Integrated Effects of NPK Fertilizer and Spent Mushroom Substrate on Lettuce Growth, Yield and Antioxidant Enzyme Activity

Abstract

The study investigates the effects of NPK fertilizer and spent mushroom substrate (SMS) on lettuce (Lactuca sativa) growth, yield, and antioxidant enzyme activity. SMS, a by-product of mushroom cultivation, is a sustainable organic fertilizer rich in organic matter and beneficial microbes, while NPK provides essential macronutrients for plant growth. A greenhouse experiment was conducted using four treatments: control (no amendment), SMS, NPK, and a combination of SMS and NPK. Key growth parameters, including plant height, number of leaves, and fresh and dry weights of leaves and roots, were measured, alongside oxidative stress markers and antioxidant enzyme activities. The results revealed that SMS and NPK independently improved lettuce growth and physiological responses, but their combined application had the most significant effects. The SMS+NPK treatment increased plant height, leaf and root biomass, and antioxidant enzyme activities while reducing oxidative stress markers like MDA and H₂O₂. This synergistic effect underlines the potential of integrating organic and inorganic fertilizers to enhance crop productivity sustainably. The findings highlight the benefits of SMS as an environmentally friendly amendment, cost-effectiveness, and its potential to complement NPK for sustainable agricultural practices. SMS enhances soil microbial diversity and organic matter content more effectively than inorganic fertilizers, leading to improved nutrient cycling and long-term soil fertility. This research offers a novel application of SMS as a low-cost substitute for fertilizers that pose environmental risks.