Estimating parental contributions to hybrid rootstocks in grafted tomato
The introgression of new traits from wild relatives using traditional and marker-assisted breeding is a proven but time-consuming and costly approach to improve tomato plants. Interspecific hybrid rootstocks offer growers an alternative, faster way of delivering traits derived from wild germplasm. Grafting to rootstock is now commonly used in annual vegetable production to control root system diseases, replace fumigation, and impart vigor. A primary objective of this study was to address the practicality of using grafted plants in soil-based production to improve the yield and quality of processing tomato cultivars. Partitioning variance into genetic and environmental components provided a measure of the heritability for important traits and allowed us to assess the relative importance of rootstock and environment. In addition, we measured the contribution of individual parents to the hybrid rootstocks. We used a randomized complete block design with two replicates, in two locations, over the course of two years. The trial included 13 experimental rootstocks, 4 commercial rootstocks, self-grafted (positive control), and un-grafted scion (negative control). Four scions were used: the commercial cultivars 'Heinz 8504' and 'Heinz 5108'; an F1 hybrid developed at The Ohio State University, FG12-407; and the high lycopene inbred line FG99-218. Yield was not significantly improved for hybrids, but was significantly improved in scion, FG99-218, which underperforms compared to other cultivars when un-grafted. Grafting improved the yield of FG99-218 without compromising its high lycopene content. Analysis of the parental contributions of hybrid rootstock to measured traits demonstrated that selections of Solanum habrochaites tend to increase the number of adventitious shoots formed by the rootstock. The parent F7547 contributes to higher scion yield. Parental contributions for vigor and quality were also analyzed, and parents for the development of new hybrid tomato rootstocks were identified. Partitioning variance from cultivar trials provides information that may improve breeding efforts in the future.
Fenstemaker, S., Miller, J., Cooperstone, J. and Francis, D. (2021). Estimating parental contributions to hybrid rootstocks in grafted tomato. Acta Hortic. 1302, 241-250
rootstock breeding, Solanum habrochaites, Solanum lycopersicum, Solanum pimpinellifolium, adventitious shoots, lycopene, yield