Enhancing lettuce productivity and nutritional value through rosemary leaf extract and nano NPK applications

This study evaluated a sustainable strategy to enhance lettuce productivity and nutritional quality while reducing reliance on conventional fertilizers. Rosemary leaf extract (RLE; 0, 3, and 6 g/L) and nano NPK fertilizer (0, 1, and 2 g/L) were applied as foliar sprays. RLE at 3 g/L significantly increased chlorophyll, carotenoids, total phenolic content, flavonoids, and antioxidant activity in inner leaves, also phenolics in outer leaves. Nano NPK at 2 g/L improved root and leaf dry matter and enhanced stem nitrogen, along with leaf phosphorus and potassium contents. The combined treatment of 3 g/L RLE and 2 g/L nano NPK resulted in the highest overall productivity and quality, whereas higher doses and the control were less effective. This integrated strategy offers an eco-friendly and efficient option for leafy vegetable production. This integrated strategy offers a potentially efficient and resource-saving approach for leafy vegetable production, though its environmental sustainability requires further investigation.