LAUSR

Abstract Two thirds of the tea growing area of North East India is covered by Tocklai vegetative (TV) cultivars. The present study investigates the principal catechins [(−)-epigallocatechin gallate (EGCG), (−)-epicatechin gallate (ECG), (−)-epigallocatechin (EGC), (−)-epicatechin (EC), and (+)-catechin (+C)], total catechin (TC) and caffeine content in thirty-one TV cultivars (TV1-TV31) and four popular cultivars, viz. Betjan, Kharijan, S.3A/3, and T.3E/3 in three harvesting seasons i.e., pre-monsoon, monsoon and autumn, along with their genetic diversity. The monsoon harvested crop showed the highest average content of TC, EGCG, ECG, and caffeine. The TC levels varied from 129 ± 0.03 to 214 ± 4.72, 151 ± 4.21 to 238 ± 8.41, and 121 ± 4.45 to 181 ± 5.82 mg g-1 in pre-monsoon, monsoon and autumn, respectively. The most predominant catechin EGCG varied from 52.2 ± 1.07 to 111 ± 1.24, 70.4 ± 1.03 to 141 ± 1.35, and 58.4 ± 2.47 to 108 ± 2.15 mg g-1in pre-monsoon, monsoon and autumn, respectively. Caffeine content varied from 27.1 ± 0.32 to 48.7 ± 0.50, 35.3 ± 1.56 to 55.0 ± 1.34 and 27.6 ± 1.11 to 40.7 ± 0.42 mg g-1 in pre-monsoon, monsoon and autumn, respectively. TC contents in cultivars TV23, TV17 and TV15; and EGCG contents in TV10, TV11, and TV9 were significantly higher (p ≤ 0.05) than for other cultivars. Environmental factors, viz. day length, sunlight, temperature across seasons might have induced seasonal variation in phenolic composition.