DETERMINATION OF THE OPTIMAL FERTILIZATION RATE BY A NEW BIOORGANIC FERTILIZER TO ENHANCE THE GROWTH PARAMETERS AND NUTRITIONAL QUALITY OF RED BEETROOT (BETA VULGARIS L. SSP. VULGARIS)

The goal of this study was to investigate the effect of different rates of a new bioorganic fertilizer and an inorganic fertilizer on the parameters growth and the nutritional quality of red beetroot. A field trial was conducted using the randomized complete block design with six treatments and six replications: (T1= inorganic fertilizer, NPK 20-45-25 ha−1, T2= Bio-Organic Fertilizer “BOF” at 10%, T3= BOF at 20%, T4= BOF at 30%, T5= BOF at 60% and T6= unfertilized control). The total carbohydrate, protein and nitrate content of harvested red beetroot was measured analytically. Quantification of betanin was determined spectrophotometrically, while the antioxidant activity assessed free radical scavenging activities against DPPH. Statistical analysis of soils treated with 20 and 30% BOF showed similar results for the total weight of red beetroot and the weight and diameter of their bulbs. However, these treatments significantly (p < 0.05) increased the betanin content of red beetroot by 16 % compared to the conventionally grown samples. However, the investigation of the effect of the different rates of BOF on the IC50 value showed a decrease of up to 52% in favor of the T5 treatment compared to the inorganic fertilizer. In contrast, organically and conventionally growing red beetroot had similar average nitrate levels. In light of the crucial role of BOF rates, high levels of macro and micronutrients in the soil negatively affect all quality parameters of red beetroot.