Based on the climate condition of Iran and most of its soils that are calcareous, it is important to
prepare the nutritional requirements of cucumber and decrease the growth and development limitations
of greenhouse cucumber. In this way, notation to pH properties is essential. Optimum pH for plants
production is slightly acidic such that it is necessary to correct soil pH to a more suitable range in order
to increase nutrients availability for plants. The goal of this research is to assess the effect of irrigation
water pH changes on yield and nutrient uptake especially on micro nutrients by plant. The experiment
consisted of three treatments of pH (5.5, 6.5 and 7.5). The experiment was carried out in a factorial
design in the research greenhouse of Khorasgan University. During growth season, Ca and
micronutrients were not used. After sampling different nutrients, concentrations were measured. At the
end of growth season, growth indices were measured. The evidences provided by this experiment
indicated that pH changes did not have significant effect on fruit yield and dry weight of plant shrub.
Also, irrigation water pH did not have effect on chlorophyll amounts, LAI and stem diameter,
significantly. However, the highest amount of LAI was achieved in pH = 5.5. The pH changes in
irrigation water had significant effect on nutrients uptake, though micronutrients uptake was increased
and the optimum concentration of nutrients was extracted in plant leaves and fruits by decreasing the
pH to 5.5. The maximum uptake of Ca and Mg was obtained when the pH = 7.5 and the maximum uptake
of N, P and K was obtained when the pH = 6.5.
Key words: Acidification, cucumber, micro and macro nutrients, growth indices.