Chromium toxicity and ultrastructural deformation of Cicer arietinum with special reference of root elongation and coleoptile growth

Chromium (Cr) is a potent heavy metal which pollutes both soil and aquatic body. Therefore, it should be considered as a hazardous element. Cr can exists in various from in the environment, among them most stable from of chromium is Cr(VI). The present study demonstrate the adverse impacts of hexavalent chromium on Cicer arietinum, development and growth morphology, including elongation of coleoptyl, number of metabolic responses related to growth and ultra structural deformation of root and shoot. Exogenous application of Cr(VI) from 20 ppm to 100 ppm progressively inhibited seed germination and coleoptyl growth and dramatically damaged root aperture (xylem and phloem) even at the lowest dose. Results also revealed that the maximum reduction of germination was recorded at 80 mg/L Cr(VI) solution during 72 h of incubation. However, at 80 mg/L of Cr(VI) solution, coleoptyle growth reduces to 30% with respect to control. The chlorophyll ('a' and 'b' and total chlorophyll) level significantly declined by chromium treatment. On the other hand, SEM picture clearly indicate the distinct structural change of xylem and phloem with increasing the concentration of hexavalent chromium from 20 ppm to 100 ppm.