Effects of grafting with wild tomato (Solanum pimpinellifolium and Solanum habrochaites) rootstocks on growth and leaf mineral accumulation in salt stress

The positive response of grafting by tolerant rootstocks or scion-stock interactions on yield and fruit traits of tomatoes under saline conditions is attributed to several physiological and biochemical changes. In this study, we investigated some tolerance mechanisms by which grafting on wild rootstocks in tomatoes can prevent or minimize the effects of salt stress in plants under hydroponics conditions. Two tomato cultivars H2274 and Galaxy were grafted onto three S. pimpinellifolium, three S. habrochaites, S. lycopersicum L. x S. pimpinellifolium and S. lycopersicum L. x S. Habrochaites hybrid tomato genotypes. Plants were grown in hydroponic culture at two electrical conductivity (EC) levels (control at 1.5 dSm(-1) and salt at 8.0 dSm(-1)). Salt stress led to a significant reduction in biomass growths of both grafted and nongrafted tomatoes. However, the plants that are least affected by salt stress are those grafted on wild tomato rootstocks. Leaf nutrient contents were significantly affected by rootstocks under both control and salt stress conditions. In this study, under saline conditions, plants grafted on wild rootstocks had higher N, P, K, Ca, Mg, S, Mn, Fe, Zn and B contents in leaf tissues and lower Na and Cl contents than ungrafted plants. Biochemical and physiological results revealed that S. pimpinellifolium and S. habrochaites have inherited salt tolerance from their genetic background. These wild tomato genotypes can be used as rootstocks in tomato breeding programs to develop salt-tolerant tomatoes or in grafting techniques under saline irrigation conditions.