Grafting Wild Tomato Genotypes and Mexican Landraces Increases Trichome Density and Resistance against Pests

To assess Mexican genotypes of tomato, Solanum lycopersicum L., in response to pests and as potential rootstocks, 10 genotypes were evaluated under field conditions from June to November 2016 in the Ciénega of Chapala region, Mexico. Two wild genotypes, eight landraces, and one commercial cultivar as a check were evaluated. Genotypes with denser trichomes and resistance against pests were evaluated as rootstocks of commercial variety ‘Rio Grande' (January-April 2017) under greenhouse conditions at Las Agujas, Jalisco, Mexico. Pest incidence, trichome density, and yield were recorded. Wild and creole genotypes differed statistically (P ≤ 0.05) by incidence of pests and density of trichomes; some had fewer pests and denser trichomes compared to the commercial variety. Density of trichomes and resistance against pests were inversely correlated (r = - 0.48 to - 0.91, P ≤ 0.05). Six genotypes with greater potential were selected as rootstocks. Except one, greater density of trichomes in landraces and wild genotypes was transferred by grafting to the commercial variety without reducing yield potential. Trichome density and pest incidence were inversely correlated (r = - 0.60 to - 0.94, P ≤ 0.05) in the grafted tomato plants. Yield of grafted plants was as many as six times greater (12.38 vs. 1.80 kg/plant, respectively) than the nongrafted variety. Results contribute to prediction of resistance of crop varieties against pests and take advantage of Mexican tomato genotypes by direct production or indirectly for improvement of commercial cultivars.