The Interactions of Cu++and CN−with Paraquat Phytotoxicity to aChlorella

The interactions between copper (Cu++) and cyanide (CN−) with 1,1′-dimethyl-4,4′-bipyridinium ion (paraquat) on phytotoxicity toChlorella pyrenoidosaChick, IAC 251, were determined by measuring chlorophyll absorbance at 434 and 670 mμ. Cu++inhibited phytotoxicity and CN−accelerated paraquat activity with highly significant mutually antagonistic interactions occurring between Cu++(2 ppm) and CN−(16 ppm) at paraquat levels to 2 ppm.