The effect of silicon application and type of substrate on yield and chemical composition of leaves and fruit of cucumber

Silicon fertilization of plants improves yields and increases plant resistance to various stress factors. The use of silicon in plant fertilization is particularly justified in soilless culture. The aim of the present study, conducted in 2009-2010, was to determine the effect of root application of silicon in the form of silica sol and two growing media with a varying silica content on yield and chemical composition of fruit and leaves of the cultivar Unicum of greenhouse cucumber. Plants were grown in 10 dm 3 cylinders filled with sphagnum peat (I) or peat mixed with large-grained river sand at a ratio of 3:1 (v/v) (II). Four rates of silicon were applied in the study: 0, 250, 500 or 750 mg dm ?3 Si. The study found asi- gnificant increase in cucumber fruit yield when plants were fertilized with silicon by root application at the rates of 500 and 750 mg dm ?3 Si, compared to the control plants. Cucumbers grown in peat with the addition of sand (v/v 3:1) produced significantly fewer fruits compared to the culture in peat alone, but these fruits contained more total soluble solids. Significantly less calcium and more silicon were found in leaves of cucumber rootfertilized with silicon compared to the control plants. Fruits of cucumber plants fed with silicon by root application contained more dry matter, total soluble solids and silicon but less zinc and copper compared to fruits of the control plants.