Increasing the productivity of cucumbers to high nutrient solutions concentration by grafting on different rootstocks

High concentrations of salts in the root zone of plants are a common problem in greenhouse vegetable production, leading to reduced yields and yield deterioration. The aim of the performed study was to establish whether grafting cucumber plants (Cucumis sativus L., ‘Kiara F₁’) onto different local cucurbitaceous and hybrid rootstocks (Lagenaria siceraria (K/LS); Cucurbita moschata ‘Moschata 51-17’ (K/CMo-M); Cucurbita maxima × Cucurbita moschata ‘Carnivor F₁’ (K/CMM-C) could increase productivity to high nutrient solution concentrations (NSC). The experiments were carried out in a greenhouse during 2013-2015. Grafted and non-grafted plants were cultivated at 3 nutrient solution concentrations (1.8 mS cm^‑1 (optimal), 3.7 and 5,5 mS cm^‑1) till full maturity. EC levels were prepared by adding all macro- and micronutrients to the irrigation water. During this period, the influence of high nutrient solution concentrations on early maturity, total and marketable yield, total number of fruits, average fruit weight, and length were studied. Salinization during the reproductive period adversely affects the productivity of non-grafted and grafted cucumber plants; the reduction is greatest at higher nutrient concentrations. In terms of early maturity, the concentration of the solution has the strongest negative effect on the graft combination ‘Kiara’/Cucurbita maxima × Cucurbita moschata ‘Carnivor F₁’ (K/CMM-C). The least affected cultivar is ‘Kiara F₁’. Early maturity is highest in the graft combination ‘Kiara’/Lagenaria siceraria (K/LC). The highest values are total and standard yields as ‘Kiara’/Cucurbita maxima × Cucurbita moschata ‘Carnivor F₁’ (K/CMM-C) in all nutrient solution concentration levels, respectively, from 17.06, 19.69%, and 42 to 21% (EC 3.7, 5.5 mS cm^‑1) above the control. The plants from this combination show higher viability, and fewer deviations in biometric, physiological, and biochemical parameters, which characterize them as a tolerant genotype.