Grafting Technologies and Their Trends

Chieri KubotaDepartment of Horticulture and Crop Science

The Ohio State University

47th Tomato Breeders Roundtable, Wooster, April 5th

www.plugconnection.com

Use of vegetable grafting - historical timelineGourd grafting for large fruit production in China

Discovery as promising IPM tool for fusarium in watermelon (Japan)

Watermelon farmers began to use grafting for intensive cultivation (Japan/Korea)

500s1920s-1930s

1940s

Breeding technology development of for disease resistance (worldwide)Tomato grafting was introduced commercially since 1970s (Japan)Globalization of seed market and supplyGrafting technology adopted in Israel and Europe

1950s-1980s

Tomato grafting introduced in hydroponic greenhouse in Holland

1990s 2000s 2010s

1990s

U.S. researchers in SE promoted grafting tomato onto jimson weed (Datura spp.) for RKN

Tomato grafting in hydroponic greenhouse in Canada

Tomato grafting in hydroponic greenhouse in US and Mexico

Vegetable grafting for retail market in US

Vegetable grafting in various crops and production systems in Mexico (and US)

Montreal Protocol (1989)

Legenaria rootstock plants and watermelon scion sprouts (Photo taken in Nagano, Japan; dated on April 5th, 1967)

Tube grafting – A breakthrough for modernizing tomato grafting

• Developed by Itagkiet al. in 1990s.

• Improved grafting speed.

• Indoor healing under electric lighting was developed together with this method.

What’s new in grafting?

• New concept of rootstock for field production

– Enhancing yield by grafting

– Environmental stress management

• Indoor growing technologies (vertical and container nurseries)

• Automation

• ToMV Déjà vu

New focus on the use of grafted plants

• Traditional: Soil-borne disease management • Graft union must be above the soil

line • High grafting technology is needed

• Stress management (water, temperature, etc.)• Graft union can be buried deep in

the soil

• Yield enhancement only• Graft union can be buried deep in

the soil

Semi-automated planting in FL tomato production

Use of indoor growing technologies (soilless & sunless production)

Grafted Growers LLCBergEarth, Japan

Key technologies• Lighting (LEDs)• Cooling (A/C)• CO2 enrichment• Air circulation• RH control• Irrigation (fertigation)• Automation

Indoor growing under electric lighting• Consistency in plant growth

• Uniformity in growth and development• Making automated grafting easier

• Full control capacity of temperature, light, CO2 and humidity• Typical conditions for tomato plants: 200-300 mmol m-2 s-1 PPFD, 400-

1,000 ppm CO2, 25°C/15°C day/night temperature, 60% RH

• Plant morphology (internode length) management by light quality, lighting cycle and temperature• End of day far-red light (700-800 nm) to elongate hypocotyls

• Higher plant density over tray• Example: 200 cell tray indoor vs. 98-128 cell tray in greenhouse

• Minimum water and fertilizer use

• Higher capital costs

• Additional electricity costs but no heating costs• Electricity costs is 1 cent or less per plant at $0.12/kWh (data by

TaiyoKogyo, Japan)

New issue: Some tomato genotypes sensitive to UV-deficient light environment (causing intumescence)• Solutions

• Avoid sensitive cultivars or rootstocks

• Providing minimum UV-B light in the system (nighttime)• 7-12 mmol/m2/d or 3-5 kJ/m2/d UV-

B dose achieved by 0.1-0.2 W/m2

UV-B for 7 hrs

• Use tomato-specific LED lighting recipe to mitigate intumescence injury (Eguchi et al., 2016)• High in blue light (>50% of PAR)• End of day far-red light (5 mmol m-2

s-1 for 4 min)

10%B 10%B+FR 50%B 50%B+FR

+ UV-B (7 mmol/m2/d)

Use of automation for tomato grafting – Slowly but surely

• Various models developed in Holland, Italy, Japan, Korea, and Spain

• On-going R&D since 1990s• Today: 20-30? machines

in Japan (450 million grafts market); ~14 machines in North America; >50 machines in other regions

• Breeding effort (automation friendly traits) can be integrated? AgriVest 2015 –Part-6-Rootility

https://www.youtube.com/watch?v=koXNA3Qkdp4

Grafting machine demonstration at the ‘ISHS symposium on Transplant Production Systems’ in Yokohama in 1992.

ToMV Déjà vu • The issue of sudden death with ToMV infection

became problematic in 1970s

• Intensive studies suggested that tomato rootstocks must be selected depending on rootstock’s and scion’s ToMV resistance genotypes

• Today, Japanese seed companies include ToMVresistance genotype (Tm-1, Tm-2a, etc.) in the seed catalogues to help growers and nurseries to select matching scion and rootstock

Photo provided by Erin Rosskopf

ToMV Déjà vu • Sudden death was found for a specific

scion/rootstock combination in heirloom tomato grafting trials in FL (Rosskopf, 2016)

• On-going study by Rosskopf lab at USDA ARS to identify the ToMV resistance genotypes of U.S. tomato cultivars and rootstocks• Rosskopf reported: “After one week of inoculation

with ToMV,• All heirlooms grafted on ‘Tygress’ or ‘Cheong Gang’

wilted

• All heirlooms grafted on ‘Maxifort’ or ‘BHN602’ did not wilt”

Photo provided by Erin Rosskopf

Dr. Erin Rosskopf

Slide by Erin Rosskopf (2016)

Possibly having Tm-2

or Tm-2a?

Likely safe to graft heirloom

tomato or tomato with

unknown genotypes

USDA Specialty Crop Research Initiative“Growing New Roots: Grafting to Enhance Resiliency in U.S. Vegetable Industries”

• Team effort of 37 investigators from 10 institutions across the country

• Collaboration opportunities

• Stakeholder-driven problem-solving research collaborations with task-oriented academic teams

• Opportunities for evaluating new rootstock materials for various cropping systems and climate zones