Bioactive constituents of red and green lettuce grown under colour shade nets

Abstract

The objectives of this study were to investigate the effects of coloured shade-nets (pearl, blue, or red all with a 50% shade index) compared to non-shaded plants on quality traits on the Discoa and ICE 40102 (green-leaf) and Eglantine (red-leaf) lettuce cultivars. Total chlorophyll content depended on the shading and lettuce genotype. The chlorophyll a and b contents were higher in shaded than unshaded plants. The cv. Eglantine had the highest total chlorophylls (637.03 μg∙g^-1 F.M.) content. The highest carotenoid content was in leaves of cv. Discoa under pearl nets (208.89 μg∙g^-1 F.M). The highest total phenols content (76.70±1.9 mg∙g^-1 GAE D.M.) was in cv. Discoa under red shade; the highest flavonoids content was for cvs. Discoa (42.97) and Eglantine (42.91 mg∙g^-1 RU D.M.) under blue shade. The blue and pearl shade nets resulted in slightly higher flavonoid contents in lettuce leaves compared to unshaded plants. The cv. Eglantine, under blue shade had the highest antioxidant capacity (EC₅₀ - 0.197 mg∙mL^-1). Red lettuce cv. Eglantine could be recommended for production due to its higher antioxidant properties. Generally blue shade can be used to retain antioxidant capacity.