eChapters

Abstract

Microbiological synthesis of nanoparticles has emerged as rapidly developing research area in nanotechnology across the globe with various biological entities being employed in production of nanoparticles constantly forming an impute alternative for conventional methods. Simple prokaryotes to complex eukaryotic organisms including higher plants are used for the fabrication of nanoparticles. In the present article, the synthesis of important plant nutrients like Mg, Zn, Ag, Au, Ti, P and Fe nanoparticles from different fungal species, their characterization and application potential of nanonutrients in agriculture is elaborately discussed.

Abstract

Microorganisms inhabiting in the rhizosphere play a vital role in ecosystem functioning. Rhizosphere is an area around the root surface where pathogenic and beneficial microorganisms repose and influence the plant growth and health. These microbial groups of bioagents found in the rhizosphere include bacteria, fungi, nematodes, protozoa, algae and micro-arthropods. Because of their rich diversity, complexity of interactions and numerous metabolic pathways, microbes are an amazing resource for biological activity. These microorganisms require organic matter for their growth and activity in soil and provide valuable nutrients to the plants and hence maintaining the plant health. The most promising fields for the use of bioinoculants are agriculture, horticulture and forestry. There are many reports on the inoculation of bioagents in agriculture and horticulture crops but only a few reports are available in forestry. This article is an overview on various bioinoculants which are used during inoculation and a compilation of scattered reports of bioinoculants in forestry only.

Abstract

Amongst various oilseed crops grown across the world, soybean (Glycine max L. Merrill) is globally important as a high source of protein and oil for human consumption and is also being used as potential feed for animals. Soybean is grown under rain-fed conditions in the tropics and subtropics in the marginal lands with less amount of external application of chemical fertilizers. The frequent climate variations have created a number of biotic and abiotic stresses, drought being a major abiotic stress which adversely affects the soybean productivity. Thus, to enhance the productivity of soybean, besides managing the nutrients, stress management is of utmost importance. There is a great opportunity of application of microbes especially arbuscular mycorrhizal fungi (AMF) where its application alone or in combination with plant growth promoting rhizobacteria (PGPR) can help in nutrient mobilization and remediation of plant stresses.

Abstract

Soil salinization is an important factor limiting crop production, mainly in the arid and semiarid regions of the world. Nevertheless, plants naturally have evolved several physiological, biochemical and molecular mechanisms to establish and thrive in salt stressed soils. In addition to breeding crops for salt tolerance, recent emphasis is on exploring the possible role of plant-microbe interactions in amelioration of salt stress in plants. It is now well established that arbuscular mycorrhizal (AM) symbiosis alleviates the effect of salt stress in plants. Further, available evidence does suggest that AM symbiosis regulates many of the plant’s salt stress alleviation mechanisms. However, the molecular basis for many of these mechanisms is yet to be ascertained. In this chapter, we summarize the current knowledge on the role of AM symbiosis in alleviation of salt stress in crop plants, which now appears to be a promising strategy to improve crop yield in salt stressed soils.

Abstract

Abiotic stresses lead to the overproduction of reactive oxygen species (ROS) in plants which are highly reactive and toxic and cause damage to proteins, lipids, carbohydrates and DNA which ultimately results in oxidative stress. The arbuscular mycorrhizal fungi (AMF)-symbiosis can confer a greater degree of tolerance against drought stress in many cash crops. The significance of heat shock proteins (Hsps) and chaperones in abiotic stress responses in plants, and co-operation among their different classes and their interactions with other stress-induced components is well known. Soil salinity is a major abiotic stress adversely affecting plant growth and crop production worldwide. Phyto-mycoremediation utilizing AMF as plant inoculants is regarded as a promising strategy to heavy metal pollution remediation. Plants have stress specific adaptive responses as well as responses which protect the plants from more than one environmental stress. The potential of phytoremediation of contaminated soil can be enhanced by inoculating hyper-accumulator plants with mycorrhizal fungi most appropriate for the contaminated site.

Abstract

Drought and salinity are two major abiotic stresses that affect various aspects of human lives of one third world population including human health and agricultural productivity. Abiotic stresses such as salinity, drought, nutrient deficiency or toxicity, and flooding limit crop productivity world-wide. A living organism is considered resistant if it tolerates a given physicochemical stress. The presence of microorganisms within the soil, specially a main group known as arbuscular mycorrhizal fungi (AMF), is a key factor in the adaptation of plants to the different ecosystems. The AMF colonizing within the plant roots can determine the success of plants in salt- and/or drought-affected areas. The symbiosis with AMF has been proposed as one of the mechanisms of salinity and water stress avoidance. Studies have shown greater drought and salinity tolerance in AMF-colonized plants by a number of mechanisms. These mechanisms include enhanced water and nutrient uptake directly by extraradical hyphae, higher leaf stomatal conductance and/or better root system architecture, higher capacity of osmotic adjustment and antioxidant defense systems, better soil structure due to higher glomalin and over expression of genes encoding antioxidant enzymes.

Abstract

A majority of the plants studied in natural ecosystems are symbiotic with microorganisms that either reside entirely (endophytes) or partially within plants. These microorganisms express different associations ranging from mutualism to parasitism. These symbiotic relationships appear to impart tolerance to various types of abiotic stresses such as heat, drought, salinity, heavy metals, etc. and sometimes may be responsible for the survival of both plant hosts and microbial symbionts in high stress habitats. The amelioration of the abiotic stresses by the endophytes assumes increasing significance in the light of rapidly changing global climate, which is likely to face frequent incidences of extreme weather conditions like high temperature, droughts, etc.

Abstract

Variously defined endophytes are highly diverse in plants in natural ecosystems, and most of them are symbiotic with of them are Asymptomatic presence of endophytic fungi in internal tissues on healthy host plants are able to play vital roles in physiology and biochemical processes. As a result of this interaction endophyte produces chemical substances having various applications. This chapter provides a brief review of certain grass and non-grass endophytes capable to extend beneficial impacts on host plants to sustain the unfavourable conditions of abiotic stresses. However, biotic stresses are also a matter of great concern, where endophytes can play important roles in combating the unfavourable situation. Endophytic fungi used in bio-control and other agriculture related sectors are also  highlighted in this review. Endophytic fungi producing volatile organic compounds reported from all over the world and their various applications find place in this article which has opened new frontiers of bioprospecting of endophytic fungi.

Abstract

Microbes are endowed with a high and exploitable potential of being useful associates with their surrounding environment and host in case of symbiotic relationship. Most of the microbes live alone but many of them require association of other living system for its survival. Hence, the beneficial role of microbes is always correlated with growth promotion and survivability of other associated living system. Now it is established that microbes play an important and key role in plant growth and development, even its survivability in case of symbiotic mycorrhizal association with orchids. They are nothing but potential tool protecting plants from different adverse conditions like diseased state, environmental stress like cold temperature, drought, metal contamination, salt and acidic or alkaline stress.

Abstract

In its natural environment, a plant faces various types of stressors. In fact, stress in moderation is a welcome event in plants. Only when it is in excess, would it compromise the productivity of plants. Beyond a threshold, stress (biotic and abiotic) has a detrimental effect on plant growth causing extensive yield losses in crop plants worldwide. Plants being sessile, have evolved a complex set of mechanisms to perceive the changes in the environment. Plants respond to minimize the potential damage due to stress while simultaneously preserving resources vital for their growth and development. The chapter presents an overview of various types of biotic and abiotic factors that act as plant stressors and the mechanisms by which plants respond to these stresses. The chapter concludes with a perspective on how the plant’s innate stress response machinery can be exploited for achieving higher tolerance to stress in crop plants.

Abstract

Impact of climate change and related stresses on plant productivity are being witnessed worldwide with developing countries being more vulnerable due to more dependency on agriculture. Microorganisms can play important role as economic and farmer’s friendly strategy to combat abiotic stress in agriculture. A wide range of microorganisms associate with plants, and many of them confer beneficial effects to their hosts through different mechanisms like production of growth promoting substances, nutrient acquisition, protection against plant pathogens etc. In the last few decades, role of microorganisms in imparting tolerance to plants against different abiotic stress has been reported in many crop plants. Under stresses conditions, plant-microbe interactions become more common towards coping with the stress. Selection and application of efficient abiotic stress tolerant microorganisms can be a fruitful strategy to alleviate negative effects of abiotic stresses in plants.

Abstract

With increasing population and subsequent human requirements; the generation of municipal solid waste (MSW) has increased all over the world. In India, the safe disposal of the municipal solid waste still remaines a problem for the authorities concerned. Depending upon the nature and type of the MSW, there are physical and chemical methods for the disposal of the waste, but these methods have their own limitations. Those limitations may be overcome by biological methods. Higher number of microorganisms are present in MSW which may either be pathogenic or nonpathogenic. These microorganisms may play a vital role in bioconversion of MSW into compost. The compost thus produced is useful in increasing soil fertility and reducing the concentration of the waste.

Abstract

The rhizomicrobiome plays a vital role in maintaining plant health and is highly influenced by the root exudates of the host plant. Plants select a subset of microbes at different stages of their development, and determine the microbiome community composition in its immediate vicinity presumably for specific functions. The rhizomicrobiome is composed of diversified microbial community with specific functions and is highly influenced by the plant type, soil type and environmental conditions. The rhizomicrobiome communities apart from promoting plant growth also elicit induced systemic tolerance to salinity and drought in stressed plants. Bacterial communities producing 1-aminocyclopropane-1-carboxylate (ACC) deaminase modulate stress ethylene in plants and alleviate the effects of abiotic stress and increases plant adaptability to stressed environment.

Abstract

Ever growing population and associated food scarcity are the major issues of concern globally. Microorganisms are the ultimate solution for addressing this severe problem in association with recent advances made in genomics and molecular biology. Many bacterial and fungal species which are in association with plant rhizosphere soil can immensely contribute in better growth and developments, ultimately leading to better yield. Exploring these novel organisms happens to be the need of an hour. Metagenomics and next generation sequencing technologies can contribute in identifying those microbes which are otherwise impossible to cultivate traditionally.

Abstract

Geochemical processes occurring within the groundwater and reactions with aquifer minerals have a profound effect on water quality. Hydrogeochemical composition of groundwater can also be indicative of its origin and history of passage through underground materials which water has been in contact. Assessing groundwater quality and developing strategies to protect aquifers from contamination are necessary aspects for proper planning and designing water resources. Anthropogenic activities like explosion of population, industrial growth, inputs of fertilizer, pesticides, and irrigation has been a crucial factor for determining the quality of groundwater. In this scenario, 43 groundwater samples were collected from the Dindigul district of Tamilnadu, a Hard rock terrain. The samples wereanalyzed for major cations and anions along with heavy metals to derive the different quality parameters and to obtain the pollution indices of different samples. This study focuses to find out the spatial relationship between the analyzed fluoride concentration in groundwater and pollution indices derived from the heavy metal concentration in the groundwater of the study area and their variation with respect to season.

Abstract

Amongst all types of major land-use change, extending irrigated agriculture using a surface-water source has the greatest influence on groundwater – both significantly increasing recharge and changing water quality as excess irrigation water infiltrates into shallow aquifers. Hence, in order to understand the impact of the landuse on the groundwater system the study has been aimed to understand the process by adopting geophysical, geochemical and microbial analysis of groundwater samples. The study has been conducted in Chidambaram taluk, with a total area of 92.51Sq.km. A total of 39 groundwater samples were collected for the analysis of major cation and anion along with the microbial analysis, like Total Coliform, Total Viable Counts, Fecal coliforms, Vibrio cholera and Total Streptococci. The geochemical studies reveal that there is no correlation between these parameters and the microbial population. The migration of the water from the elevated regions (urban region) is witnessed and the concentration of the microbial population is higher in these regions except in the southern region which has impermeable clay and this arrest the movement of water.

Abstract

Groundwater is most favored as a source of drinking water in all over world. It is often thought to be cleaner and easier to treat when compared with surface water and as a result, many wells have been sunk. Uranium and other radionuclides in water can lead to health problems if present in higher concentrations. In order to study the behavior and to understand the influence of lithology in groundwater of Madurai district, a study was conducted by collecting a total of 216 samples of different seasons (Premonsoon, South west monsoon, Northeast monsoon and Post monsoon) with respect to lithology and the number of samples was depending upon their spatial coverage in the study area. The groundwater samples were analysed for U, Ca²⁺, Mg²⁺, Na⁺, K⁺, HCO₃^-, Cl^-, SO₄^2-, PO₄^3-, NO₃^-, F^-, H₄SiO₄, pH, EC, TDS. It was identified that the higher concentration of Uranium (156 ppb) were noted in the northern part of the study area. They are chiefly restricted to the Granitic terrain and nearby Charnockitic regions. The weathering process induces the release of higher U ions from the granitic terrain and the evaporated recharge water from the tank /reservoir  also induces the release of U ions from the rock matrix, it may also be due to fertilizer enriched agricultural return flows. The key source for all these processes and hydrogeochemical processes is identified to be lithology which inturn controls all the other processes in the study area.

Abstract

Dissolved Organic Carbon (DOC) consisting of water soluble organic molecules and by products of organic decomposition and chemical degradation processes, constitutes a critical link in carbon and nutrient cycles. The quality, or chemical and physical character, of DOC affects the degree to which it is transformed by biological and chemical processes. The significance of DOC was studied in layered coastal aquifers of the Pondicherry region during four different seasons. Pondicherry region has varied geological set up ranging from Cretaceous to Recent formations. A total of 52 groundwater samples were collected from various aquifers like Alluvium, Tertiary(Upper Cuddalore, Lower Cuddalore) and Cretaceous for two different seasons of pre- monsoon(PRM), and post-monsoon (POM). The samples were analyzed for major ions and DOC. The range of DOC in the study area is 0-14 mg/l. Very high DOC concentrations were measured during PRM in the samples from Alluvium and Lower Cuddalore Formation. The samples of these formations were compared with pH, Ionic strength, log pCO₂ and carbonate minerals concentration. The alluvial aquifer shows that pH governed dissolution along the coastal tracts and in Upper Cuddalore formation it’s based on interaction between aquifer matrix and groundwater.

Abstract

The development and management of fresh groundwater resources in coastal aquifers are seriously constrained by the impact of seawater intrusion. The coastal aquifers are fragile and this situation becomes more intense like that of the coastal Cuddalore region. The geochemical signature of groundwater of Cuddalore coast was studied for Pre Monsoon, Southwest, North east and Post Monsoon seasons by collecting total of 64 groundwater samples in each season. The collected samples from were analysed for physical parameters, such as electrical conductivity (EC), pH and major ion concentrations, such as Ca, Mg, Na, K, Cl, HCO₃, PO₄ and SO₄. Interpretation of analytical data shows the predominance of  Na–Cl type   in PRM and Ca- Mg-Cl type  is the dominant facies during POM. The Chaddas evaluation diagram shows that the hydrogeochemical evaluation plot for PRM samples fall in  Na-Cl type. The ratios of Na/Cl and Cl/HCO₃ is also enumerated the fact that the most of the samples from PRM and few samples from other seasons also indicates dominance of salt water intrusion.

Abstract

In Gadilam river basin, groundwater is found in both hard rock and sedimentary terrain and is the most important source of rural/urban drinking water supply. Gadilam river basin has gained its importance due to the presence of Neyveli Lignite open cast mine (NLC), group of industrial estate (SIPCOT), extensive depressurization of Cuddalore aquifer and boreholes of New Veeranam Scheme (NVS) in the downstream of the basin. A total of 178 water samples were collected in four different seasons at various lithologies. The collected samples were analyzed for various physico-chemical parameters using standard procedures. Geochemical indicators of groundwater were used to identify the chemical processes that control hydrogeochemsitry. Interpretation of hydrogeochemical data suggests that leaching of ions followed by weathering and anthropogenic impact controls the chemistry of the groundwater. Isotopic study reveals that recharge from meteoric source in sedimentary terrain and rock water interaction with significant evaporation prevails in hard rock region. This thorough understanding helps us to make judicial usage and to maintain the quality of this commodity.