Interactions between Chromium and Plant Growth Regulators on the Growth of Spirodela polyrrhiza (L.) Schleiden

Chromium is one of the most toxic heavy metals which reduces the growth of plants at relatively low concentrations, whereas IAA, kinetin, GA3 and 24-epibrassinolide (24-epiBr) are well known plant growth regulators (PGRs) which enhance the growth of plants. The present study was undertaken to determine the effect of binary combinations of Cr(VI) and PGRs on Spirodela polyrrhiza (L.) Schleiden, an aquatic macrophyte, grown on Hoagland’s E-media. We observed that Cr(VI) at 1, 2 and 3 mM in the absence of exogenous PGRs significantly decreased the growth of plants, whereas IAA, kinetin, GA3 (0.1, 10, 1000 nM) and 24-epiBr (0.01, 1, 100 nM) in the absence of Cr(VI) significantly increased the growth. Multiple regression models revealed that Cr(VI) inhibits the activity of exogenous PGRs leading to a further decrease in the growth of S. polyrrhiza cultured in binary combinations of Cr(VI) and PGRs. _____________________________________________________________________________________________________________