High bicarbonate (HCO3-) content and associated high pH of irrigation water are detrimental to plant nutrient absorption. This experiment was arranged as a factorial in the framework of a completely randomized design with two factors, rootstock (ungrafted cucumber, Cucurbita moschata, and Cucurbita maxima) and bicarbonate (10 mM NaHCO3 or AS and 10 mM NaCl or SS). Regardless of rootstock, bicarbonate increased the pH of nutrient solution in all treatments. Under NaHCO3 treatment, the uptake and leaf concentration of K and Fe, and Mn uptake were not affected in plants grafted onto C. moschata rootstocks, whereas a significant decrease of them recorded in the control plants. Although the effect of alkalinity and rootstocks on Mg concentration was not significant, the highest Mg uptake observed in plants grafted onto C. moschata rootstocks. It is concluded that using C. moschata rootstock could reduce the deleterious effects of alkalinity stress on nutrient uptake by cucumber plants.
