Grape Tomato Growth, Yield, and Fruit Mineral Content as Affected by Rootstocks in a High Tunnel Organic Production System

Abstract

Recently, so-called “vegetative” and “generative” rootstocks have been identified by seed companies as rootstock types that have different impacts on tomato scions. In this experiment of grafted grape tomato production in an organically managed high tunnel system, we characterized the effects of vegetative and generative rootstock cultivars on tomato yield components and fruit mineral contents. Grape tomato scions ‘BHN 1022’ (determinate) and ‘Sweet Hearts’ (indeterminate) were grafted onto ‘DR0141TX’ (vegetative), ‘Estamino’ (generative), and ‘Multifort’ (noncharacterized) rootstocks with self- and nongrafted scions as controls. Experiments were conducted twice with different transplanting dates (Expt. 1: 31 Jan. vs. Expt. 2: 9 Mar.) in 2018. No rootstock by scion interaction effects on whole-season fruit yield components were observed, indicating similar responses of determinate and indeterminate grape tomato scions to all rootstocks tested. For Expt. 1, the three rootstocks increased marketable fruit number, marketable yield, and total yield by 23.3%, 37.9%, and 34.4% on average, respectively, compared with the self- and nongrafted controls, primarily due to improved productivity during the peak and late harvest periods. For Expt. 2, the rootstocks did not significantly benefit any whole-season yield components. ‘DR0141TX’ and ‘Multifort’ increased stem diameter in both experiments, whereas ‘Estamino’ only increased stem diameter in Expt. 2 relative to the nongrafted controls. Consistent increase in aboveground dry biomass of rootstock treatments at crop termination in Expt. 1 corresponded to the greater yield of rootstock-grafted plants in that experiment. All rootstocks in both experiments consistently increased fruit P, K, Ca, Zn, and Fe contents on a dry weight basis at peak harvest regardless of the tomato scion used. Despite a relatively low level of root-knot nematode infestation, plants grafted with ‘DR0141TX’ or ‘Estamino’ tended to have lower root galling index ratings than scion controls and ‘Multifort’-grafted plants, which was more evident in Expt. 1. Given the different environmental conditions during the tomato production period between the two experiments conducted in high tunnels, our findings highlight the important influence of production environment on grafted tomato performance. This study on grafted grape tomatoes in high tunnel organic production systems also demonstrated that so-called “vegetative” and “generative” rootstocks had similar impacts on tomato scion yield components and fruit mineral contents.