eBook Chapters

The demographic transition theory is one of the most important population theories which is the best documented by the data and statistics of recent demographic history. In its original form, the demographic transition theory was put forward by W. S. Thompson (1929) and Frank W. Notestein (1945). These scholars based their statements and arguments on the trends in fertility and mortality, being experienced in Europe, North America and Australia.

The theory postulates a particular pattern of demographic change from a high fertility and high mortality to a low fertility and low mortality when a society progresses from a largely rural agrarian and illiterate society to a dominantly urban, industrial, literate and modern society. The three very clearly stated hypotheses involved in the process are:

1. The decline in mortality comes before the decline in fertility.
2. The fertility eventually declines to match mortality and
3. Socio - economic transformation of society takes place simultaneously with its demographic transformation.

In the present – day world, as would true of any point in time, different countries of the world are at different stages of the demographic transition. In the opinion of Trewartha, this is largely due to the dual nature of man. According to him, biologically, man is same everywhere and is engaged in the process of reproduction but culturally man differs from one part of the world to another. It is the cultural diversity of man that gives rise to varying fertility patterns in different areas resulting in different stages of demographic transition.

The demographic transition theory is characterized by conspicuous transition stages. The transition from high birth and death rates to low rates can be divided into stages. In the words of E.G. Dolan, “Demographic transition refers to a population cycle that begins with a fall in the death rate continues with a phase of rapid population growth and concludes with a decline in birth rate”.

Abstract

Population of Rajasthan as per Census 2011 is 68,621,012 persons which is much higher than census 2001 that records 56,507,188. It includes 12 districts of Rajasthan. Western Rajasthan covers about 61% area of the total geographical area and 39.51% population of the total population of the Rajasthan. The growth rate of population is much higher than that of the Rajasthan State. In the census 1981 Western Rajasthan had registered a phenomenal increase of 35.48 per cent over 1971 population. Regional pattern of growth rate in western Rajasthan shows that extreme hot arid region district (Barmer) is on top having 32.55 per cent growth rate whereas Indira Gandhi Canal Region (Ganganagar) district has least population growth of 10.06 per cent only. In 1981, the average urban growth rate had been 54.52 per cent. In 2001, the rural density of population was 83 persons per sq. km.

Experiment - 1
 
Aim: Molecular analysis of putative transformed plants by Polymerase Chain Reaction

The expression of transgenes are not identified at that time but it can be achieved through DNA analysis of that plant. The presence of transgene are generally identified of PCR-based detection followed by gel electrophoresis and comparison with standard samples. The main achievement of PCR-based detection is that it is very sensitive. The Polymerase Chain Reaction (PCR) provides a rapid and sensitive method to amplify a specific gene sequence. 

Electrophoresis is a method used to separate charged particles from one another based on differences in their migration speed. In the course of electrophoresis, two electrodes (typically made of an inert metal, e.g. platinum) are immersed in two separate buffer chambers. Gel electrophoresis is a technique used to separate molecules based on physical characteristics such as size, shape, or isoelectric point. A gel is composed of agarose or polyacrylamide. Agarose is used for separating DNA fragments in size range of 100bp to 20kb. Polyacrylamide is preferred for smaller DNA fragments. Separation is achieved by moving the negatively charged nucleic acid molecules through agarose matrix with an electric field. Rate of migration of DNA molecules is inversely proportional to their molecular weight. Smaller molecules move faster than larger ones. But conformation of the DNA molecule is also an important factor. Conformations of a DNA plasmid that has not been cut with a restriction enzyme will move with different speeds such as: supercoiled plasmid DNA will move fastest followed by linearised DNA, while open circular DNA will move at the slowest pace. To visualise DNA, gels are stained with ethidium bromide which intercalates in DNA and fluorescse under UV.

Experiment- 1

Aim: Direct DNA delivery to Plant by Particle Bombardment
 
In direct gene transfer method, the foreign gene of interest is delivered into the host plant cell without the help of vector. Klein and Coworkers (1987) evolved a procedure through which the delivery of DNA into cells of intact plant organs or cultured cells is done by a process called Projectile Bombardment. The microprojection (Small and high density particles) are accelerated to high velocity by particle gun apperatus. These particles with very high kinetic energy penetrate the cells and membranes and transmit foreign desired DNA inside of the bombardment cells.

Experiment - 1 
Aim: Mobilization of recombinant Ti plasmid (with gene of interest) from  
(E. coli) to an Agrobacterium tumefaciens strain. 

Principle: Due to ease of cloning and harvesting plasmids, E. coli is most popular for maintenance of plant transformation vectors. Consequently, the plant transformation vector with cloned gene of interest is mobilized to recipient Agrobacterium strain harbouring vir plasmid. Plasmid are closed, circular DNA molecules that are able for autonomous replication with a host cell. 

Experiment - 1

Aim: Isolation of plant genomic DNA through modified CTAB method

Principle: Genomic DNA is extracted from plant material requires cell lysis, inactivation of cellular nucleases and separation of the desired genomic DNA from cellular debris. Ideal lysis method is rigorous enough to disrupt the complex starting material (plant tissue), yet gentle enough to preserve the target nucleic acid. The cetyltrimethylammonium bromide (CTAB) procedure is sufficient for the extraction and purification of DNA from plants and plant derived food stuff.  This is particularly suitable for the elimination of polysaccharides and polyphenolic compounds otherwise affecting the DNA purity and hence quality.

Koch‘s Postulates (Pathogenicity test)

Robert Koch developed the following postulates in 1883 on the basis of which an organism could be attributed to be the cause of a specific disease.

i)Recognition: The suspected organism must be found in every case of disease (Presence of organism in the diseased tissues).

ii)Isolation: The organism must be isolated in pure culture from every case of disease (Isolation in pure form).

iii)Inoculation: The isolated pure culture when introduced into the same species or variety of susceptible host must be capable of reproducing the original disease with its typical symptoms (Pathogenicity).

iv)Re-isolation: The organism must be re-isolated from the artificially infected host and its characteristics must be exactly like those observed in step 2 (This step was added by E.F. Smith).

If all the postulates are proved true, then the isolated pathogen is identified as the actual causal organism responsible for the disease.

Object: Demonstration of leaf anatomy or structure of C₃ and C₄ Plants (demonstration by already prepared slides).

Material required: Already prepared slides of corn and wheat leaves and microscope.

Dendrobium is a huge genus of orchids. It was established by Olof Swartz in 1799. The name is from the Greek word “Dendron” means “tree” and “bios” means “life”; it means “one who lives on trees”, or essentially, “epiphyte”. The truly spectacular genus Dendrobium contains the largest diversity of horticulturally interesting specimens. More than 1,000 natural species make dendrobium the second-largest orchid genus. Dendrobiums are among the most commonly encountered orchids in the retail trade. Flowers are very long-lasting both on the plant and once cut, looking fresh for up to three weeks or more. Faded flowers on the bottom of the stem can be removed to encourage upper buds to open. Dendrobiums are sturdy orchids that can add a focal point to any room.

Dendrobium is a huge genus of orchids. It was established by Olof Swartz in 1799. The name is from the Greek word “Dendron” means “tree” and “bios” means “life”; it means “one who lives on trees”, or essentially, “epiphyte”. The truly spectacular genus Dendrobium contains the largest diversity of horticulturally interesting specimens. More than 1,000 natural species make dendrobium the second-largest orchid genus. Dendrobiums are among the most commonly encountered orchids in the retail trade. Flowers are very long-lasting both on the plant and once cut, looking fresh for up to three weeks or more. Faded flowers on the bottom of the stem can be removed to encourage upper buds to open. Dendrobiums are sturdy orchids that can add a focal point to any room.

ORIGIN AND DISTRIBUTION

Dendrobiums are originally from Southeast Asia. The geographic distribution is from India through China, Japan, Malaysia, Philippines and the islands of the South Pacific with the largest diversity in New Guinea. Dendrobium species are either epiphytic or occasionally lithophytic. They have adapted to a wide variety of habitats from the high altitudes in the Himalayan mountains to lowland tropical forests and even to the dry climate of the Australian desert.

Dengue is a mosquito-borne viral disease and considered to be a major health problem globally. It is also called break-bone fever, dandy fever, denguero bouquet fever, giraffe fever, Polka fever and 5 days or 7 days fever. There are two important manifestations, namely dengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS) which are responsible for heavy morbidity and mortality every year causing serious concern to health. It is an important disease caused by an arbovirus worldwide especially in the tropical and subtropical regions. The severity of the disease can be judged from simple statistics that over 40 per cent (2.5 billion) of the world's population in 100 countries continue to live under threat of contracting dengue infection. Annually, dengue virus infections are responsible for up to 100 million cases of dengue fever and more than 500,000 cases of haemorrhagic fever. Besides, every year the disease forces nearly 500,000 people to hospitalization of which 90% are children and causing 24,000 deaths. Mostly these deaths are due to lack of early diagnosis of dengue virus infection. In DHF case fatality rate generally exceeds 20 per cent in a non-endemic population and it can be reduced to less than 1 per cent with the aid of modern supportive therapy based on early diagnosis of the type of viral infection.

Dengue fever (DF) is an acute febrile viral disease characterized by headaches, bone or joint and muscular pains, rash and leucopenia as symptoms. Dengue haemorrhagic fever (DHF) is characterized by four major clinical manifestations: high fever, haemorrhagic phenomena, 73 often with hepatomegaly and in severe cases, signs of circulatory failure. Such patients may develop hypovolaemic shock resulting from plasma leakage. This is called dengue shock syndrome (DSS) and can be fatal.

The year 2001 witnessed unprecedented global dengue epidemic activity in the American hemisphere, the Pacific Islands and continental Asia. During 2002, more than 30 Latin American countries reported over 1 million DF cases with large number of DHF cases. This has been followed by extensive epidemics of DHF in several parts of India during 2003.

Dengue fever (DF) is caused by ingestion of viraemic blood containing dengue virus by mosquitoes of Aedes sp. followed by passage to a second human host. An extrinsic incubation period is required before the virus appears in the saliva of the transmitting female Aedes mosquitoes. After the bite, there is an incubation period of 3 to 14 days (average 4 to 7 days) followed by the onset of fever and nonspecific signs and symptoms (frontal headache, retro-orbital pain, body aches, nausea and vomiting, joint pains, weakness and rash). The febrile phase is self limiting and may last for 2 to 10 days followed by remission of fever in most cases. Laboratory abnormalities include neutropenia followed by a lymphocytosis and thrombocytopenia.

Introduction

The various reactions of nitrogen (N₂) cycle, transform one form of the element to another. Mineralization liberates nitrogen in inorganic form, immobilization converts its back to an unavailable state, while nitrification changes the nitrogen from a reduced to oxidized state. Certain transformations of nitrogen lead to a net loss of element from the soil through volatilization. For the purpose of crop production, nitrogen volatilization has a deleterious influence because it depletes part of soils reserve of an essential nutrient. The sequence of steps that results in gaseous loss is called denitrification. So denitrification refers to the reduction of nitrates and nitrites to gaseous nitrogen products, principally di-nitrogen and nitrous oxide, coupled to energy production through oxidative phosphorylation.

10.1 Introduction

Biomass fuels are a potential source of renewable energy. One of the major barriers to their widespread use is that biomass has a lower energy content than traditional fossils fuels, which means that more fuel is required to get the same amount of energy. When combined — low energy content with low density -the volume of biomass handled increases enormously. Compaction or densification is one way to increase the energy density and overcome handling difficulties.

Densification means compaction of loose material or to increase density of loose biomass so that its volumetric efficiency can be increased. Densification essentially involves two parts; the compaction under pressure of loose material to reduce its volume and to agglomerate the material so that the product remains in the compressed state. The resulting solid may be a briquette, a pellet and a cube. It will be briquettes if roughly, it has a diameter greater than 30 mm. Smaller sizes are normally termed pellets though the distinction is arbitrary. The process of producing pellets is also different from the typical briquetting processes. The densified product can be developed in the cubical shapes as well.

If the material is compacted with low to moderate pressure (0.2-5 MPa), then the space between particles is reduced. Further, increasing the pressure will, at a certain stage particular to each material, collapse the cell walls of the cellulose constituent, thus approaching the physical, or dry mass and more, density of the material. The pressure required to achieve such high densities are typically 100 MPa plus. This process of compaction is entirely depending on to the pressure exerted on the material and its physical characteristics including its moisture content.

3.1 Determination of Bulk Density of Soil

3.1.1 Determination of Bulk Density of an undisturbed Soil

Bulk density of soil is expressed as the ratio of the mass (weight) of soil particle to their total volume including the pore space between the soil particles. Alternately, it is the weight of unit volume of dry soil. It is usually expressed in the unit of gram per cubic centimeter (g/cc) or mega gram per cubic meter (Mg/m³). In fine textured soil bulk density varies from 1.00 to 1.60 g/cc, whereas in coarse textured soil from 1.20 to 1.80 g/cc.

3.1. Determination of Bulk Density of Soil

3.1.1. Determination of Bulk Density of an Undisturbed Soil

Bulk density of soil is expressed as the ratio of the mass (weight) of soil particle to their total volume including the pore space between the soil particles. Alternately, it is the weight of unit volume of dry soil. It is usually expressed in the unit of gram per cubic centimeter (g/cc) or mega gram per cubic meter (Mg/m³). In fine textured soil bulk density varies from 1.00 to 1.60 g/cc, whereas in coarse textured soil from 1.20 to 1.80 g/cc.

Overview of Inland Fisheries Status

In Thailand, inland capture fisheries are carried out mainly in rivers, lakes, swamps and reservoirs. These fisheries are an important source of animal protein for the rural people. Since 2005, production from inland capture fisheries has increased by almost 13 percent. Gillnets, longlines, hook-and-line, scoop nets, cast nets, and lift nets are some of the fishing gears being used. Among these fishing gears, gillnets are the most popular and efficient, particularly in swamps and reservoirs. Thai silver barb, snakehead, walking catfish, local carps, and Nile tilapia are caught. Nile tilapia, hybrid catfish, silver barb, snakeskin gourami, giant river prawn, striped catfish and striped snake-head contributed 95 percent in quantity and 92 percent in value in fresh water aquaculture.

Sustainable development and efficient management of water is an increasingly complex challenge in India. Increasing population, growing urbanization and rapid industrialization combined with the need for raising agricultural production generates competing claims for water. Ground water has an important role in meeting the water requirements of agriculture, industrial and domestic sectors in India. About 85 percent of India’s rural domestic water requirements, 50 percent of its urban water requirements and more than 50 percent of its irrigation requirements are being met from ground water resources. Ground water is annually replenishable resource but its availability is non-uniform in space and time. Technically, the dynamic ground water refers to the quantity of ground water available in the zone of water level fluctuation, which is replenished annually. Hence, the sustainable development of ground water resources warrants precise quantitative assessment based on reasonably valid scientific principles. National Water Policy, 2012 has laid emphasis on periodic assessment of ground water resources on scientific basis. The trends in water availability due to various factors including climate change must also be assessed and accounted for during water resources planning. To meet the increasing demands of water, it advocates direct use of rainfall, desalination and avoidance of inadvertent evapo-transpiration for augmenting utilizable water resources. The National Water Policy, 2012 also states that safe water for drinking and sanitation should be considered as pre-emptive needs followed by high priority allocation for other domestic needs (including needs of animals), achieving food security, supporting sustenance agriculture and minimum eco-system needs. Available water, after meeting the above needs should be allocated in a manner to promote its conservation and efficient use.

1. Introduction

The Indian economy is heavily dependent on agriculture (employing 53 % population). Around 84 % of the holdings are less than 2 ha while approximately 67% of the farms have less than 1 ha of operational farmland (Government of India, 2013; Pandey and Suganthi, 2015). A large fraction of the farming population is mostly reliant on monsoon rains for irrigation. The condition of the farmers is found to be deteriorating year after year with the revelation that 27% of farmers did not consider farming as a profitable enterprise and 40% were ready to migrate to other avenues for employment (NSSO, 2005; Pandey and Suganthi, 2015). 

Individuals suffering from the more pronounced types of mental disorder are sometimes said to be insane, but the term insanity is a legal one, not a medical term. An insane person is one who cannot distinguish right from wrong or assume responsibilities for his own actions. In the case of a psychotic patient the whole personality is involved. And he is completely out of touch with real world around. Not so the neurotic patient. Only a small part of his personality is involved. Psychotic patients often require hospitalization; neurotic patients rarely do, unless they have some additional physical problem.

Another distinction between these two major groups is that his friends usually bring the psychotic patient to the doctor, while the neurotic comes of his own accord. He knows he is sick, and he usually wants help. Most often he is suffering from a nervous depression.

Dermatophilus congolensis was first described from clinical case of exudative dermatitis in cattle in Congo by Van Saceghem (Van Saceghem, 1915). It is primarily known as an animal pathogen causing acute, sub acute or chronic skin disease. The first cases of human infection with D. congolensis were reported in 1961 in four people who developed skin infection after handling an infected deer in a wildlife reserve in USA (Dean et al., 1961).

Properties of genus

1.   Morphology

Dermatophilus is a gram positive, non-acid fast, unusual bacterium having branched filaments. It follows a life cycle with different morphological features. It can be found in smears prepared from clinical samples in any form of its life cycle. Young filaments are 0.5 to 1.5 μm in diameter.  They enlarge within epidermis as they produce layers of transverse and longitudinal septations and reach 5 to 8 μm in diameter, surrounded by a mucoid capsule. The septations result in the formation of a sporangia (a kind of fungal fruiting body, sac like structure with spores) containing up to eight cocci cells. In the presence of liquid, the cocci are released and converted into flagellated motile zoospores, the infective form of the organism. It can infect the new site in the same animal or new host. These zoospores become visible in smear as parallel lines forming a ‘railway-track’ or ‘trum-track’ appearance (Fig.1). Under favourable conditions, the zoospores form germ tubes that develop into branching filaments. These filaments are the invasive form of the organism and the cycle is repeated.

It is a fungal infection of skin and the term favus is used for the disease in poultry. The disease is world wide in distribution.

Etiology

Microsporum gallinae, a fungus. The fungus is zoonotic. Lesions of ring worm are produced in humans in contact with infected birds.

Etiology

Canine dermatophytosis (canine ring worm) is a relatively common dermatological condition caused by Microsporum canis, Trichophyton mentagrophytes and Microsporum gypseum. These fungi are keratinophilic in nature. It can occur mostly in the face and forelegs.

In the classification given below only those groups have been given emphasis which contain plant pathogenic fungi or which are important from taxonomic point of view. The description includes only critical features.

Vero (monkey, African green, kidney) 
Morphology: Fibroblast
Species:, African green monkey 
Tissue: Kidney

Properties: Virology, virus titration, virus replication, plaque assays, bacterial cytotoxicity

Introduction

Flowering plants (Angiosperms) are identified by their morphological characteristics like flower, fruit and seeds that help their taxonomic characterization into different species, genera, families and orders. The floral characters which are used for taxonomic characterization of plants include the type of inflorescences, perianth structure, floral symmetry, arrangement of floral leaves, type of androecium, stamens, gynoecium, carpel, ovule, etc. The type of fruit and seed also play important roles in taxonomic classification. In this chapter we will briefly discuss about various morphological features of flowering plants (in botanical terms) that are useful in taxonomy.

Nomenclature of Plant

Nomenclature of plant is the formal and scientific naming of plants. It is related to but distinct from taxonomy for grouping and classifying plants and provide botanical name.

The scientific/botanical nomenclature started with Species Plantarum by Carolus Linnaeus in 1753. Botanical nomenclature is governed by the International Code of Nomenclature for algae, fungi, and plants (ICN), which replaces the International Code of Botanical Nomenclature (ICBN).

ICBN and ICN

International Code of Botanical Nomenclature, (ICBN) was adopted by the VIIth International Botanical Congress held in Stockholm, July1950. While the International Code of Nomenclature for algae, fungi, and plants (ICN) was adopted by the XVIIIth International Botanical Congress held in Melbourne, Australia in July 2011.

This chapter contains the description of the Indigenous Traditional Knowledge practices as subject wise manner viz, Traditional varieties, Crop management, Crop protection measures, Post harvest methods, Storage structures, Farm tools, Medicinal plants, Ethnoveterinary practices, Fisheries and others related to agriculture.

Moniliformis means ‘like a string of beads’ signifying the arrangement of flowers on the spike. The tree is native of tropical Australia. It is valued for afforestation and beautification. It grows in warm climate under both dry and moist atmosphere. It is a medium-sized, thornless, quick growing, evergreen tree of 13 to 15 m height.

Leaves: True leaves are present only in early seedling stage. The apparent leaves are the modified midrib called phyllode, leathery, sickle-shaped, tapered at each end, up to 18 cm long and 6 cm broad; nerves parallel.

Annuals are the group of plants that complete their life cycle in one season or in one year during which they grow, flower and produce seed; and after this they wither out. A true annual (like zinnia) is a plant that will grow from seeds, flower, produce seeds and die in one season. Zinnias provide a succession of flowers for summer colour in any sunny location with good soil drainage.

5.1. INTRODUCTION

Mean and standard deviation summarizes the salient features of a data set. But they do not describe adequately the full characteristics of the data. For an adequate description of the characteristics of a data set, a convenient method is to plot a frequency distribution curve. Such curve is constructed by first drawing a frequency polygon, which may then be smoothened to a frequency curve, indicating the distribution. The frequency curve or distribution of specific biological variables generally has a specific form and plays a very important role in statistical theory and practice. It is customary to describe a curve in terms of its symmetry or assymmetry and its flatness or peakedness.

The following types of distribution are commonly seen in the biological world:

3.1. INTRODUCTION

In this chapter, we will study the measures of central tendency which is a numerical method to explain the data in brief. We can see examples of summarizing a large set of data in day to day life like average marks obtained by students of a class in a test, average rainfall in an area, average production in a factory, average income of persons living in a locality or working in a firm etc.

One of the most important objectives of statistical analysis is to get one single value that describes the characteristic of the entire mass of data. Such a value is called the central value or an ‘average’ or the expected value of the variable. This single value is the point of location around which individual values cluster and, therefore, called the measure of location. Since this single value has a tendency to be somewhere at the center and within the range of all values it is also known as the measure of central tendency. The purpose of computing an average value for a set of observations is to obtain a single value which is representative of all the items.

The branch of statistics which describes the data is called descriptive statistics. After collection, the data are presented in form of tables, diagrams or graphs. This facilitates the further analysis of data. The most basic form of data analysis is descriptive analysis of data collected and presented for the study. The descriptive statistics summarises the data and helps to find the representative value of the entire data set and the variation of the other values in the data set around the representative value. The descriptive statistics includes the measures of central tendency or averages, measures of dispersion or scatteredness, measures of skewness and the measures of kurtosis. Before going to discuss the R codes for various measures of descriptive analysis, we would first discuss in brief about these measure. This will help in better understanding of the R codes.

Measures of central tendency or averages: They are the representative values of the data series. They give an idea about the concentration of the values in the central part of the distribution of the data. There are five types of averages. They are 1. Arithmetic Mean (A.M.) 2. Geometric mean (G.M.) 3. Harmonic Mean (H.M.) 4. Median 5. Mode.

Introduction

Importance of basic statistics in everyday life cannot be stressed enough. Inclusion of basic statistics in high school curriculum is uncommon but proves highly beneficial to supplement certain careers in future. This field may be the most widely used of all and most people don’t even know they are using it. Many of today’s brightest business minds use this study to create charts and graph that allow them to stress a certain aspect of the business they are dealing with. Market research agencies, News rooms, marketing divisions of large corporations, NGOs, accounting firms etc. are full of people who specialize in basic statistics.

Statistics is concerned with the describing, interpreting and analyzing data. It is, therefore, an essential element in any improvement process. Statistics is often categorized into descriptive and inferential statistics. It uses analytical methods which provide the math to model and predict variation. It uses graphical methods to help making numbers visible for communication purposes.

Descriptive Statistics

• Descriptive statistics summarizes or describes characteristics of a data set.

• They help to make sense of large numbers of individual responses, to communicate the essence of those responses to others

• Helps exploring and making conclusions about the data in order to make rational decisions.

• Includes calculating things such as the average of the data, its spread and the shape it produces.

• Are displayed as tables, charts, percentages, frequency, distributions and reported as measures of central tendency

• Determine if the sample is normally distributed (bell curve) as most statistical tests require the sample to have normal distribution

• Determine if the sample can be compared to the larger population

Difference between Descriptive and Inferential Statistics

Nowadays, statistics is playing a major role in the field of research; that helps in the collection, analysis and presentation of data in a measurable form. It is quite hard to identify, whether the research relies on descriptive statistics or inferential statistics, as people usually, lacks knowledge about these two branches of statistics. As the name suggests, descriptive statistics is one which describes the population. On the other end, Inferential statistics is used to make the generalisation about the population based on the samples.

4.1. INTRODUCTION

Dispersion is the extent to which values in a distribution differ from the average of the distribution. To quantify the extent of the variation, there are certain measures namely:

1. Range
2. Quartile Deviation
3. Mean Deviation
4. Standard Deviation

Range and Quartile deviation measure the dispersion by calculating the spread within which the values lie. Mean Deviation and Standard Deviation calculate the extent to which the values differ from the average.

Introduction

Desert soils are the soils of arid regions that remain dry for most part of the year and support sparse xerophytes. The amount of water received by precipitation is far less than what is lost by evapotranspiration. Most deserts receive an average precipitation of less than 400 mm. Because of extreme imbalance between evapotranspiration and precipitation, many desert soils contain salts.

Distribution

Deserts occupy about one-third of the areas of Africa and Australia, 11% of Asia and about 8% of the Americas (Boul et al. 1997). Desert soils include both cold and hot desert. In India, desert soils occur in three agro-ecological regions (AER). The cold arid desert of extreme north (Leh, Ladakh region of Jammu & Kashmir ), the hot arid desert of north western India (Rajasthan, southern parts of Haryana and Punjab and northern parts of Gujarat) and the tropical arid desert of the Deccan plateau in South India represents AER 1, 2 and 3, respectively. The three different desert regions in India have characteristic climatic and soil conditions.

Introduction

Low and erratic precipitation, diurnal fluctuations in temperature and low humidity are the typical characteristics of deserts and their margins. Further, strong winds, sunny and very bright days and unpredictable periods of drought and famines are regular features. These lands are poor in fertility. Uninterrupted increase in human and animal pressures is violating carrying capacity of the natural resources, thus resultant is desertification.

Arid zones are described as a part of the drylands, and have the most severe edapho-climatic conditions. The major distinguishing feature for defining and for planning for the arid zone is the low rainfall (below 500 mm or Aridity Index <0.20) with more than 50% inter-annual variability. This makes a great difference in terms of the nature of the ecosystem, the socio-economic environment and the challenges for sustainability. High wind and solar regimes further increase the effect of rainfall variability and the whole complex makes a fragile ecosystem in which small disturbances may cause great loss to the sustainability, which are sometimes irreversible (Hou’erou, 1996). The hot arid zones of the world are economically and environmentally disadvantaged, with unique problems. The ecosystems of these zones are highly fragile with large risks that cause severe impediments to development programs. Of the total land area in the world, arid zones cover 18.8% and the hyper-arid zones account for 22.3% of the total arid zones (FAO, 1989).

Abstract

Burkina Faso is a landlocked country in West Africa with a dry tropical climate characterised by a short rainy season and a long dry season. The annual rainfall varied between 300mm in the northern part of the country to 1200mm in the meridian part. Since many years, the degradation of climatic conditions is observed. Therefore, the annual rainfalls of the 1971-1981 period were inferior to those of the precedent periods, and also the deterioration of the climatic conditions led the limits of some ishoteques “isohyète” to move southward, more than 50km farther. Furthermore, the decennial rainfalls since 1920 were subjected to a latitudinal displacement to the south. For example the ishoteque “isohyète” 500mm which were located at the North of the 15°N outside Burkina Faso during the years 1950-1960 moved gradually year by year and reached the 14°N during the years 1970-1980 inside Burkina Faso.

Abstract

Conversion of an already arid land into a desert through indiscriminate human actions magnified by droughts. Such actions include overgrazing, repeated burning, intensive farming, and stripping of vegetation for firewood. One quarter of the earth’s surface is threatened by desertification - an area of over 3.6 billion hectares. Since 1990, Six million hectares of productive land are lost every year due to land degradation. Desertification threatens the liveihoods of more than one billion people and has already made over 135 million people homeless. Desertification does not occur in linear, easily mappable patterns. Deserts advance erratically, forming patches on their borders. Areas far from natural deserts can degrade quickly to barren soil, rock, or sand through poor land management.

Concept and Definition

Desertification is a major problem in the drylands of India, affecting the way of life for its inhabitants. The problem is more severe in the arid lands in the northwestern part of the country. There have been a few numbers of definitions of the word “Desertification”. However for simplicity of its origin and meaning we would refer to two of the frequently used ones; (1) proposed in 1991 by UNEP: “Land degradation in arid, semi-arid and dry sub-humid areas resulting mainly from adverse human impact and (2) prepared for the Earth Summit at Rio, held in June 1992, for inclusion in Agenda 21, as “Land degradation in arid, semi-arid and dry sub-humid areas resulting from climatic variations and human activities. (Anonymous 1992).

Comparing two of these initial definitions, it would show that first one indicated desertification as a state of natural resources like soil and vegetation, mainly resulting from human activity while the second one included climate as a major cause. However, it reduced the emphasis of human activities as being the primary responsible factor and tried to link the possible impact of climate change on desertification. But the simplicity of the 1992 definition of desertification helped researchers to bring in sharp focus on the special environmental and socio-economic problems of the drylands.

So over the years, the key words that explains the term “desertification” has been changing or are being amended for specific purposes. This would at least mean that the problem of desertification is still debated world-wide, and its impact is not limited to some nations/regions as was presumed and discussed in first of UNCCD platforms. Therefore, as a precaution and combating this process, few catchy words like non-sustainable management, productivity, over-exploitation of natural resources, dryland livelihood, droughts are found to surround the word desertification. Earlier, some, people equated desertification with advancing boundaries of the existing desert and in India, examples of expansion / contraction of geographical boundary of Thar desert was a public debate among various researchers and planners. In the same time, some of the definitions tried to broaden its geographical scope so that greater populations suffering from adverse effects of land degradation would benefit out of various remedial measures.

Introduction

Desertification is now accepted as a major environmental issue because of the fact that 69.5 percent area of the world’s dry lands and more than 1.2 billion people in over 110 countries living in this habitat are affected by various land degradation processes. During last 20 years, researchers have focused their discussion either on a condition or a cause or a set of processes to assess different paradigms of desertification. Several studies carried out in arid western part of Rajasthan (Singh et al., 1992, Kar, A. 1993b, Kar, 1995, Dregne, H.E. 2000, Kar et al.2007) show that wind erosion is still a major problem. Though, there are many instances of location specific problems like water erosion, salinity/ alkalinity and water logging, about 75% area in arid western Rajasthan is affected by wind erosion hazard of different intensities (SAC, 2007, Kar et al. 2009). Decreasing rainfall gradient from east to west and increasing wind strength in that direction are responsible for the spatial variability in sand reactivation pattern. Water erosion in the form of sheet, rill and gully erosion is a major problem in areas, where average annual rainfall exceeds 350 mm, the rainfall intensity is high and the topographic and soil characteristics favour high run-off. Destruction of vegetation cover and excessive ploughing of shallow soils, especially on the sloping lands, accelerate the problem.

Introduction

Desertification, which is considered a major threat in the drylands of the world, is not about advancing boundaries of the existing deserts, but about land degradation in the arid, semi-arid and the dry sub-humid regions, which together form the drylands (Anon., 1995). Secular variation in climate that has resulted in periodic expansion and contraction of the desert boundaries and regional-scale changes in vegetation condition (Tucker et al., 1991; Nemani et al., 2003; Hickler et al., 2005) is one of the drivers of desertification. Human activities constitute the other major driver. According to Geist and Lambin (2004) the prominent core variables that drive degradation are climatic, economic, institutional, national policies, population growth and remote influences.

We let you know that the type of people in a given region is closely linked to the kind of resources found in the concerned region; and which are necessary for human beings to survive.

In fact, more than 100 countries possess arid lands, where more than 40% of the global population lives. The soils of these regions present too much fragility and they are too degraded that they can’t allow people to survive.

Let’s emphasize that in Africa, two third of the total area are arid zones. Thus, for Africans, the type of their struggle for adaptation to the context of their land, illustrates their ingenious capacity to model their hostile surroundings and to leave marks of their cultures all over prehistory and history.

Social organizations in those arid areas are closely linked to modes of exploitation and valuation of resources (water and land). However, human productions in those areas are doubly menaced; on one side by the action of humans who exploit resources for their immediate needs, and on the other side, by climate adverse effects during long periods of drought. It means that climate change and violent meteorological phenomenon worsen circumstances. That leads to environmental degradation and biodiversity reduction; alarming deterioration of vital conditions; and intensification of poverty, both in rural and urban areas; particularly among women and young. Consequently, there are non durable (viable) agricultural practices, overexploitation, overgrazing, excessive and illegal forestry exploitation; destruction of forests and bushes by non-controlled fires, pillages and conflicts with weapons; reduction of vegetation, due to the scarcity of rain; of water in general and menaces of heaps of sands.

Agroforestry systems are more complex than the agricultural systems. The long-term nature of trials involving woody species and the varying objectives of agroforestry trials demand that adequate caution be exercised in their design. Several characteristics of the trees like slow growth, long term effects on their surroundings, long life, age of trees, the area over which the influence of trees extend, etc. complicate the issue of designing experiments for these systems. Agroforestry experiments are often established on marginal sites which include sloping lands, and sites with infertile and degraded soils. It is thus difficult to find homogeneous sites of such problem areas, especially sloping lands where plots along contour lines are long and linear. Germplasm of many agroforestry tree species are usually collected from different origins which lack uniformity. Therefore, experimental materials in an agroforestry experiment may not be of uniform quality.

There are several features of agroforestry systems that require some modification of the methods usually used in agricultural experiments. Important issues related to agroforestry experiments include

Agroforestry systems are more complex than the agricultural systems. The long-term nature of trials involving woody species and the varying objectives of agroforestry trials demand that adequate caution be exercised in their design. Several characteristics of the trees like slow growth, long-term effects on their surroundings, long life, age of trees, the area over which the influence of trees extend, etc. complicate the issue of designing experiments for these systems. Agroforestry experiments are often established on marginal sites which include sloping lands, and sites with infertile and degraded soils. It is thus difficult to find homogeneous sites of such problem areas, especially sloping lands where plots along contour lines are long and linear. Germplasm of many agroforestry tree species are usually collected from different origins which lack uniformity. Therefore, experimental materials in an agroforestry experiment may not be of uniform quality.

There are several features of agroforestry systems that require some modification of the methods usually used in agricultural experiments. Important issues related to agroforestry experiments include

Introduction

In almost all biological studies, it will be impossible to account for every individual in a population. Therefore, it is necessary to examine a sub-group of the total population and extrapolate from this to the whole population. The process by which the sub-group of the population is selected is sampling. Nearly, all statistical tests make a fundamental assumption that sampling of individual will be at random from all the individuals that could possibly be sampled. It is very important that timing is taken into account either by sampling strategy or by later analysis. Most population will be affected by season, time of day and local weather conditions.

What is considered here is the problem faced by an ecologist working in the field and trying to design a suitable sampling strategy. The use of the very powerful statistical technique; analysis of variance (ANOVA) is more common in the situation of a controlled experiment, where, we are analyzing the effects of different levels of a treatment (e.g. feed, fertilizer, temperature etc.) on some measured aspect of population, Then, to get a true estimate of the effect of the treatment, experimental design will be of paramount importance.

Greenhouse refers to a structure which provide relatively better environment for plant growth. The goal is to create congenial temperature and relative humidity in desired range. The greenhouse covered with polythene sheet, also called as polyhouse, has polythene sheet (UV stabilized 200 micron LDPE sheet) as covering over a relatively rigid frame (made of GI pipes, angle iron, boomboo or wooden) which entraps the solar energy to increase the temperature and provide light for plant propagation. A normal greenhouse has four basic components: 1) frame made from rigid material like GI pipes, wood or bamboo; 2) glazing material, which is transparent to provide enough light for plant propagation; 3) climate control system, which may be natural ventilation or forced ventilation using fans with or without cooling pads, shading nets, pigment painting, etc. and 4) plant growing medium (soil or artificial media like cocopeats) with needful arrangement for supplying inputs (water, fertilizers, pesticides, etc.). The design of greenhouse involves structural design of frame with enough climate control mechanism. It mainly depends on shape, size, material of frame, local climatic conditions, wind pressure, and desired height from crop production point of view. Fabrication of greenhouse should be such that it provides enough structural stability with wind pressure and other factors, perfect joints, anchoring of polythene, and minimum hindrances in crop production practices.

Design and Construction of a greenhouse involves five distinctly different aspects viz. (a) Basic form or type, (b) structure/designs, (c) covering materials and its fixing, (d) foundation and constructional detail, and (e) crop-support, irrigation and drainage planning.

All the above aspects are interlinked. To have a clear idea, these individual aspects are discussed separately.

4.1. Basic Forms of Greenhouse

Before considering anything about construction, one should finalize the form of construction. There are different forms of greenhouses for different climatic and crop situations. These types of structures are planned according to the requirement of farmer/promoter and obviously according to the purpose. Now we will describe, in brief, some of the important form or type of greenhouses.

4.1.1. Greenhouse covered with transparent and impervious material

These structures are covered with water/rain impermeable transparent materials which allow necessary solar radiation for optimal growth of plants. Simultaneously it protects crops from temperature-fluctuation, rain, wind, and creates a favourable situation in respect of CO₂ and humidity. This covering is also used to prevent the re-radiation of heat energy and conserve the heat generated in daytime to raise night temperature inside.