A growing global population and worsening global environmental change necessitate the development of improved crop varieties and cultivation techniques. In tomatoes, the world’s most popular vegetable crop, grafting has emerged as a cultivation technique for addressing these challenges through improving tomato crop vigor and stress resistance, especially to abiotic stresses that are becoming more widespread including heat, salinity, and drought stress. In order to expand the offerings of tomato rootstocks, we have conducted multiple trials to assess the beneficial impact of 10 novel tomato rootstocks on ‘Celebrity’ scion vigor and stress resistance. The rootstocks, developed by colleagues at the King Abdullah University of Science and Technology (KAUST) consist of interspecific Solanum spp. hybrids including two tetraploid hybrids. We conducted three trials to assess the impact of grafting with the novel rootstocks, including a greenhouse pot trial to quantify growth and vigor and two controlled environment trials to assess stress resistance. In each trial, ‘Celebrity ’ scions were grafted with either the novel rootstocks, ‘Maxifort’, ‘Multifort’, or left ungrafted. In the greenhouse trial, measurements of stem diameter, shoot height, shoot canopy projection area, and fresh and dry weights at harvest were used to determine overall vigor. We identified five and eight of the novel rootstock grafting combinations that outperformed the ungrafted and ‘Maxifort’-grafted plants, respectively. Additionally, measurements of SPAD and observations of foliage coloration provided initial evidence of differential nutritive requirements between the novel rootstocks. In our controlled environment trials, chlorophyll fluorescence, SPAD, and porometer data demonstrated differential susceptibility to salinity, heat, and drought stress between the rootstocks. This presentation will highlight key differences in morphological and physiological traits that assisted us in selecting a narrow set of rootstocks for a forthcoming evaluation in a passive high tunnel to demonstrate the utility of these new rootstocks.
