Final Report on Graduate Student Project “Guidance in selecting optimal combinations of rootstock and scion varieties for organic grafted tomato production”
Bizhen Hu (Graduate Student) and
Matthew D. Kleinhenz (Major Advisor and Extension Vegetable Specialist)
Department of Horticulture and Crop Science,
The Ohio State University,
Ohio Agricultural Research and Development Center,
1680 Madison Avenue, Wooster, OH 44691-4096
Grafting produces an immediate physical hybrid of two varieties. Rootstock varieties are chosen for root system traits while scion varieties are selected for shoot and fruit traits. Grafting has the potential to move desirable traits to farms and gardens more quickly since it bypasses the lengthy process of true genetic hybridization involving breeding, selection and balancing the value of individual root, shoot and fruit traits. Organic tomato growers look to benefit from the use of grafted plants and their reportedly greater performance under optimal and sub-optimal conditions. However, both organic grafted plant suppliers and users are hampered by the lack of research-based information on rootstock and scion varieties; specifically, combinations that: a) can be grafted most effectively, b) resume growth most quickly after grafting and c maximize fruit yield on real farms. The overall goal of this project was to provide comprehensive assistance to organic growers in the area of rootstock and scion variety selection. Three specific studies were completed and three major conclusions were drawn:
- The growth of seedlings of eighteen rootstock and five scion varieties (selected based on growers’ nominations and publicly available information) was charted in the greenhouse. The results indicate that seeding dates and grafting operations must be scheduled carefully to accommodate inherent differences in seedling vigor among varieties.
- Grafts involving ninety rootstock-scion variety combinations were attempted and the percent success rate was calculated. The results indicate that ‘incompatibility’ is unlikely to be a barrier to grafting these varieties in the future.
- A total of approximately 1,000 grafted plants representing all ninety rootstock-scion variety combinations were provided to thirty-one growers in eleven states throughout Ceres Trust Region and two states at other locations in the U.S. for on-farm evaluation. Overall, cooperating growers shared images, observations, and yield data of the grafted plants. Grafted plant performance varied by rootstock-scion combination and farm, and growers remain interested in additional evaluation and use of grafted plants.