Tomato Grafting: Developing Grower Recommendations for the Great Plains and Enhancing Our Understanding of the “Rhizobiome”

View the project final report

• 2014 annual report
• 2015 annual report

Commodities

• Vegetables: tomatoes

Practices

• Crop Production: biological inoculants
• Education and Training: demonstration, extension, mentoring, on-farm/ranch research, participatory research, workshop
• Farm Business Management: budgets/cost and returns, risk management
• Natural Resources/Environment: biodiversity
• Pest Management: biological control, genetic resistance, integrated pest management, prevention
• Production Systems: agroecosystems, organic agriculture, transitioning to organic
• Soil Management: soil microbiology
• Sustainable Communities: new business opportunities, urban agriculture

Vegetable grafting is a technique new to the US that is being rapidly adopted by organic growers, particularly those that utilize high tunnels and grow specialty and/or heirloom varieties for direct markets.  For tomato, inter-specific (L. esculentum x wild spp.) hybrid rootstocks are utilized which confer resistance to many economically-important soilborne pathogens and provide added vigor. Preliminary data from our group showed that grafting can significantly increase yield for high tunnel growers in the Great Plains. However, further research trials that evaluate new rootstocks over multiple years are required to determine the utility of grafting. Growers in the region have identified the need for information related to grafted propagation and we propose to develop best management practices for the production of grafted plants. In addition, it is unclear how the implementation of rootstocks affects the ‘rhizobiome’, the community of native soil microbes that inhabit the rhizosphere, the soil environment surrounding the root. The objectives of this project are (1) to identify rootstocks that improve productivity and reduce disease losses in the Great Plains through a series of on-farm and university research trials, (2) to determine optimum grafting/healing conditions that reduce risk of crop failure and increases the successful implementation of grafting for small-scale growers, (3) evaluate the effects of rootstocks on rhizosphere microbial communities; and (4) disseminate grafted propagation methods as well as the results of our research through an integrated extension program. We will perform a series of replicated field studies including at least two on-farm trials per year that evaluate tomato rootstocks for their performance in regards to soilborne disease, crop yield, and marketability.  Specific outputs include (1) Extension publications, field tours, web materials, videos, and hands-on workshops; (2) Research journal publications, presentations, and teaching materials. Short-term outcomes include (1) Increased grower knowledge for grafting implementation; (2) Increased scientific community understanding of rhizobiome interactions. Mid- and Long-term outcomes include: (1) Changes in grower behavior related to propagation of grafted plants and rootstock selection; (2) Increased local availability of grafted plants; (3) Further scientific exploration of grafting and rhizobiome interactions, in support of fuller understanding of mechanisms of disease resistance and increased vigor. This proposal builds on a current project that was recently awarded by the Ceres Trust Organic Research Initiative.  See below for a detailed explanation of how components of each project are combined to form a synergistic collaborative team.

Because growers need information regarding rootstock selection and grafted plant propagation methods, and since the impact of rootstock genotype on soil microbial diversity is unclear, there exists a critical need for further research in these areas. The specific objectives of this project are:

1)    to identify rootstocks that improve productivity and reduce disease losses under Great Plains conditions through a series of on-farm and university research station trials,

2)    to determine optimum grafting/healing conditions that reduce risk of crop failure and increase the successful implementation of grafting for small-scale growers,

3)    evaluate the effects of rootstocks and grower/location on soil and rhizosphere microbial communities, and

4)    disseminate information related to grafting as well as the results of our research through an integrated extension and outreach program.