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United States Department of Agriculture

Agricultural Research Service

Research Project: Carrot Improvement for Organic Agriculture with Added Grower and Consumer Value

Location: Vegetable Crops Research Unit

2013 Annual Report


1a.Objectives (from AD-416):
Develop carrot breeding stocks for production in organic agriculture systems with improved nutritional value, trial carrots in diverse growing locations, and release germplasm to the seed industry. Evaluate microflora and nutrient differences of conventional and organic systems.


1b.Approach (from AD-416):
a) Plant carrot seed with elite nematode and alternaria resistance and weed tolerance for testing in conventional and organic fields, three replicates each entry. b) Evaluate seedling emergence. c) Hand weed organic plots as needed; control weeds in conventional trials. d) Evaluate top size of each entry at one month, 3 months, and harvest. e) Harvest crop and provide root samples to PI's lab. f) Analyze soil physical, chemical, and biological characteristics for samples from all trial sites.


3.Progress Report:

This project was renumbered from 3655-21000-048-45A to 3655-21000-062-19A. Carrot breeding stocks were planted in May 2012 and again in May 2013 at the Purdue Meig’s research farm south of Lafayette, Indiana. Organic carrot plots were hand-weeded at least 3 times each season, and conventional plots were treated with herbicide and hand-weeded one time each season. In each year, carrot entries were/are being evaluated for top size 3 times and root samples were/will be submitted to Wisconsin after harvest. Field trials in Indiana were highlighted during a Seed Saving Workshop in 2012, and will be highlighted during a field day in 2013. Soil samples from each field trial (IN, WI, WA, and CA) are being collected 3 times each season and sent to Purdue University for analyses. Pre-plant soil samples are being evaluated for nutrient and soil organic matter analyses. Soil samples collected after carrot emergence at each site are being evaluated for a range of soil chemical and biological properties including plant available Nitrogen (N), enzyme activity, active soil carbon, and microbial community diversity (bacteria, fungi and archea). Soil samples collected prior to harvest are analyzed for plant available N. In 2012, we practiced various techniques for extracting root rhizosphere samples from field soil for use in rhizosphere analyses, but were not very successful. We have been experimenting with various techniques to culture beneficial microbial species from field soil and rhizosphere and endosphere root compartments, and to add to molecular analyses of diversity and activity. We also initiated a greenhouse trial to identify the most optimal field soil mix to grow carrot genotypes and collect rhizopshere and endosphere root samples. Once this experiment is complete, we will plant six carrot genotypes with wide genetic backgrounds into pots with soil collected from organic and conventionally managed plots in Indiana. A subset of carrot root systems from each soil treatment X genotype will be collected at various crop developmental stages and the rhizosphere and endosphere microbial communities will be quantified using next-generation sequencing. Additional plants from each soil treatment X carrot genotype will be vernalized and allowed to go to seed, and seed collected and analyzed for vertical transmission of endophytes. Finally, we are attempting to isolate a virulent strain of Pythium irregulare from carrot soil for use in experiments evaluating the role of the soil rhizosphere community on carrots genotypes with and without pythium resistance.

This research relates to the objective "Develop carrot breeding stocks for production in organic agriculture systems with improved nutritional value, trial carrots in diverse growing locations, and release germplasm to the seed industry. Evaluate microflora and nutrient differences of conventional and organic systems" by growing carrots under conventional and organic practices and by evaluating growth in these conditions.


Last Modified: 11/27/2014
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