Grafting hoophouse tomatoes for improved yields and profitability

Final Report for ONE09-103

Project Type: Partnership
Funds awarded in 2009: $9,525.00
Projected End Date: 12/31/2009
Region: Northeast
State: Maine
Project Leader:
Dr. Mark Hutton
University of Maine Coope
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Project Information

Summary:

Twenty-five growers and five seed company employees participated in a hands-on tomato grafting workshop held at University of Maine’s Highmoor Farm Experiment Station in Monmouth. Participants were taught the procedures to make both cleft and side grafts and then each participant made 30 to 40 grafts using the scions ‘Trust’ and ‘Big Beef’ and the rootstocks ‘Beaufort’ and ‘Maxifort’. The grafted plants were grown at Highmoor and then made available to the workshop participants. A pre-workshop questionnaire showed that fewer than 80% of the participants used or had used grafted plants and 25% of the participants believed the process too difficult to attempt. Following completion of the workshop and subsequent follow-up 27 of 30 participants indicated that the process of grafting was not too difficult and could fit into their operations. Three said that the process while not difficult did not fit their operation. All participants saw improved performance of grafted compared to un-grafted plants however only 60% planned to used grafted plants in the future.

The results of the grafted tomato experiment at Highmoor Farm indicate that grafting does increase yield and plant size and that there are differences between scion and rootstock combinations. ‘Trust’ produce greater yields and larger plants when grafted onto ‘Maxifort’ rootstocks. When grafted onto ‘Beaufort’ rootstocks ‘Trust’ plants were larger than on-grafted plants and produced greater yields compared to un-grafted plants though the yield difference was not significant. Yields produced by ‘Big Beef’ grafted onto either rootstock were not significantly different from those of un-grafted plants. However, there was a significant increase in plant fresh weight of the grafted plants.

Introduction:

Profitable tomato production in Maine and New England is difficult due, in large part, to the region’s cool, short growing season. Hoophouses are unheated greenhouse structures used to extend the growing season. These structure make it possible to plant earlier in the spring; they provide a more favorable environment for plant growth; and provide protection from early fall frosts. Hoophouses are generally considered to be non-permanent or even movable structures in which crops are grown directly in the soil. Vegetable growers in Maine make great use of these structures, with about 60% of the State’s mixed vegetable growers having at least one hoophouse. Almost any vegetable crop grown in Maine can be grown inside a hoophouse, however; most of the growers in the region have chosen to grow tomatoes in high tunnels or hoophouses.

Tomatoes are the most common and profitable vegetable crop grown in hoophouses by Maine vegetable farmers. Mixed vegetable growers are reluctant to grow crops other than tomatoes in hoophouses because of the high demand for tomatoes and the high prices consumers are willing to pay for the crop. The intensive cultivation of tomatoes in hoophouses has lead to a buildup in the level of soilborne pathogens. Additionally, hoophouse tomatoes are often challenged with foliar diseases such as grey mold or powdery mildew which are not common in open field production. Consequently, growers are selecting cultivars bred for greenhouse production which possess tolerance/resistance to many of these foliar pathogens but often have weak root systems unable to grow well in hoophouse soil. Grafting tomatoes onto vigorous rootstocks has been used to overcome a wide range of biotic and Abiotic problems limiting tomato production including soilborne diseases, salinity, waterlogged soils. Many growers are using grafted tomatoes to improve yields and quality but the technique is not widespread.

Project Objectives:

We are proposed a solution involving: hands-on grower training, a research based critical evaluation of using grafted tomatoes, and an education program involving grower experience case studies, and development of materials for presentation at meetings and through print and electronic media.

Specifically our objectives were the following:

Conduct a workshop for up to 30 hoophouse tomato growers.

Provide the growers with up-to-date production information and hands on experience grafting tomatoes.

Provide 30 growers with 20 grafted tomato plants for production in their hoophouses. Track growers experiences using pre- and post-season evaluations and on-farm visits.
Conduct detailed comparison of un-grafted and grafted tomatoes in hoop houses.

Cooperators

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Research

Materials and methods:

Workshop component:

A grafting workshop was held at University of Maine’s Highmoor farm on 9, April 2010. At this meeting, 30 participants will be asked to complete pre-workshop questionnaires. Workshop participants were taught how to graft tomato plants and then had the opportunity to graft 40 tomato plants to grow in hoophouses on their farm. Rootstock and scion plants were grown at Highmoor Farm using organic practices.

How-to slide show and video were produced from the workshop.

Research component:

In this part of the project we are interested in quantification of how grafted, self grafted and un-grafted tomatoes compare in terms of plant health, fruit quality and yield, and economic return. Replicated experiments were conducted at Highmoor Farm using scions and rootstocks commonly grown in Maine; ‘Trust’, ‘Big Beef’ as the scions and ‘Beaufort’ and ‘Maxifort’. The experiment was conducted as split-plot design with three replicates using the tomato cultivar as the main plots: 1) Check treatment, un-grafted plants; 2)grafted onto ‘Maxifort’ or ‘Beaufort’ rootstocks. Treatment plots consisted of 7 plants. During the growing season the plants were pruned and trellised to single stems As fruit mature, the were harvested fruit and graded by size and quality; cull fruit will be graded for the type and extent of the defect i.e. blossom end rot, cracking, sunburn, insect, etc. Data were collected on all costs and time associated for each treatment. Yields will then be statistically analyzed to compare the grafting treatments.

In the original proposal research plots were planned to take place on four commercial grower farms. However, this portion of the project was not done due because the late timing of grafted plants from the project.

Research results and discussion:

In the pre-workshop questions, approximately 25% of the workshop participants though grafting would be to difficult. The remaining 75% believed the skill would be easy to learn and fit into their production plans. Following competition of the workshop and subsequent follow-up 27 of 30 participants indicated that the process of grafting was not too difficult and could fit into their operations. Two said that the process while not difficult did not fit their operation. One grower enthusiastically thanked us for the workshop and the opportunity to learn grafting and said that while it was fun he would never invest in grafting tomatoes for his operation. “It was too finicky”.

The grafting efficiency of the 30 participants in the project ranged from 0% successful grafts up to 85% success with an average success rate of 55%. The highest success was achieved by participants with previous experience grafting. None of the workshop participants wanted to receive their grafted plants. Over a third of the participants had started plants and made grafts at their location. The remaining participants cited logistical reasons for not taking their plants.

The results of the grafted tomato experiment at Highmoor Farm indicate that grafting does increase yield and plant size and that there are differences between scion and rootstock combinations. ‘Trust’ produce greater yields and larger plants when grafted onto ‘Maxifort’ rootstocks. when grafted onto ‘Beaufort’ rootstocks ‘Trust’ plants were larger than on-grafted plants and produced greater yields compared to un-grafted plants though the yield difference was not significant. Yields produced by ‘Big Beef’ grafted onto either rootstock were not significantly different from those of un-grafted plants. However, there was a significant increase in plant fresh weight of the grafted plants.

The project did not unfold as we had planned. Due to the timing of plant production we were unable to provide grafted plants to the growers taking part in the research component of the project. However, each of the four growers are now using grafted plants.

Research conclusions:

The workshop had thirty participants, five of which work for regional seed companies. The participants from the seed companies report using the knowledge and skill gained from the workshop to assist their customers in doing their own grafting. Of the remaining 25 participants, 15 are using some grafted plants in their operation either from producing the plants or purchasing.

Participation Summary

Education & Outreach Activities and Participation Summary

Participation Summary:

Education/outreach description:

The workshop had thirty participants, five of which work for regional seed companies. The participants from the seed companies report using the knowledge and skill gained from the workshop to assist their customers in doing their own grafting. Of the remaining 25 participants, 15 are using some grafted plants in their operation either from producing the plants or purchasing.

An educational program was developed that included step-by-step instructions and the experimental results from the Highmoor Trial was presented at the 85 growers at the 2011 Maine Vegetable and Small Fruit Growers Annual Meeting, and to 145 people at the Maine Small Fruit and Vegetable School.

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.