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Erin Silva, University of Wisconsin-Madison

Aug 10, 2015
Dr. Erin Silva

Dr. Erin Silva

How did you originally become interested in pursuing research in the field of organic and sustainable agriculture?

Erin Silva full body (2 of 5) 2I became interested in organic agriculture and organic agricultural research while working as an undergraduate student in the program of Dr. Philipp Simon, a carrot breeder with USDA’s Agricultural Research Service. At the time, John Navazio, now a breeder with Johnny’s Selected Seeds and co-founder of the Organic Seed Alliance, was a graduate student working with Dr. Simon. John was the source of many stimulating discussions about the importance of organic agriculture and the role of plant breeding in furthering organic agriculture practices. These early discussions followed through my career as a graduate student working in pollination ecology and then while I was an assistant professor at New Mexico State University—and now as an assistant professor at the University of Wisconsin-Madison. I feel very lucky to be able to work in organic agricultural research in Wisconsin, a state with a long history in the organic movement and a diverse and thriving organic community.

What are some of the projects your lab is currently working on?

My program works broadly across organic agricultural systems. We work with row crops (corn and soybean), cereal grains, and vegetable crops—the diverse cropping systems that represent the diversity of Wisconsin agriculture. One component of my program focuses on understanding the impact of organic agricultural practices on soil quality and health, including the use of organic no-till techniques. However, another area on which we focus that is of great interest to organic farmers involves the evaluation of variety performance under organic management. I’ve been lucky to become involved with two national efforts creating collaborations between breeders, farmers, organic researchers, and seed companies to identify and develop varieties of vegetables with exceptional performance in organic production systems: NOVIC (the Northern Organic Vegetable Improvement Collaborative) and CIOA (Carrot Improvement for Organic Agriculture).IMG_5179

These projects, funded by USDA’s Organic Research and Extension Initiative, adopt a multi-regional, team-based approach to ensure that these efforts are connected with organic farmers and relevant to a wide range of organic environments. With a partnership between Oregon State University, University of Wisconsin-Madison, Cornell University, and the Organic Seed Alliance, the first phase of NOVIC focused on farmer-breeder partnerships for variety development of broccoli, sweet corn, snap peas, carrots, and butternut winter squash. This phase of the project resulted in several cultivar releases, including the “Who Gets Kissed” variety of sweet corn that was selected for cold-soil tolerance under organic management—an issue of primary concern for organic sweet corn growers hoping to capture an early market without the use of conventional fungicide seed treatments, which are prohibited in organic management. As we move into the second phase of NOVIC, we will be focusing on tomatoes, delicata and acorn squash, cabbage, peppers, and sweet corn, working to identify and breed varieties with superior disease resistance and taste.

There are so many vegetable varieties developed already for conventional farmers. Why do we need research to develop new varieties for organic farmers?

Organic production environments are certainly unique from the conventional environments under which many of the vegetable varieties currently available to organic producers were developed. Plant breeding is most effective when the selection environment matches the target production environment; the selection environment of most vegetable varieties bred under conventional management is characterized by the inclusion of synthetic fertility and pest management inputs that are quite different from the management practices characteristic of organic farms. Instead, the organic production environment integrates a myriad of techniques including cover crops, crop rotation, compost additions, inter-planting, and enhancing beneficial habitat. By developing and trialing vegetable varieties under these selection environments, we are more effectively selecting for traits that would be most synergistic with these types of production approaches commonly used by organic farmers.

What are some of the characteristics you look for in organic varieties that are different from conventional varieties?

We’ve conducted a survey of organic vegetable growers in Wisconsin to identify characteristics of top concern for our farmers. Our Wisconsin organic producers listed disease tolerance, insect tolerance, yield, and superior germination as traits most important for organic breeding efforts (Lyon et al., 2015). While included in screening in conventional breeding programs, disease and insect tolerance are of even greater importance to organic farmers who are required to use proactive approaches in pest management and have less access to and emphasis on the use of pesticides in their production approaches. Additionally, with respect to yield, several published research studies have documented that cultivars grown in partnered organic versus conventional production environments exhibit different rank orders with respect to their performance and yields in these environments.IMG_1098


For example, the top-performing cultivar in organic environments is not the top-performing cultivar in conventional environments (Murphy et al., 2007). While we can measure this trait (yield) of the various cultivars, and use this as a selection parameter for new cultivars, we do not necessarily yet understand the complex system (genotype X environment) interactions that confer this advantage to certain cultivars under organic management. This is indeed a new thrust of our research program. With new funding from the USDA-Agriculture and Food Research Initiative, we will begin to measure genotype x system genotype x location interactions of model crops for several key economic traits, as well as the heritability of traits in the two systems, and additionally use next generation sequencing methods to discover changes at the genome level from selection in organic vs. conventional systems. Some of the differences that we might expect might lead to superior performance are those related to nutrient-use efficiency, interactions with symbiotic or plant-growth promoting microorganisms, tolerance to weed competition, and broader biotic and abiotic stress resistance.


One of the vegetables that you are trying to improve for organic cultivation is the carrot. Tell us about this project.


IMG_1103The carrot breeding and trialing efforts—“Carrot Improvement for Organic Agriculture” (CIOA)—is a collaboration between USDA-ARS, University of Wisconsin-Madison, University of California, Purdue University, and the Organic Seed Alliance. Carrots are a crop of significant interest to organic farmers. Currently, 14% of U.S. carrot acreage is certified organic (Greene, 2013). Led by Dr. Phil Simon, these efforts aim to evaluate both commercially available carrot cultivars and breeding materials in a range of paired organic and conventional production environments across the U.S., particularly with respect to disease and nematode resistance and flavor. Additionally, we are evaluating the impact of carrot stand establishment and top height on effective weed management, a main challenge for organic carrot growers. Over the past four years, incorporating research sites on both organic land at university research stations as well as on working organic farms, we have measured carrot top growth, root yield, nutritional value, and flavor over a range of organic conditions. We have observed quite a bit of variation in top height and horticultural performance between varieties at a given location—but not as much variation across environments. This could help with the identification of proven “workhorse” varieties for organic producers—varieties with which they could have confidence in their performance under organic management.

What does added consumer value mean, and how do you add consumer value to a carrot?

IMG_5316The nature of “consumer value” can differ depending on the type of produce. But, when considering fresh vegetables, added consumer value often is associated with vegetable types or varieties with superior nutritional composition, health benefits, flavor profiles, or unique colors or culinary characteristics. Nutritional value is a particular concern among organic consumers, who consider this the most important product quality in organic food (Yiridoe et al., 2005).

Carrots are highly regarded by consumers as nutritious and popular with adults and children alike. Breeding efforts and the development of carrot varieties that meet organic farmers’ production needs while providing high nutrition, novel color and flavor characteristics will help fill the demand of expanding organic markets while offering new market niches for organic farmers.



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