Potential of grafting to improve nutrient management of heirloom tomatoes on organic farms

Project Overview

Project Type: Graduate Student
Funds awarded in 2007: $10,000.00
Projected End Date: 12/31/2009
Grant Recipient: North Carolina State University
Region: Southern
State: North Carolina
Graduate Student:
Major Professor:
Mary Peet
North Carolina State University
Major Professor:
Dr. Frank Louws
NC State University

Annual Reports


  • Vegetables: tomatoes


  • Crop Production: biological inoculants, cover crops, fertigation, foliar feeding, organic fertilizers, tissue analysis
  • Education and Training: demonstration, display, extension, on-farm/ranch research, workshop
  • Farm Business Management: value added
  • Natural Resources/Environment: habitat enhancement, soil stabilization
  • Pest Management: biological control, cultural control, economic threshold, field monitoring/scouting, genetic resistance, integrated pest management, mulching - plastic, sanitation, soil solarization, weather monitoring
  • Production Systems: general crop production
  • Soil Management: nutrient mineralization, organic matter, soil analysis


    The nutrient uptake and fruit yield of grafted tomatoes was evaluated in greenhouses and on farms in North Carolina. The physical effects of grafting stimulated plant growth and nutrient accumulation in our greenhouse study, while utilization of commercial rootstocks increased the level of grafting effects. In our two-year systems comparison trial, the total fruit weight of the high tunnel system out-produced the field system by 12-30% and the heirloom tomato Cherokee Purple grafted onto the rootstock Maxifort produced 23% more fruit compared to non-grafted plants. All three collaborative farmers were enthusiastic about incorporating grafting into their future farm practices.


    The goals of this project were to evaluate the nutrient uptake of grafted and non-grafted tomatoes as well as compare the productivity of grafted tomato crops. Fertilizer applications are commonly required in low input soil-based tomato systems. Supplying post-planting nutrients to an organic tomato crop is a challenging task for reasons such as matching nutrient release with crop requirements and the expense of soluble materials that meet the National Organic Program (NOP) standards. Literature from Asia, the Mediterranean, and Morocco suggests that grafted herbaceous plants are more efficient at absorbing certain macro- and micro- nutrients which could be a great advantage in low input systems such as organic operations. If grafted tomato plants are more efficient at taking up nutrients then a reduction of fertilizer inputs may be possible or perhaps greater yields could be achieved at the same N input rate? If either of these factors are true than using grafted plants could make production systems more economically viable for farmers. This research project included: 1) the evaluation of the nutrient content and plant productivity of grafted tomatoes in a controlled research greenhouse, 2) a multi-year organic, high tunnel and open field systems comparison trial with nested grafting and N input level treatments, and 3) three, organic, on-farm research trials.

    Project objectives:

    1. Establish nitrogen growth curves for grafted tomato plants.

      Compare crop productivity and nutrient uptake of grafted heirloom tomatoes given different nitrogen input levels.

      Assess the interaction between rootstock and heirloom scion combinations on crop productivity and nutrient uptake.

      Compare the performance of grafted heirloom tomatoes in organic high-tunnels compared to open field production.

      Develop and disseminate research-based knowledge via workshops, extension publications, research tours, etc. that can be used by growers to successfully and profitably adopt this emerging technology into their current growing practices.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.