How does grafting affect the ionome of cherry tomato plants under water stress?

The response of grafted vegetables to stress conditions owing to the nutrient status may be different than that of self-rooted plants, depending mainly on the rootstock genotype. The aim of the present work is to determine the response of reciprocal grafts made between cherry tomato cultivars (Solanum lycopersicum) to moderate water stress, examining uptake and concentration of nutrient. The tomato cultivars Zarina (drought-tolerant) and Josefina (drought-sensitive) were reciprocal grafted and selfgrafted, and ungrafted were used as control. The total content and uptake fluxes of macro- and micronutrients were determined in leaves. Our results show that the use of drought-tolerant cv. Zarina like rootstocks (ZarxJos) showed improve ionome, with increases in nitrogen (N), phosphorus (P) and potassium (K) concentration and uptake fluxes, and an increase in iron (Fe) and copper (Cu) concentration and uptake under water stress. Besides, the vigorous root system of rootstocks is often capable of absorbing plant nutrients more efficently than scion root, and we have showed that cv. Zarina and ZarxJos develop a better radicular system. This result confirms the hypothesis that grafted plants on vigorous rootstocks can improve mineral nutrition and nutrient uptake with respect to ungrafted plants, especially under water stress conditions.