Low temperature is one of the major environmental factors determining the growth rate of Camellia sinensis (L.), and photosynthesis is one major metabolic process commonly used as a tool for identifying low temperature stress effects on plants. The Fv/Fm values at 6:30 a.m. ($300-400mu mol m^{-2} s^{-1}$) did not vary much between the clones of tea plants. Further, when the light incidence increased at mid noon hours ($1700-1800mu mol m^{-2} s^{-1}$), the Fv/Fm values recorded a decline, irrespective of the clones. Of the 10 clones of tea plants under investigation, 3 clones, namely CRA-6017, TTL­6 and SMP-l, recorded a sharp decrease in the Fv/Fm ratio by 2 p.m. The malondialdehyde (MDA) levels in all the clones increased from 9 a.m. ($1500-1700mu mol m^{-2} s^{-1}$) to 2 p.m. and from 4:30 p.m. ($900-1100mu mol m^{-2} s^{-1}$) onwards it started to decrease and reach the levels equivalent to 6:30 a.m. by 7 p.m. ($5-10mu mol m^{-2} s^{-1}$). But the clones of TTL­1, TTL-4 and UPASI-9 showed low temperature tolerance as appeared in chlorophyll a fluorescence response. They showed a higher percentage increase in MDA levels, as compared to TTL-6, CRA-6017 and SMP-l, which showed low temperature susceptibility. But the reduction in the level of MDA by 4:30 p.m. (recovery) was faster in the clones TTL­l, TTL-4 and UPASI-9, as compared to TTL-6, SM/OM/54 and SMP-l. The result indicates that in TTL-6, SMP-l and SM/ OM/54, the toxic oxygen species scavenging mechanisms may be less functional as compared to other clones. The percentage increase of proline and carotenoids was higher in clones TTL-l, TTL-4 and UPASI-9 as compared to TTL-6, CRA-6017 and SMP-l.