47 th Tomato Breeders Roundtable, Wooster, April 5th Grafting Technologies and Their Trends Chieri Kubota Department of Horticulture and Crop Science The Ohio State University www.plugconnection.com
Gourd grafting for large fruit production in China 500s Use of vegetable grafting - historical timeline Discovery as promising IPM tool for fusarium in watermelon (Japan) Watermelon farmers began to use grafting for intensive cultivation (Japan/Korea) 1920s- 1930s Breeding technology development of for disease resistance (worldwide) Tomato grafting was introduced commercially since 1970s (Japan) Globalization of seed market and supply Grafting technology adopted in Israel and Europe 1950s- 1980s 1990s Montreal Protocol (1989) Tomato grafting introduced in hydroponic greenhouse in Holland 1940s 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 1990s 2000s 2010s Vegetable grafting for retail market in US Vegetable grafting in various crops and production systems in Mexico (and US)
Legenaria rootstock plants and watermelon scion sprouts (Photo taken in Nagano, Japan; dated on April 5 th, 1967)
Tube grafting A breakthrough for modernizing Developed by Itagki et al. in 1990s. Improved grafting speed. Indoor healing under electric lighting was developed together with this method. tomato grafting
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) Key technologies Lighting (LEDs) Cooling (A/C) CO 2 enrichment Air circulation RH control Irrigation (fertigation) Automation BergEarth, Japan Grafted Growers LLC
Indoor growing under electric lighting Consistency in plant growth Uniformity in growth and development Making automated grafting easier Full control capacity of temperature, light, CO 2 and humidity Typical conditions for tomato plants: 200-300 mmol m -2 s -1 PPFD, 400-1,000 ppm CO 2, 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/m 2 /d or 3-5 kj/m 2 /d UV- B dose achieved by 0.1-0.2 W/m 2 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) + UV-B (7 mmol/m 2 /d) 10%B 10%B+FR 50%B 50%B+FR
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? Grafting machine demonstration at the ISHS symposium on Transplant Production Systems in Yokohama in 1992. AgriVest 2015 Part-6-Rootility https://www.youtube.com/watch?v=koxna3qkdp4
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 ToMV resistance genotype (Tm-1, Tm-2 a, 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
Likely safe to graft heirloom tomato or tomato with unknown genotypes Slide by Erin Rosskopf (2016) Possibly having Tm-2 or Tm-2 a?
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 taskoriented academic teams Opportunities for evaluating new rootstock materials for various cropping systems and climate zones