Comparative evaluation of conventional and vermicompost fertilizers on broccoli (Brassica oleracea L.) in different agroecological zones

This study evaluated the effects of geographical locations (Adıyaman and Pozantı) and fertilizer types (vermicompost and conventional) on yield, vitamin C content, total phenolic content and other quality parameters of two broccoli cultivars (‘Orantes’ F₁ and ‘Robredo’ F₁). Over 2 years of field trials conducted in open-field conditions using a randomised complete block design (RCBD) with three replications, both location and fertilizer type had a significant effect on broccoli growth and yield parameters. In Pozantı, conventional fertilizer achieved the highest total yield for ‘Orantes’ F₁ (1403.74 kg · da⁻¹) and the highest soil and plant analyzer development (SPAD) chlorophyll meter readings (85.72). In Adıyaman, ‘Robredo’ F₁ adapted better, reaching 1256.43 kg · da⁻¹, while ‘Orantes’ F₁ had the highest vitamin C (1392.13 mg · kg⁻¹) and phenolic content (434.11 mg · kg⁻¹) with conventional fertilizer. Nitrogen content generally decreased with vermicompost application compared with conventional fertilizer, showing a reduction of up to 24.03% in ‘Robredo’ F₁ grown in Pozantı during the second year. By contrast, potassium content increased by 29.39% in ‘Orantes’ F₁ (Adıyaman, first year) under vermicompost, while ‘Robredo’ F₁ showed a decrease of 32.96% under the same conditions. Iron (Fe) concentrations were higher in ‘Orantes’ F₁ with vermicompost, with an increase of 24.98% in Adıyaman and 15.65% in Pozantı, whereas conventional fertilizer led to a much higher Fe content (79.06% increase) in ‘Robredo’ F₁ (Adıyaman). Zinc (Zn) levels were generally enhanced by vermicompost, particularly in Pozantı—’Orantes’ F₁ where a 41.46% increase was recorded, while ‘Robredo’ F₁ in Adıyaman showed a 16.23% decrease. These results emphasise the importance of genotype and location in determining the efficiency of organic vs. conventional fertilizers. These results highlight the need for site-specific fertilizer strategies to optimise broccoli yield and quality.