Chromium-induced alterations in photosynthesis and associated attributes in Indian mustard.

Contamination of soil and water by chromium (Cr) is increasing enormously due to anthropogenic activities. The potential of plants to accumulate or stabilize Cr compounds forthe purpose of remediation of Cr contamination has been recognized in recent years. We conducted pot experiments to study photosynthesis and associated attributes in cv Pusa Jai Kisan of Indian mustard under natural as well as Cr-loaded environmental conditions. High doses of Cr caused toxic effects in plants, as evident by a reduction in photosynthetic rate (24.3 to 8.7 micromol CO2 m(-2)s(-1) at 80 DAS), nitrate reductase activity (3.76 to 1.30 micromol nitrite g(-1) f. wt. h(-1) at 80 DAS) and the contents of chlorophyll (1.49 to 0.86 mg g(-1) f. wt. at 80 DAS) and soluble protein (2.96 to 1.93 mg g(-1) f. wt. at 80 DAS). Since plants lack a specific Cr-transport system, mineral nutrient contents also changed due to Cr toxicity. Cr accumulation in different plant parts was affected by both duration and dose of Cr treatments, with a maximal localization of Cr in roots (up to 0.77 mg g(-1) d. wt) at initial stages (40 DAS) and in stem (up to 4.19 mg g(-1) d. wt) at the later stage (80 DAS) of plant growth. Thus, Indian mustard was able to withstand Cr stress and protect itself from Cr toxicity by altering various metabolic processes. Owing to its ability to accumulate large amounts of Cr, it may be useful in the process of land reclamation.