Vol. 11, Issue 12 (2022)

Author(s):
Tariq A Bhat, JIA Bhat, Haleema Bano, Auyoub Bhat, Imran Khan and I T Nazki

Abstract:
Spirodela polyrhiza L. a monocotyledonous aquatic macrophyte was investigated for its capacity to phytoremediate heavy metal-polluted water. The plants were grown in Hoagland nutrient solution and exposed to different concentrations of Copper, Lead and Cadmium (0 ppm, 0.5 ppm, 1 ppm, 2 ppm, 4 ppm and 8 ppm) separately for a period of 15 days under in-vitro conditions. Metal accumulation, Bio concentration factor (BCF), Relative growth rate (RGR), Tolerance index (TI) and effect on photosynthetic pigments were recorded after the experimental period. Results showed that Cu, Pb and Cd accumulation increases in a concentration dependent manner and was found in the order: Cu>Cd>Pb. Bio concentration factor (BCF) varied at different concentrations of heavy metals tested. Maximum values of Bio concentration factor (BCF) for Cu, Pb and Cd were 780, 405 and 600 respectively at 0.5 ppm concentration. Indicating that the accumulation potential of Spirodela polyrhiza L. for Cu is higher than Cd and Pb. Furthermore, BCF decreases with increase in concentration of heavy metals in the medium. RGR, TI and Photosynthetic pigments declined with increasing in concentration of metals in the medium as compared to control. RGR was found maximum in control (0.007 g/g/day), while as in case of Cu, Pb and Cd decline in growth rate was observed at all concentrations. The maximum decline in growth rate was observed in Cd, followed Pb and Cu. Tolerance index (TI) of Spirodela polyrhiza L. against Cu, Pb and Cd was found maximum at 0.5 ppm (Cu: 75.17%, Pb: 66.82% and Cd: 61.37%) while as minimum TI was found at 8 ppm concentration (Cu: 37.38%, Pb: 27.21% and Cd: 20.23%), Furthermore TI of Spirodela polyrhiza L. against copper was maximum as compared to lead and cadmium. The maximum content of photosynthetic pigments were detected in control plants without treatment, while as decline in photosynthetic pigments were found among all the heavy metals tested. Copper, however, had the least impact on photosynthetic pigments when compared to lead and cadmium. The results suggests that Spirodela polyrhiza L. could tolerate heavy metals and can be a good candidate for phytoremediation of polluted water with low and moderate concentration of heavy metals.