Absorption of Fe by spinach on chromium (VI) treated soil

Abstract

In a replicated field experiment on an alluvial soil (organic carbon‐0.44%; pH 7.44; and CEC‐15 meq/100 g soil) spinach was grown on soil treated with 0 to 100 ppm Cr(VI) as K₂Cr₂O₇. The Fe content of plant organs (root, stem + petiole, and leaf blade on 38th and 53rd day after sowing and seed at harvest) was determined after wet digestion by the method described by Jackson (1973). In plant samples taken on the 38th day after sowing, Fe concentration in root, stem + petiole and leaf blade increased considerably at Cr(VI) levels of 7.5 and 10.0 ppm. Fe concentration in top growth was lower than control at Cr(VI) level of 2.5 and 5.0 ppm but at Cr(VI) level of 25 ppm, Fe concentration in stem + leaf became significantly lower than Fe concentration at 10 ppm Cr(VI). In root, Fe concentration increased progressively up to 25 ppm Cr(VI). At higher level of Cr(VI), the germination of spinach seeds was completely inhibited. Fifteen days of subsequent growth resulted in marked decrease in the concentration of Fe in the root, stem + petiole, and stan + leaf of spinach plants treated with Cr(VI). Fe concentration in leaf blade also decreased with subsequent growth at Cr(VI) level above 7.5 ppm. As compared to control, the Fe concentration of spinach seeds from Cr(VI) treated soil was, in general, higher. With increase in Cr(VI) level, Fe/Mn ratio in seed decreased in spite of increase in Fe/Mn ratio in vegetative parts. Evidently, high Cr concentration in vegetative organs reduced the translocation of Fe to seeds.

Key words:

• Fe absorption
• Cr(VI) treated soils
• spinach plant parts