2019 ASHS Annual Conference

Grafting in tomato using vigorous rootstock is mostly carried out to increase tolerance to biotic and abiotic stresses and improve crop productivity. However, limited information is available about the impact of somatogenetic interactions between rootstock and scion in tomatoes especially in defining the qualities of fruits. In this 2-year study, the effect of grafting on metabolic traits contributing to the quality of tomato fruits was evaluated in high tunnel (HT) and open field (OF) production systems across different growing environments (Overton, Uvalde, and Weslaco) in Texas. Six grafted treatments of two root-stocks (‘Estamino’ and ‘Multifort’) and two scions (‘TAM Hot Ty’ and ‘Tycoon’) in 2017; (‘TAM Hot Ty’ and ‘HM1823’) in 2018 were considered in each of the two growing seasons. Greater differences in fruit quality traits were due to the production system than grafting treatments. Except for a 10 to 18% significant decrease in ascorbic acid (Vit C) of grafted fruits, other metabolic traits including sucrose, glucose, fructose, ^oBrix, titratable acidity, polyphenol, and carotenoids (lycopene, β-carotene, lutein) were not significantly different between grafted and non-grafted fruits. In contrast, the production system (HT vs. OF) had a significant influence on the fruit quality. Specifically, significant increases in lycopene (36%), β-carotene (27%), fructose (16.7%), glucose (14.3%) and Brix/acid ratio (22%) were detected in tomatoes grown under the high-tunnel structure in 2017, but not in 2018. Tomato fruit quality was also impacted by the location in both the seasons. A significant seasonal variation explicitly for sugars (sucrose, glucose, and fructose) and anti-oxidants (lycopene, β-carotene, and lutein) was confirmed among the growing environments. Taken together, grafting along with the production system and growing environment greatly influenced quality traits in tomato fruits.