Phytoremediation is a plant based environmental cleanup technology to contain (rendering less toxic), sequester and degrade contaminated susbtrates. As can be seen from data metrics, it is gaining cosiderable importance globally. Phytoremediation approach is being applied for cleanup of inorganic (potentially toxic metals), organic (persistent, emergent, poly-acromatic hydrocarbons and crude oil etc.) and co-contaminated (mixture of inorganic and organic) and/or polluted sites globally. Recently new approaches of utilizing abundantly available natural organic amendments have yielded significant results. Ricinus communis L. (Castor bean) is an important multipurpose crop viz., Agricultural, Energy, Environmental and Industrial crop. The current status of knowledge is abundant but scattered which need to be exploited for sustainable development. This review collates and evaluates all the scattered information and provides a critical view on the possible options for exploiting its potential as follows: 1. Origin and distribution, 2. Lead toxicity bioassays, 3. Progress in arbuscular mycorrhizal fungi-assisted phytoremediation, 4. Promising bioenergy crop that can be linked to pytoremediation, 5. A renewable source for many bioproducts with rich chemical diversity, 6. It is a good biomonitor and bioindicator of atmospheric pollution in urban areas, 7. Enhanced chelate aided remediation, 8. Its rhizospheric processes accelerate natural attenuation, 9. It is suitable for remediation of crude oil contaminated soil, 10. It is an ideal candidate for aided phytostabilization, 11. Castor bean is a wizard for phytoremediation and 12. Its use in combined phytoextraction and ecocatalysis. Further, the knowledge gaps and scope for future research on sustainable co-generation of value chain and value addition biobased products for sustainable circular economy and environmental security are described in this paper.
Alternanthera philoxeroides (alligator weed) grows abundantly in polluted Peri-urban Greater Hyderabad, India. It is collected at no cost and sold in the market as a leafy vegetable in the name of “Ceylon Spinach”. The plant accumulates iron (Fe), manganese (Mn), cadmium (Cd), lead (Pb) and zinc (Zn) in roots and leaves. Soil samples were analyzed for pH, EC, available nitrogen (N), phosphorus (P) and potassium (K) and showed significant metal concentrations of Pb, Mn and Zn, which varied from one location to another. The metal accumulation order in the plants is root>leaf>stem in all the studied sites. The results revealed that the massive roots of alligator weed are effective in the bioconcentrating Fe, Mn, Zn, Pb and Cd, although the plant parts are rich in nutraceuticals like phenolics and antioxidants. Therefore, low income community prefers to consume it as vegetable. However, its consumption as a leafy vegetable can cause health risks.
Ultraviolet radiation (UV) altered plant metabolism. Hence Trigonella foenum-graecum L. (Fenugreek) exposed to UV-B radiation for studying the bioactive changes that may be useful in captive farming. UV-B treatment altered plant growth, and extent of alterations depended on the duration of radiation treatment. Photosynthetic pigments such as chlorophyll and carotenoids decreased after radiation exposure. But bioactive components such as anthocyanin, flavonoids, and phenolics increased after UV-B treatment. Phenylalanine lyase enzyme activity and peroxidase activity also increased with 4.0 hr UV-B exposure even though 8.0 hr exposure decreased the activity of these enzymes. Total lipid content of the plants increased after UV-B exposure. Changes in aromatic oil composition observed due to UV-B exposure, and the changes pointed shifting of plant metabolism towards the synthesis of short chain fatty acid contain lipids and non-enzymatic antioxidants.