Phytoremediation potential of some agricultural plants on heavy metal contaminated mine waste soils, salem district, tamilnadu.

The Pot culture experiment performed for phytoextraction potential of selected agricultural plants [millet (Eleusine coracana), mustard (Brassica juncea), jowar (Sorghum bicolor), black gram (Vigna mungo), pumpkin (Telfairia occidentalis)] grown in metal contaminated soils around the Salem region, Tamilnadu, India. Physiochemical characterization of soils, reported as low to medium level of N, P, K was found in test soils. The Cr content higher in mine soils than control and the values are 0.176 mg/L in Dalmia soil and 0.049 mg/L in Burn & Co soil. The germination rate low in mine soil than control soils (25 to 85%). The content of chlorophyll, carotenoid, carbohydrate and protein decreased in mine soils than control. The morphological parameters and biomass values decreased in experimental plants due to metal accumulation. Proline content increased in test plants and ranged from 0.113 mg g(-1) to 0.858 mg g(-1) which indicate the stress condition due to toxicity of metals. Sorghum and black gram plants reported as metal tolerant capacity. Among the plants, Sorghum produced good results (both biomass and biochemical parameters) which equal to control plant and suggests Sorghum plant is an ideal for remediation of metal contaminated soils.

Cellulosimicrobium funkei-like enhances the growth of Phaseolus vulgaris by modulating oxidative damage under Chromium(VI) toxicity.

Contamination of agriculture land by heavy metals is a worldwide risk that has sped up noticeably since the beginning of the industrial revolution. Hence, there arise the demands of heavy metal tolerant plant growth promoting bacterial strains for specific metal contaminated agricultural sites restoration. In this study, 36 bacterial isolates were screened out from the rhizospheric soil of Phaseolus vulgaris. Among these, two bacterial strains AR6 and AR8 were selected based on their higher Cr(VI) tolerance (1200 and 1100 µg/mL, respectively) and the maximum production of plant growth promoting substances. In the molecular characterization study, both the bacterial strains showed 99% homology with Cellulosimicrobium funkei KM032184. In greenhouse experiments, the exposure of Cr(VI) to P.vulgaris inhibited the growth and photosynthetic pigments and increased the enzymatic and non-enzymatic antioxidant expressions. However, rhizosphere bacterial inoculations alleviated the negative effect of Cr(VI) and enhanced the seed germination rate (89.54%), shoot (74.50%),root length (60%), total biomass (52.53%), chlorophyll a (15.91%), chlorophyll b (17.97%), total chlorophyll (16.58%) and carotenoid content (3.59%). Moreover, bacterial inoculations stabilized and modulated the antioxidant system of P. vulgaris by reducing the accumulation of Cr in plant tissues. The present finding shows the Cr(VI) tolerance and plant growth promoting properties of the rhizosphere bacterial strains which might make them eligible as biofertilizer of metal-contaminated soils.