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Heavy metals, one of the major pollutants in the environment, are spilled in the soil through several
agencies. Plants often take up these metals which eventually exert toxic effects on them.
In present study the laser spectrofluorometer with computer-controlled data acquisition system is
used which provides fluorescence information. A cw argon ion laser (Spectra Physics, USA model
2016) operating at 488 nm was used for exposing the full intact leaf with the help of the beam
expander. It has been found that the leaves treated with higher concentration of metals showed, an
increase in fluorescence intensity than the lower concentration. The bandwidth decreases in the red
band region and increases in the far red band region due to metal stress. In red region bandwidth is
minimum for nickel treated plant. In far red region bandwidth is maximum for mercury treated
plant. From the various observations it has been cleared that the higher concentration of heavy
metals like Aluminium, Nickel and Mercury affect the photosynthetic activity adversely by
decreasing the amount of chlorophyll content in the Soybean plant. Mercury proved pronounced
stress as compare to Nickel, Aluminium and Copper.
Key words: Metal stress, Fluorescence, Photosynthesis