The ever-increasing industrial activities over the decades have generated high toxic metal such as chromium (Cr) that hampers the crop productivity. This study evaluated the effect of Cr on two chickpea (Cicer arietinum L.) varieties, Pusa 2085 and Pusa Green 112, in hydroponic and pot-grown conditions. First, growth parameters (seed germination, seedling growth, and biomass production) and physio-biochemical parameters (oxidative stress and the content of antioxidants and proline) were measured to evaluate the performance of both varieties grown hydroponically for 21 days at concentrations of 0, 30, 60, 90 and 120 μM Cr in the form of potassium dichromate (K2Cr2O7). In both varieties, significantly deleterious effects on germination and seedling growth parameters were observed at 90 and 120 μM, while growth was stimulated at 30 μM Cr. Significant increases in malondialdehyde and hydrogen peroxide content and electrolyte leakage demonstrated enhanced oxidative injury to seedlings caused by higher concentrations of Cr. Further, increasing concentrations of Cr positively correlated with increased proline content, superoxide dismutase activity, and peroxide content in leaves. There was also an increase in peroxisomal ascorbate peroxidase and catalase in the leaves of both varieties at lower Cr concentrations, whereas a steep decline was recorded at higher Cr concentrations. In the pot experiments conducted over two consecutive years, growth, yield, yield attributes, grain protein, and Cr uptake and accumulation were measured at different Cr concentrations. Pusa Green 112 showed a significant reduction in plant growth, chlorophyll content, grain protein, pod number, and grain yield per plant when compared with Pusa 2085. Overall, our results indicate that Pusa 2085 has a higher Cr tolerance than Pusa Green 112. Therefore, Pusa 2085 could be used to further elucidate the mechanisms of Cr tolerance in plants and in breeding programmes to produce Cr-resistant varieties.

One hundred and sixty two genotypes of different Lens species were screened for salinity tolerance in hydroponics at 40, 80 and 120 mM sodium chloride (NaCl) for 30 d. The germination, seedling growth, biomass accumulation, seedling survivability, salinity scores, root and shoot anatomy, sodium ion (Na+), chloride ion (Cl-) and potassium ion (K+) concentrations, proline and antioxidant activities were measured to evaluate the performance of all the genotypes. The results were compared in respect of physiological (Na+, K+ and Cl-) and seed yield components obtained from field trials for salinity stress conducted during two years. Expression of salt tolerance in hydroponics was found to be reliable indicator for similarity in salt tolerance between genotypes and was evident in saline soil based comparisons. Impressive genotypic variation for salinity tolerance was observed among the genotypes screened under hydroponic and saline field conditions. Plant concentrations of Na+ and Cl- at 120 mM NaCl were found significantly correlated with germination, root and shoot length, fresh and dry weight of roots and shoots, seedling survivability, salinity scores and K+ under controlled conditions and ranked the genotypes along with their seed yield in the field. Root and shoot anatomy of tolerant line (PDL-1) and wild accession (ILWL-137) showed restricted uptake of Na+ and Cl- due to thick layer of their epidermis and endodermis as compared to sensitive cultigen (L-4076). All the genotypes were scanned using SSR markers for genetic diversity, which generated high polymorphism. On the basis of cluster analysis and population structure the contrasting genotypes were grouped into different classes. These markers may further be tested to explore their potential in marker-assisted selection.

The increasing prevalence of environmental pollution, especially soil contamination with heavy metals has led to their uptake in the human food chains through plant parts. Accumulation and magnification of heavy metals in human tissues through consumption of herbal remedies can cause hazardous impacts on health. Therefore, chemical profiling of nine heavy metals (Mn, Cr, Pb, Fe, Cd, Co, Zn, Ni and Hg) was undertaken in stem and leaf samples of ten medicinal plants (Acacia nilotica, Bacopa monnieri, Commiphora wightii, Ficus religiosa, Glycyrrhiza glabra, Hemidesmus indicus, Salvadora oleoides, Terminalia bellirica, Terminalia chebula and Withania somnifera) collected from environmentally diverse regions of Haryana and Rajasthan states in North-Western India. Concentration of all heavy metals, except Cr, was within permissible limits in the tested stem and leaf samples. Leaf samples had consistently more Cr compared to respective stem samples with highest concentration in leaf samples of Bacopa monnieri (13.19 ± 0.0480 ppm) and stem samples of Withania somnifera (4.93 ± 0.0185 ppm) both collected from Bahadurgarh (heavy industrial area), Haryana. This amount was beyond the permissible limit of 2.0 ppm defined by WHO for raw herbal material. Other two most perilous metals Pb (2.64 ± 0.0260) and Cd (0.04 ± 0.0274) were also recorded in Bahadurgarh region, although below permissible limits. Concentration of Hg remained below detectable levels in all the leaf and stem samples tested. These results suggested that cultivation of medicinal plants and other dietary herbs should be curtailed near environmentally polluted especially industrial areas for avoidance of health hazards.

Chromium (Cr) presently used in various major industries and its residues possess a potent environmental threat. Contamination of soil and water resources due to Cr ions and its toxicity has adversely affected plant growth and crop productivity. Here, deleterious effects of different levels of Cr (VI) treatments i.e., 0, 30, 60, 90, and 120 μM on two mungbean cultivars, Pusa Vishal (PV) and Pusa Ratna (PR), in hydroponic and pot conditions were evaluated. Germination, seedling growth, biomass production, antioxidant enzyme, electrolytic leakage, oxidative stress (hydrogen peroxide and malondialdehyde), and proline content were determined to evaluate the performance of both cultivars under hydroponic conditions for 15 days. The hydroponic results were further compared with the growth and seed yield attributes of both the genotypes in pot experiments performed over 2 years. Seedling growth, biomass production, total chlorophyll (Chl), Chl-a, Chl-b, nitrogen content, plant height, seed protein, and seed yield decreased significantly under the 120 μM Cr stress level. Activities of antioxidant enzymes superoxide dismutase, catalase, ascorbate peroxidase and peroxidase increased in the leaves following Cr exposure at 60–90 μM but declined at 120 μM. Cr-induced reductions in growth and seed yield attributes were more in the sensitive than in the tolerant cultivar. Cr accumulation in the roots, stems, leaves, and seeds increased with an increase in Cr concentrations in the pot conditions. Furthermore, for both cultivars, there were significant negative correlations in morpho-physiological characteristics under high Cr concentrations. Overall results suggest that (PR) is more sensitive to Cr stress (PV) at the seedling stage and in pot conditions. Furthermore, (PV) can be utilized to study the mechanisms of Cr tolerance and in breeding programs to develop Cr-resistant varieties.

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