Toward More Effective Selection of Tomato Rootstock and Scion Varieties for Use in US Soil-Based Production, Including Organic

North American propagators and fruit growers look ever more often to preparing and using grafted tomato plants to enhance income potential. Selecting rootstock (RS) and scion (Sc) variety combinations is the first step in that process. Scientists also gain from choosing varieties reliably. The technical and lay literature, however, currently satisfy neither community. Our goal has been to develop decision aids through rigorous documentation beginning at seeding and concluding with post-harvest fruit quality assessment. Our most recent effort involves 18 RS and 5 Sc varieties (90 combinations). Seedling growth rate, graft success, grafted plant vigor and fruit yield are being recorded at OARDC and by grower-cooperators in thirteen states. Varieties were chosen based on grower input, market type and reported traits. Seedling growth and grafted plant vigor are monitored directly and indirectly using destructive and non-destructive measures. Graft success and grafted plant yield are assessed using standard protocols. Data are analyzed to account for variation assigned to variety combination, grafter and date of grafting, location of yield test and other sources. Narrowly, the data will help identify combinations among the ninety tested that: a) can be grafted most effectively, b) resume growth most quickly after grafting and c) maximize fruit yield. More widely, the effort will also help establish protocols for high-throughput assessment of the large and growing number of possible RS-Sc variety combinations on farms and within research-extension programs.