Browsing by Author "Amit Kumar Mishra"

Now showing 1 - 13 of 13

Anaerobic Biotechnology: A Useful Technique for Biofuel Production
(CRC Press, 2023) Saurabh Singh; Amit Kumar Mishra; Jay Prakash Verma; Shashi Arya; Vijay Nimkande
The increasing attention on the utilization of the lignocellulosic biomass for the production of alternative fuels seeks the exploration of new strategies. One such area that needs to be explored in detail is the anaerobic biotechnology for second-generation biofuel production. Technology development in second-generation biofuel production started long back in 1940s. The current estimate of biomass is more than 200 billion tonnes, sufficient to meet almost 13% of the world energy demands. The different types of biomasses range from forest residues to agricultural waste, which includes C3 as well as C4 plants. However, accounting for the efficiencies of C3 versus the C4 plants, the latter presents a straight 60% significant increase. Anaerobic bacteria have been widely used as tools for the production of bioproducts at the industrial level. Anaerobic treatment process offers a lot of advantages during the production of value-added products. For instance, anaerobic treatment utilizes almost 90% of the organic matter for the production of methane, remaining 10% or less converted to biomass, while requiring no further treatment for the sludge other than dewatering, as it is already well stabilized. In this chapter, the focus has been emphasized upon the recent advances in anaerobic treatment technologies for the production of biofuels. © 2023 selection and editorial matter, Rena and Sunil Kumar; individual chapters, the contributors.
Assessment of ozone toxicity among 14 Indian wheat cultivars under field conditions: growth and productivity
(Springer International Publishing, 2018) Aditya Abha Singh; Adeeb Fatima; Amit Kumar Mishra; Nivedita Chaudhary; Arideep Mukherjee; Madhoolika Agrawal; Shashi Bhushan Agrawal
Tropospheric ozone (O3) is a well-known threat to global agricultural production. Wheat (Triticum aestivum L.) is the second most important staple crop in India, although little is known about intra-specific variability of Indian wheat cultivars in terms of their sensitivity against O3. In this study, 14 wheat cultivars widely grown in India were exposed to 30 ppb elevated O3 above ambient level using open top chambers to evaluate their response against O3 stress. Different growth and physiological parameters, foliar injury and grain yield were evaluated to assess the sensitivity of cultivars and classified them on the basis of their cumulative stress response index (CSRI). Due to elevated O3, growth parameters, plant biomass, and photosynthetic rates were negatively affected, whereas variable reductions in yield were observed among the test cultivars. Based on CSRI values, HD 2987, DBW 50, DBW 77, and PBW 550 were classified as O3 sensitive; HD 2967, NIAW 34, HD 3059, PBW 502, HUW 213, and HUW 251 as intermediately sensitive, while HUW12, KUNDAN, HUW 55, and KHARCHIYA 65 were found to be O3-tolerant cultivars. Cultivars released after year 2000 were found to be more sensitive compared to earlier released cultivars. Path analysis approach showed that leaf area, plant biomass, stomatal conductance, net assimilation rate, and absolute growth rate were the most important variables influencing yield under O3 stress. Findings of the current study highlight the importance of assessing differential sensitivity and tolerance of wheat cultivars and response of different traits in developing resistance against elevated O3. © 2018, Springer International Publishing AG, part of Springer Nature.
Biochemical and physiological characteristics of tropical mung bean (Vigna radiata L.) cultivars against chronic ozone stress: an insight to cultivar-specific response
(Springer-Verlag Wien, 2015) Amit Kumar Mishra; S.B. Agrawal
Surface-level ozone (O3) has been regarded as one of the most significant phytotoxic pollutants worldwide. Investigations addressing adverse impacts of elevated O3 on mung bean (Vigna radiata L.), an important leguminous crop of the Indian subcontinent, are still limited. The present study analyzed the differences on the foliar injury, reactive oxygen species (ROS) generation, antioxidative defense system, physiology, and foliar protein profile of two tropical mung bean cultivars (HUM-2 and HUM-6) exposed to elevated O3 under near-natural conditions. Both cultivars were negatively affected by the pollutant, but the response was cultivar-specific. Results revealed that elevated O3 induced higher levels of ROS (O2 ·− and H2O2) and lipid peroxidation leading to greater foliar injury in HUM-2 compared to HUM-6. Photosynthetic pigments, photosynthetic rate, stomatal conductance, and photochemical efficiency reduced under elevated O3 exposure and the extent of reduction was higher in HUM-2. Principal component analysis revealed that photosynthetic performance and quantum yield were drastically affected in HUM-2 as compared to HUM-6. Activities of antioxidative enzymes were also stimulated, suggesting generation of oxidative stress under elevated O3. HUM-6 showed higher induction of antioxidative enzymes than HUM-2. One-dimensional gel electrophoresis analysis showed drastic reductions in the abundantly present ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) large and small subunits and the decrease was higher in HUM-2. Altogether, results suggested that higher accumulation of ROS and limited induction of antioxidant defense system led to more leaf injury and impairment of photosynthesis in HUM-2 than HUM-6 depicting its higher sensitivity towards elevated O3. © 2014, Springer-Verlag Wien.
Comparative analyses of genotoxicity, oxidative stress and antioxidative defence system under exposure of methyl parathion and hexaconazole in barley (Hordeum vulgare L.)
(Springer Verlag, 2015) Pragyan Dubey; Amit Kumar Mishra; Ashok Kumar Singh
The present study aims to evaluate the comparative effects of methyl parathion and hexaconazole on genotoxicity, oxidative stress, antioxidative defence system and photosynthetic pigments in barley (Hordeum vulgare L. variety karan-16). The seeds were exposed with three different concentrations, i.e. 0.05, 0.1 and 0.5 % for 6 h after three pre-soaking durations 7, 17 and 27 h which represents G1, S and G2 phases of the cell cycle, respectively. Ethyl methane sulphonate, a well-known mutagenic agent and double distilled water, was used as positive and negative controls, respectively. The results indicate significant decrease in mitotic index with increasing concentrations of pesticides, and the extent was higher in methyl parathion. Chromosomal aberrations were found more frequent in methyl parathion than hexaconazole as compared to their respective controls. Treatment with the pesticides induced oxidative stress which was evident with higher contents of H2O2 and lipid peroxidation, and the increase was more prominent in methyl parathion. Contents of total phenolics were increased; however, soluble protein content showed a reverse trend. Among the enzymatic antioxidants, activities of superoxide dismutase and peroxidase were significantly up-regulated, and more increase was noticed in hexaconazole. Increments in total chlorophyll and carotenoid contents were observed up to 0.1 % but decreased at higher concentration (0.5 %), and the reductions were more prominent in methyl parathion than hexaconazole as compared to their respective controls. Methyl parathion treatment caused more damage in the plant cells of barley as compared to hexaconazole, which may be closely related to higher genotoxicity and oxidative stress. © 2015, Springer-Verlag Berlin Heidelberg.
Differential response of dwarf and tall tropical wheat cultivars to elevated ozone with and without carbon dioxide enrichment: Growth, yield and grain quality
(2013) Amit Kumar Mishra; Richa Rai; S.B. Agrawal
In past few years, atmospheric concentrations of carbon dioxide (CO2) and tropospheric ozone (O3) have increased due to anthropogenic activities. CO2 enhances the plant growth and surface level of O3 is a well-known phyto-toxic pollutant. Present study was conducted to assess the impact of elevated levels of CO2 and O3, singly and in combination on two wheat cultivars HUW-37 and K-9107 on their growth, yield attributes and grain quality in open top chambers (OTCs). Wheat plants under elevated CO2 (EC) showed increment in growth parameters while exposure to elevated O3 (EO) showed an opposite trend than EC. In elevated CO2+O3 (ECO) exposure, elevated CO2 fully protected wheat cultivars against negative effects of O3. Yield parameters showed significant increase in EC followed by ECO and in EO, significant reductions in yield were noticed in both the cultivars. Protein and total free amino-acids decreased in grains of EC, ECO and EO in both the test cultivars. Total soluble sugars and starch contents in grains increased due to EC and ECO and decreased in EO, however reducing sugars showed an opposite trend in both the cultivars. The yield data obtained from the experiment showed cultivar specific response as cultivar HUW-37 proved to be sensitive as compared to K-9107 against ambient and elevated levels of O3. The study also concludes that elevated CO2 nullified the negative impact of elevated O3 in both the test cultivars of wheat. © 2013 Elsevier B.V.
Differential sensitivity of barley (Hordeum vulgare L.) to chlorpyrifos and propiconazole: Morphology, cytogenetic assay and photosynthetic pigments
(Academic Press Inc., 2015) Pragyan Dubey; Amit Kumar Mishra; Pratiksha Shukla; Ashok Kumar Singh
The present investigation was performed to evaluate the effects of an insecticide and fungicide, namely, chlorpyrifos (CP) and propiconazole (PZ) on barley (Hordeum vulgare L. variety Karan-16). The seeds were treated with three concentrations of CP and PZ, i.e., 0.05%, 0.1% and 0.5% for 6 hours after different pre-soaking durations of 7, 17 and 27 hours. Different pre-soaking durations (7, 17 and 27 h) represent three phases of the cell cycle i.e., G1, S and G2, respectively. Double distilled water and ethyl methane sulfonate were used as negative and positive controls, respectively. As compared to their respective controls, treated root tip meristematic cells of barley showed significant reductions in the germination percentage, seedling height, mitotic index and comparative increase in chromosomal aberrations against both the pesticides, and the magnitude was higher in CP. After treatment with the pesticides, chlorophyll and carotenoid contents increased up to 0.1% but reduced at 0.5% and the decrease was more prominent in CP as compared to PZ. In treated cells, fragmentation, stickiness, bridges, multipolar anaphase and diagonal anaphase were observed as aberrations. As compared to control, chromosomal aberrations were higher in CP as compared to PZ. The results of the present study concluded that CP induced chromosomal aberrations were more frequent than PZ; hence it has higher probability to cause genotoxicity in barley. © 2015 Elsevier Inc.
Effect of Lockdown Amid COVID-19 on Ambient Air Quality in 16 Indian Cities
(Frontiers Media S.A., 2021) Amit Kumar Mishra; Prashant Rajput; Amit Singh; Chander Kumar Singh; Rajesh Kumar Mall
The COVID-19 pandemic has affected severely the economic structure and health care system, among others, of India and the rest of the world. The magnitude of its aftermath is exceptionally devastating in India, with the first case reported in January 2020, and the number has risen to ~31.3 million as of July 23, 2021. India imposed a complete lockdown on March 25, which severely impacted migrant population, industrial sector, tourism industry, and overall economic growth. Herein, the impacts of lockdown and unlock phases on ambient atmospheric air quality variables have been assessed across 16 major cities of India covering the north-to-south stretch of the country. In general, all assessed air pollutants showed a substantial decrease in AQI values during the lockdown compared with the reference period (2017–2019) for almost all the reported cities across India. On an average, about 30–50% reduction in AQI has been observed for PM2.5, PM10, and CO, and maximum reduction of 40–60% of NO2 has been observed herein, while the data was average for northern, western, and southern India. SO2 and O3 showed an increase over a few cities as well as a decrease over the other cities. Maximum reduction (49%) in PM2.5 was observed over north India during the lockdown period. Furthermore, the changes in pollution levels showed a significant reduction in the first three phases of lockdown and a steady increase during subsequent phase of lockdown and unlock period. Our results show the substantial effect of lockdown on reduction in atmospheric loading of key anthropogenic pollutants due to less-to-no impact from industrial activities and vehicular emissions, and relatively clean transport of air masses from the upwind region. These results indicate that by adopting cleaner fuel technology and avoiding poor combustion activities across the urban agglomerations in India could bring down ambient levels of air pollution at least by 30%. Copyright © 2021 Mishra, Rajput, Singh, Singh and Mall.
Growth, ultrastructural and physiological characteristics of Abelmoschus cytotypes under elevated ozone stress: a study on ploidy-specific responses
(CSIRO, 2024) Priyanka Singh; Naushad Ansari; Amit Kumar Mishra; Madhoolika Agrawal; Shashi Bhushan Agrawal
Tropospheric ozone (O3) is a significant abiotic stressor whose rising concentration negatively influences plant growth. Studies related to the differential response of Abelmoschus cytotypes to elevated O3 treatment are scarce and need further exploration to recognise the role of polyploidisation in stress tolerance. In this study, we analysed the changes in growth pattern, ultrastructure, physiology and foliar protein profile occurring under O3 stress in Abelmoschus moschatus (monoploid), Abelmoschus esculentus (diploid) and Abelmoschus caillei (triploid). Our findings showed that higher stomatal conductance in A. moschatus triggered higher O3 intake, causing damage to stomatal cells and photosynthetic pigments. Additionally, it caused a reduction in photosynthetic rates, leading to reduced plant growth, total biomass and economic yield. This O3-induced toxicity was less in diploid and triploid cytotypes of Abelmoschus. Protein profiling by sodium dodecyl sulpate-polyacrylamide gel electrophoresis showed a significant decrease in the commonly found RuBisCO larger and smaller subunits. The decrease was more prominent in monoploid compared to diploid and triploid. This study provides crucial data for research that aim to enhance plant ability to withstand O3 induced oxidative stress. Our findings may help in developing a tolerant variety through plant breeding techniques, which will be economically more advantageous in reaching the objective of sustainable production at the high O3 levels projected under a climate change scenario. © 2024 The Author(s).
Individual and interactive effects of elevated carbon dioxide and ozone on tropical wheat (Triticum aestivum L.) cultivars with special emphasis on ROS generation and activation of antioxidant defence system
(2013) Amit Kumar Mishra; Richa Rai; S.B. Agrawal
The effects of elevated CO2 and O3, singly and in combination were investigated on various physiological, biochemical and yield parameters of two locally grown wheat (Triticum aestivum L.) cultivars (HUW-37 and K-9107) in open top chambers (OTCs). Elevated CO2 stimulated photosynthetic rate (Ps) and Fv/Fm ratio and reduced the stomatal conductance (gs). Reactive oxygen species, lipid peroxidation, anti-oxidative enzymes, ascorbic acid and total phenolics were higher, whereas Ps, gs, Fv/Fm, protein and photosynthetic pigments were reduced in elevated O3 exposure, as compared to their controls. Under elevated CO2 + O3, elevated levels of CO2 modified the plant performance against O3 in both the cultivars. Elevated CO2 caused significant increase in economic yield. Exposure to elevated O3 caused significant reduction in yield and the effect was cultivar-specific. The study concluded that elevated CO2 ameliorated the negative impact of elevated O3 and cultivar HUW-37 was more sensitive to elevated O3 than K-9107.
Modern pollen–vegetation relationships along an altitudinal transect in the Western Higher Himalaya, India: Palaeoclimatic and anthropogenic implications
(SAGE Publications Ltd, 2022) Amit Kumar Mishra; Ruchika Bajpai Mohanty; Ruby Ghosh; Kriti Mishra; Uma Kant Shukla; Ratan Kar
Palynology is one of the most reliable tools for the reconstruction of past vegetation and climate and modern pollen analogues are important for the calibration of fossil pollen assemblages. The present study analyses the pollen–vegetation relationships along a steep altitudinal gradient (2700–3680 m), in the western Higher Himalayan region. On the basis of altitude, three vegetation zones were demarcated: Zone I (2700–3100 m) is composed of mixed-temperate forest vegetation, dominated by Quercus semecarpifolia and Rhododendron arboreum; Zone II (3100–3250 m) is marked by sub-alpine forest vegetation, characterised by R. campanulatum and R. barbatum, along with Abies spectabilis and Q. semecarpifolia; Zone III (3250–3680 m) is above the tree-line (3250 m) and represented by alpine-scrub and meadows. Thirty-five surface soil samples (twenty, seven and eight from each zone, respectively) were analysed along the altitudinal transect to decode the representation of the extant vegetation in the pollen-rain. The pollen–vegetation relationship is non-linear due to the over-representation of extra-local Pinus pollen in each zone. Nonetheless, the modern pollen assemblages show a general correlation with the local broad-leaved taxa and the herbaceous elements; with the exception of Rhododendron pollen, which is under-represented. Among the non-pollen palynomorphs (NPPs), the presence of coprophilous fungal spores is compatible with the grazing activities in the area. Multivariate statistical analyses performed on the surface pollen data indicate that the dataset can efficiently distinguish the different vegetation zones across the altitudinal gradient. This work provides the modern analogues for pollen-based palaeoclimatic reconstructions for the Western-Higher Himalayan region, and would also help to decipher the inception and intensification of anthropogenic activities in the region. © The Author(s) 2022.
Responses of an old and a modern Indian wheat cultivar to future O3 level: Physiological, yield and grain quality parameters
(Elsevier Ltd, 2020) Durgesh Singh Yadav; Amit Kumar Mishra; Richa Rai; Nivedita Chaudhary; Arideep Mukherjee; S.B. Agrawal; Madhoolika Agrawal
A field study was conducted to understand the physiological responses, yield and grain quality of an old (HUW234) and a modern (HD3118) wheat cultivar exposed to elevated ozone (O3). The cultivars were grown under ambient O3 (NF) and ambient +20 ppb O3 (NF+) conditions using open-top chambers (OTCs). The comparative study of an old and a modern cultivar showed variable physiological responses under elevated O3 exposure. Elevated O3 in old cultivar caused high reductions in Rubisco activity (Vcmax) and electron transport rate (J) compared to modern cultivar with simultaneous reductions in the rate of photosynthesis and chlorophyll fluorescence. In modern cultivar, high stomatal density and conductance caused higher O3 uptake thereby triggering more damage to the adjacent stomatal cells and photosynthetic pigments coupled with reductions in photosynthetic rate and photosynthetic nitrogen use efficiency (PNUE). Modern cultivar also showed relatively high reduction in grain yield compared to old one under NF + treatment. Furthermore, grain quality traits (such as starch, protein and amino acids) of modern cultivar were better than old cultivar under ambient O3, but showed more deterioration under NF + treatment. Results thus indicated that modern cultivar is relatively more susceptible to O3 and showed more negative impacts on plant performance, yield and quality of grains compared to old cultivar. © 2020 Elsevier Ltd
Rising atmospheric carbon dioxide and plant responses: Current and future consequences
(Elsevier, 2019) Amit Kumar Mishra; Shashi Bhushan Agrawal; Madhoolika Agrawal
The industrial revolution, population explosion, urbanization, and the use of advanced technological instruments have accelerated the consumption of fossil fuels leading to changes in the gaseous composition of the Earth’s atmosphere. The combustion of fossil fuel acts as a principal source of carbon dioxide (CO2) and is still contributing to its continuous rise in the atmosphere. The levels of CO2 in the atmosphere have significantly increased since the preindustrial era and future projections predict that its concentration will be doubled in the next 50 years, which will cause a significant impact on global weather patterns, including temperature increases by an average of 0.5°C per decade. As per future projections regarding greenhouse gases made by the Intergovernmental Panel on Climate Change, the projected levels of CO2 will range from 500 to 1000 ppm by the end of the 21st century. Currently, crop plants are exposed to CO2 levels that have not been experienced from the time of the preindustrial era, and agriculture is facing a future of uncertain consequences of global climate change. An understanding of the influence of climate change on future crop production requires an appreciation of the general responses of a range of crop types to elevated CO2 contents and the ways in which those affects interact with other factors. Rising CO2 is considered an important aspect of global climate change as it has the potential to enhance crop productivity, which will be required to feed the increasing population across the globe. The objective of this chapter is to present an overview of the responses of plants to high CO2 and the fundamental mechanisms behind those responses. © 2019 Elsevier Inc. All rights reserved.
ROS production and its detoxification in early and late sown cultivars of wheat under future O3 concentration
(Elsevier B.V., 2019) Durgesh Singh Yadav; Richa Rai; Amit Kumar Mishra; Nivedita Chaudhary; Arideep Mukherjee; S.B. Agrawal; Madhoolika Agrawal
The present field study was planned with an objective to unravel the mechanisms behind the differential responses of early and late sown wheat cultivars with respect to their defense capacity to scavenge ROS induced under elevated O3 (EO3). Experiments were performed under ambient and elevated levels of O3 (ambient + 20 ppb) to plants inside open-top chambers (OTCs). Ozone concentrations, stomatal flux of O3 and meteorological parameters were measured throughout the experiment. Contents of superoxide radicals ([rad]O2 −) and hydrogen peroxide (H2O2) and their localization, lipid peroxidation, antioxidative enzyme activities, ascorbic acid and total phenolic contents were measured at vegetative and reproductive developmental stages. EO3 exposure induced higher stomatal flux of O3 in early sown cultivars. Higher contents of [rad]O2 −, H2O2 and lipid peroxidation were noticed under EO3 in all the cultivars but the magnitude of increases was higher in late sown cultivars at the reproductive stage. Activities of glutathione reductase (GR) and ascorbate peroxidase (APX) were higher in late sown cultivars under EO3. Ascorbic acid and total phenolic contents were significantly higher in early sown than late sown cultivars under EO3 treatment. The present study concludes that early sown cultivars are more efficient in their defense response due to higher induction of enzymatic and non-enzymatic antioxidants, while the induction of enzymatic antioxidants was more distinct in late sown cultivars. Non-enzymatic linked defense mechanism requires additional metabolic cost than enzymatic defense, making early sown cultivars more susceptible to EO3. Differential response of early and late sown cultivars with respect to antioxidative defense against O3 stress suggests that yield responses are governed by the time of sowing and intrinsic defense responses of the cultivars. In future with rising trend of O3, early sown cultivars are expected to be more vulnerable to oxidative stress compared to late sown cultivars. © 2018 Elsevier B.V.