Combined application of zinc and iron-lysine and its effects on morpho-physiological traits, antioxidant capacity and chromium uptake in rapeseed (Brassica napus L.)

Environmental contamination of chromium (Cr) has gained substantial consideration worldwide because of its high levels in the water and soil. A pot experiment using oil seed crop (rapeseed (Brassica napus L.)) grown under different levels of tannery wastewater (0, 33, 66 and 100%) in the soil using the foliar application of zinc (Zn) and iron (Fe)–lysine (lys) has been conducted. Results revealed that a considerable decline in the plant growth and biomass elevates with the addition of concentrations of tannery wastewater. Maximum decline in plant height, number of leaves, root length, fresh and dry biomass of root and leaves were recorded at the maximum level of tannery wastewater application (100%) compared to the plants grown without the addition of tannery wastewater (0%) in the soil. Similarly, contents of carotenoid and chlorophyll, gas exchange parameters and activities of various antioxidants (superoxidase dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX)) were also reduced significantly (P < 0.05) with the increasing concentration of tannery wastewater (33, 66 and 100%) in the soil. In addition, a combined application of Zn and Fe-lys reduced the accumulation and uptake of toxic Cr, while boosting the uptake of essential micronutrients such as Zn and Fe in different tissues of the plants. Results concluded that exogenous application of micronutrients chelated with amino acid successfully mitigate Cr stress in B. napus. Under field conditions, supplementation with these micronutrient-chelated amino acids may be an effective method for alleviating metal stress in other essential seed crops.

Soil applied glycine betaine with Arbuscular mycorrhizal fungi reduces chromium uptake and ameliorates chromium toxicity by suppressing the oxidative stress in three genetically different Sorghum (Sorghum bicolor L.) cultivars

Background Chromium is the most toxic pollutant that negatively affects a plant’s metabolic activities and yield. It reduces plant growth by influencing the antioxidant defence system’s activities. In the present study, a completely randomized block design experiment with three plants/pot in three replication was conducted on three varieties of sorghum viz. SSG 59–3, HJ 513 (multi-cut) and HJ 541 (single-cut) for amelioration of chromium toxicity (2 & 4 ppm) by exogenous application of GB (50 & 100 mM) with and without AMF in soil. The ameliorative effects were tested at two growth stages viz. vegetative (35 DAS) and grain filling (95 DAS), in terms of Cr uptake, grain yield, antioxidative defence system parameters (viz. enzymes – SOD, APX, CAT, GR, POX and metabolites – proline, glutathione, ascorbate, β-carotene) and indices of oxidative stress parameters (viz. PPO, H2O2, and MDA). Results The results delineated that Cr uptake and indices of oxidative stress were increased with increasing concentration of Cr stress in all the varieties (HJ 541, HJ513 & SSG 59–3) at both the growth stages (35 & 95 DAS). At higher concentration (4 ppm), Cr stress decreased the grain yield (45–50%) as compared with controls. Polyphenoloxidase activity, MDA and H2O2 content increased at both growth stages in all the varieties. However, antioxidative enzymes and metabolite activities increased due to Cr stress but this increase was not sufficient to counteract with ROS generated under Cr stress which was enhanced on the application of AMF and GB either individually or in combination (spiked in soil). It decreased the indices of oxidative stress and ameliorated the Cr toxicity and increased grain yield (65–70%) in all the varieties. Conclusions Both GB and AMF improved the antioxidative activities and stress tolerance capacity of the plant. Glycine betaine at both 50 and 100 mM level, significantly ameliorated Cr toxicity. However, AMF concomitantly with GB further boosts up the amelioration behaviour of the plant against Cr toxicity, at both growth stages in all the varieties. The combination of 100 mM GB with 10 g AMF was observed most effective among all the treatments. Among the varieties, SSG 59–3 had the lowest chromium uptake, indices of oxidative stress, and highest antioxidative system’s activity as compared to HJ 513 followed by HJ 541 variety. Thus AMF and GB either individually or in combination may be used to maintain plant yield attributes under Cr toxicity.

Bacterial Remediation of Chromium From Industrial Sludge

Chromium-like heavy toxic metals seriously influence the metabolism of living organisms and cause permanent threatening of health. Microorganisms can help to detoxify those hazardous heavy metals in the environment by the process of bioremediation. Two bacterial genera were isolated from industrial sludge designated P1 and P2. From the 16srRNA study, it is revealed that P1 is Bacillus cereus and P2 is Enterobacter sp. They are deposited in NCMR and NCBI and received the accession no. MCC 3868 for P1 and MCC 3788 for P2. P1 is gram positive, motile, and P2 is gram negative, motile. Eighteen antibiotics have been taken for antibiotic assay; P1 is resistant to 12; P2 is resistant to 8 antibiotics. For growth pattern analysis in chromium, three parameters have been selected, and they are temperature, pH, and biomass. In LD50 and above parameters, total chromium uptake by those bacteria in stressed conditions have been recorded. The two bacteria are not antagonistic to each other so they are used to bioremediate chromium from their contaminated sites and also treated as consortium.

Exogenous AMF with Glycine Betaine Reduces Cr (VI) Uptake and Alleviates Chromium Toxicity by Supressing the Oxidative Stress in Three Genetically Different Sorghum (Sorghum bicolor L.) Cultivars

Background: Chromium is most toxic pollutant that negatively affects plant’s metabolic activities and yield. It reduces plant growth by influencing the antioxidant defense system’s activities. The aim of the present research was to examine the ameliorative capability of exogenous GB and AMF spiked in soil, either individually or in combination against Cr toxicity. The ameliorative effects were studied in terms of Cr uptake, grain yield, antioxidative defense system parameters (viz. enzymes – SOD, APX, CAT, GR, POX and metabolites – proline, glutathione, ascorbate, β-carotene) and indices of oxidative stress parameters (viz. PPO, H2O2, and MDA). Results:The results delineated that Cr uptake and indices of oxidative stress were increased with increasing concentration of Cr stress in all the varieties (HJ 541, HJ513 & SSG 59-3) at both the growth stages (35 & 95 DAS). At higher concentration (4 ppm), Cr stress decreased the grain yield (45-50%) as compared with controls. PPO activity, MDA and H2O2 content increased at both growth stages in all the varieties. However, antioxidative enzymes and metabolite activities increased due to Cr stress but this increase was not sufficient to counteract with ROS generated under Cr stress which was enhanced on the application of AMF and GB either individually or in combination (spiked in soil). It decreased the indices of oxidative stress and ameliorated the Cr toxicity and increased grain yield (65-70%) in all the varieties. Conclusions:Both GB and AMF, improved the plant growth and stress tolerance capacity of the plant. GB at both 50 and 100 mM level, significantly ameliorated Cr (VI) toxicity. However, AMF concomitantly with GB further boost up the amelioration behavior of the plant against Cr toxicity, at both growth stages in all the varieties. The combination of 100 mM GB with 10 g AMF was observed most effective among all the treatments. Among the varieties SSG 59-3 had the lowest chromium uptake, indices of oxidative stress, and highest antioxidative system’s activity as compared to HJ 513 followed by HJ 541 variety. Thus AMF and GB either individually or in combination may be used to maintain plant yield attributes under Cr toxicity.