Phytotoxicity of chromium (VI) on germination, growth attributes and pigmentation in cluster bean

An investigation was carried out to study the phytotoxic effect of chromium (VI) on seed germination, plant growth parameters and biosynthesis of pigments in cluster bean ( Cyamopsis tetragonoloba ). Four concentrations (1, 2, 4 and 8 µg ml-1) of Cr (VI) as potassium dichromate were applied to cluster bean seeds in solution culture. The rate of seed germination was observed every hour. Growth parameters were measured at the early seedling stage. The concentrations of chlorophyll, carotenoid and anthocyanin in leaves were estimated. All the studied concentrations of Cr (VI) were found to be toxic to cluster bean. The speed of seed germination slowed down under Cr (VI) stress. The root-shoot length, root-shoot fresh weight and root-shoot dry weight decreased with increasing concentrations of Cr (VI). The most deleterious effect was observed at 8 µg ml-1. Anthocyanin contents in cluster bean showed a significant ( P -1 and 2 µg ml-1 were moderately toxic while 4 µg ml-1 and 8 µg ml-1 were highly toxic to cluster bean.