Response of cucumber (Cucumis sativus L. ‘Kiara’) plants, grown on own root or grafted onto different rootstocks, to high nutrient solution concentrations

The aim of the performed model study was to establish whether grafting cucumber plants (Cucumis sativus L. ‘Kiara F₁’) onto different Cucurbitaceae rootstocks (Lagenaria siceraria (K/LS); C. moschata ‘Moschata 51-17’ (K/CMo-M) and C. maxima × C. moschata ‘Carnivor F₁’ (K/CMM-C) could improve their tolerance to high nutrient solution concentrations (NSC). The experiments were carried out in a greenhouse during 2013-2015. Grafted and own root grown plants were cultivated hydroponically on inert substrate at three NSC (1.8 dS m^‑1 (optimal), 3.7 dS m^‑1, or 5.5 dS m^‑1) until full maturity. The response of cucumber plants to higher NSC was monitored twice in the vegetation period through morphological (root length, plant height, fresh biomass, leaf area, number of leaves, etc.) and physiological (photosynthetic pigments, chlorophyll fluorescence, leaf gas exchange, plant water potential, electrolyte leakage) parameters. Cucumber plant growth was inhibited at high NSC, but it was more severe in those grown from their own roots. The depression of leaf water potential revealed that both groups of plants experienced physiological water stress, especially those, exposed to the highest NSC (5.5 dS m^‑1). An increased electrolyte leakage from the leaves was established, which was more pronounced in the own root-grown plants. Leaf gas exchange was diminished, but mаximal efficiency of PSII was not affected. The grafting of cucumber plants onto Cucurbitaceae rootstocks can potentially increase tolerance to NSC, but more research is needed to clarify the most suitable rootstocks.