eBook Chapters

What is Audio

Audio refers to sound that is within the range of human hearing. This encompasses everything from the spoken word and music to ambient sounds and electronic signals. In technical terms, audio often refers to the representation of these sounds in a form that can be recorded, transmitted, and reproduced, typically using electronic devices.

History and Evolution of Audio Communication and Aids

Ancient to Early Modern Period

1. Early Communication

• Oral Tradition: In ancient times, communication was predominantly oral. Stories, knowledge, and news were passed down verbally.

• Musical Instruments: Early instruments like drums, flutes, and stringed instruments were used for communication, rituals, and entertainment.

2. Writing and Instruments

• Written Language: The invention of writing allowed for more permanent records of communication but was separate from audio.

• Bell Towers and Horns: In medieval times, bells and horns were used for signaling and communication over distances.

Planning is the beginning of all the other processes of management, namely, organizing, staffing, directing, communicating and controlling.

Planning is deciding in advance what to do, how to do, when to do and who is to do it. Planning bridges the gap from ‘where we are’ to ‘where we want to go’ (Koontz and O’Donnell).

In the words of Theo Haimann, “Planning is the function that determines in advance what should be done". It consists of selecting the objectives, policies, programmes and procedures of the enterprise and also the means of achieving their objectives.

As a part of planning process, the manager has to ensure that his team members understand the purposes and objectives of his enterprise and also methods to achieve them.

Abstract

Current trend of global agricultural systems entails preference towards sustainable crop production through organic agriculture (ecology based) as compared to conventional (synthetic input based). In order to claim as organic, it needs to be certified as per requirements organic standard. The soil fertility management organic standard requirements of major countries are outlined. This review article compares the agricultural management practices of organic and conventional systems so as to assess its impacts on microbial biodiversity, microbial activities on soil functioning and long term fertility based on long term field studies conducted in different parts of the globe.

Introduction

Plants possess complex, systematic and specific mechanisms to cope up with abiotic as well as biotic stresses in the existing environment. ‘Do plants respond to sound ? How can plants perceive sound without a hearing organ?’- are interesting queries among the scientific community. Responses of plants to different factors such as temperature, moisture, light, wind, pests and microbes are well understood. However, information on the effects of audible sound frequencies on plants are still lacking. Recent evidences suggest that audible sound stimulation can contribute to better plant growth and improved quality of plant produce. It also represents a new trigger for plant protection. Sound is an acoustic energy in the form of a mechanical wave which transmits through gases, liquids and solids. Acoustic spectrum consists of three regions, infra sound (less than 20 Hz), audible region (20-20,000 Hz) and ultrasound (greater than 20,000 Hz). Infra sound and ultrasound are used in clinical diagnosis and therapeutics.

Research on plant responses towards different stimuli started during 1880s by Charles Darwin. In 1848, Dr. Gustav Theodor Fechner, a German experimental psychologist, suggested that plants are capable of feeling emotions and that one could promote healthy growth of plants with talk, attention, attitude and affection. Later, J. C. Bose (1926), famous Indian botanist and physicist, made several studies on the effect of sound vibrations on plants. According to him, a plant treated with care and affection gives out a different vibration than a plant subjected to torture. In addition, Bose found that plants grew more quickly in pleasant music and more slowly in loud noise or harsh sounds. He also noticed that plants can “feel pain and understand affection” based on variation of cell membrane potential under different sound frequencies. Retallack (1973) also described several experiments involving plants and music.

The term rare amino acid is misleading in some respects. It refers to all those amino acids that are not incorporated into proteins. We already got to know some of them like ornithine or citrulline that are rather common intermediates of the basic metabolism. Roughly 220 different structures are known, most of which occur in plant cells in a free state though glutamate-, oxalate- or acetyl- derivatives can also sometimes be found.

The growth and productivity of crops depend on various factors, with the nutrient content of plant parts like leaves and stems playing a crucial role. These parts are often used as indicators to assess the nutrient status of plants. Each crop requires essential elements at specific concentrations during different growth stages, known as ‘critical levels’. When the nutrient content falls below these critical levels, plants may display symptoms of deficiency.

Nutrient requirements and availability can be evaluated through: i) plant diagnosis, ii) soil analysis, and iii) plant analysis using qualitative or quantitative methods. By conducting these tests, necessary nutrients can be identified and applied to crops to sustain growth and correct deficiencies. While rapid tissue tests offer quick solutions for nutritional problems, quantitative estimation of both plant and soil nutrient concentrations is more economical and provides a long-term strategy for managing nutritional issues. Implementing quantitative estimation allows for informed application of fertilizers, whether as basal or foliar, thus addressing deficiencies effectively and ensuring sustainable crop growth.

Plant analysis includes tests on fresh tissue in the field and analysis of total nutrients in plants in the laboratory. Plant analysis is based on the relationship between nutrients in a plant and nutrient availability in a soil. Plant analysis is not a direct method of soil fertility evaluation, but it can serve as a valuable supplement to soil testing in the task of soil fertility evaluation. Plant analysis is useful in confirming nutrient deficiencies, toxicities and imbalance and identifying hidden hunger. Plant analysis generally provides more current plant-based information than soil testing, entails more effort in terms of sampling, sample handling and analysis and, perhaps, expensive.

Different diagnostic tools are designed to avert nutrient deficiency or sufficiency and if properly used both loss of yield and quality of crop can be minimized. Among several diagnostic tools, nutrient analysis of standing crop seems to be an efficient method in arriving at the need-based fertilizer scheduling for various crops.

Nutrient uptake by plants indicates the actual accessibility of nutrients in soil to the plants. Also, concentration of certain heavy metals in plant indicates their solubility in soil which leads to poor crop quality.Although, different plant species and even different varieties of same species may differ in their nutrient requirements, the concentration of nutrient element in plant can act as guide to support the soil test result in assessing nutrient supplying capacity of a soil and as a tool for correcting any deficiency if carried out early enough to prevent yield loss. However, analysis of harvested or mature crop is like a post mortem as this information only can help in nutrient management planning in subsequent years.

Like soil testingplant analysis also suffers from some limitations. Amongthem, the most important are the risk of sampling error as well as the chances of incorrect interpretation of test report in recommending fertilizers. Selection of right plant part and right stage of crop growth are very crucial for successful plant analysis.

4.1 Sampling and Preparation for Analysis

The determination of nutritional need of crops is an important aspect of nutrient management of any plant analysis programme. The need of fruit plants for mineral nutrients differ from those of annual crop species in a number of ways, many of which are related to the perennial nature of tree crops. In perennial tree crops, there is a need to supply nutrients both for ultimate fruit production, the fruits and the vegetative organs, which persist from year to year. The need for leaf analysis in perennial horticultural crops and forest trees has proved its superiority over soil diagnostic methods. This is essentially because of their deeper root system and the fact that nutrients supplied in one year may have its effect on both the nutrition and crop production in following years. However, it is largely being used not as an alternative method to soil testing, but as a supplement to soil testing. Results of foliar analysis are usually interpreted using the critical nutrient level (CNL) approach. Accurate interpretation of foliar analysis using the CNL approach is possible only when sampling is restricted to the same growth stage at which standard reference values have been established (Beaufils, 1971, 1973). The general purposes of plant analyses are:

Accumulation of nutrient elements in plant tissues indicates the accessibility of the concerned elements from the soil to the plant. Although different plant species and even different varieties of the same species may vary in their nutrient requirements, composition of a part or of the whole plant may well be adopted as a guideline to support the soil-test results for factual assessment of soil’s nutrient supplying power.

Introduction

Plant architecture is defined as a three-dimensional organization of plant body in terms of its size, shape position of leaves, flower organs and branching pattern. Earlier this was the only criterion for systematic and taxonomic classification of plant species and the best means of identifying them (Stecconi, 2006). Study of plant architecture emerged as a new scientific discipline some 30 years ago. The subject derives its base from earlier works on plant morphology (Halle and Oldeman, 1970) but currently it is integrated with several disciplines of plant sciences ecology and engineering. Modification in plant architecture causes alteration in primary and secondary growth. This occurs due to differences in phyllotactic arrangement, branching pattern and floral differentiation. Plant architecture can be modulated by various parameters like climate, agronomic practices and human interventions. Manipulation of plant architecture is a major area in plant science which is currently adopted for productivity improvement by breeders, agronomists, horticulturists and landscape managers. However, the basis for such manipulation lies in the knowledge of the basic architecture of plants and its significance.

Introduction

Vast proportions of the population of the world are dependent on plants as their principal source of food either directly or indirectly. Recent decades have also seen increased numbers of people turning to alternative medical therapy based upon traditional folk medicine or food as a form of medicine. These alternative therapies emphasise the importance of a ‘good diet’ in maintaining and restoring health. Under these circumstances, vast majority of population may see diet therapy, dietary supplements and non-invasive alternative therapies as a safer, less technological and more natural way of maintaining health and treating and preventing individuals from illness. These alternatives may be seen as empowering the consumer and shifting the locus of control away from the medical establishment. This chapter covers many crucial topics to understand the chemistry and bioactivity of the active compounds of plant origin. It also aims to cover the latest research on the bioactive compounds.

20.1 INTRODUCTION

With rapid increase in area under micro irrigation, now fertigation is getting momentum in many states in the country. At present, most of the soluble fertilizers are imported in the country. Hence, these are very expensive and beyond the reach of common farmers. It is interesting to record that for number of nutrients, which are becoming constraints in most of the Indian soils, soluble formulations have yet to be developed. This calls for some alternative options. As an alternatives liquid manures like cow urine, biogas slurry, or fermented manures etc can be sprinkled on the soil, applied with irrigation water or diluted and sprayed as foliar fertilizers (Frank et al; 2005).To our understanding, organic fertilizers /organic liquid manures referred now as bio-enhancers are essential to maintain the activity of microorganisms and other life forms in the soil. These are prepared locally, can resolve number of apprehensions and will be helpful in boosting production and mitigating number of nutritional disorders in most of soils and crops. It is interesting to record that these can be prepared at the farm with some infrastructure facilities and hands on training. Most of these formulations are used through irrigation. These organisms (bacteria and moulds) improve the soil health by solubilzing the complex organic substrates into simple forms and make it available to the plant, resulting in increased productivity. If these are integrated with micro irrigation techniques after proper filtration their efficacy can further be improved.

Cow dung and urine are important component in organic farming. Cow dung is rich source of microbial consortia Actinomycetes, which are helpful in control of many plant diseases. A potential species Streptosporangium psedovulgare of Actinomycetes and four strains of Bacillus subtalis have been identified at CISH, Lucknow (Pathak et.al., 2009).These showed anti pathogenic potential against anthracnose gummosis, stem end rot and dieback pathogens. These were observed to attack mycelia cell wall and finally the host cell degenerates completely. Organic liquid manures play a key role in promoting growth and providing immunity to plant system ( Sreenivasa et al., 2010).

Introduction

Plant growth and productivity are adversely affected by various abiotic stresses. Plants are frequently exposed to a plethora of stress conditions such as low temperature, salt, drought, flooding, heat, and oxidative stress. Various anthropogenic activities have accentuated the existing stress factors. All these stress factors prevent them from reaching their full genetic potential and limit the crop productivity. In the event of growing concerns of uncertainties in climatic conditions, the abiotic stresses have become the major threat to agriculture production worldwide (Bray et al., 2000). The plant responses to abiotic stress condition are believed to be complex in nature as these are the reflections of integration of stress effects and responses at various levels of plant organization. To provide tolerance against stresses, plants are equipped with several inbuilt physiological and biochemical mechanisms occurring at cellular level. An understanding of processes linked to these mechanisms is vital in optimizing the crop growth and productivity under stress conditions.

6.1 Introduction

Water deficit stress is a serious and frequently encountered abiotic stress in the terrestrial surface. Its deleterious effects on plant growth and productivity are well documented. Plant responses to water stress are believed to be complex as these operate at various levels of plant organization. Several in built physiological and biochemical mechanisms provide resistance to plants against stress. An understanding of the processes linked to these mechanisms is vital for optimizing crop growth and productivity under stress. Plants respond and adapt to water stress by altering cellular metabolism, thus invoking stress tolerance. Alteration in endogenous concentrations of growth regulators along with accumulation of osmolytes, modifications in antioxidant cascade, changes in protein profiles and induction of gene expression in plants under stress are important characteristic metabolic changes that invoke stress tolerance at the cellular level. Alteration in endogenous concentrations of plant bio-regulators under stress helps plants through better turgor maintenance and efficient water usage by influencing stomatal functioning, hydraulic conductivity and morphological adaptation. Progress made in plant adaptation to water stress is an outcome of advances made in analytical techniques on endogenous growth regulator analysis and powerful and reliable molecular and genetic techniques.

2.1 Introduction

Dear students, you shall be taught plant biotechnology during the third semester in the course ‘Elementary Plant Biotechnology’. But, for understanding of non-conventional breeding methods/techniques you should acquire some knowledge of basic plant biotechnology. Hence, in this chapter plant biotechnology is introduced to you in brief.

2.2 Definition

The term ‘biotechnology’ stems from fusion of ‘biology’ and ‘technology’. It was coined by Karl Ereky, a Hungarian agricultural engineer, in the beginning of 20th century. According to him, all processes used to yield finished products from raw materials with the help of living organism come under biotechnology. It may be defined in number of ways. However, in simple terms, biotechnology may be defined as ‘the controlled use of biological agents, such as microorganisms, or cellular components, for beneficial use’ (U.S. National Science Foundation).

Development of Plant Body

A vascular plant begins in existence as a morphologically simple unicellular zygote (2n). The zygote develops into the embryo which in the long run develops into the mature sporophyte. The development of the sporophyte (2n) involves division and differentiation of cells and organization of cells into the tissue systems. The embryo of the seed plant possesses relatively simple structure as compared to the mature sporophyte. The embryo bears a limited number of parts containing generally only axis bearing one or more cotyledons. The cells and the tissues of this structure are less differentiated. However, the embryo grows further, because of the presence of the meristems, at two opposite ends of the axis, of future shoot and root. After germination of the seed during development of the shoot and root new apical meristems appear which cause a vegetative growth and reproductive stage of the plant attained.

Fundamental Parts of the Plant Body

The plant body consists of a number of organ i.e., root, stem, leaf and flower. Each part has different functions for plant growth.Flower consists of sepal, petals, stamens, carpels and sometimes also sterile members. Each organ is made up of number of tissue systems; each tissue system consists of number of tissues. Tissue consists of group of cells that are alike in origin, structure and function.

Abstract

The establishment of All-India Coordinated Wheat Improvement Project in 1965 coincided with the introduction of high yielding semi-dwarf wheat varieties. Since then India has made very impressive progress in increasing wheat production over the past three and half decades. India now ranks as the second largest wheat-producing nation in the world. In fact from a state of “Ship to mouth” in 30 years or so India has become a nation of surpluses. The significant contribution made by the project in helping the increased wheat production cannot be ignored. Through coordinated research and development, nearly 200 wheat varieties have been developed during the last 35 years in India. However, only a small number of them produced without backing of specific quality breeding programs excel in quality traits also. The increasing demand of baked and pasta products in the country along with economic liberalization and global trade have offered opportunities for better utilization of the surplus wheat. Thus, in the current decade and beyond, wheat quality needs uppermost attention to meet the trade requirements for domestic and export purposes. Therefore, there is a need to reorient the wheat improvement programs in the country.

Definition

Based on various standard sources, plant breeding has been defined in various ways. A few important and standard definitions are:

The art and science of changing plants genetically.

Plant breeding is the genetic adjustment of plants to the service of man.

Improvement of crop plants as the result of process of evolution directed by man for his own ends. The basic principles of plant breeding are thus the principles of evolution. Directed evolution as imposed in plant breeding differs from natural evolution chiefly in a greatly reduced time-scale, and in a more precise control over the factors which govern hybridization and selection.

The science and art of manipulating the heredity of plants for a specific purpose.

Plant breeding is a deliberate effort by human to nudge nature, with respect to the heredity of plants, to an advantage. The changes made in plants are permanent and heritable and the professionals who carry out this task are called plant breeders. This effort at adjusting the status quo is instigated by a desire of humans to improve certain aspects of plants to perform new roles or enhance existing ones. As a result, the term “plant breeding” is often used synonymously with “plant improvement” in recent years. Normally the term plant breeding connotes the involvement of sexual process in effecting a desired change; however, it is also true that modern plant breeding also includes the manipulation of asexually reproducing plants (plants that do not reproduce through the sexual process). Breeding is therefore about manipulating plant attributes, structure, and composition, to make them more useful to humans.

Gepts and Hanock (2006) have defined plant breeding as an applied, multidisciplinary science. It is the application of genetic principles and practices associated with the development of cultivars more suited to the needs of human than the ability to survive in the wild; it uses knowledge from agronomy, botany, genetics, physiology, pathology, entomology, biochemistry and statistics. Of particular importance is the ability to transfer, in addition to major genes, large suites of genes conditioning quantitative traits such as productivity and other traits of interest to humans. The ultimate outcome of plant breeding is mainly improved cultivars. Therefore, plant breeding is primarily an organismal science even though it is eminently suited to translate information at molecular level (DNA sequences, protein products) into economically important phenotypes. The traditional definition of plant breeding includes only those scientists who develop new cultivars and improved germplasm, however, many feel this definition should be expanded to include scientists who contribute to crop improvement through breeding research.

Introduction
Plant breeding and genetics are at the forefront of agricultural innovation, playing a crucial role in enhancing crop traits to meet the ever-growing demands for food, fiber, and fuel. This chapter delves into the scientific principles, methods, and modern advancements in plant breeding and genetics, providing a comprehensive understanding of how these disciplines contribute to global food security and environmental sustainability. The chapter begins by exploring the fundamental principles of plant breeding, including heredity, genetic variation, selection, and hybridization. These concepts form the foundation for developing new plant varieties that exhibit desirable traits such as improved yield, disease resistance, and environmental adaptability. The importance of genetic variation is emphasized as a key driver of plant improvement, with discussions on the sources of genetic variation, the role of germplasm resources, and the impact of genetic diversity on plant adaptation. As the chapter progresses, various breeding techniques and strategies are examined, including mass selection, pedigree breeding, backcrossing, and markerassisted breeding. These methods are crucial for developing new plant varieties that can withstand the challenges posed by climate change, pests, and diseases. The chapter also addresses the role of genomics in plant breeding, highlighting the significance of genomic selection, gene editing, and bioinformatics in accelerating the breeding process and enhancing crop traits. The chapter further explores the controversial topic of genetically modified organisms (GMOs), discussing the principles of genetic engineering, the rise of genetically modified crops, and the associated controversies and concerns. The importance of GMOs in addressing global food security and environmental challenges is also discussed, providing a balanced perspective on their potential benefits and risks. The chapter concludes by emphasizing the critical role of plant breeding and genetics in ensuring food security and combating global warming. By developing climate-resilient crop varieties, improving water efficiency, and enhancing disease and pest resistance, plant breeding and genetics can contribute to sustainable agricultural practices that reduce greenhouse gas emissions and conserve natural resources

1. Mendel presented his results in the form of

   a) Two paper in French langua

   b) Two paper in German language

   c) One paper in German language

   d) None of the above

2. The alternative forms of a gene are called

   a) Allelomorph

   b) Gene

   c) Alleles

   d) None of these

Plant breeding is the art and science of changing and improving the heredity of plants. The art of plant breeding lies in the breeder’s skill in observing and selection of superior plants. The value of selection largely depends upon the skill of the breeder. The skill that a breeder develops though a close and deep study of the concerned crop species. Before the rediscovery of the Mendelian Laws in 1900 AD, the plant breeding is as an art. The modern age of plant breeding began in the early part of the twentieth century, after Mendel’s work was rediscovered. Today plant breeding is a specialized technology based on genetics. It is now clearly understood that within a given environment, crop improvement has to be achieved through superior heredity. Plant breeding developed into a science as knowledge progressed towards the genetics, cytogenetic, physiology, pathology, biochemistry, biotechnology and biometry. The fundamental of plant breeding was based on recognition of the genes. The genes were identified by their effects on the visible expression of plant traits such as whether a plant was a dwarf or tall, or the flower color was white or pink. Through systematic hybridization, a desirable gene could be transferred from one to another cultivar. More recently the science of molecular genetics proposes to advance plant breeding. Molecular genetics was ushered in with the description of chemical structure of deoxy-ribonucleic acid (DNA), the material that constitutes the genes. DNA carries the instructions for synthesis of specific proteins that determine the visible expression of particular characters. The new technology does not supplant nor diminish the importance or need for traditional selection and crossing procedures in the breeding of improved cultivars. The performance of today’s cultivars reached at high levels through refined selection and hybridization breeding procedure.

The early developments in plant breeding that took place are based on archaeological evidence. The first efforts to grow wild plants probably occurred in Southeast Asia culminated in the domestication of some of the many plants with which humans experimented in 13000 BC. By 10000 BC, advanced knowledge existed of such plants as rice (Oryza sativa), several legumes such as pea (Pisum sativum), runner bean or broad bean (Phaseolus or Vicia spp.) and possibly soybean (Glycine max). At this point crops became domesticated.

Although the beginning of civilization in China and Southeast Asia are obscure and fragmented. The number of successful species domesticated indicates considerable success in plant breeding. The third site of independent agricultural development and plant breeding was in south-central Mexico between 6700 and 5000 BC. Squash and avocados were domesticated first and a number of species of maize. Domestication in the Middle East and China included the self-fertilized crop like cereals and soybean.

Systematic scientific efforts to improve genetic potential of crops in India were initiated in 1905 at the Imperial/Indian Agricultural Research Institute. In 1929, with the establishment of the Indian Council of Agricultural Research (ICAR), several associated developments took place in the first half of the 20th century leading to establishment of several crop-based institutes (sugarcane, cotton, jute, rice, oilseeds, tobacco, potato) and multidisciplinary institutes such as the Indian Agricultural Research Institute (IARI), Central Arid Zone Research Institute (CAZRI), and Central Plantation Crops Research Institute (CPCRI). Additionally, a Project on Intensification of Regional Research in Cotton, Oilseeds and Millets (PIRRCOM) was implemented during 1950s with establishment of several research stations in different regions.

Crop improvement

Crop improvement refers to the genetic alteration of plants to satisfy human needs. It deals with the improvement of crops and production of new crop varieties, which are far superior to existing types in all characters. In pre-history, our ancestors in various parts of the world brought into cultivation a few hundred species from the hundreds of thousands available. In the process they transformed elements of these species into crops though genetic alterations that involved conscious and unconscious selection, the differential reproduction of variants. Through a long history of trial and error, a relatively few plant species have become the mainstay of agriculture and thus the world’s food supply. This process of domestication involved the identification of certain useful wild species combined with a process of selection that brought about changes in appearance, quality, and productivity.

Broadly and conceptually breeding methods can be classified into four groups. These are:

• Selection breeding
• Combination breeding
• Hybrid breeding
• Special breeding techniques

There are fluid transitions and similarities between the individual groups of breeding methods. Selection not only takes place in the group termed selection breeding but also in other groups. In breeding varieties by combination, new variation is generated by crossing genetically different parents followed by application of various selection methods and ultimately development of a new recombinant type pure-line. In hybrid breeding, inbred lines of different genetic constitution are produced by selfing, pair crossing and other methods and from these best lines are selected and new hybrids are developed. In addition, breeding methods can also be classified according to other criteria. For example, breeding methods have also been classified according to the manner of propagation of the varieties. These are:

Definition

Plant breeding can be defined as an art, a science, and technology of improving the genetic makeup of plants in relation to their economic use for the mankind.

OR

Plant breeding is the art and science of improving the heredity of plants for the benefit of mankind.

OR

Plant breeding deals with the genetic improvement of crop plants also known as science of crop improvement.

OR

Science of changing and improving the heredity of plants

The word cell was coined by Robert Hooke with the help of compound microscope. Cell is the basic unit of life. A plant cell has three distinct components a). Cell wall b). Protoplasm and c). Vacuole. Cell wall  and  vacuole are considered as non-living substances. The protoplasm which is living is  composed of 1. Cytoplasm and 2. Nucleus. The cytoplasm contains several organelles such as mitochondria, chloroplast, ribosomes, endoplasmic reticulum, golgi complex, lysosomes, plastids etc.

21.1 Introduction

Plants and insects share a wonderful relationship. Both are dependent on each other at different levels and chemicals emitted by plants connect them to a large extent.  “Plants” contribute to a major share of occupancy on earth and makes several organisms such as insects & microbes and also humans to depend on them for their survival. This dependency leading to several interesting interactions between plants & insects which are often utilized by humans for their own benefit. Plants maintain incredible communication with their associated organisms. Since plants are rich banks of chemicals and constantly emit them in to its immediate environment which contributes in communication between insects and plants. Insects are the major organisms that have a long relation with the plants and there are several incredible ways how plants can interact with insect species.

Plant collection and field preparation of specimens are the fundamental aspects of study, training and research in plant systematics. Herbarium specimens are the permanent records of plant species of a particular place at a given time. Therefore, the plants should be carefully collected, selected, and the herbarium specimens should be properly prepared and preserved.
6.1 Which Type of Specimens Should Be Collected?
The points to be kept in mind during a plant collection are:
1. Collect entire, vigorously growing typical specimens.
2. Select such individuals that represent almost all phases of the natural population.
3. Avoid collecting insect-damaged specimens.
4. Collect underground parts (e.g. roots, bulbs, rhizomes, tubers, etc.) of herbaceous perennials.
5. Collect those specimens of flowering plants that contain flowers, fruits, and seeds, because keys are prepared mainly on the basis of these characters.
6. Specimens larger than the size of a single sheet, should be divided an pressed on a series of sheets.
7. Collect plants with the leaves intact as different kinds of foliage prove helpful in identification.
8. Collect the bark and wood samples of the woody plants.
9. Avoid collecting rare or uncommon plants. Never collect the only plant of a species at a locality.

· Plants have structural and biochemical defense mechanisms against pathogens.

· Structural defense mechanisms can be pre-existing (e.g. wax, thick cuticle) or post-infectional (e.g. cork layer formation, tyloses).

· Pre-existing biochemical defenses include inhibitors and phenolics; post infectional defenses include phytoalexins and plantibodies.

· Disease development depends on a successful host-pathogen interaction; defense mechanisms are ineffective during a compatible reaction.

Summary

This review addresses various defense strategies evolved by plants to resist pathogen attack.Of the different defensive strategies, pathogen attack either induces or enhances constitutively the synthesis of a spectrum of diverse chemical compounds in various plant species. These chemical compounds also called secondary metabolites are classified broadly as nitrogen compounds, terpenoids and phenolics and have been documented to possess broad range antifungal, antimicrobial and pesticidal activities. Such defensive compounds could be extracted and developed as eco-friendly biopesticides/microbicides because of their natural occurrence, ephemeral nature and biodegradability. These will be favorable alternative strategies compared to chemical pesticides that are fraught with various harmful side effects.

Resistance to disease in a host plants is a condition in which the plant conquer the pathogen’s attack and thus suffers small or no injury. Resistant hosts prevent or slow the development and reproduction of the majority of pathogen propagules that they come into contact with. Different plants defend themselves in different ways. Each kind of plant, probably, employ different defense mechanism against each of the pathogens that attack it. The defense barriers erected by plants are a co-ordinated system of molecular, cellular and tissue-based responses to pathogen attack.

There are various mechanisms of defense used by plants. For convenience, such mechanisms can be considered under two broads heads;

1. Pre existing or passive defense (Defense present on or inside the plant since beginning)

a. Pre existing structural defense

b. Pre existing biochemical defense

2. Post infection or active defense (Defense in response to attack by the pathogen)

a. Post infection structural defense

b. Post infection biochemical defense

CONCEPT

The word “epidemic” is derived from the greek word, epi= (on) and demons=(people) and in true sense applies to those disease of human being which appear very virulently among a large section of population. To carry the same sense in the case of plant diseases the term epiphytotic has been coined. an epiphytotic disease is one which occur widely but periodically. it may be present constantly in a locality but assumes severe form only on occasions. Of late, the term “epidemiology” has come to have a broad meaning within plant pathology. The term has been variously defined as the study of disease in populations; the study of environmental factors that influence the amount and distribution of diseases in population, and the study of either increase or decrease in the amount of disease in time, in space, or both.

Elements of An Epidemic

Generally, the elements of an epidemic are referred to as the “disease triangle”: a susceptible host, pathogen, and favorable environment. For disease to occur all three of these must be present. Where all three items get together there is disease. As long as all three of these elements are present disease can commence, an epidemic will only arise if all three continue to be present. Sometimes a fourth factor of time is added as the time at which a particular infection occurs, and the length of time conditions remain viable for that infection, can also play an important role in epidemics If all of the criteria are not met, such as a susceptible host and pathogen are present but the environment is not conducive to the pathogen infecting and causing disease, disease cannot occur.

Factors that affect the development of epidemics

Plant disease epidemiology is the study of how plant diseases develop and spread. It involves understanding the causes of diseases, how they spread, and their impact on plants and crops. This knowledge is used to develop strategies for managing and controlling plant diseases, such as predicting outbreaks, breeding resistant plants, and implementing cultural and chemical controls.

Element of an epidemic: Plant disease epidemics develop as a result of the timely combination of the element in plant disease: Susceptible host plant, a virulent pathogen and favourable environmental conditions over a relatively long period of time. Humans may unwillingly help initiate and develop epidemics. Thus, the chance of an epidemic increases when the susceptibility of the host and virulence of the pathogen are greater, as the environmental conditions approach the optimum level for pathogen growth, reproduction and spread and as the duration of all favourable conditions.

DEFINITION

Fore casting involves all the activities in ascertaining and notifying the grower of community that conditions are sufficiently favourable for certain diseases, that application of control measures will result in economic gain or on the other hand, and just as important that the amount expected is unlikely to be enough to justify the expenditure of time , energy and money for control. The above statement made explicit distinction between positive forecast and negative forecast and both have value for growers as well as society in general.

Positive forecast: Employs need based chemical sprays, provides adequate protection to crop and reduces damage to environment.

Negative forecast: Avoids unnecessary chemical sprays, no risk to the crop health and no disruption of environment.

Methods for plant diseases control were first classified by Whetzel (1929) into exclusion, eradication, protection and immunization.

Two more principles - avoidance and therapy were created (NAS, 1968).

4.1. Physical methods

Employed for reduction or elimination of primary inoculums that may be present in seed, soil or planting material.

Introduction

In Organic farming; agricultural management system uses eco-friendly management practices and biological fertilizers derived largely from plant residue, animal excreta and nitrogen-fixing cover crops. It favorably affects the quality and yield attributes of crops. In modern agriculture system, development of organic farming in relation with the environmental hazard triggered by the huge application of inorganic pesticides and synthetic fertilizers in conventional agriculture, and it has abundant ecological aids. Spent mushroom substrate (SMS) can be used as such fertilizer. It is an organic mass that can be converted into humus in the soil.

Mushrooms are a fleshy, macroscopic, saprophytic, spore-bearing fruiting structure of a fungus (edible fungus) belonging to class Basidiomycetes except few which belong to Ascomycetes. It grows on dead and decaying organic materials derived from the agriculture, horticulture, poultry, brewery waste materials for its cultivation. Mushrooms are delicate, nutritional and medicinal fruit bodies of fungus which are used as an important ingredient of human dishes. It contains protein, minerals, vitamins and essential amino acid. Mushroom industries does not only produce edible mushroom but also produces virtually in-exhaustible supply of a co-product called spent mushroom substrate (SMS). Mushroom industry is flourishing day by day and not just mushroom as a whole is being used but many of its other uses are also studied and performed like using mushroom production for bioremediation or using mushroom waste which is known as SMS for different purposes. Therefore, growing mushrooms just for consumption is not true but its growth has many underlying purposes through which not just humans but the entire ecosystem is benefitted (Staments, 2005; Phan and Sabaratnam, 2012).

6.1. Fungicides

Fungicide originated from two latin words viz., fungus and caedo.

Word caedo means to kill.

Fungicide is a chemical agent which has the ability to reduce or prevent the damage caused to plants and their products.

Physical agents like ultra violet light and heat should also be considered as fungicides.

Antisporulant and fungistatic compounds do not kill the fungi, they are included under the broad term fungicide

What is Plant Disease Resistance and Its Mechanisms

There are two main types of plant disease resistance:

Innate Resistance (Non-Host Resistance): This is a broad-spectrum resistance that prevents most potential pathogens from infecting the plant. It is often due to the lack of essential factors required for the pathogen’s survival or the presence of preformed physical and chemical barriers.Plant disease resistance is the ability of a plant to prevent or reduce the damage caused by pathogens (disease-causing organisms) like fungi, bacteria, viruses, and nematodes. It involves a complex interplay between the plant’s defense mechanisms and the pathogen’s virulence factors.

History

 • The fossil evidence also indicates the presence of plant diseases 250million years ago.

 • The diseases caused by fungi and nematodes were discovered by Monocernin 1735.

 • Johan Needham (1743) identified wheat gall caused by a nematode.

 • Adolf Mayer (1886), demonstrated the transmission of Tobacco mosaicvirus (TMV).

 • EF Smith (1890) described bacterial wilt in cucurbits.

• The thrips (Thysanoptera) as vectors of plant viruses were identified thescientific studies made by Samuel and his team.

 • Karl Maramorosch (1952) demonstrated the multiplication of Asteryellows virus (AYV) in leafhopper vector.

 • The mite Aceriatulipae has been identified as a vector of Wheat streakmosaic virus by JT Slykhuis in 1955.

 • The term “vir

5.1. Cultural methods

5.1.1. Eradication

Elimination of pathogen after it has become established in the area where host is growing.

Disease is one of those terms that are very difficult to define. It is realized that disease (literally dis-ease) implies lack of ‘comfort’and therefore, involves deviation from normal functioning. From time to time several definitions which have been proposed, in fact descriptive but not simultaneously exclusive. The definitions for the term disease are.

Introduction

Indigenous Technological Knowledge (ITKs) refers to the knowledge that acceptable to all as absolute hearing and developed about the meticulous altitude by the people irrespective of gender that is women and men ancient to an a specific geographical area. This ancient technological knowledge that humans in an accustomed association accept developed over time and abide to advance it, is predicated on animal kingdom adventures on accumulation scale, activating and changing, activated throughout a lot of cases over centuries of use. Highest accessible knowledge to bounded knowledge and ambiance and put greater weightage on abbreviate risks instead of maximizing profit. The traditional technological knowledge (ITKs) covers a complicated sphere of subjects, viz. crop production, livestock rearing, accustomed knowledge management, ailment preparation, healthcare, insect administration, and others. The utilization of non-chemical methods for protecting lives and crop aegis is already accepting in several countries including India. The administration strategies developed and answer by the Governments is now supported the utilization of plant extracts. If an accomplishment is fabricated arise the cultivation of Indigenous Technological Knowledge (ITK) based articles on the small scale, it is often an economically applicable advantage for the appropriate development of eco-friendly chemicals.

Indian agriculture has been started over 10,000 years old, over millennia, farmers developed innumerable practices to auspiciously abound crops and accession animals within the awful adapted agro ecological regions of the Indian subcontinent. About 170 years of acceptance brought in new techniques, some advantageous in addition to a few harmful event of ancient Technological knowledge (ITK) systems, including administration of accustomed environment, has been a bulk of adaptation to the humans who generated these systems continued aback. Million of ITKs were supported to avail knowledge of actual and living assets to construct sure basal livelihoods for bounded people.

Biodiversity is the foundation stone of human survival on the earth. Very appropriately, the theme of the World Food Day celebration, 16 October, 2004 was “Biodiversity for Food Security” Biological diversity is fundamental to agriculture and food production. Scientists have identified so far about 1.4 million of the plant and animal species that exist on earth. A rich variety of cultivated plants and animals serves as the foundation for agricultural biodiversity. Yet people depend on just 14 mammal and bird species for 90 % of their food supply from animals. Just four plant species, namely, wheat, maize, rice and potato provide half of our energy from plants (FAO, 2004).

India is located between 8^°- 38^° N and 68^°- 97^ºE and exhibits extreme variation in altitude — from sea level to heights above vegetational limits in the Himalayas (ca 4500 m), and climate — from monsoon- tropical in south to temperate and alpine in the north-western Himalayas and extremely arid to semi-arid in the north-western plains. It is floristically extremely rich with about 33 percent of its botanical wealth (over 15,000 species of higher plants) being endemic. There are about 141 endemic genera distributed over 47 families. Further, of the 4,900 endemic species, larger percentage is localised in the Himalayas (about 2,532 species) than in other regions, namely, the peninsular tract (1,788 species), and the Andaman and Nicobar Islands (185 species). It is also estimated that floristic richness is maximum in the north-eastern region, which holds about 50 percent of India’s total species diversity, i.e., more than 7,000 species, and is considered as the cradle of flowering plants. Of 990 species of orchids, 700 species occur in this region (Nayar, 1989). This, thus, makes the Indian region botanically unique and interesting (Arora, 1991).

2. 1. Plant domestication

Process of bringing wild species under human management.

2.1.1. Changes in plant species under domestication

Elimination or reduction in shattering of pods, spikes, etc.

Elimination of dormancy

Decrease in toxins of other undesirable substances. Eg. Bitter principle of cucurbits.

Cultivated plants show altered tillering, branching, leaf characters.

Decrease in plant height. Eg. Cereals and millets.