Variations in quality constituents of green tea leaves in response to drought stress under south Indian condition

Soil moisture stress seriously limits the growth and development of tea plants (Camellia sinensis), thus affecting crop yield and quality. Soil moisture reduction generally affects accumulation of tea secondary metabolites. To elucidate the variations in plant genotype response to abiotic stress during depleting soil moisture stress and changes in biochemical constituents of green leaf which determines the quality of black tea was investigated. An experiment was conducted at UPASI Tea Research Foundation Tea Research Institute, Distinctiveness-Uniformity-Stability center with drought tolerant clones namely UPASI-2, UPASI-6, UPASI-9, ATK-1, TRI-2025 and drought susceptible clones UPASI-3, UPASI-8, UPASI-17, TRF-1 of same age. Green leaves were collected from each plot was subjected to HPLC analysis for dihydroxyflavan-3-ols, trihydroxyflavon-3-ols and caffeine, and the results were statistically analyzed. The study indicated that the levels of total polyphenols, individual catechins, reducing sugars, amino acids and total lipids were significantly different at P ≤ .05 among the treatments. Caffeine level increased (P ≤ .05) with decrease in soil moisture for all the clones. Principal component analysis and hierarchical cluster analysis revealed differences between tea cultivars with respect to their quality and tolerance. Our study further indicated that the tolerant clones were able to accumulate higher levels of bio constituents during soil moisture stress than the susceptible ones. Quality of green tea leaf precursors is directly influenced by the soil moisture availability and is varietal dependent. This could be an important tool for the assessment of clonal performance and drought tolerance in tea cultivars.