The aim of this study was to compare the selected aquatic plants ability to remove nitrate from wastewater. Excess of these nutrients in water can directly affect human health (methemoglobinaemia) or indirectly through the products of secondary pollution include eutrophication. Negative impact of nutrients excess in surface water often causes the destruction of water ecosystems, and therefore, common substances of these elements must be monitored and managed. Spectrophotometric technique was commonly used for quick and simple analyses of nutrients in waste water. There are calibration curves for each nutrient and for the determination of their concentration. Phytotechnology is one of the biological wastewater treatment methods or processes to eliminate nitrate contaminant from aquatic system. So as to avoid the eutrophic formation of fresh water and to determine the efficiency of nitrate utilization by specific aquatic plants which include Utricularia aurea and Salvinia molesta were collected from a eutrophic lake at Theerthamkara, Kerala. The samples were allowed to grow in nitrate solution for about one month at different concentrations. The optical density (OD) of nitrate solution at 410 nm was measured on alternative days of the experiment by using UV spectrophotometer. After 33 days of treatment periods, the maximum amount of nitrate removed in terms of percentage was found to be 95% by Utricularia aurea and 92% by Salvinia molesta at 100 ppm nitrate concentration. The results revealed that the aquatic plant (carnivorous) based system of phytotechnology was productively removed the nitrate load from the synthetic wastewater containing nitrate.

Inoculation of endophytic bacteria has been accepted as a promising technique to assist phytostabilization of heavy metal-contaminated soils. This study investigated the effects of inoculating a bacterial strain closely related to Pseudomonas pyschrophila on the plant growth, and phytostabilization of fast-growing trees Acacia mangium and Eucalyptus camaldulensis, growing on artificial spiked soil with Pb up to 1500 mg/kg. After 60 days, the results showed that the strain closely related to P. pyschrophila slightly increased Pb bioavailability and Pb uptake by A. mangium, compared to non-inoculated controls. It slightly reduced Pb bioavailability in soil, but it did not affect the Pb uptake by E. camaldulensis, compared to non-inoculated controls. Interestingly, it was able to significantly increase Pb content in shoots by 3.07-fold in A. mangium and 2.95-fold in E. camaldulensis, compared to non-inoculated controls. Although the inoculation of the strain closely related to P. pyschrophila slightly increased the translocation factor (TF) of Pb in both tree species, their TF values were less than 1. This indicates that plants associated with the strain closely related to P. pyschrophila are suitable for phytostabilization of A. mangium, which may be used for cleaning up Pb contaminated sites. This strain displayed different influences on plant species and was found not suitable for phytostabilization of E. camaldulensis.

Heavy metal contaminated soil raises major global environmental and agricultural concern. Recently soil pollution through lead (Pb) and chromium (Cr) becoming serious problem and remediation or utilization of those contaminated soil with potential crops is of the outmost importance. The objectives of present study were to examine the effects of Pb and Cr on three different kenaf and mesta varieties for seed germination, seedling establishment and amount of Pb and Cr uptake by tested varieties in laboratory condition. Three varieties were used for the study namely, HC-95 (kenaf), CPL-72126 (mesta) and Samu-93 (mesta) and the treatments were combination of Pb and Cr chemical at (0,0), (60,60), (80,80), (100,100) and (120,120) mg/L. Increased level of lead and chromium gradually reduced the germination percentage and primary growth parameters compared to control. The shoot and root lengths were affected only little, whereas, the biomass showed a considerable reduction with the increase of Pb and Cr toxicity. Stress tolerance indices showed a gradual and negative response by the plant with the increase of metal concentrations. However, in all the levels of Pb and Cr treatment, the seedlings were capable to tolerate the toxicity and seedlings were established. Bioaccumulation of Cr was higher than that of Pb in all varieties and in all treatments. The interaction of Pb and Cr reduced the toxic effect of both metals to the plants. The findings are helpful for selecting fiber crop varieties for cultivation in contaminated soils or phytoremediation of Pb and Cr from the contaminated soils.