Variability of morphology, phytochemical traits and essential oil profile of tea (Camellia sinensis (L.) Kuntze) accessions in the southern region of the Caspian Sea

Abstract

Tea (Camellia sinensis (L.) Kuntze) leaves are an important beverage crop due to their high caffeine content. Although the north of Iran is the main region for high-quality tea plants, there is no document on variations of phenotypic traits of different accessions. The present study was to assess the biodiversity of 12 tea accessions originating from four tea main sites in Iran (Langroud, Siahkal, Kobijar and Bazkiaguorab) using multivariate analysis. Two-year-old tea plants were cultivated in a completely randomized design with five replicates in a greenhouse. One year after plant establishment, phenotypic characteristics were studied. The tea accessions showed different responses in chlorophyll and total ash contents. The highest and lowest amount of caffeine in tea accessions was found in Kobijar A7 and Langroud A2, respectively. Epicatechin was obtained in a 6.48–15.44 mg g−1 range, and the maximum variability was found in epigallocatechin gallate (EGCG), differing from 0.94 to 21.03 mg g−1. Langroud A2 and Bazkiaguorab A11 contained the maximum EGCG and the total polyphenolic content in Bazkiaguorab was greater than other accessions. Heat map analysis showed the maximum variability of EGCG, catechin, and GA among the accessions. The main essential oil compounds were 2-pentyl furan followed by hexanal, gamma-terpinene, octane, ortho-cymene, terpinen-4-ol, alpha-copaene and E-caryophyllene. In conclusion, changes in phytochemical traits caused by genetics and origin can significantly alter the quality of tea compounds. The results of this study can be utilized as raw materials in future breeding projects to improve new cultivars with superior characteristics.