fields that were located less than 1 km apart, near Edmonton, Alberta.
The researchers then selected the top 10% of all the lines, based on nine traits including grain yield and protein, from each management system. The result? Less than half of the lines chosen were selected in both systems. If the top eight lines were selected based only on yield, only a single line was chosen in both systems. Clearly, the lines that did well under organic management did not necessarily do well under conventional management, and vice versa.
Based on this result, the researchers concluded that the “selection of spring wheat cultivars for organic production systems should be done on organically managed land.”
Why did the lines perform differently under organic and conventional management? The short answer is that the two systems create different environments for the plants. How a plant grows and develops depends on its genes and its environment. So the same set of genes can produce a different looking (and different yielding) plant, depending on its environment.
Furthermore, the heritability, or genetic contribution to performance, was the same in the organic and conventional systems. So, a variety developed under organic management would be expected to produce crops with similar appearance and yield on commercial organic farms, just like the conventional varieties.
And that is good news for organic farmers. If organic varieties are developed to meet the demands of organic farming, then a big part of the guesswork will be eliminated for the farmer. No longer would he or she have to pick a conventional variety, hoping that by luck it will work in their region.
Now, the next step is to determine what traits are important for organic farming, select parent varieties accordingly, and then start breeding and selecting for organic!
This article was written by Kristine Hammel on behalf of the OACC with funding provided by Canada’s Organic Science Cluster (a part of the Canadian Agri-Science Clusters Initiative of Agriculture and Agri-Food Canada's Growing Forward Policy Framework). The Organic Science Cluster is a collaborative effort led jointly by the OACC, the Organic Federation of Canada and industry partners. For more information: email@example.com or 902-893-7256.
Posted December 2011