Plant genetics matter for organic farmers

Date:11-26-2018


Plant genetics can make a big difference in yield to organic and conventional-to-organic transitioning farmers, according to Mark Schonbeck, PhD, who presented “Plant Genetics: Breeding and Variety Selection” as a recent webinar. Organic Farming Research Foundation and eOrganic hosted the event. Schonbeck represents the Organic Farming Research Foundation.

Schonbeck said that in a 2015 survey in which more than 1,000 farmers were surveyed, 74 percent of organic farmers cited soil health as a research priority. In addition, organic farmers need new crop varieties that: thrive in organic systems; utilize nutrients effectively from organic sources; resist major diseases; are resilient to weeds, pests and climate change; and meet market demand for quality and nutritional value.

He added that the right cultivars can: help organic farmers build healthy soils of the heritable traits; facilitate organic production; confer resilience to locally prevalent stresses; reduce need for inputs; reduce erosion; add organic matter; improve tilth; support beneficial soil life; and enhance market appeal.

The crops should be easy to grow organically if they’re “regionally adapted, resistant to diseases, germinate rapidly, vigorous seedlings, resilient to drought, pests, weeds, respond well to organic practices and have desired market traits.”

The “South Anna” butternut squash offers a good example, as it combines high vigor, downy mildew resistance, excellent flavor and long shelf life.

“They need fewer inputs,” Schonbeck said. “They efficiently absorb and utilize nutrients from organic sources, need less fertilizer, utilize water efficiently, need less irrigation, outcompete, tolerate, or suppress weeds, and need less cultivation.”

All of these traits are highly desirable for organic growers.

One example is the “Tennessee red cob” dent corn, which Schonbeck said beat the weeds and yielded well on minimal nitrogen input in Virginia.

Schonbeck referenced research from Mandaamin Institute in Lake Geneva, Wisconsin, which found that by planting nitrogen-efficient field corn, which requires half as much nitrogen as standard hybrids, the nitrogen-fixing bacteria in the crop root zone met up to 50 percent of the crop’s nitrogen need, offering similar yield, higher protein percentage and quality compared to standard hybrids. This can help maintain yield on poor soils and the large root system enhances drought tolerance, too.

The right variety can also help restore the soil.

“Decades of corn breeding in nitrogen-fertilized soils appear to have modified root microbiomes, reduced nitrogen fixation capacity and increase nitrogen fertilizer needs,” Schonbeck said. “Breeding and selection in organic systems have yielded nitrogen-efficient hybrids.”

The seeds are now available to farmers and scientists.

Drought-resistant varieties also help farmers, including drought-hardy cultivars of pepper, okra, lima bean, and many other vegetables and cereal grains.

Schonbeck also said that carefully bred vegetable cultivars can also improve flavor, nutrition and plant vigor.

Among weed competitive carrots, for example, “lines that emerged and formed a full canopy earlier than others resulted in the greatest crop yield in the presence of weeds as well as the greatest ability to suppress weeds. Selection of lines that favor early and full top canopy growth can be used as a low input, integrated weed management tool,” Schonbeck said, quoting Philipp Simon from Carrot Improvement for Organic Agriculture, final report for OREI 2011-01962, CRIS Abstracts.

The right varieties can also protect and build soil and feed soil life — an emerging concern of organic farmers.

They can provide high biomass, dense canopy, deep, extensive root system, abundant root exudates to feed soil organisms, and enhanced association with mycorrhizal fungi and other beneficial soil organisms.

“It is not just cover crops that build soil,” Schonbeck said. “These sweet potato and squash crops protect the soil and add organic matter.”

Plant varieties can also exhibit variation in branching pattern, root hair density, root depth and water and nutrient efficiency.

Greater root development can help plants better tolerate drought and sustain production and quality in summer weather, which is important for plants such as lettuce.

Tomato organic management through breeding, biofungicides and induced systematic resistance can help stimulate plant defenses against foliar disease. But Schonbeck said that not all cultivars are protected from late blight and gray mold.

More plant genetic and root-microbe interaction examples include the ability to host endophytic microbes that protect against Alternaria dauci leaf blight and enhanced association with mycorrhizal fungi.

“Breeding cover crops for soil health includes genetic variability in vigor, biomass, nitrogen fixation (legumes), cold hardiness, flowering date, ease of termination, weed suppression, disease and pest nematode suppression and water use efficiency,” Schonbeck said.

Desirable cover crop traits that are heritable include cold hardiness, maturity date, nitrogen fixation, biomass, early vigor and weed suppression.

“The challenge is finding the best crop cultivars to build healthy soil and make a living organically,” Schonbeck said.

The first challenge is that today’s crop varieties aren’t designed for organic systems but for conventional. The second challenge is that cultivar choices are limited and not often adapted to locale. The third challenge facing organic growers is that public plant breeders are an “endangered species,” Schonbeck said. “Diminished funding for university and USDA public plant breeding and cultivar development programs and a steep decline in numbers of university and other public plant breeders means an urgent need to recruit, train and establish the next generation of plant breeders.

The fourth challenge is intellectual property and farmers’ rights. The Open Source Seed Initiative, or OSSI, hopes to make users free to grow, share, sell or trial and study seed and any new variety developed from OSSI germplasm must remain open source.

Schonbeck said that offering seed developers a licensing agreement and a royalty such as 10 percent can help them make a living while more organic farmers can benefit from and propagate their work on their own farms.

He thinks that more farmer and researcher collaboration can help improve organic seed varieties and availability.

In the meantime, farmers must work with what they have.

“Seek locally produced seed,” Shonbeck said. “Choose cultivars bred in and for organic systems. Select regionally adapted varieties that emerge and establish rapidly, compete with weeds, resist major diseases and pests in your region, utilize nutrients from organic sources efficiently, and tolerate drought or other stresses. Conduct on-farm variety comparisons.”

A directory of organic seed suppliers can be found at https://attra.ncat.org/attra- pub/organic_seed and the Organic Seed Alliance, found at http://www.seedalliance.org, can prove a good resource.