SUSTAINABLE TEA PRODUCTION: A COMPARATIVE ASSESSMENT OF THE GROWTH, YIELD, AND QUALITY OF TEA UNDER CONVENTIONAL AND ZERO- INPUT ORGANIC MANAGEMENT AT QUEENSBERRY ESTATE, SRI LANKA

Abstract

Sri Lanka, a leading global tea producer and a pioneer in organic tea cultivation, holds strong potential for expanding the organic tea sector. Comprehensive scientific validation through systematic assessment of organic and conventional tea management systems can generate evidence to promote the expansion of organic tea in Sri Lanka. Growth, yield, and quality attributes of tea (cultivar DN) were evaluated under organic with zero inputs (T1) and conventional with chemical inputs (T2) at Queensberry Estate, Nawalapitiya, Sri Lanka, using a Randomized Complete Block Design (RCBD) with three replicates. Growth and yield parameters, soil and leaf nitrogen content, and leaf chlorophyll content (measured with SPAD) were recorded. Additionally, the quality of brewed tea was assessed through sensory evaluation by untrained panelists. Growth, yield, and chemical parameters were analyzed using one-way ANOVA in R, while sensory data were evaluated through the Friedman test in Minitab. Results revealed that soil available nitrogen was significantly higher (p<0.05) in conventional treatment (0.090%) compared to organic treatment with zero inputs (0.065%). Similarly, leaf total nitrogen content in T2 (1.145 %) is significantly greater (p<0.05) than in T1 (0.898%). Correspondingly, leaf area, shoot growth rates, and mean shoot length were significantly (p<0.05) higher in T2 (6.60 cm) compared to T1 (4.23 cm). In contrast, the mean number of shoots in 100g was significantly greater (p<0.05) in T1 than in T2. Leaf chlorophyll content and yield were not significantly different (p>0.05), yet greater in T2 than in T1. Sensory evaluation showed no significant quality differences between T1 and T2. In conclusion, conventionally managed tea has superior growth, yield, and quality attributes compared to organically managed tea with zero inputs. A long-term application of organic inputs is recommended to achieve better growth, yield, and quality in organically managed tea.