eChapters

3.1 Introduction

One of the most important objectives of statistical analysis is to summaries the information contained in the data which may be considered either as a population or as a sample (or sub-population). If the set of data consists of all conceivably possible (or hypothetically possible) observations of a certain phenomenon or a variable, we call it as population. If a set of data contains only a part of these observations, that is selected values of a variable, we call it as sample. Frequency distribution and graphical representation summarize to some extent.  They reduce a mass of data to a more understandable form but not to a single value. The aim of this lesson is to determine descriptive measures or statistical constants which will describe the nature of the data.

2.1 Quantitative Classification

It the data are classified on the basis of phenomenon which is capable of quantitative measurement like age, height, weight, prices, production, income expenditure, sales, profits, etc., it is termed as quantitative classification. The quantitative phenomenon under study is known as variable.  For example the daily incomes of different retail shops in a town may be classified as under.

1.1 Definition of Statistics

Statistics has been defined differently by different ‘Statisticians’ from time to time. These definitions emphasize precisely the meaning, scope and limitations of the subject.  The reasons for such a variety definitions may be stated as follows:

    i.    The field of utility of statistics has been increasing steadily and
    ii.    The word statistics has been used to give different meanings in singular (the science of statistical methods) and plural (numerical set of data) senses.

In order to have a clear grasp of the subject, we give below some selected definitions of statistics which are grouped under two main heads: ‘Statistics as numerical data’ and ‘Statistics as Methods’.  The former one is in plural sense and the latter singular sense.

Animal protein has a great importance in human health by providing essential amino acids. It is supplied by the milk, meat, fish, eggs etc. Specifically meat has a prime position in the human’s diet particularly for those who are non- vegetarians. As per Indian Council of Medical Research (ICMR) recommendations a normal human being requires 60 gram protein in a day with the net protein utilization (NPU) of 65. In ideal cases 30 to 50 percent of daily protein intake should be from animal sources to get optimal range of amino acids. In present scenario human beings all over the globe are getting 29 gram of protein while developing countries have 15 g per day availability and developed nations are getting 60 grams protein per day per head. However, in India availability of protein is only 10 grams/day/head.

Abstract

Ectomycorrhizal symbionts are important natural resources to revive degraded and deforested areas. Artificial inoculum of these mycobionts improves the growth of tree seedlings in nutrient poor soils due to the formation of extensive network of fungal mycelium responsible for the transfer of water and nutrients to the plants. Seedlings of tree species like, Pinus insularis, Quercus griffithii and Schima wallichii with ectomycorrhizae formed by Suillus bovinus, Boletus edulis and Scleroderma citrinum were studied in field condition. The study was conducted at two different stages of degraded sites. Results of the study indicated that seedlings with ectomycorrhizae were able to generate numerous lateral roots of greater length and thereby utilize water and nutrients more effectively than non- mycorrhizal ones The degree of mycorrhizal development varied in different host species with different fungal species. There was a strong relation between the colonization by mycorrhiza and the survival of seedlings. The study has suggested that mycorrhiza has a potential in reclamation of soil and reforestation of degraded land. S. bovinus., B. edulis and S. citrinum successfully colonized and promoted the growth of P. insulates Q. griffithii and S. wallichii respectively in reforestation programmes of degraded lands of Nagaland.

Abstract

The word “mycorrhiza” literally means “fungus root” to describe the mutualistic association between roots of higher plants and certain fungi. Arbuscular mycorrhizae (AM) are the most common and widely occurring of all the mycorrhizal associations and have great economic significance. They belong to the phylum Glomeromycota. Mycorrhizal associations are potential factors in determining the diversity in ecosystems. They can probably modify the structure and functioning of a plant community in a complex and unpredictable way. Currently there is considerable resistance against the use of chemical pesticides and fertilizers, because of their hazardous influence on the environment, and on soil, plant, animal, and human health. Hence, use of biofertilizers and biocontrol agents are recommended in practical agriculture/horticulture/forestry.

Abstract

Photosynthetic blooms of toxin producing marine algae are often referred to as “red tides”. Proliferations of freshwater toxin-producing cyanobacteria are simply called “cyanobacterial blooms” or “toxic algal blooms.” Biotoxins of cyanobacteria are water-soluble and heat stable and they are released upon aging or lysis of the cells. The primary types of cyanobacterial biotoxins involves three types of toxins: hepatotoxins (microcystin; cylindrospermopsin and nodularin), which are taken up by the liver and cause weakness and anorexia (loss of appetite); neurotoxins (usually anatoxin and saxitoxin), which effect the nervous system and dermatotoxins (aplysiatoxin and lyngbyatoxin, LPS), which cause skin and mucous irritations upon contact. Unlike freshwater toxic algal blooms, marine algal toxins become a problem primarily because they may concentrate in shellfish and fish that are subsequently eaten by humans, causing syndromes known as paralytic shellfish poisoning/PSP (paralysis due to saxitoxin and gonyaulatoxins), diarrhetic shellfish poisoning/DSP (diarrhea due to okadaic acid) , amnesic shellfish poisoning /ASP(memory disturbances due to domoic acid), neurotoxic shellfish poisoning/NSP (paresthesia due to brevetoxin; also bronchial spasms). Coral reef fishes are the vectors of another algal poisoning, the ciguatera fish poisoning/CFP (paresthesia, warm-cold sense inversion etc., due to ciguatoxins and maitotoxin).

Abstract

The traditional forage production systems and grazing lands are under extreme pressure due to the population growth of both human and livestock, decreasing area and inputs. In the central India, especially the Bundelkhand region, the soil is highly weathered, degraded and have low inherent nutrient, which was further worsened due to use of chemical fertilizers and pesticides, for enhancing crop production to meet the escalating demand of the population.

Abstract

Microorganisms that harbour in the root region are the most befitting candidates for use as biocontrol agents. The rhizosphere provides the frontline defense for root against attack by pathogens. Pathogens face a complicated phenomena of antagonism from roots. They also compete with each other for site of colonization on the root surface and plant nutrients. The ideal biocontrol agent introduces and /or promotes the antagonists only, whenever required and are most effective in minimizing the wasteful application of inoculum to non-targets. Many genera belonging to bacteria, fungi, actinomycetes and viruses are used as biocontrol agents to combat several important plant diseases. The present review focuses on the use of bacterial antagonists ,particularly rhizobacteria, as biocontrol agents of fungal diseases of plants , their mechanism of action, molecular and genetic basis of antagonistic property and possible genetic manipulations to bring about desirable changes. 

Abstract

Extensive occurrence of alkaline soils has been reported from the Indo-Gangetic plains of Northern India, which is commonly known as ‘usar’ or ‘reh’. High alkalinity and high exchangeable sodium percentage (ESP) of such soil render it inhospitable for normal crop production. Research efforts over the past few decades have resulted in evolving a number of practices for the reclamation and management of such soils. However, application of biological inputs in combination with some moderately salt tolerant plant species seems to be a better option. AM fungi is well known to enhance the ability of plants to cope with environmental stresses generally prevalent in the degraded ecosystems and stress conditions by providing a number of nutritional and non-nutritional benefits. Since isolates of AM fungi differ in their tolerance to adverse physical and chemical conditions in soil and are better adapted to their native stressed microhabitat, selection of appropriate native AMF isolate is necessary for any large scale reclamation program. Taxonomic diversity of AM fungi in the alkaline soils of Upper Gangetic plains of district Allahabad and adjoining areas has been investigated and it was found that such soils have a detrimental effect on the AM spore population, distribution and diversity. Maximum spore population occurred in winter and minimum in summer. Glomus followed by Acaulospora was the most dominant genus. Acaulospora scrobiculata and Glomus fasciculatum were the most frequent species followed by Glomus mosseae and Glomus aggregatum. Glomus fasciculatum was the most abundant species followed by Glomus mosseae and Acaulospora longula.

Abstract

Today more than 70% of energy is generated by coal-based thermal power plants. Indian coal contains about 40% ash, these power plants generate enormous amounts of fly ash, which is dumped in the nearby areas. This creates not only economy constraints but also imposes serious environmental problems, which are the potential hazards to the ecosystem. However, recent attempts in India and abroad are being made for biological association of fly ash e.g. in soil improvement, in wasteland management and also as a source of essential plant nutrients for nutrient deficient soil in terrestrial eco-system and agro-ecosystem. Fly ash has been found to have manifold advantages in agriculture especially in modification of soil texture and bulk density, in optimization of soil pH, in improvement of water holding capacity of soil, in the improvement of yield as a micronutrient supplement to soil and in creation of conducive condition for better plant growth. In this article utilization of fly ash along with VAM fungi and other microbes especially nitrogen fixers and phosphate solubilizers in removing the constraints of salt affected soils has been discussed.

Abstract

The ability of life to dwell in extreme environments on our mother planet earth right from a thirsty desert environment to highly water saturated oceans, gave the scientists a new area to work in during the 1990’s. The discovery of microbial life which had the ability to survive in conditions which were highly inhospitable for the normal life gave rise to a revolution in the field of science and technology. Extremophiles are one of the most primitive forms of life on earth since they have accustomed themselves to the present day harsh conditions compared to the normal environment. The last few years have seen a massive increase in their discovery, since the areas which once were thought barren by the scientists are now found inhabited by the microbial life. The extremophiles endure conditions right from extreme temperatures, pressure, salt concentration to radiations, metal tolerance, pH etc. During the past few years the industrial applications associated with the extremophiles and their products have led to their intensive exploration. Keeping in view the present and the future scenario, extensive efforts are still required in order to exploit the extreme environments for extremophiles and their products.

Abstract

A field study of seven arid districts of Rajasthan was undertaken to evaluate the occurrence of selected tree species and arbuscular mycorrhizal fungal (AMF) associations with them. Five genera were identified in the rhizosphere of these selected tree species. A high diversity of AMF was observed which varied between different host tree species. Among the five genera, Glomus occurred most frequently, with four species, Acaulospora and Gigaspora were found with three species, while Entrophospora and Scutellospora was detected with two species. Gigaspora margarita, Gigaspora rosea, Glomus deserticola, Glomus constrictum, Glomus fasciculatum, Glomus mosseae and Scutellospora calospora were the most dominant species. The AMF spore density was not clearly affected by the host tree suggesting that biotic factors may be relatively less important than abiotic/edaphic factors for establishing population pattern. The spore density of AMF had a strong positive correlation with soil pH and organic carbon content and a negative correlation with Olsen’s P content of the soil. The association with AMF of these tree species native to the harsh environmental conditions of the Indian Thar Desert may play a significant role in the re-establishment and conservation of these multipurpose desert tree species.

Abstract

Agroforestry is an intensive land use management system that integrates trees, shrubs, crops, etc. on a landscape level to achieve optimum benefits. Agroforestry is not only concerned with beneficial effects of one component on another, but it also involves the manipulations of negative effects to minimize their influence on the productivity of the overall system. In an agroforestry, trees and crops compete inevitably for light, nutrients, moisture and other resources. The interactions between tree and crop roots can also have an effect on soil organisms, which play an essential role in the functioning and productivity of agroforesty systems. Arbuscular mycorrhizal fungi (AMF) are one of the most important components of the soil biota in monoculture and agroforestry systems. AM fungi can rehabilitate degraded lands subjected to agroforestry systems and common mycorrhizal network may further enhance the benefits of agroforestry through vertical niche expansion of AMF. However, management practices of agroforestry affect mycorrhization, AMF community composition and diversity of AM fungi. This review focuses on AMF diversity, which plays a significant role in agroforestry systems.

Abstract

C. albicans is a diploid, dimorphic yeast producing three morphologic forms: yeast cells, pseudohyphae and true hyphae. It is an opportunistic pathogen causing various types of candidiasis which are on the increase around the globe. It is a polymorphic yeast with its genome organized in eight diploid chromosome with its genome size ranging between 14.3 and 16 Mb having 5,733 to 6, 318 genes. It has two mating-type like (MTL) alleles that control the mating behavior. In its genetic makeup it resembles with Saccharomyces cerevisiae hence classified in the Saccharomycetales. The chromosome number from tetraploid to diploid is brought about by the parasexual mechanism. Keeping in view the increase of incidence of candidiasis due to C. albicans around the globe, it is important to identify the causative organisms to the species level correctly. Morphological, biochemical, germ tube test and growth on different media are often used for identifying isolated yeasts which sometimes takes days to week to develop in culture hence, rapid identification of Candida species in clinical laboratory is becoming increasingly important. Molecular techniques utilizing amplification of target DNA or PCR amplification of conserved regions of the genome and sequencing of the resulting PCR product and restriction fragment length polymorphism (RFLP) analysis of the ribosomal DNA, provides quick and precise methods for diagnostics or, identification of Candida species.

Abstract

Eight species including 1 variety, 2 macro and 6 micro-lichens from Garhwal Himalaya, c 1500-2700 m, have been found to glow and emit fluorescent light, when exposed to long wave-length (254 nm) ultra-violet radiataions. Taxonomy and chemistry of all these species have been critically evaluated. The recorded taxa belong to families Physciaceae (4 species); Pertusariaceae, Rhizocarpaceae (1 species each) and Lichen imperfecti (2 species). The reported taxa are: Buellia hemispherica Singh and Awasthi, B. sub-glaziouana Singh and Awasthi; Pertusaria pertusa (Weig.) Tuck., Pyxine berteriana (Fee) Imsh. var. himalayensis Awasthi; P. cocoes (Swartz) Nyl., Rhizocarpon geographicum (L.) DC.; Lepraria taxonomic species I and II.

Abstract

Higher plants can be exploited for the discovery of new bioactive products that could serve as lead compounds in pesticide development because of their novel modes-of-action. Different secondary metabolites of higher plants have been reported to exhibit efficacy as fungitoxicants as well as mycotoxin inhibitors. Pest controls using the botanicals are safer to the user and the environment because they break down into harmless compounds within hours or days in the presence of sunlight. The article presents different plant products found efficacious as antimicrobial and inhibitory to mycotoxin secretions by fungi. Their prospect as safe alternatives to synthetic antimicrobials in plant protection has been discussed.

Abstract
 
Much attention has been paid to mycorrhza as a tool for improving the growth and health of plants.  The use of mycorrhiza in agricultureal, horticultural and forestry has been described. The significance of AM fungi in sustainable agriculture has been a subject of growing interest for the past several decades. In sustainable agriculture it is imperative to maximize benefits with low input costs. The fact remains that stable and lower human population is an integral component of sustainable agriculture and more so in an Indian context. Therefore, it is imperative to collect further information on the different aspects of AM fungal symbiosis as discussed in this article so as to utilize this plant microbe symbiotic system for the increased production and productivity in a sustainable manner. This may become possible when the integrated approach is made to study AM fungi right from the isolation of AM fungal spores to the high quality inoculum production and its application in the field. It is also imperative to stimulate new mutualism between mycorrhizal scientists and ecologists. It this regard, recent advancement made in the molecular techniques should be encouraged in order to obtain more authentic results. Adequate field testing of mycorrhizal inoculation and commercial exploitation of the potential benefits of mycorrhiza still rests on the development of suitable technology for mycorrhizal inoculum preparation.

Abstract

Production technology has been worked out for crops and several inputs have been recommended which are to be applied in proper quantity at most suitable time to get the maximum return. Nutrition in the form of fertilizers is a must. However, injudicious use of agro-chemicals has resulted in diseases called ‘iatrogenic plant diseases’. Under the circumstances it is important to know the relationship between soil nutrients and plant pathogens which are causing the diseases of economic importance. Author has given adequate emphasis to micronutrients as at a very minor quantity they reduce the disease to an acceptable level. He has also discussed in detail about all the major and minor nutrients required by the plants and how their deficiency or over doses affect the plant pathogens and in turn the diseases.

Keywords:  Soil nutrients, plant pathogens, diseases, relationship

Abstract

Various cropping systems and ecologies illustrate the positive use of chemicals both as fertilizers and pesticides and organic/biological sources within the frame work of Integrated Plant Nutrition and Plant Protection System (IPPS). While considering the organic/biological sources, green manures seem to be the best alternative that may largely suffice to the organic matter requirements of the soil under crop cultivation. Green manuring can be defined as a practice of ploughing or turning into the soil undecomposed green plant tissues for the purpose of improving physical structure as well as fertility of the soil. “Green manure” refers to fresh plant matter, which is added to the soil largely for supplying the nutrients contained in its biomass. The agricultural practices consisting of growing and ploughing under a green crop or addition of a green organic matter in the form of leaves and other succulent parts from outside to improve soil productivity is known as green manuring. In this review, advantages of green manuring, decomposition of green manure,   process of decomposition, factors affecting decomposition and effects of green manuring have been discussed in detail.