In this review, we briefly describe the biological application of PGPR for purposes of phytoremediating heavy metals. We address the agronomic practices that can be used to maximize the remediation potential of plants. Plant roots have limited ability ability mental from soil, mainly because metals have low solubility in the soil solution. The phytoavailability of metal is closely tired to the soil properties and the metabolites that are released by PGPR (e.g., siderophores, organ acids, and plant growth regulators). The role played by PGPR may be accomplished by their direct effect on plant growth dynamics, or indirectly by acidification, chelation, precipitation, or immobilization of heavy metals in the rhizosphere. From performing this review we have formed the following conclusions: The most critical factor is determining how efficient phytoremediation of metal-contaminated soil will be is the rate of uptake of the metal by plants. In turn, this depends on the rate of bioavailability. We know from our review that beneficial bacteria exist tha can alter metal bioavailability of plants. Using these beneficial bacteria improves the performance of phytoremediation of the metal-contaminated sites. Contaminated sites are often nutrient poor. Such soil can be nutrient enriched by applying metal-tolerant microbes that provide key needed plant nutrients. Applying metal-tolerant microbes therefore may be vital in enhancing the detoxification of heavy-metal-contaminated soils (Glick 2003). Plant stress generated by metal-contaminated soils can be countered by enhancing plant defense responses. Responses can be enhanced by alleviating the stress-mediated impact on plants by enzymatic hydrolysis of ACC, which is intermediate in the biosynthetic pathway of ethylene. These plant-microbe partnerships can act as decontaminators by improving phytoremediation. Soil microorganisms play a central role in maintaining soil structure, fertility and in remediating contaminated soils. Although not yet widely applied, utilizing a plant-microbe partnership is now being recognized as an important tool to enhance successful phytoremediaton of metal-contaminated sites. Hence, soil microbes are essential to soil health and sustainability. The key to their usefulness is their close association with, and positive influence on, plant growth and function. To capitalize on the early success of this technique and to improve it, additional research is needed on successful colonization and survival of inoculums under field conditions, because there are vital for the success of this approach. In addition, the effects of the interaction of PGPR and plant root-mediated process on the metal mobilization in soil are required, to better elucidate the mechanism that underlines bacterial-assisted phytoremediation is important. Finally, applying PGPR-associated phytoremediation under field conditions is important, because, to date, only locally contaminated sites have been treated with this technique, by using microbes cultured in the laboratory.

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The deficiency of potassium (K) has resulted in decreasing the yield and quality of food grains. Moreover, with decreasing water resources the use of wastewater in agriculture as an alternative source of water and nutrients is being debated. This study was therefore undertaken to test wastewater for its suitability as irrigation water together with uniform basal doses of nitrogen (N) and phosphorus (P) and varying doses of potassium (K 0, K 20 , K 40 and K 60 ). It was observed that the plants receiving wastewater as a source of irrigation water performed better with a lower K dose. Potassium at 20 kg ha À1 along with wastewater resulted in better growth, photosynthetic rate (P N ), stomatal conductance (g s ) and yield of the chickpea (Cicer arietinum L.). Thus fertilizer rates could be lowered with the use of wastewater which can serve not only as the source of water but of nutrients also. However, regular monitoring of wastewater and soil for any buildup of heavy metal is necessary. The physical and chemical parameters of wastewater were also tested and most of them were found to be well within the permissible limits as set by the Food and Agriculture Organization (FAO).

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The use of effluents or marginal water in agriculture is an unavoidable practice and its largest source is the urban wastewater. In order to evaluate its effect on agricultural crops, an experiment was conducted to study its impact on Cicer arietinum L. along with different levels of phophorus. Three levels of water used for irrigation included ground water (GW), 50% wastewater (50%WW) and 100% wastewater (100%WW) and the varying levels of phosphorus (P 0 , P 20 , P 40 , P 60) were also applied along with the basal application of nitrogen and potassium at the rate of 15 and 20 kg ha-1 respectively. The effect was evaluated on the basis of growth, biochemical attributes, photosynthesis and yield of the crop. From the results it was clear that the wastewaters proved not only effective source of water but the nutrients also and enhanced growth and photosynthetic capacity and thereby yield of the plants. Moreover the fertilizer (P) requirement of the crop was also reduced. In conclusion the urban wastewater showed no inhibitory effect on the growth of the crop and thus could effectively supplement not only the nutrient requirement of the crop but may also act as the source of water.

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Plastic pollution is the buildup of unwanted plastic products in the environment by its abundant and limitless use by a greedy human population in various ways. Plastics are usually made of chains of monomer units of ethylene and propylene linked together. Plastics are durable and resistant to degradation and tend to accumulate where they are disposed. One more disaster this material causes is the release of toxic chemicals with time which badly affects the ecosystem where it is dumped. Same is the case with aquatic ecosystem, because tons of plastic wastes are dumped into it in one way or the other. The major threats of this menace on aquatic ecosystem include ocean acidification, degradation of water quality, increase in number of invasive species, overfishing, pollution and choking of water bodies, habitat degradation, loss of aesthetic value, blocking of sea routes, and above all, it badly affects plant and animal life there.