The use of effluent from various industries by agriculture sector in developing countries may help to mitigate water scarcity and cost of fertilizers but pose considerable threats to entire ecosystem when heavy metals enter the food chain. The aim of the present study was to compare the growth and development of two biofuel tree species Jatropha curcas L. and Pongamia pinnata L. when exposed to 20 and 40 mL L −1 of effluent discharged from a local tannery along with tap water as a control. The physico-chemical attributes assessed for quality of effluent showed higher values and significantly higher chromium (Cr) concentration than other metals. Application of effluent induced profound formation of malondialdehyde (MDA) in P. pinnata. With regard to growth and pigments of plant species, a significant reduction (p≤0.05) in root length, dry shoot biomass, leaf area, chlorophylls and carotenoids occurred in P. pinnata but shoot length, collar diameter and root dry biomass remained unaffected. Similarly, J. curcas sustained root and shoot growth, dry biomass production, collar diameter and leaf area. Increased pigment contents were found at both effluent levels. The roots of P. pinnata accumulated 6 and 11 times more Cr at 20 and 40 mL L −1 , respectively, than control. While in J. curcas Cr accumulation was up to 9 folds in shoots at 40 mL L −1. Thus, the two species exhibited differential potential for Cr accumulation in their above and below ground tissues. The study signified the use of contaminated water for irrigation and potential of the species to act as phytoremediator to alleviate both water scarcity and metal contamination.

Highlights The growth, biosynthesis of pigments and other macromolecules appeared to be strong predictors in appraisal of Pb tolerance/susceptibility in durum wheat. Germplasm of CBD59, CBD63 and CBD66 can be exploited for future selection and breeding programs. The bioaccumulation of metal in grains of some cultivars of durum wheat much below than permissible limits set by FAO/WHO is of great significance owing to its implications for food safety.

Pakistan currently faces an acute shortage of water, which has increasingly been devastating for the past few decades. In order to mitigate water scarcity, agriculture sector of the country started using wastewater discharged from various industries. The present study aims to assess the impact of fertilizer industry effluent on Jatropha curcas L. and Pongamia pinnata L., which are popular biofuel tree species. Initially, one-year-old saplings were acclimatized in pots, then wastewater was applied in diluted concentrations of effluent using 20 and 40 mL L-1 to the treatment group while control plants were irrigated with tap water. The physico-chemical properties of the effluent showed high values 179 mg L-1 for biological oxygen demand (BOD), 257 mg L-1 for chemical oxygen demand (COD) and 1200 mg L-1 for total dissolved solid (TDS), respectively. Surprisingly, high concentrations of arsenic (15 μg L-1) and cadmium (0.78 mg L-1) were present but chromium (Cr) concentration was found within permissible limit to WHO. The levels applied caused a significant (p≤0.05) increase in plant growth and biomass. The extent of membrane damage assessed via malondialdehyde (MDA)production was also greater in the roots of P. pinnata while reverse was true for shoots of J. curcas. A more profound (p≤0.05) reduction in photosynthetic pigments and carotenoids was observed in P. pinnata at concentrated level of effluent. Overall, the study signifies a 2-folds potential of biofuel tree species for efficient reuse of wastewater, as well as for remediation of metals from wastewater and soil.

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