2019 ASHS Annual Conference

With proper rootstock and scion selection, vegetable grafting could ensure improved and stable yield in tomato even in the presence of biotic or abiotic challenges of specific production systems. In this study, grafted and non-grafted tomato treatments as genotype (G) were evaluated in different environments (E) to (i) determine the magnitude of genotype by environment interaction (G × E), and (ii) identify grafted tomato combinations with high stability for yields and yield components across different environments in Texas. Different sets of grafted treatments were included in each trial in the 2017 and 2018 spring seasons. In 2018, the six grafted treatments involved non-grafted tomato cultivars ‘TAMU Hot’ (TAM) and ‘HM1823’ (HM) and grafted on ‘Estamino’ (TAM/ES, HM/ES) and ‘Multifort’ (TAM/MU, HM/MU). Genotypes were tested in eight environments including high tunnel (HT) and open-field (OF) in Lubbock (LU-HT, LU-OF), Overton (OV-HT, OV-OF), Uvalde (UV-HT, UV-OF), and Weslaco (WE-HT, WE-OF). The combined analysis of variance indicated highly significant effects of E, G, and G ×E interaction for total and marketable yields, fruit number per plant and average fruit weight. Environment accounted for 71 to 86% of the total variation in the sum of squares for all these traits, whereas genotype accounted for 4.8 to 10.8%, and G × E for 4.3 to 6.7%. Marketable yield varied from 61.9 to 88.4 Mg ha^-1 with a grand mean of 73.1 Mg ha^-1. HM/MU had the highest marketable yield while HM, TAM and TAM/MU exhibited yield lower than the grand mean. In both seasons, total and marketable yields in OF system across the testing locations were lower than the grand means. LU-OF had the lowest yields while LU-HT and UV-HT exhibited the highest yields. Moreover, higher yields in HT relative to OF were mainly due to significantly higher number of fruits per plant. Based on the univariate and multivariate stability measures, HM/MU for total yield and HM/ES for marketable yield were the most stable graft combination while TAM/ES was very unstable for the yields across test environments. These high-yielding and stable graft treatments could be evaluated further and promoted for a successful integration of grafting technique into current tomato production practices in Texas.