Crop Protection & Environmental Biology
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Item "Biochar in combination with compost reduced Pb uptake and enhanced the growth of maize in lead (Pb)‑contaminated soil exposed to drought stress "(Springer, 2010) Adejumo, S. A.; Arowo, D. O.; Ogundiran, M. B.; Srivastava, P.Crops are constantly faced with the challenges of different abiotic stresses on the field. Development of sustainable approach for stress amelioration on crop is pertinent. This study investigated the ameliorative roles of biochar and compost on maize crop simultaneously subjected to drought and heavy metal (Pb) stresses. Metal stress was imposed by growing maize on Pb-contaminated soil while drought stress was imposed by reducing the soil field capacity to 25 and 50%. Four levels (0, 5, 10 and 15 t/ha) of biochar and compost replicated three times as well as their combinations were used. Pb uptake, translocation factors, photosynthetic pigments, osmolytes (proline and cysteine), biomass accumulation in stressed maize crop, and post-cropping soil Pb concentration were determined. Combination of stresses reduced biomass accumulation in maize. Biochar in combination with compost, however, enhanced biomass production in stressed maize crop by 50–75% compared to unamended soil (control). Proline accumulation was more under the single stress of heavy metal (100% FC) compared to combined stresses. Unlike proline, combined stresses of Pb and 50% FC enhanced chlorophyll and cysteine accumulation more than single stress. Their concentrations were further increased with amendments compared to control. Pb accumulation in maize crop was more under combined stresses than single stress (100% FC). Compared to other soil amendments, application of biochar alone at 10 t/ha, generally reduced Pb uptake by maize and post-cropping soil Pb concentration. Biochar and compost reduced Pb uptake, and enhanced biomass and osmolyte production in stressed maize crop.Item Mechanisms of lead and chromium hyperaccumulation and tolerance in plant(Enproct Consultants Ltd., 2019) Adejumo, S. A.Heavy metal contamination of agricultural lands poses serious threat to food security. Lead (Pb) and Chromium (Cr) are among the most toxic heavy metals reported but least studied. Their presence in soils has detrimental effects on crop productivity. Among different ways of remediating contaminated sites, phytoremediation technology like phytoextraction is now receiving greater attention. It involves the use of plants for cleaning heavy metal polluted media. It is environment-friendly, aesthetically appealing, cost-effective and can be applied in-situ. The plant species that are used for this process are metal tolerant and some of them called hyperaccumulators possess the ability of accumulating high concentrations of specific metals in the above-ground tissue. They have developed several mechanisms both at the genetic and molecular levels for their adaptability and efficiency. The molecular mechanisms could either be enzymatic or non-enzymatic. The enzymatic mechanism involves the participation of different antioxidant enzymes while the non-enzymatic strategies are based on the production of different antioxidant compounds for scavenging reactive oxygen species which are produced in heavy-metal stressed plants. For tolerance and metal accumulation in the above-ground parts of an hyperaccumulator, metal homoestasis through over-expression of different genes have also been reported. In this review, heavy metal toxicity, phytoremediation options and mechanisms of hyperaccumulation and tolerance in plants are discussed with focus on Pb and Cr.Item Evaluation of lead and chromium tolerance and accumulation level in Gomphrena Celosoides: a novel metal accumulator from lead acid battery waste contaminated site in Nigeria(Taylor & Francis, 2019) Adejumo, S. A.; Tiwari, S.; Thul, S.; Sarangi, B. K.Biology, tolerance, and metal (Pb and Cr) accumulating ability of Gomphrena celosoides were studied under hydroponic conditions. The seedlings were raised in Hoagland’s solution containing different concentrations of Pb (0, 500, 1000, 1500, 2000, 3000, 4000, and 5000mg l_1) and Cr (0, 50, 100, 150, 200, 300, and 400mg l_1). Biomass and metal accumulation in different plant parts were determined at seven (7) and fourteen (14) days after stress. Antioxidant enzyme activities, protein, and proline contents were estimated in stressed and unstressed plants. Gomphrena celosoides was able to tolerate Pb and Cr concentrations up to 4000 and 100mg l_1, respectively in hydroponic solution. Metal accumulation was concentration and duration dependent with the highest Pb (21,127.90 and 117,985.29mg kg_1) and Cr (3130.85 and 2428.90mg kg_1) in shoot and root, respectively found in the plants exposed to 5000mg l_1 Pb and 400mg l_1 Cr for 14 days. Proline, antioxidant enzyme activities, and protein contents were the highest in plant exposed to higher Pb and Cr concentrations for 7 and 14 days. Gomphrena celosoides could be considered as Pb and Cr accumulator with proline and increase in antioxidant enzyme activities being the tolerance mechanismsItem Heavy metal (Pb) accumulation in metallophytes as influenced by the variations in rhizospheric and non- rhizospheric Soils physico-chemical characteristics.(Taylor & Francis., 2018) Adejumo, S. A.; Tiwari, S.; Shinde, V.; Sarangi, B. K.Activities at root-soil interface determine the solubility and uptake of metals by plants. Metal accumulation in plant species (Imperata cylindrical, Cynodon dactylon, Eleucine indica, Gomphrena celosoides, Sporobolus pyramidalis, Chromolaena odorata and Rhynchospora corymbosa) growing on Pb contaminated site as influenced by variations in physico-chemical characteristics, dissolved organic matter (DOM), Pb fractionation and different functional groups (using Fourier Transmittance Infra-red) of rhizospheric and non-rhizospheric soils was assessed. The electrical conductivity (2660–5520 ms) and Pb concentrations (51390.0–64080.0 mg/kg) were more in non-rhizospheric than rhizospheric soils having 276 ms to 3160 ms EC and 3289.0 to 44850.0 mg/kg Pb. More nutrients, DOM and carbohydrates functional groups (C-O; 1100 -1000 and O-H; 3700–3600) were found in rhizospheric compared to non-rhizospheric soils. The pH was slightly acidic (5.0–5.54) and E. indica with the lowest pH (5.0) accumulated highest Pb concentrations in shoot (8030 mg/kg) and root (16380 mg/kg) while C. odorata with highest values of pH, P, Ca and Mg in rhizospheric soil accumulated the least (root; 331.6 and shoot: 209.0 mg/kg). Pb was more in organic and residual fractions of rhizospheric and non-rhizospheric soils respectively. Reduction in pH, EC coupled with nutrients and DOM availability increased Pb uptake by plants.Item Seasonal variations in distribution, heavy metal uptake and proline production of native plants growing on Pb-contaminated site in Ibadan, South-Western,(Ecological Society of Nigeria, 2015) Adejumo, S. A.; Adeosun, A. A.; Olaniyan, A. B.; Awodoyin, R. O.Effects of seasonal variations on metal (Lead, Chromium and Cadmium) uptake, proline concentration, density and distribution of metallophytes inhabiting heavy metal polluted site in Ibadan, South-Western Nigeria were investigated. Vegetation surveys and Relative Importance Values (RIV) of different plant species were carried out both at the rainy and dry seasons. The metal uptake and partitioning in plants at different seasons as well as proline content were also determined. The results showed that the Relative Importance Value (RIV), metal uptake and proline production by plants varied depending on the prevailing environmental conditions. During both sampling seasons, same plant species were enumerated on the contaminated site. However, their RIV varied in the two seasons. Sporobolus. pyramidalis was prevalent in the rainy season while Imperata cylindrica had the highest RIV during the dry season. Heavy metal accumulation in different plant species also differed depending on the sampling period and higher concentrations of metals were accumulated during the rainy season compared to the dry season except in Gomphrena celosioides with Pb being the highest at both seasons. The proline concentrations were also species and season dependent. The concentrations varied in different plant species and G. celosioides accumulated more during both seasons while Eleucine indica and Rhyncospora corymbosa had higher concentrations during the dry season compared to rainy season. Plant species abundance, metal uptake and osmolyte production by metallophytes are therefore dependent on the prevailing environmental conditions.