AbstractThe influence of age after pruning on the biochemical constituents such as catechin fractions, the key enzyme phenylalanine ammonia lyase (PAL) and other compounds which contribute to black tea quality as well as root carbohydrates was investigated. Analyses were done consecutively for 4 years after pruning. The concentration of total catechins was found to be highest in the ‘Cambod’ cultivar UPASI‐17, followed by UPASI‐3 and UPASI‐9 representing ‘Assam’ and ‘China’ jats respectively, under prevailing conditions. A concomitant increase in total catechin content was found up to 3 years followed by a decrease in the fourth year of the pruning cycle, irrespective of the cultivar. PAL, the precursor of catechin biosynthesis, also increased up to 3 years and showed a sharp decrease thereafter. On the other hand, the root carbohydrate reserve and the caffeine content of tea leaves increased steadily up to the fourth year. All the genotypes studied showed the same trend. However, variability in catechin contents was prominent in different clones. Copyright © 2005 Society of Chemical Industry