Determination of antioxidative and enzymatic activity in green and red lettuce cultivars affected by microbiological fertilisers and seasons

Lettuce is a worldwide grown leafy vegetable rich in phytochemicals which are essential in human diet. The aim of this study was to examine the effect of genotype, microbiological fertilisers and season on the rosette fresh weight and components of antioxidant activity. Six cultivars (green ‘Kiribati’, ‘Aleppo’, ‘Aquino’ and red ‘Murai’, ‘Carmesi’, ‘Gaugin’) were grown in a greenhouse experiment during three consecutive seasons (autumn, winter and spring) with application of microbiological fertilisers (EM Aktiv, Vital Tricho and their combination). Green cultivars showed higher fresh weight than red in spring and winter. Green cultivar ‘Aleppo’ showed the highest fresh weight in control during spring. Microbiological fertilisers led to increased fresh weight in autumn. Mainly, red cultivars showed higher quality parameters compared to green (total antioxidant capacity, total phenolic content, total carotenoids and POD activity). Red cultivar ‘Carmesi’ showed the highest total antioxidant capacity, total carotenoids, and total phenolic content in winter with combination of fertilisers, Vital Tricho, and in control. In spring, ‘Carmesi’ and ‘Gaugin’ showed the highest POD activity with Vital Tricho, and combination of fertilisers. The present study suggested that genotype, fertilisers and season jointly influenced quantity and quality parameters with emphasis on Vital Tricho, and/or combination of fertilisers