Sustainable valorization of tea waste for promoting plant growth, secondary metabolites production and environmental sustainability in tea cultivation

Camellia sinensis (L.) Kuntze, represents a commercially significant crop, primarily recognized for its pharmacologically active secondary metabolites, including catechins and caffeine. However, excessive reliance on agrochemicals threatens both soil fertility and the biochemical quality of tea leaves, underscoring the urgent need for sustainable agronomic alternatives. The present study evaluates the agronomic and biochemical efficacy of Tea Waste Manure (TWM), an organic amendment derived from post-industrial tea processing residues, as a sustainable substitute for synthetic agrochemicals. Field experiments were conducted from July 2023 – October 2024 at two distinct tea-growing areas of Uttarakhand, India. Pre-and post-treatment assessments encompassed quantitative analysis of vegetative biomass, photosynthetic pigment concentrations (chlorophyll a, chlorophyll b, and total carotenoids), as well as targeted metabolite profiling, including total phenolic content, total flavanol content, catechins, and caffeine content. The research additionally emphasizes on evaluating the impact of TWM on soil health via enumerating bacterial load, determining physicochemical and nutritional properties, and enzymatic activity of soil. Application of TWM resulted in statistically significant enhancements in plant growth, pigment biosynthesis, and metabolite accumulation with an increase in catechin and caffeine concentration in leaves. Additionally, soil analyses demonstrated enhanced fertility attributes, including optimised pH, elevated macronutrient levels, and increased microbial proliferation, as well as increased enzymatic activity. In conclusion, the findings reaffirm the viability of converting agro-industrial waste into organic inputs, not only enhancing resource efficiency but also promoting environmentally sustainable tea cultivation practices, paving the way for a greener and more environmentally friendly agricultural future.