Rhizobia are a group of organisms that are well known for their ability to colonize root surfaces and form symbiotic associations with legume plants. They not only play a major role in biological nitrogen fixation but also improve plant growth and reduce disease incidence in various crops. Rhizobia are known to control the growth of many soilborne plant pathogenic fungi belonging to different genera like Fusarium, Rhizoctonia, Sclerotium, and Macrophomina. Antagonistic activity of rhizobia is mainly attributed to production of antibiotics, hydrocyanic acid (HCN), mycolytic enzymes, and siderophore under iron limiting conditions. Rhizobia are also reported to induce systemic resistance and enhance expression of plant defense-related genes, which effectively immunize the plants against pathogens. Seed bacterization with appropriate rhizobial strain leads to elicitation and accumulation of phenolic compounds, isoflavonoid phytoalexins, and activation of enzymes like L-phenylalanine ammonia lyase (PAL), chalcone synthase (CHS), peroxidase (POX), polyphenol oxidase (PPO), and others involved in phenylpropanoid and isoflavonoid pathways. Development of Rhizobium inoculants with dual attributes of nitrogen fixation and antagonism against phytopathogens can contribute to increased plant growth and productivity. This compilation aims to bring together the available information on the biocontrol facet of rhizobia and identify research gaps and effective strategies for future research in this area.
Biofilmed biofertilizers have emerged as a new improved inoculant technology to provide efficient nutrient and pest management and sustain soil fertility. In this investigation, development of a Trichoderma viride-Mesorhizobium ciceri biofilmed inoculant was undertaken, which we hypothesized, would possess more effective biological nitrogen fixing ability and plant growth promoting properties. As a novel attempt, we selected Mesorhizobium ciceri spp. with good antifungal attributes with the assumption that such inoculants could also serve as biocontrol agents. These biofilms exhibited significant enhancement in several plant growth promoting attributes, including 13-21 % increase in seed germination, production of ammonia, IAA and more than onefold to twofold enhancement in phosphate solubilisation, when compared to their individual partners. Enhancement of 10-11 % in antifungal activity against Fusarium oxysporum f. sp. ciceri was also recorded, over the respective M. ciceri counterparts. The effect of biofilms and the M. ciceri cultures individual on growth parameters of chickpea under pathogen challenged soil illustrated that the biofilms performed at par with the M. ciceri strains for most plant biometrical and disease related attributes. Elicitation of defense related enzymes like L-phenylalanine ammonia lyase, peroxidase and polyphenol oxidase was higher in M. ciceri/biofilm treated plants as compared to uninoculated plants under pathogen challenged soil. Further work on the signalling mechanisms among the partners and their tripartite interactions with host plant is envisaged in future studies.
Reduction in biomass and pollen fertility are the two major constraints resulting in poor grain yield in major pulses grown under rainfed agrosystem. Generally, pulses are encountered into both heat and drought stresses during terminal reproductive stages. Though pulses have many adaptive features to counter the adverse effects of various abiotic stresses but yield is substantially reduced when the magnitude of these stresses is very high. The factors have been identified to enhance grain yield under stress environments which include promotion of biomass in the above ground part enabling crops to reserve a maximum amount of photosynthesis and water in the plant system itself before the onset of drought and heat stresses during reproductive stages. Various physiological mechanisms and fertility enhancement components including genetic diversity in key traits have been discussed here to improve yield of pulses under stressed conditions.
Both cyber security and information security are frequently used interchangeably. The latter adds a new dimension to the former by considering human variables throughout the security process, making the individual the focus of attention and a potential target. However, such talks about cyber security often revolve around social facets of society and have significant implications. To aid in cyber security, several models and systems have been developed. Both the number and complexity of hacks have increased dramatically over the past few decades. Because of this, developing a plan that cannot be compromised by online assaults is essential. As hackers become more sophisticated in their use of state-of-the-art techniques and cutting-edge technology, we are seeing an increase in hacking, attacks, and data leaks. In this chapter, the authors investigate few models and recent trends of threats and attacks of security models. In addition, they have also studied their shortcomings and the methods previously employed to counteract such hazards.
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