ABSTRACT
Sewage sludge used as agriculture fertilizers contains a conspicuous amount of potentially toxic metals. In order to prevent the contamination in the food chain, there is an urgent need for the development of sewage sludge clean up technology. The use of non-food, multi-harvest aromatic crops for phytoremediation of sewage sludge has many benefits. Besides the eco-friendly approach, plant biomass generated can be used to extract economically important essential oil free of heavy metals. Cymbopogon martinii was grown in soil (s) amended with different ratios of sewage sludge (ss), that is, 100s:0ss (control), 80s:20ss, 60s:40ss, 40s:60ss, 20s:80ss, and 0s:100ss. The experiment was conducted in a plastic sack under an open environment for 1 year and harvesting was done thrice. Plant growth and essential oil yield were significantly increased with the increasing dose of sewage sludge. Accumulation of toxic metal (Cd, Cr, Pb, Ni) and micronutrient (Fe, Zn, Cu, Mn) increased significantly in the shoot tissues confirmed by estimation of bioaccumulation and bioconcentration, and scanning electron microscopy and X-ray microanalyses. Soil enzyme activities were significantly improved with the plant growth period and increased doses of sludge. Results showed C. martinii acts as hyper-accumulator and thus could be used for phytoremediation of sewage sludge.
Subject(s)
Cymbopogon , Metals, Heavy , Soil Pollutants , Biodegradation, Environmental , Sewage , SoilABSTRACT
Restoration of salt-affected soil through cultivation Chrysopogon zizanioides is a promising approach. The two way benefit of such an approach is that reclamation of salt-affected soil concomitant to improve plant growth and increased yield of essential oil produced in the plants roots. Earlier studies showed physiological changes and reduced growth of C. zizanioides under salinity. In the present study, plant growth promoting microorganisms viz. Pseudomonas monteilii, Bacillus megaterium, Azotobacter chroococcum and Rhizophagus intraradices were used as bio-inoculants for cultivation of C. zizanioides under salt-affected soil. Bio-inoculants in combination with vermicompost significantly increased the growth and productivity of C. zizanioides under salt-affected soil, and simultaneously improved soil health. When compared to control, the soil physico-chemical and biological properties of bio-inoculants treated plants was significantly improved. The reclamation of salt-affected soil was evident by the significant decrease in the level of soil pH (11.0%), electrical conductivity (23.5%), sodium adsorption ratio (15.3%), and exchangeable sodium percent (12.4%) of bio-inoculants treated plants. The improvement of soil cation exchange capacity indicated the decrease in soil salinity. Whereas increase in the microbial count (four-fold), AMF spores (447 spores), dehydrogenase (six-fold), acid (two-fold) and alkaline phosphatase (five-fold) activities in rhizosphere soil of bio-inoculant treated plants indicated the improved biological properties. A positive correlation of plant biomass production to soil organic carbon, total Kjeldahl nitrogen, available phosphorus and cation exchange capacity depicted improved nutrients content in rhizosphere soil of bio-inoculant treated plants. The findings of this study suggest that P. monteilii and R. intraradices with vermicompost can be effectively used as bio-inoculants for encouragement of phytoremediation in salt-affected soil.
ABSTRACT
Andrographis paniculata Nees is an annual erect herb with wide medicinal and pharmacological applications due to the presence of andrographolide and other active chemical constituents. The large-scale cultivation of the kalmegh is not in practice. The aim of this study was to establish sustainable production systems of A. paniculata cv CIM-Megha with the application of different bioinoculants and chemical fertilisers. A. paniculata herb and andrographolide yield in the dried leaves was found to be highest (218% and 61.3%, respectively) in treatment T3 (NPK+Bacillus sp.) compared with T1 (control). The soil organic carbon, soil microbial respiration, soil enzymes activity and available nutrients improved significantly with combined application of bioinoculants and chemical fertilisers.
