Effects of different fertilizer sources and rates on proximate and phytochemical composition of three cucumber varieties (Cucumis sativus L.)

Abstract

Proximate and phytochemical analysis of three cucumber varieties (Poinsett, Marketer and Marketmore) as influenced by the application of fertilizer types and rates was carried out at the Department of Biochemistry and Molecular Biology of the Obafemi Awolowo University, Ile-Ife. Cucumber was subjected to four fertilizer types: Organic fertilizer, Liquid organic fertilizer, Urea fertilizer and NPK fertilizer applied at the rate of 0, 75 and 120kg N/ha. Proximate compositions showed several disparities with the different treatments. Poinsett, Marketer and Marketmore varieties responded well to Liquid organic fertilizer treatment at all rates to produce significantly (p<0.05) high percentage carbohydrate contents and dry matter contents. Higher rates of Urea and Organic fertilizer favoured the production of crude protein. The qualitative phytochemical analysis showed that Marketer and Marketmore varieties accounted for the highest secondary metabolites. Phenols were readily available in all varieties regardless of the nutrient source. NPK and Urea fertilizer produced more phenols and at higher rates, accounted for more flavonoids in Marketer and Marketmore varieties. 120 Kg N NPK increased the percentage carbohydrate in Poinsett, Markerter and Marketmore by 48%, 5% and 1% respectively. Also, 120 Kg N NPK accounted for 30% and 2 % increase in proximal fruit dry matter for both Poinsett and Marketmore varieties respectively whereas 120 Kg N Liquid Organic fertilizer boosted fruit dry matter in Marketer by only 10%. Results showed that organic fertilizer improved the nutritional values in cucumber fruit compared with inorganic fertilizer but increased the perishability by increasing the moisture content. However, there is the need to further quantify the concentration of the secondary metabolites in cucumber fruits for nutritional values.

Keywords: Cucumber, Fertilizer, Phytochemicals, Proximate Composition