eChapters

Introduction
It has been universally acknowledged that breeding for hybrids is the most effective conventional plant breeding technique. When two genetically distinct parent lines typically inbred lines are crossed, the resultant progeny is referred as a hybrid. It has been demonstrated that hybrids are larger, more productive, and hardier than their parental lineages. When we talk about hybrids, it is also imperative to understand two other related jargons: heterosis and hybrid vigour. The word “heterosis” was first coined in 1914 by Gottingen to refer the hybridization process in which two homozygous individuals (inbreds) are crossed to produce a hybrid. Darwin first used the phrase “hybrid vigour” in 1876 to denote the superiority of the F1 offspring produced by heterosis (i.e., the hybrids show superior performance with increased characteristics when compared with the two parental lines).
In general, the goal of plant breeding is to create better crop varieties by utilizing genetic variation found in the germplasm of the given plant species. Traditionally, two genetically different accessions of the given crop were selected and crossed to produce a hybrid. The genotype of this hybrid is the outcome of the fusion of the male and female gametes, those produced a zygote, from which the progeny eventually emerged. It would be appropriate to recollect the point that a plant’s life cycle consists of a gametophytic generation that produces gametes. Therefore, the genotypes of the gametophytes reflect the genetic diversity of the gametes.
Gametophytes are derived from spores, which are created via sporophytic reproduction during the course of the plant’s life cycle. Meiosis is a specialized kind of cell division that produces spores from differentiated cells that are located in the reproductive organs of plants. Two important processes (viz., recombination and chromosomal segregation) occur during meiosis and this results into independent assortment and creation of novel combinations of the genetic components of a diploid genome into a haploid genome of the gametophytes. Consequently, the genotype of a progeny is made up of the genotypes of the male and the female gametes that merged to create a new sporophyte. Therefore, meiosis can be viewed as a crucial stage in the life cycle of a plant and is responsible for generating genetic diversity. To generate desired plants with novel traits, this diversity or variability is frequently employed. In many cases, a hybrid plant outperforms a homozygous (parental) plant because it combines the best traits of the two parents. However, the creation of such hybrids is quite difficult. In order to evaluate the combining ability of hybrids, multiple putative parental lines are first produced at homozygous conditions by employing several generations of inbreeding and selection. The best pairs are then kept, and the corresponding parental lines produce a vigorous hybrid. Although hybrids were originally generated in maize during the 1930s, they are now employed in a wide variety of economically important plant species because they significantly surpass their parental inbreds. The main reason quoted for the wide-spread application of hybridization in breeding programs is because of the reason that hybrid seeds are easier and faster to growing homogenous plants

Causes and Mechanism
I. External Causes/ Extrinsic Causes
1. Physical Causes
1. Trauma by cutting objects and blunt objects
2. Electrical – Lightning, high frequency current
3. Heat -Sun stroke, burns, fever
4. Cold Local tissue freezing, cold shock
5. Radiation
UV / X /cosmic radiations
6. Pressure
Increased or decreased pressure

The Review of literature is a critical summary of published academic research and other sources on a particular topic or research question. It involves identifying, analyzing, and synthesizing relevant research studies, books, articles, and other sources to provide a comprehensive overview of what is known and not known about the topic.

A good review of literature should be well-structured, focused, and provide a balanced and objective analysis of the existing literature. The following are the key elements of a literature review:

1. Introduction: The introduction should provide background information on the topic and highlight the importance of the research question.

2. Search Strategy: The search strategy should outline the databases and search terms used to identify relevant literature.

3. Inclusion and Exclusion Criteria: The inclusion and exclusion criteria should be clearly defined to ensure that only relevant studies are included in the review.

This chapter is an extensive survey of all past studies relevant to the field of investigation which gives a knowledge of what others have found out in the related f ield of study. In any scientific investigation or research a comprehensive presentation of review of literature is a statutory requirement. Its main functions are to develop a better understanding of the problem to be investigated, delineate a new area of study and avoid unnecessary duplication, decide on the tools and techniques to be adopted including developing some new ones, also to relate the present study with the previous ones by finding out the areas of agreement and disagreement.

The review of literature of the present study is based on the major concepts related to the f ield of investigation. As direct references on all the item are not in abundance, certain specific references along with some indirect references have been incorporated in this chapter for the purpose of meaningful use.

Review of literature has been organized with a view to provide hard evidences as to clinically justify the reasons, logic, and contemplation leading to heuristically infer the different echelons of resilience issues.This is also catered to isolate the apparently less attempted genre of resilience study and analysis. Climate change, uncertainty, decline of soil organic carbon, fatigued genes on land, loss of biodiversity and fragile ecology of society have only been some of myriad of factors causing the loss of resilience, from ecology and from society as well.

The Review of literature is a systematic, explicit and reproducible method of identifying, evaluating and synthesizing the existing body of a completed and a recorded work produced by researchers, scholars and practitioners. The Review of literature is also a resource paper which includes the current knowledge including substantive findings as well as the theoretical and the methodological contributions to a particular topic. These are available mostly in academic and scholastic journals.

Review of literature provide the basics for research in nearly every academic f ield. This chapter is an extensive survey of all past studies relevant to the field of investigation which gives knowledge of what others have found out in the related field of study. In any scientific investigation or research, a comprehensive presentation of the review of literature is a statutory requirement.

The aim of review of literature is to highlight what has been done so far in the field of interest and how our findings are related to earlier research.

Its main functions are to develop a better understanding of the problem to be investigated, delineate a new area of study and avoid unnecessary duplication, decide on the tools and techniques to be adopted including developing some new ones and also to relate the present study with the previous ones by finding out the areas of agreement and disagreement.

The review of literature may

(a) Indicate the following by providing referential inputs – Approaches, Methods, Variables used, Statistical procedure, Expected results.

(b) Provide theoretical background to the study.

(c) Help to justify how the findings are related to the body of knowledge in the f ield of research.

(d) Establish a link between what we have proposed to study and what has already been found. It helps us to refine the research methodology.

2.1. Concept of review of literature

Research is a continuous process. For any scientific investigation, previous f indings provide basis to the research. It also helps to know the previous research work done in that area and acts as a torch for the new researchers. The review of literature is one of the important aspects in the research process. It helps the researcher to keep his work going in right and appropriate direction. To point out prior research in the area of interest and how our findings connect to past studies, a review of the literature is conducted. The proposed study is new in its subject treatment. However, an attempt is made here to put together some of the closely related research findings in the area.

The Review of literature is a systematic, explicit and reproducible method of identifying, evaluating and synthesizing the existing body of a completed and a recorded work produced by researchers, scholars and practitioners. The Review of literature is also a resource paper which includes the current knowledge including substantive findings as well as the theoretical and the methodological contributions to a particular topic. These are available mostly in academic and scholastic journals.

Review of literature provide the basics for research in nearly every academic f ield. This chapter is an extensive survey of all past studies relevant to the field of investigation which gives knowledge of what others have found out in the related field of study. In any scientific investigation or research, a comprehensive presentation of the review of literature is a statutory requirement.

The aim of review of literature is to highlight what has been done so far in the field of interest and how our findings are related to earlier research.

Its main functions are to develop a better understanding of the problem to be investigated, delineate a new area of study and avoid unnecessary duplication, decide on the tools and techniques to be adopted including developing some new ones and also to relate the present study with the previous ones by finding out the areas of agreement and disagreement.

A thorough examination of relevant literature is crucial in any scientific investigation and research. Apart from identifying previous work conducted in the problem area or the specific field of study, the primary function of a literature review is to provide insights into the methods and procedures used, while also establishing a foundation for interpreting the findings. A literature review involves a comprehensive and critical assessment of prior research, offering a summary and overview of a particular research area. This allows readers to understand why the current research program is being pursued. A well-executed literature review delves into the reasons behind selecting a specific research question, integrating and evaluating previous studies, and demonstrating how they relate to the proposed research program. It is important to present all sides of the argument in a clear manner to avoid bias, while also highlighting areas of agreement and disagreement among the existing literature.

In this chapter, we have attempted to provide a concise overview of various studies and writings related to migration. This overview serves to enhance our understanding of the significance and purpose of our current research. Some relevant reviews have been categorized and presented under the following sub headings:

Farmers require a diverse range of information to support their farm enterprises. Information is needed not only on best practices and technologies for crop production, but also for post -harvest aspects. Agricultural Extension is an essential pillar for research and development in agriculture. Despite a wide range of reform initiatives in agricultural extension in India in the past decades, the coverage of, access to, and quality of information   provided to marginalized and poor farmers is uneven. Approaches to agricultural extension in India and worldwide continue to evolve.

A brief description of IGMC is given in Para 6.6 with details of the canal sections. Here an attempt is made to review the hydraulic performance of the Main Canal.

7B.1 Study of Flow Characteristic of the Main Canal

The main canal is designed for a maximum discharge of 524 m3/s at head i.e. at Km. 0. Large of number of branches, distributaries and minors off take from the main canal at different location all along the canal. These are shown in the L- section, Figure 7B.1 and a statement off taking canals is given Table 7B.1. Many distributaries such as lift canals have been planned subsequently. Also discharges of few off taking channels have been changed. A clear and updated data are not readily available. So data available are indicated in the Table and plotted in the L - section. A half bottom plan of the canal is also shown in Figure 7B.2

In recent years, there has been a considerable interest in the new technological interventions for enhanced livestock productivity in the Indian sub-continent, because of the increased demand for livestock products for human consumption. Bypass nutrients defined as a nutrients fed in such a form that provides an increase in the flow of the nutrient (s) unchanged to the abomasum, yet is available to the more important nutrient (high BV) should escape from the rumen or face minimum ruminal fermentation. The reasons for protecting different nutrients are based on their mode of utilization in the rumen. The literature on the effect of the bypass fat and protein on nutrient utilization, milk production and reproductive performance has been reviewed and presented in following subheads

In this chapter, an attempt has been made to review some of the earlier studies related to shrimp farming and its socio-economic and environmental impacts. The related pieces of literature are classified into the following five categories.

Shrimp Pond Management

Economic Impact of Shrimp Farming

Social Impact of Shrimp Farming

Impact of Shrimp Farming on Environment

Acts and Policies Relating to Shrimp Farming

Research being a continuous process for a scientific study, previous study provides basis for the research. The review of literature is necessary for developing conceptual frame work and suitable design for the study. It assists the researcher to keep his work going in right direction. The available literature related to the present study has been reviewed under the following heading:

2.1 Differential role accomplished by women dairy farmers from different social strata

Toppo et al. (2004) examined the participation of women farmers in dairy occupation in Anand district of Gujarat and their result revealed that 18.34 percent of the farm women were mostly engaged in activities related to artificial insemination, majority of the respondent (68.34%) participated in cleaning of the shed, while 25.00 percent of the farm women practised manure preparation and 95.00 percent of the respondent were not involved in preparation of gobar gas mixture.

Badole (2006) reported that majority of the responded had low socio-economic status.

A Literature Review is a systematic and comprehensive analysis of books, articles and research papers to a specific topic providing a base of knowledge on the topic. Literature reviews are designed to identify and critique the existing literature on a topic to justify your research by exposing gaps in current research. This investigation should provide a description, summary, and critical evaluation of works related to the research problem and should also add to the overall knowledge of the topic as well as demonstrating how your research will fit within a larger field of study. A literature review should offer critical analysis of the current research on a topic and that analysis should direct your research objective. This should not be confused with a book review or an annotated bibliography both research tools but very different in purpose and scope. Key to a good Literature Review is to document your process.

This chapter reviews the research work done in the fields related to the objectives of the study. In any scientific investigation or research a comprehensive review of relevant literature is very essential. Its main function apart from determining the work done before concerning the problem area i.e. area of investigation, it provides an insight into the methods and procedures and create a basis for interpretation of findings. As direct references on all the item are not in abundance, certain specific references along with some indirect references have been incorporated this chapter for the purpose of meaningful use.
2.1. Ecosystem Services and Conservation Agriculture
Acharya, S. K. and Chatterjee, R. (2019) found that conservation agriculture may help in re-building agro-ecology by maintaining carbon sequestration, maintaining soil health, checking soil erosion and ground water depletion, energy balance, mitigating climate change related problems through maintaining ecosystem services.
Ayyam, V., Palanivel, S., and Chandrakasan, S. (2019) stated that CA embraces higher rates of carbon sequestration, organic matter accumulation, soil erosion reduction, and its associated improvement in soil biological properties. Additionally, there is reduction in greenhouse gas emission as a result of CA. Adoption of CA-based farming practices particularly in areas facing notable land degradation and depleting natural resources delineates a win-win scenario due to improved crop yield and trends of increasing soil fertility and scope for climate change adaptation to recuperate degraded soils and improve ecosystem services.

The systematic identification, evaluation, and integration of the body of published work produced by researchers, scholars, and practitioners is achieved through a rigorous and repeatable method called the review of the literature. It acts as a comprehensive resource, incorporating the most recent information, important discoveries, and theoretical breakthroughs linked to a certain field. The literature review is a useful compilation of important discoveries as well as methodological and theoretical contributions within a certain topic that is frequently seen in academic and scholarly journals.

In all academic areas, the review of literature is a crucial component of research. Its main goal is to assess, evaluate, and make links between our findings and previous research on a particular subject of interest. In addition, the literature review acts as a point of reference and offers helpful insights in the following ways:

i. Approaches

ii. Methods

iii. Variables

Cyanobacteria have been identified as one of the most promising groups of organisms from which novel and biochemically active natural products are isolated. Cyanobacteria such as Microcystis, Anabaena, Nostoc and Oscillatoria produce a great variety of secondary metabolites. The only group comparable to cyanobacteria is actinomycetes, which has yielded a tremendous number of secondary metabolites. The rate of discovery from traditional microbial drug producer like actinomycetes, which is in the focus of pharmaceutical research for decades, is decreasing and it is the time to turn to cyanobacteria and exploit their potential. Recently, there has been an increasing interest in cyanobacteria as a potential source of new drugs (Glombitza and Koch, 1989; Schwartz et al., 1990). This is of paramount importance to fight increasingly resistant pathogens and newly emergent diseases (Hayashi et al., 1994).

Cyanobacteria are photosynthetic microorganisms that have flourished on earth for more than 3 billion years with some genera showing only minor morphological changes since that time (Hagmann and Juttner, 1996). The medicinal and nutrient qualities of cyanobacteria were first appreciated as early as 1500 BC, when Nostoc species were used to treat gout, fistula and several forms of cancer (Pietra, 1990; Bladon, 2002; Liu and Chen, 2003).

Hausman (1920a) worked on the microscopic structure of hair from the commercial fur. The hair samples of 27 different species of animals were used for the study. He described in detail the structural features of guard hair. He classified medulla of hair into 4 different types as discontinuous, continuous, fragmental and interrupted on the basis of composition of medullar cells. He also classified the cuticular scale pattern into two types as imbricate interrupted and imbricate coronal. He mentioned in detail the methods for the preparation of slides for the study of microscopic structures of hair. He also studied the cortex and pigment granules.

A literature review is an organized, in-depth examination of books, journals, and research papers related to a particular subject that serves as a foundation of knowledge. By pointing out gaps in the present body of knowledge, literature reviews aim to identify and evaluate the body of existing research on a certain subject in order to support your own study. This inquiry needs to include an explanation, synopsis, and critical assessment of previous studies pertaining to the research challenge. It should also contribute to the body of knowledge on the subject and show how your findings will fit into a broader body of knowledge. Your research goal should be guided by the critical examination of the most recent research on the subject provided by a literature review. This is not the same as a book review or an annotated bibliography, which are research instruments with quite distinct goals and purposes. Writing a process document is essential to a successful literature review.
Purpose
A literature review’s objectives are to:
• Offer a solid foundation of information on the subject.
• Locate areas of earlier study to avoid repetition and to acknowledge the contributions of other experts.
• Determine the need for further research (include evidence to support your findings).
• Determine how one piece relates to the other and to the theme in the context of both.
• Set your own research in the framework of previously published works that argue for the necessity for further research.