Chlorophyll a fluorescence measurements for validating the tolerant bryophytes for heavy metal (Pb) biomapping.

Chlorophyll a fluorescence measurement has been used as a probe to examine and compare the tolerance of bryophytes against heavy metals stress caused in field trials and under laboratory conditions. The ratio of variable fluorescence (Fv) to the maximal fluorescence (Fm) in dark-adapted leaves termed as 'maximal photochemical efficiency' of PS II (Fv/Fm) was measured in selected bryophytes to study their quantum efficiency. Tolerance potential for lead (Pb) in bryophytes was evaluated statistically by using Dunkun's Multiple Range Test, which indicates that lead-treated moss Grimmia anodon and liverwort Riccardia pinguis exhibited the most physiological damage of PS II. Conversely, minimal changes were observed in Barbula vinealis and Thuidium cymbifolium. Field trials of all the selected bryophytes exhibited moderate changes in the Fv/Fm ratio except G. anodon and R. pinguis. This variation in susceptibility is due to stress caused by metal pollution. Therefore, it is desirable to study the relative tolerance potential of bryophytes as little is known about their susceptibility to metals. Validated tolerant bryophytes species will have multiple applications in studies of biomapping, forest enrichment and carbon gain. [ABSTRACT FROM AUTHOR]