eChapters

‘Nematodes’, otherwise known as ‘eel worms’, ‘thread worms’, ‘round worms’, and ‘nemas’ are unsegmented, smooth-bodied, mostly minute, worm-like metazoan organisms. They are classified under the Phylum - Nematoda. The term ‘Nematode’ has been derived from the two Greek words ‘Nema’ = thread and ‘Eidos’ = form, which means thread-like organisms. At present, the nematodes, which are exclusively parasitic on man and livestock are studied under ‘Helminthology’ or ‘Parasitology’, while the plant parasitic or phytonematodes, as well as free-living nematodes are studied under ‘Nematology’, a branch of biological science that exclusively deals with nematodes. Cobb coined the term Nematology in about 1920.

Nematodes are ubiquitous and are found every where life can sustain. They can survive in any type of environment and are found from the arctics to the tropics and from the oceans to the top of hills. Though basically aquatic, nematodes have adopted terrestrial habits. They are mostly found in the soil around the rhizosphere of roots of plants. They constitute 80 - 90 per cent of all multicellular organisms and the number of nematodes may vary from 1.8 - 120.0 million per sq. m. of soil according to Kevan (1965). At present the number of established species is about 15,000, but there may be several thousands more.

All control measures are directed to bring down the nematode population low enough to raise the crop successfully and profitably. The choice of control measures to be taken depends upon the nematode species to be tackled and the crops involved.

1. Cultural methods 
The objective of these methods is to adopt suitable land management practices, so as to bring down the nematode population in the field to a low level, which may not cause economic injury to the crop or to keep the field free from parasitic nematodes by adopting suitable preventive measures. Besides causing direct damage to the crops, several nematode species are known to transmit many fungal, bacterial and viral pathogens, which aggravate the extent of damage caused to the crops. Many of these pathogens gain access to the host plants only through mechanical injury caused by the nematodes. By controlling the nematode parasites, the incidence of diseases caused by such phytopathogens can also be avoided to a large extent. Cultural methods, though may not give spectacular results within a short span of time of a single season or year, as in the case of chemical control measures, if followed over a number of years is sure to give encouraging results. Cultural methods include crop rotation, fallowing, ploughing, flooding, trap cropping, use of organic amendments, selection of seeds and seed materials, use of resistant and tolerant varieties etc.

The mites belong to the Class - ‘Arachnida’, Order - ‘Acarina’. Most of the phytopathogenic mites are classified under the two Families - Tetranychidae and Eriophyidae.

The mites belonging to the Family - Tetranychidae are generally known as Tetranychids. They are very minute, and less than 100 microns in size. The body is non-segmented and the head, thorax and abdomen are  not distinct, but rather fused together. The life cycle of a tetranychid mite consists of an egg stage, three nymphal stages viz., protonymph, deutonymph and tritonymph and an adult stage. In the protonymphal stage, which is also called the larval stage, the mites have only 3 pairs of legs. In all the other nymphal stages and the adult stage they have 4 pairs of legs. The mites are roundish or oval in shape, with biting and chewing, as well as piercing and sucking type of mouthparts (Fig.190).

INTRODUCTION

Iron in the terrain’s crust is more oxidized now than it was when life evolved. It has been hypothesized that dissolved ferrous iron could have been a convenient oxygen acceptor and that deposition of oxidized iron in sediments must have taken place before oxygen could have entered the atmosphere in significant quantities. Obviously, during early evolution on this planet, the essential elements are present only in reduced form. Today a number of elements are present only in a highly oxidized form and considerable energy must be expanded to reduce them to a form similar to that on early earth which plants can utilize.

Iron represents essential elements which are usually available in oxidized form but must be reduced, often using metabolic energy, before they can be utilized. For the first time, Gris (1844) observed yellowing of grapevine leaves in absence of iron in the nutrient solution in which these plants were growing. Later, iron was reported to be essential for diverse group of plants. Due to a great variation in iron requirement by different plant species, it is difficult to decide whether iron is a macro or micronutrient.

Phospholipids are the most abundant lipids of biological membranes. They serve primarily as structural components of membranes and are never stored in large amounts. As the name of phospholipid implies, this group of lipids contains phosphorus in the form of phosphoric acid groups. The major phospholipids found in membranes are the phosphoglycerides (phosphatides) (Fig.1). Which have two fatty acid molecules esterified

INTRODUCTION

The metabolism of carbohydrates is vital for plant growth and development, and to the yield of major plant products such as starch and sucrose. Starch, sucrose and fructose are the three important carbohydrates which are utilized in most of the higher plants. The majority of sucrose that is synthesized in higher plants during photosynthesis is exported to non-photosynthetic cells (ap Rees, 1992). Starch serves as an important storage for carbohydrate residues. The degradation (breakdown) of starch ensures retaining of important life processes in plants when there is carbon shortage, for instance, during night period in leaves or in resting organs such as potato tubers.

INTRODUCTION

Among plant nutrients, our soils are particularly low in nitrogen and therefore, require is high doses of nitrogenous fertilizers for getting optimum productivity. Added to this is the problem of poor efficiency of nitrogeneous fertilizers which under normal conditions is only 40 – 50 %, still less for rice ranging from 25 – 35 %, and the residual effect for the succeeding crops is never more than 10 %. The rest of the applied nitrogen is lost either through volatilization, leaching or denitrification (Kashyap, 1978). The high cost of nitrogenous fertilizers and their poor utilization efficiency very much add to the high cost of cultivation. Hence, the need of the hour is to decrease our dependence on chemical fertilizers and increase the efficiency of the fertilizer thus used. The increase in nitrogen efficiency in crop plants can be achieved by reducing denitrification with the use of nitrification inhibitors, reducing the soil compaction, improving drainage conditions, use of soil improving crops, and adopting carefully the irrigation procedures (Carlson, 1980). No doubt exploration of this possibility is a big task, nevertheless, the understanding of physiology and biochemistry of nitrogen nutrition at molecular level is obligatory and is likely to add insight to achieve the hard task goal.

INTRODUCTION

The purpose of writing this chapter is to develop a comprehensive understanding of the role of functions of water in plant growth and development. Water is essential to life on earth as the living organisms contain 80-90 per cent water. A typical crop or grassland will transpire approximately 500 ml of water per 10 g of dry matter produced. Water has a tremendous effect on the environment near the earth, which on regional basis we call ‘climate’. Ecological importance of water is due to its physiological importance because water affects the plant growth through physiological processes. All metabolic activities in the plant cell or tissue depend on water status of the plant. For example, in a maturing seed, respiration rate is highest as it moves towards maturation stage, water content decreases and hence rate of respiration slow down. At the harvesting stage, when the water content is 10-20%, the respiration rates become negligible. Now in a stored seed if the water content will be high it will result into higher respiration, thus release energy, which will increase the temperature and will finally destroy the seed.

INTRODUCTION

One of the most dangerous ecological crises being faced by all living organism now-a-days is the pollution of the environment. It is easier to describe pollution rather than to define it. It is presumed that the environment in past was more or less pure. But due to various activities of man such as industrialization, urbanization, agricultural practices etc, composition of the environment gets changed which is called environmental pollution. Any substance that creates pollution is called ‘pollutant’. There are different types of pollution among which pollution caused by toxic level of heavy metal pollutants is called heavy metal pollution.

Heavy metal pollution is a problematic field of research and is gaining immense importance now-a-days. We have 104 elements in the periodic classification of which 80 are metals. According to Passow et al. (1961), heavy metals are those having densities more than five (5 g cc^-1) and atomic weight twenty three. The term ‘heavy metal’ is imprecise but is widely used although others such as ‘toxic metal’, ‘trace element’ are possible alternatives. Sources of these heavy metals are varying; some of these are encountered in water, air effluent, solid waste and sewage. They are emitted out from various sources e.g. waste water from electroplating industry (Cr, Ni), air emission from fluorescent lamps (Cd, Be), paint pigment waste (Pb, Cr), auto-exhaust emissions (Pb, Te) etc.

Introduction

After water, nitrogen is the most critical nutritive element for crop productivity and human efforts to produce food and energy have greatly changed the nitrogen cycle of the earth. Sustainable cropping systems throughout history and across the world have relied on the combination of a cereal with an N-fixing legume. In recent history, cereals have dominated global agriculture, while legume areas and productivity have stagnated or even declined. An atmosphere around us contains nearly 78% nitrogen, which is in free form. Hence it is not available to plants. At present, India produces around 206 million metric tones of foodgrains for its growing population, increased foodgrain cannot be produced unless we carefully make use of biological nitrogen. Biological nitrogen fixation is the key to sustain agricultural productivity through the application of biofertilizers in the field. However, there is an urgent need to transfer this technology on the field to farmers and industry by producing these fertilizers on large scale.

Introduction

To keep pace with the ever-increasing demand for crop yield by the exploding population, use of chemical fertilizers and pesticides in agricultural production has become indispensable.  Production cost of agriculture has skyrocketed owing to the abandoning of green, organic farmyard manure and use of chemicals. However, the problems associated with chemical pesticides are abundant. The excessive application of chemical fertilizers causes soil sealing, fertility diminishing and residual problems. The leftover chemical fertilizers and pesticides have seriously affected the quality of agricultural products, people’s health and caused environmental pollution.  The over use of fertilizers has also damaged the soil’s original micro-ecological balance and deteriorated the diseases spread by soil.  While some pesticides must be abandoned because of their unacceptable non-target effect, there will always be a need in agriculture for safe and selective chemicals to limit the effects of pests.  More significantly, it is becoming increasingly more difficult and expensive to find new kinds of synthetic chemical pesticides.  Implications of chemical pesticides in ecological, environmental and human health problems have increased public awareness and concern regarding the continued use of agrichemicals that are damaging to human or  environmental health thereby obviating the search for effective alternative approaches which have minimal deleterious effects, more environmentally friendly, and will contribute to the goal of sustainability in agriculture.  In this line Plant growth-promoting rhizobacteria (PGPR) present immense potential and promise as effective substitutes for chemicals.  PGPR enhance plant growth and survival, control soil-borne fungi, and induces systemic resistance to phytopathogens and is used as inoculants for biofertilization, phytostimulation and biocontrol.

Introduction

India has a big challenge in fruit production in the current backdrop of decreasing per capita land holding and static fruit productivity. In recent years, China has surpassed and secured top position in the fruit production in the world accounting for 4,44,651 mt production followed by India and Brazil.  Now Chinese share in the fruit production is around 13 per cent while India contributes 10.2 per cent, Brazil 8 per cent and USA 6 per cent of total fruit production.

India is bestowed with a wide variety of agro-climatic conditions and enjoys an enviable position in the horticultural map of the world. Almost all types of fruit crops (tropical, sub-tropical and temperate) are grown in one or other part in the country.  The major tropical and sub-tropical fruits grown in India include mango, banana, papaya, orange, mosambi, guava, grape, pineapple, coconut, sapota, ber, pomegranate, litchi, aonla, bael, jackfruit etc.  Cashew nut cultivation has a big potential and its production, productivity and export has increased significantly in recent decades. Indian grape has recorded highest productivity per unit area in the world. The productivity of fruit per unit area in India has increased nearly from 10 t/ha to 12 t/ha in almost one decade.  However, the average productivity in most of the fruit crops is far below than satisfactory except grape and banana in few states.  It is paradox to record that India’s contribution in the overseas market is almost (0.11 per cent) negligible (Chadha, 2000). However, other countries like Mexico, Philippines and Venezuela, which produce far less, export 4 per cent of their total production.

Preference of herbicides for weed management in Agriculture and Horticulture

Weeds are unwanted and undesirable plants which interfere with the utilization of land and water resources and pollute atmosphere with their allergic pollen thus affecting human welfare adversely.  They are the plants out of place, growing where we want other plants or no plants at all.  They compete with desirable and beneficial vegetation reducing the yield and quality of the produce.  The effect of weeds in agriculture or horticulture is greatest.  There is a scanty reliable study of worldwide damage to crop yields due to weeds.  Whether the data are available or not, it is well known that losses caused by weeds exceed the losses from any category of agricultural pest, viz., insects, nematodes, diseases, rodents etc. Weeds account for 45% while insects 30%, diseases 20% and other pests 5% of the total annual loss of agricultural produce186.

Introduction

Plants are responsive to the applied Non-scheduled caste, which constitute most of the vital macromolecules and metabolites related to its vegetative and reproductive cycle. The applied fertilizer N enhances crop productivity per unit area, as agricultural soil deficient in N worldwide. The fertilizer application is thus considered essential to meet the requirement of the burgeoning population, particularly in the developing countries (Abrol et al., 1999; Chanda and Sati, 2005). The farmers practicize heavy dressing of N-fertilizers in crop fields for high productivity, which has resulted into world including Indian sub-continent and China have resulted into the excessive use of N-fertilizers intending to maximize crop yield. Decrease in the organic fertilizer input and depletion of micronutrients in intensive cultivation zones have caused a decline or stagnation in the crop productivity, which  has been attempted with a further loading of soluble chemical fertilizers (Maleshwar, 2003; Kumar and Yadav, 2003; Anonymous, 2004; Chanda and Sati, 2005; Abdin et al., 2006).

Introduction

The life cycle of a plant passes through biotic and abiotic stresses and plants are being attacked at different stages of growth by a number of disease causing organisms. These organism including bacteria, fungi, viruses, and nematodes attacks plants. These pathogens caused large crop losses and probably since the beginning of agriculture have contributed to human hunger and malnutrition. The control of plant diseases is thus of fundamental importance and is a major objective of plant breeding and pathology programme and agriculture chemical industry. Plants resists pathogens attack both with preformed defenses such as antimicrobial secondary compounds and by inducing defense responses (Hammond and Jones, 2000, Heath, 2000). Inducible defenses can be activated upon recognition of general elicitor such as bacterial flagellin and even host cell fragments released by pathogens damage (Gomez and Boller, 2000, Hammond and Jones, 2000). However, plants also involved sophisticated recognition systems to detect proteins produced during infection by specific races of pathogens (Martin et al., 2003).

Introduction

Seed, the basic input of crop production technology, is exposed to various stress factors right from its formation to the completion of its germination. Even after germination, the stressed seeds may fail to emerge into a healthy plant and thus, the subsequent seed formation is also affected both quantitatively and qualitatively.

The stress factors may be abiotic, biotic or mesobiotic. Environmental factors such as climatic parameters, nutritional deficiencies, soil factors and conditions of storage are the examples of abiotic stress factors. Insects, fungi, bacteria, nematodes and other plant parasites constitute biotic stress factors whereas viruses, viroids and virusoids and similar agencies are the examples of mesobiotics factors that bring about stress over the seed. Apart from these conspicuous causes of stress, there are certain other factors also, which may affect the influence of stress over the total performance of the seed. For example, the crop improvement efforts bring about changes in seeds quality that can have considerable effects on the vulnerability of the seed to invasion by various biotic factors.

Introduction

The respiratory electron transport pathway of plant mitochondria comprises the cytochrome (Cyt) pathway and alternative pathway (McDonald et al., 2002). Both the cyt and the alternative respiratory pathways start at protein complex I when NADH is being oxidized. One H+ (proton) is transported by the complex I to inner membrane space, whereas two electrons are transported within the inner membrane by the ubiquinone, which at its reduced state (Qr) transfers these electrons either to complex III or to the Alternative oxidase (AOX). Ubiquinone is the point in which reactions can proceed in different ways, and it is called the branch point. Cyt respiratory pathway is present in all living organisms. It proceeds while complex III pulls out a proton from the mitochondrial matrix to the inter membrane space. The electrons are received by cytochrome c which spreads up to the outer side of the inner membrane towards protein complex IV, which then pulls out another proton similar to complexes I and III, and transports the electrons back to inner domain of the mitochondria. As a result, oxygen is consumed with a proton and the two electrons to produce water (Fig 1).

Introduction

Phenolic compounds have been shown to be of importance in regulation of plant growth, development and metabolism, therefore now they are not considered as passive by products of any catabolic or anabolic processes. Salicylic acid is one of them and it is a naturally occurring phenolic which has received much attention due to its association with economically important plant responses to disease and other stresses (Raskin, 1992; Borsani et al., 2001; Clarke et al., 2004). Centuries before medical scientists had identified numerous therapeutic effects of salicylates. Leaves and barks of willow tree were used by women as a pain reliever during child birth in 4th century B.C. It also cured aches and fevers. Due to a number of curative properties of willow bark, in 1828 Jahann Buchner, a scientist from Munich had isolated a small amount of silicin - a salicylic alcohol glucoside, the major salicylate in willow bark. In 1838, Rafaela Piria had given the name salicylic acid (SA), from the Latin salix, a willow tree. Further during 19th century SA and other salicylates, mainly methyl esters and glucosides easily convert to SA, isolated from a number of plants. Salicylic acid has an aromatic ring which bears a hydroxyl group or its functional derivative (Fig. 1).

Introduction

The term ‘lectin’ was coined by William C. Boyd in 1954 for their property of selectivity (Latin ‘legere’, to pick up or choose). In 1888 H. Stillmark of Russia gave the first description of what we now know as lectin. While investigating the toxic effects on blood of extracts of the castor bean (Ricinus communis), Stillmark observed that the red blood cells were being agglutinated by a protein and gave it the name ‘ricin’. Shortly afterward ‘arbin’ was extracted from Arbus precatorius. Because they were first isolated from plants, lectins came to be known as phytohaemaglutinin. Now it has become clear that lectins are present not only in plants but also in some bacteria, vertebrates and invertebrates. However, lectins are most widely distributed in plants, reported in almost 1000 plant species.

Plant lectins are a very heterogeneous group of proteins; as far as their occurrence within the plant kingdom and distribution over tissues are concerned. They show high degree of heterogeneity with respect to biochemical and physiological roles, because of their widely different carbohydrate binding specificities (Etzler 1986; Rüdiger 1988; Goldstein and Hayes, 1978). Besides the fact that they all exhibit carbohydrate binding activity, most of the plant lectins behave as typical storage proteins (Peumans and Van Damme, 1995 b).

Introduction

There are a number of chemicals in the environment, some natural other man-made, some toxic other non-toxic. These are toxic chemicals, whether natural or man-made, which has created problems for the environment and biota on the earth. Of these toxic chemicals, heavy metals are extremely hazardous. Metals are present naturally in the earth’s crust at various levels. However, increasingly widespread heavy metal pollution resulting from anthropogenic activities has caused serious environmental problems and is posing threat to both wild life and human population (Nriagu and Pacyna, 1988). Natural sources include weathering of mineral and metal ions from rocks, displacement of certain contaminants from groundwater or subsurface layers of soil, atmospheric deposition from volcanic activity, and transport of dust. The anthropogenic sources include deposition of industrial effluents, application of sewage sludge, deposition of air-borne industrial wastes, military operations, mining, landfill operations, use of agricultural chemicals, gas exhausts and energy and fuel production (McIntyre, 2003).

Introduction

The phytohormone abascisic acid (ABA) was discovered in connection to studies related to shedding of fruits and leaves, also called abscission, and the dormancy of buds. It was first identified and characterized by Frederick Addicott and his associates in 1963 while studying the compounds responsible for the abscission of cotton fruits. Inhibition of growth and maintenance of the dormancy of buds are the most important visible effects of ABA. The concentration of ABA does not remain constant as its concentration decreases in the buds significantly after sprouting and rises during seed and fruit production. Its concentration in dormant seeds is very high and considered as an efficient inhibitor of germination. The role ABA plays during the abscission of fruits and leaves is not clearly understood as its effect is very clear in case of fruit abscission where as it is not very clear on the abscission of leaves. However, the regulatory effect of ABA on the water balance is established in plants. It also induces stomatal closure to inhibit further loss of water. Being a growth inhibitor, ABA also reverses the effect of growth-stimulating hormones like auxin, gibberellins and cytokinin in different tissues of a plant. One of the main goals of phytohormonal ecology is to study the interactions between biotic and abiotic stress at hierarchical levels of biological organization.

Introduction

The study of abiotic stresses in plants has advanced significantly in recent years. However, the majority of experiments testing the response of plants to changes in environmental conditions have focused on a single stress treatment applied to plants under controlled conditions. In contrast, in the field, a number of different stresses can occur simultaneously. These may include conditions such as high irradiance, low water availability, extreme temperature, or high salinity and may alter plant metabolism in a novel manner that may be different from that caused by each of the different stresses applied individually. The response of plants to abiotic stresses in the field may therefore be very different from that tested in the laboratory (Cushman and Bohnert, 2000).

Introduction

It is an established fact that water in terms of direct deficit (drought) as well as water surfeits (flooding and water logging) and poor irrigation water quality (salinity)- are major constraints on the use of solar energy for food, feed and fiber production in almost all the agricultural regions of the world. The various biophysical, physiological, genetic, agronomic and ecological aspects of plant water relations have been thoroughly reviewed in recent years with the objective aimed at water availability as a constraint on crop production. This review will attempt a limited synthesis of these aspects, drawing mainly from research on drought resistance in grain crops, rice in particular, and emphasizing the progress- theoretical and practical- that could result from collaboration between physiologists, geneticists and plant breeders. A central theme will be research and development aimed at fitting crop plants to fluctuating drought prone environments. It is noteworthy that shortage of water restricts crop productivity all over the world-not just in those areas classified as arid or semiarid, but in any area in which the evaporative demand exceeds rainfall during the growing season. As such, the interaction between genotype and environment in situations has an important bearing affecting the physiology and also biochemistry at cellular level vis-à-vis the crop phenology. Cultivars with better ability to access soil water and improved water use efficiency could increase yields in an economic and environmentally sustainable way.

Introduction

Chickpea, the world’s third most important food legume, is currently grown on about 10 m ha worldwide, with 95% cultivation in the developing countries. India is the largest producer of chickpea in the world. Chickpea is grown under rainfed conditions in winter in India subjecting it to abiotic stresses. Consequently it experiences water deficit stress at one or the other growth stage(s) which affects the crop productivity.  Among the abiotic stresses to which chickpea is subjected to drought stands to be the number one problem in major chickpea growing regions because the crop is grown on residual moisture and the crop is eventually exposed to terminal drought (Johansen et al., 1994). A distinctive variation exists between the plant in sensitivity to water stress. Chickpea is considered relatively more tolerant, possibly because of its deeper root system is and its smaller leaves and canopy. Several adaptive mechanisms are evoked by plants in response to water stress (Chaves et al., 2003). These traits enable chickpea to ensure its survival in different environmental conditions.

Introduction

Salinity is a significant environmental stress for crop plants it account for about 70% of the losses in the crop yield. It adversely affects seed germination, seedling growth and different metabolic activities in plants (Begum et al. 1997). It reduces DNA, RNA and protein synthesis and differentially influences the activities of the hydrolytic enzymes (Kumar et al. 1996).

Plants are classified as glycophytes or halophytes according to their capacity to grow on high salt medium. Most crop plants are glycophytes and cannot tolerate salt stress. High salt concentration decreases the osmotic potential of soil solution creating a water stress in plants. Secondly they cause severe ion toxicity since Na+ is not readily sequestered into vacuoles as in halophytes.

The widespread nature of saline soils compounded by the geographical distribution of man’s population and agricultural practices are largely succeeded in increasing salinization in arid and semi-arid lands. Most of the crops are sensitive to even low concentration of NaCl.

Process of life of an organism is defined, driven and depicted by its genetic constitution, or the genome. A genome is a collection of genetic material present in the cell as nuclear or organelle DNA. To be precise, it is the sum of all single copy genetic materials present in the cellular subcompartments. Thus a diploid organism having two copies of each chromosome contains genetic material constituting two copies of the genome, while a gamete of the same organism contains single copy of the same. Organelle genome is shared by chloroplast and mitochondria. In these two organelle genetic material is present in single copy per organelle, although many copies of organelle ensures that a cell harbours many copies of mitochondrial or plastid genome. Unraveling the structure and function of the genome is, therefore, the central objective of biological science. Technologies that would help to understand the basis of genetic, biochemical and physiological processes are pivotal to execute the knowledge for the betterment of mankind and environment.

The information that drives the process of life is encoded in the genome of the organism. Structurally defined, a genome is an organization of genetic information consisting of nucleic acids (deoxyribonucleic acid or ribonucleic acid). Arrangement of nitrogenous bases in the nucleic acid codes the information for execution of cellular processes. Four types of bases (Adenine, Guanine, Cytosine and Thymine) are present in deoxyribonucleic acid (DNA) while in RNA Uracil replaces thymine group of any three bases on transcribed RNA represent a codon. With four types of bases, sixty four types of codons can be formed. Genetic information encrypted in these codons is released in the form of arrangement of polypeptides consisting proteins via mRNA intermediate. This universal process of flow of genetic information from DNA to RNA to protein is known as the central dogma of life. The whole set of information coded in 64 codons, out of which 61 codes for one or more amino acids (building block of polypeptides/proteins) and three indicating where to stop is called the book of life or genetic code.

One of the primary targets of genome analysis is to manipulate it at the level of genes, the units of inheritance. Genes, as explained earlier have distinct positions and sequence configurations in the genome which are expressed in the form of RNA or proteins controlling the functionality and identity of an organism. To understand the function of a gene several methodologies may be adopted. As genes have conserved sequences like promoters preceding the reading frame, initiation sequences, exon-intron junctions and end sequences, these features can be used to screen genome sequence to identify the regions containing genes. An open reading frame (ORF) is the sequence of a gene for which functions have been assigned, i.e., the sequence codes for a protein or RNA. On the other hand, an unassigned reading frame (URF) is a sequence which has structural features of a gene, but no function has yet been assigned to it.

The primary target of genomics is identification and characterization of genes and gene products. Starting point of genomics may be a whole genome sequence, from which gene and protein structures can be predicted by computational and bioinformatics approaches (in silico genomics), or genes can be identified step by step starting from identification of a phenotype by induction and detection of mutation, construction of a genetic map demarkating the position of the character, physical location, identification of the gene, cloning and characterization of the gene or genome sequence by sequencing followed by expression analysis to correlate the phenotypic expression (in vivo genomics). Alternatively, genes can be identified by developing knockout mutants by random or site directed disruption of a reading frame and then determining the protein product as well as phenotypic expression.

While structural genomics aims to describe the protein structures coded by the genes present in the genome, functional genomics deciphers meaning of the coded information at transcriptome, proteome and interactome level. In the previous chapter we have seen how a gene can be identified by creation of mutants, genetic and physical mapping, and by sequencing the gene. Another source of possible gene structures come from genome sequence information, which by using computational algorithms identifies a number of ORFs that have the structural configuration of a gene. A third option of identifying a gene is identification of differences between wild type and mutant at RNA level, by analyzing the transcriptome. If we are able to identify differences in RNA expression pattern between these two, the information can be used to search back the gene sequences responsible for the differences. From proteome analysis inferences on expression of proteins and their interaction in the functional network of the cell with other proteins, DNA, RNA and cellular 

Molecular markers or DNA markers are considered to be one of the most successfully applied component of molecular biology techniques that have relevance in almost every sphere of biology, from paleobotany to transgenic technology. In true sense, a marker is a characteristic of an individual that differentiates the individual from others. Morphological descriptions like cotyledon colour of Pea, eye colour of Drosophila, shape and size of fruits in summer squash etc. are examples of typical morphological markers. However, a single morphological marker is not sufficient for describing the uniqueness of an individual, for many pea plants will have green cotyledon or many Drosophila may have red eye. To define the uniqueness of an individual, we have to find a number of marker traits characteristic of that individual. Unfortunately, morphological variations are not sufficient to differentiate between a large number of individuals, or between groups or sub groups within a species, simply because the level of polymorphism is low. Besides, morphological characters or phenotypic expressions are affected by environmental changes, so stability of expression is low and sometimes uncertain.

Preternatural development of recombinant DNA technology has established genetic engineering in animals the most important field in application of biology for human benefit, from production of genetically modified animals to providing crucial technologies to medical science sector. On the basis of the nature of the target tissues, genetic engineering may target single cell line, particular tissue sectors or the organism as a whole. The purpose of transformation may be basic research involving elucidation of gene function, study effect of directed mutations, examination of physiological and developmental processes in animals or may be target oriented, such as production of proteins or metabolites in large quantities in a cell line, incorporating rDNA in the germline cells, gene therapy, use of rDNA in disease diagnostics, or production of transgenic animals for specific purposes.

Food is the basic requirement for maintaining the life process. Plants supply the bulk of foods required for human and animal. With limited cultivable area and ever increasing pressure of human population, the demand for food is constantly rising which can not be alone met by conventional plant breeding technologies. Novel techniques like plant genetic engineering are gaining momentum for production of superior plants or yield enhancement of a species.  It has been observed that the most commercially successful application of recombinant DNA technology is in genetic engineering of plants, which led development of multinational seed companies deriving monetary benefit from genetically modified crop and food products. From production of herbicide resistant or insect pest tolerant plants to alter the inherent quality composition of human food, plant genetic engineering has established firmly the commercial viability of recombinant DNA technology.

Words like rDNA (recombinant DNA) technology, cloning, genetically modified organism (GMO), living modified organism (LMO) and transgenics are of today’s common knowledge. However rather than scientific interest, debates on biosafety issues have made these terms more agnized among general people. Global, sectorial and individual protests against transgenic plants and animals are enunciated allover the world raising issues and concerns over risks and health hazards of using these organisms. Despite these protests and concerns, commercial use of transgenic organism as food, feed or other purposes are increasing at an exponential rate. Although there is not much scientific evidence where transgenics have caused havocs on ecological balance or human health, the biosafety issues need to be solved to provide a safer environment rather than be sorry and lament in the future for today’s mistakes. One of the major problems in supporting use of GMOs lies in the incapability of biosafety science to draw reliable and widely acceptable conclusions for labeling a safe tag on these organisms and their derivatives.

Rabbit domestication dates back no farther than the previous millennium. It were the Phoenicians who are said to have discovered the wild rabbit Oryctolagus cuniculus of Southern Europe and North Africa when they reached the shores of Spain about 1000 B.C. In Roman times, the rabbit was still emblematic of Spain. The Roman spread the rabbit throughout the empire as a game animal. Like the Spaniards, the Romans also ate foetuses or new born rabbits, which they called laurices. It then becomes a practice that the rabbits were kept in leporarian, stone –walled pens or parks for hunting purposes. These leporaria ultimately paved the way for the development of game parks in the middle Ages. The monks ate laurices during lent because they were an aquatic dish. In France, only the lord of the manor could maintain a warren.

Brief History

Fondness of man for rabbits is well established by its appearance in the Aesop’s fables and Vishnu Sharma’s ‘Panchtantra, both of which date back to 2nd century B.C. However, domestic rabbits are descendents of wild species of Western Europe and North Western Africa where Oryctolagus still exists. Interestingly, it was the Romans who first raised rabbits in leporaria (enclosed warrens) as a game animal. Like Spaniards, Romans also ate fetuses of newborn young ones whom they called laurices. These leporaria ultimately paved the way for development of game parks in the Middle Ages. The monks ate laurices during Lent because they were an aquatic dish.

Breeds of Rabbit

There are many breeds of domestic rabbits in the world and all have different qualities. Out of the number of breeds and varieties about 38 breeds and 87 varieties are recognized and well established world wide.

For commercial purposes, the most important differences between rabbits are their size, colour breeding ability and suitability to the climate. Examples of several different breeds of rabbits are given below. Some of these might be used for improving local rabbit herds.

Introduction: Most young rabbits will be used for meat and skins; some will be kept for breeding. Whatever they are used for, the rabbit keeper will benefit if they are well cared for.

Handling of Rabbits: There will be times in any rabbitry when the animals will have to be picked up, e.g. when a doe is moved to a breeding hutch or when young rabbits are weaned.

When it is necessary to pick up a rabbit for any purpose, the aim should be to cause it no discomfort and to prevent it struggling. So it must be handled gently but firmly. There are three ways to hold a rabbit according to its size. 

A suitable site for housing is very important. It is better to select a site which has good drainage, adequate shade like under trees, and with sufficient surrounding space from strong winds. Basically the shelter must protect rabbits from extreme temperatures and predators like snakes, mongoose, dogs and other animals.

Rabbits can be raised inside the building also or outside in hutches with a protective roof. A hutch is a small building containing cages for housing a few rabbits (6 to 12) a back-yard scale. They are generally made of wood or stone one and chicken wire mesh. The floor may be made of a stronger ranger mesh or soil floor bedded with straw. Hutches can also be constructed with local building materials such as tree and woven split bamboo, etc.

Definitions

Pen Enclosure for housing rabbits that allows for freedom of movement by rabbits and allows for the provision of a variety of environmental enrichment strategies. Cage Fully enclosed container for housing rabbits which, because of its size, restricts freedom of movement by rabbits and limits the provision of environmental enrichment strategies. Cages are usually constructed from metal or plastic, with solid or mesh sides.

Rabbits are produced for meat, wool and research and as pets or for a hobby. Meat production is the most important commercial aspect of rabbitry. The domestic rabbit is primarily herbivorous and will consume most types of grains, oil seed cakes, brans, greens and hay. Diets provided, whether home grown or commercially prepared, consist almost entirely of ingredients from plant sources. Although, the producers / farmers mostly rely on home grown feeds, a good portion of the rabbit feed presently used is commercial pelleted feed. Since the rabbit can utilize a certain amount of forage, it has a place in food production by making use of some non-competitive feeds.

Sanitation in the Rabbitry is the best disease-prevention system. Daily cleaning of cages or hutches, containers and surrounding is the easiest way to ensure sanitary condition and hence control disease. The most common diseases found in rabbits are cocciodosis. Pasteurella type pneumonia and enteritis. There are generally caused by lack of sanitation in the rabbitry. With strict sanitation practices such as cleaning all cages and water containers everyday, removal of manure, soiled bedding. Contaminated feed and collecting roughage from uncontaminated areas can drastically reduces chances of any disease in the rabbitry.

Important by product from Rabbit are meat, wool, fur and skin. It can be made highly profitable if products are properly processed and marketed. Many rabbit products are wasted because people do have not enough knowledge about processing.
 
Slaughtering: Know when and how.

Skinning

Familiar with how to remove skin and carcass preparation. How the skin has to be processed and how the products which can be obtained from skin.

Manure collection and preservation.

Slaughtering : It depends on demand, type of animal where meat is consumed more, it can be achieved in 2 methods.

Food, furs, research, hobbies, pets – these are the major uses of rabbits around the world. It should be noted that rabbit production for meat and wool has become increasingly important in the last few years.

Angora wool rabbits are a commercial rabbit which is raised for its fine wool and meat as well, but primarily raised for wool production. Cooler climate is most conducive to raising this breed of rabbit. Angora rabbit does not differ from other breeds of rabbit except for its unusual length of valuable fur(wool). This modifies its raising compared to other rabbits.
 
The term ‘Angora’ qualifies those mammals which are covered with fur or wool composed of very soft hair of more than normal length – double or more than double the normal length.

Normal Physiology
Rectal Temperature    :    38.6 to 40.1ºC (AV: 39.5ºC)

Health care is an important way of making sure that rabbits stay productive. Every rabbit keeper should know how to recognize and, if possible, prevent and cure illnesses which can affect rabbits.

It is always better to prevent disease incidence than to let animals get ill and then try to treat them. Allowing rabbits to get sick is expensive for several reasons, sick animals stops growing and reproducing so money is lost with this decrease in production, some disease results in the death of rabbits, replacing the dead rabbits is expensive , treatment for the ill rabbits is usually expensive.

Introduction

In recent years aquaculture has become the fastest growing food production sector in the world with 10% annual growth rate in comparison with 3% for livestock and 1.6% for capture fisheries. FAO (2000) estimates that by 2030, over half of the fish consumed by the world’s people will be produced by aquaculture. It is not only the demand for animal protein but the high returns associated with aquafarming when compared with agriculture or animal  husbandry that has accelerated the growth of aquaculture. Thus, in the last two decades aquaculture with greater emphasis on shrimp farming made fast strides among Asian countries including India. The culture of carps in freshwater and shrimps in brackishwater are the two main culture practices followed in India. During nineties around 10% of 2.7m ha. brackishwater area has been put under farming along with a number of other supporting and ancillary units viz.; hatcheries, feed mills, processing and packaging industry etc.

Fish is the most important source of protein for the people of Northeastern India where almost 100% people are fish eaters. So fish culture is very popular in this region. There is a huge demand for fish here and the most popular aquaculture practice is pond culture. The state of Tripura particularly progressed well in fish production and became self sufficient in fish seed production. The state is blessed with 22,895 ha of water bodies where more than 50% (12,895 ha) of area is used for aquaculture purpose. Composite fish culture and integrated aquaculture are very common here. These fish ponds are very productive both in eco-physiological and faunistic point of view. Most of the farmers have a pond area of less than one hectare for fish culture and are unable to go for any supplementary feeding. Average fish productivity is estimated as 1800 kg/ha. Preliminary experiments conducted in the Institute showed that timely application of the fertilizer and/or restricted supplementary feeding improves total production.

Introduction

In present times aquaculture is being practiced using both conventional or non-conventional methods with considerable variations. Aquaculture can be termed as – extensive, semi-intensive and intensive based on operations and involvements. An increase in the intensity of aquaculture requires an increase in capital as well as operational costs.

Here we will examine the three main levels of aquaculture used in various habitats and later consider the conventional methods of aquaculture.

Different Levels of Aquaculture

Fish culture practices can be classified into three different kinds or levels on the basis of the intensity of aquaculture in terms of capital as well as operational costs. The chances of crop failure often increase with increasing intensity of aquaculture, which may involve: 

Fish production of the country has improved considerably in the post-independent India with the total production going up from 7.52 lakh tons in 1950-51 to 90.4 lakh tons in 2010-11, with an average growth rate of 4.35% per year after 1990. The real jump has come from inland aquaculture sector. Production from inland waters which used to be less than 30% of the total till sixtees, gradually rose at a fast pace and crossed the 50% mark by the end of 20th century. The present contribution of inland sector to the country’s total fish production of 52.09 lakh tons is 58% recording an average annual growth rate of 8.4% per year after 2011.

This increase in contribution from inland sector is because of the quantum jump in production from freshwater aquaculture, made possible mainly due to development of technologies of hypophysation of Indian Major carps and composite fish culture during late fiftees and sixties respectively. Development of these two technologies, along with their wide extension through Fish Farmer’s Development Agency, initiated by Govt. of India in latter part of 1970s, have in fact revolutionised freshwater aquaculture scenario of the country. It is presently contributing to over 70% of the total fish production  from inland resources of this country.