Soil amendment with biochar is evaluated globally as a means to improve soil fertility and to mitigate climate change. However, the effects of biochar on soil biota have received much less attention than its effects on soil chemical properties. A review of the literature reveals a significant number of early studies on biochar-type materials as soil amendments either for managing pathogens, as inoculant carriers or for manipulative experiments to sorb signaling compounds or toxins. However, no studies exist in the soil biologyliterature that recognize the observed largevariations ofbiochar physico-chemical properties. This shortcoming has hampered insight into mechanisms by which biochar influences soil microorganisms, fauna and plant roots. Additional factors limiting meaningful interpretation of many datasets are the clearly demonstrated sorption properties that interfere with standard extraction procedures for soil microbial biomass or enzyme assays, and the confounding effects of varying amounts of minerals. In most studies, microbial biomass has been found to increase as a result of biochar additions, with significant changes in microbial community composition and enzyme activities that may explain biogeochemical effects of biochar on element cycles, plant pathogens, and crop growth. Yet, very little is known about the mechanisms through which biochar affects microbial abundance and community composition. The effects of biochar on soil fauna are even less understood than its effects on microorganisms, apart from several notable studies on earthworms. It is clear, however, that sorption phenomena, pH and physical properties of biochars such as pore structure, surface area and mineral matter play important roles in determining how different biochars affect soil biota. Observations on microbial dynamics lead to the conclusion of a possible improved resource use due to co-location of various resources in and around biochars. Sorption and therebyinactivation of growth-inhibiting substances likelyplaysa rolefor increased abundance of soil biota. No evidence exists so far for direct negative effects of biochars on plant roots. Occasionally observed decreases in abundance of mycorrhizal fungi are likely caused by concomitant increases in nutrient availability,reducing theneedfor symbionts.Inthe shortterm,therelease ofavarietyoforganic molecules from fresh biochar may in some cases be responsible for increases or decreases in abundance and activity of soil biota. A road map for future biochar research must include a systematic appreciation of different biochar-types and basic manipulative experiments that unambiguously identify the interactions between biochar and soil biota.

http://www.css.cornell.edu/faculty/lehmann/pictures/publ/SoilBiolBiochem%2043,%201812–1836,%202011%20Lehmann.pdf

Biochar effects on soil biota – A review

Statistical Methods For Agricultural Workers

https://www.cell.com/trends/microbiology/pdf/S0966-842X(08)00192-3.pdf

Properties of bacterial endophytes and their proposed role in plant growth.

Recent molecular studies on endophytic bacterial diversity have revealed a large richness of species. Endophytes promote plant growth and yield, suppress pathogens, may help to remove contaminants, solubilize phosphate, or contribute assimilable nitrogen to plants. Some endophytes are seed-borne, but others have mechanisms to colonize the plants that are being studied. Bacterial mutants unable to produce secreted proteins are impaired in the colonization process. Plant genes expressed in the presence of endophytes provide clues as to the effects of endophytes in plants. Molecular analysis showed that plant defense responses limit bacterial populations inside plants. Some human pathogens, such as Salmonella spp., have been found as endophytes, and these bacteria are not removed by disinfection procedures that eliminate superficially occurring bacteria. Delivery of endo-phytes to the environment or agricultural fields should be carefully evaluated to avoid introducing pathogens.

https://apsjournals.apsnet.org/doi/pdf/10.1094/MPMI-19-0827

Bacterial Endophytes and Their Interactions with Hosts

The loss of carbon from roots (rhizodeposition) and the consequent proliferation of microorganisms in the surrounding soil, coupled with the physical presence of a root and processes associated with nutrient uptake, gives rise to a unique zone of soil called the rhizosphere. In this review, we bring together evidence to show that roots can directly regulate most aspects of rhizosphere C flow either by regulating the exudation process itself or by directly regulating the recapture of exudates from soil. Root exudates have been hypothesized to be involved in the enhanced mobilization and acquisition of many nutrients from soil or the external detoxification of metals. With few exceptions, there is little mechanistic evidence from soil-based systems to support these propositions. We conclude that much more integrated work in realistic systems is required to quantify the functional significance of these processes in the field. We need to further unravel the complexities of the rhizosphere in order to fully engage with key scientific ideas such as the development of sustainable agricultural systems and the response of ecosystems to climate change. Contents I. Introduction 460 II. What is rhizodeposition? 460 III. Regulation of rhizodeposition 460 IV. How large is the root exudation C flux? 463 V. How responsive is the root exudation C flux? 463 VI. How responsive is the microbial community to root exudation? 464 VII. The role of root exudates in nutrient acquisition 464 VIII. Mycorrhizal fungi and rhizodeposition 471 IX. Future thoughts 474 Acknowledgements 474 References 474.

https://nph.onlinelibrary.wiley.com/doi/epdf/10.1111/j.1469-8137.2004.01130.x

Plant and mycorrhizal regulation of rhizodeposition

Indices of oxidative stress viz., superoxide radical and H2O2 content increased in leaves of all the cultivars with the rise in salinity level, the increase was more pronounced and significant in salt-sensitive varieties and non-significant in resistant cultivars. Except for glutathione reductase (GR), basal activities of all other antioxidative enzymes viz. superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX) and glutathione reductase (GR) were significantly higher in leaves of all the resistant cultivars as compared to the sensitive ones. A differential response of salinity was observed on various enzymatic and non-enzymatic components of antioxidant system in leaves of salt-tolerant and salt-sensitive cultivars of rice (Oryza sativa L.). Activities of superoxide dismutase and glutathione reductase enhanced in all the tolerant cultivar while declined in the sensitive cultivars with increasing salinity from 0 to 100 mM. Salt-stress induced the activities of catalase and peroxidase in all the cultivars but the magnitude of increase was more pronounced in the sensitive cultivars than in the tolerant cultivars. Contrarily, APX activity increased in the salt-sensitive cultivars but showed no significant change in the salt-tolerant cultivars. The amount of ascorbic acid content, reduced glutathione (GSH), reduced/oxidized glutathione (GSSG) ratio was higher in leaves of the tolerant cultivars than that of the sensitive cultivars under saline conditions. It is inferred that leaves of salt-tolerant cultivars tend to attain greater capacity to perform reactions of antioxidative pathway under saline conditions to combat salinity-induced oxidative stress.

Salinity induced oxidative stress and antioxidant system in salt-tolerant and salt-sensitive cultivars of rice Oryza sativa L

Statement of problem Tooth wear is a complex process, which, if not prevented, may adversely affect the integrity of the stomatognathic system. Different restorative dental materials may affect the amount of wear on natural enamel antagonists. Purpose The purpose of this in vivo study was to evaluate and compare the wear of enamel opposing natural enamel, zirconia, and metal ceramic crowns after 1 year. Material and methods Ten participants between 18 and 35 years of age requiring 2 complete crowns, 1 on either side of maxillary or mandibular molar region, and having healthy natural teeth in the opposing arch were selected. For each participant, 1 monolithic polished zirconia crown and 1 glazed metal ceramic crown were fabricated and cemented. To evaluate the wear of the antagonistic natural enamel (premolar and molar), polyvinyl siloxane impressions were made immediately (baseline) and at 1 year after cementation. The wear of natural enamel against natural enamel was evaluated as the control. The resulting casts were scanned (using a 3D white light scanner), and 3D software was used to calculate the maximum amount of linear wear. Results One-way repeated measures ANOVA was conducted to analyze data. Mean ±SD occlusal wear of the antagonistic enamel 1 year after the cementation of metal ceramic crowns was 69.20 ±4.10 μm for premolar teeth and 179.70 ±8.09 μm for molar teeth, whereas for zirconia crowns, it was 42.10 ±4.30 μm for premolar teeth and 127.00 ±5.03 μm for molar teeth. Occlusal wear of natural enamel opposing natural enamel was 17.30 ±1.88 μm in the premolar region and 35.10 ±2.60 μm in the molar region. The Bonferroni post hoc test revealed that the occlusal wear of antagonistic enamel 1 year after the cementation of a metal ceramic crown was significantly higher ( P Conclusions Zirconia crowns led to less wear of antagonist enamel than metal ceramic crowns, but more than natural enamel.

Clinical study to evaluate the wear of natural enamel antagonist to zirconia and metal ceramic crowns.

We have studied intercellular colonization of wheat roots by Azorhizobium caulinodans and other diazotrophic bacteria, using strains marked with the lacZ reporter gene to facilitate their detection and identification. A. caulinodans was observed by light and electron microscopy to enter the roots of wheat at high frequency at the points of emergence of lateral roots (lateral root cracks). After lateral root crack colonization, bacteria moved into intercellular spaces within the cortical cell layer of roots. The flavonoid naringenin at 10 and 100 mmol m ‐3 significantly stimulated root colonization. The roles of the structural nodABC genes and the regulatory nodD gene were also studied; lateral root crack colonization of wheat was shown to be Nod factor- and NodD-independent. Similar frequencies of lateral root crack colonization were observed following inoculation of wheat with Azospirillum brasilense. Colonization by A. brasilense was stimulated by naringenin and also by other flavonoid molecules.

The flavonoid naringenin stimulates the intercellular colonization of wheat roots by Azorhizobium caulinodans

To evaluate the outcome of fresh amniotic membrane transplantation (AMT) for ocular surface reconstruction in acute chemical burns. A prospective study of 15 consecutive eyes with acute chemical burns was performed. In all, 10 eyes had lime burns and five eyes had acid burns. There were three eyes of grade II, four eyes of grade III and eight eyes of grade IV burns. AMT was performed within 3 weeks of injury. Patients were followed up for 10.14±4.41 months. All patients had immediate relief of pain postoperatively. Of 15 eyes, nine (60%) showed epithelialization within 1–4 weeks (15.33±9.91 days). The final visual acuity improved in 10 of 15 eyes (66.66%). Eyes with burns of grade II and III showed more visual improvement than those with grade IV burns. None of the eyes showed perforation. Symblepharon was seen in nine of 15 eyes (60%). Of 15 eyes, 12 (80%) experienced limbal stem cell deficiency and showed superficial corneal vascularization. Amniotic membrane transplantation with fresh amniotic membrane increases patient comfort and reduces inflammation. In mild burns, AMT alone restores corneal and conjunctival surfaces. In moderate to severe burns, it probably reduces conjunctival scarring sequelae, but does not prevent the sequelae of limbal stem cell deficiency that requires further limbal stem cell transplantation. In the acute stage, amniotic membrane transplantation probably has a protective role against the progressive melting and perforation.

/pdf/amniotic-membrane-transplantation-in-acute-chemical-burns-2jqwbywwfc.pdf

Amniotic membrane transplantation in acute chemical burns.

Purpose of study : Proper color match of a dental restoration with the adjacent teeth is important not only at the initial stage of giving the restoration but also over a longer period of time. Out of different materials Porcelain has established itself as being color stable and durable but composites are known to be susceptible to discoloration because of internal mechanisms, external contamination and staining. The newer universal composite systems are optimized in terms of composition to minimize internal discoloration but still not much attention is given to resistance to external staining. Procedure : Visual shade matching and color determination being a psychophysical phenomenon suffer from subjective variations in interpretation, therefore the present study was undertaken to evaluate and compare the color stability of a porcelain (Vitadur alpha) and two universal composites (Filtek Z 250 and Tetric Ceram) after exposure to commonly consumed beverages i.e. tea, coffee, coca-cola and distilled water (as control) by using a reflectance spectrophotometer and CIELAB system. Conclusion : T0 he color match of esthetic restorations in the oral cavity is affected by dietary habits

Veena Jain

Papers

Salinity induced oxidative stress and antioxidant system in salt-tolerant and salt-sensitive cultivars of rice Oryza sativa L

Clinical study to evaluate the wear of natural enamel antagonist to zirconia and metal ceramic crowns.

The flavonoid naringenin stimulates the intercellular colonization of wheat roots by Azorhizobium caulinodans

Amniotic membrane transplantation in acute chemical burns.

A spectrophotometric evaluation of color changes of various tooth colored veneering materials after exposure to commonly consumed beverages