eChapters

A system is a unit which possess a group of interacting components, operating together for a common purpose, capable of reacting as a whole to external stimuli. It is unaffected directly by its own outputs and has a specified boundary based on the inclusion of all significant feedbacks. For example, the human body is a system-it has a boundary (skin) enclosing a number of components (heart, lungs) that interact (the heart pumps blood to the lungs) for a common purpose (to maintain and operating the living body).

Ecosystem: Any collection of organisms that interact or have the potential to interact along with the physical environment in which they live form an ecological system or ecosystem. Ecosystems are not static entities but, they are dynamic systems with characteristic pattern of energy flow, nutrient cycling and structural change.

Agro ecosystem: Agro ecosystems are ecological systems modified by human beings to produce food, fibre or other agricultural products. Like the ecological systems, agro ecosystems are structurally and dynamically complex. But their complexity arises from the interaction between socio economic and ecological processes.

Crop system: An arrangement of crop population that transform solar energy, nutrients, water and other inputs into useful biomass that produce food, feed, fuel and fibre. Crop system comprise of soils, crop, weed, pathogen and insect subsystems. The crop can be of different species and variety, but they only constitute one crop system if they are managed as a single unit.

Cropping systems: It is defined as the order in which the crops are cultivated on a piece of land over a fixed period of time. Cropping system is the way in which different crops are grown. In the cropping systems, sometimes a number of crops are grown together or they are grown separately at shorter intervals in the same field.

The crop production is affected by the plant type, climatic condition, soil type and management factors. The production of the plant might be increased by changing plant type and increasing the grain filling period under certain climatic condition where management and soil factors are not limited. There is a direct relationship between the plant type and crop yield because the orientation and number of leaves play an important role in carbon fixation (photosynthesis). Again any variety/cultivar will contribute 21-25 per cent to the total yield of any crop in general. In recent years due to development of photoinsensitive varieties and hybrids which are more fertilizer responsive and high yielding varieties lead to increase overall production in the country.

Plant ideotypes

Refers to plant type in which morphological and physiological characteristics are ideally suited to achieve high production potential and yield reliability. The concept of ideotype was given by Donald in 1968 and he illustrated that there should be minimum competition between the crops and crop must be competent to compete with weeds. Ideotype is defined as a biological model which is expected to perform or behave in a predictable manner within a defined environment. On the basis of environment, Donald and Hamblin (1976) identified two forms of ideotypes that is isolation ideotypes and competition ideotypes. Isolation ideotypes are suitable for mono/single cropping and competition ideotypes are suitable for mixed cultivation.

An area with similar soil, climatic conditions and resource availability resulting in similar type of crops and cropping systems. Ex. Rice based cropping system, Ragi based cropping system, Wheat based cropping system, Cotton based cropping system etc.

Efficient cropping zone: An analysis of productivity efficiency of crop was made by Kanwar (1972) using relative yield index (RYI) and relative spread index (RSI).

A zone where both yield and spread indices are maximum that is above 90 per cent is called most efficient and in case of indices below 90 is the least efficient zone of a crop.

Taxonomic classification of avian species is beyond the scope of this booklet. However, since the preliminary knowledge of bird species for students of avian medicine class is of interest, the following description of most common pet and wild birds are being attempted for their benefit.

GALLINEFORMES: This order includes domestic chicken, turkey, pheasants, peafowl, grouse, quail, guinea fowl, guans and curassows.

COLUMBIFORMES: Includes pigeons and doves.

PSITTACIFORMES: Includes parrots, which have strongly hooked maxilla with a flexible attachment to the skull. They also have dexterous zygodactyl feet (two digits point forward and two backwards). The order includes.

Introduction

Disease caused by motile Salmonella species in birds is called “Paratyphoid infections”. Paratyphoid infections are present in all parts of the world.

Etiology

Salmonella enterica includes six subspecies. Only one of that subspecies; S. enteric subspecies enterica includes more than 2500 motile serotypes.

Disease is worldwide in distribution

Etiology

Pasteurella multocida, a gram negative non spore forming, non motile rods which stain bipolar.

Epizootiology

Most species of birds are infected. Turkeys are more susceptible than chickens, and older chickens are more vulnerable than young chickens. Geese and ducks of all ages are highly susceptible to fowl cholera. Survivors of fowl cholera outbreaks become carriers and are the reservoir of infection. P. multocida isolates of pigs are pathogenic to fowls. Spread of P. multocida in a flock is by feed and water contaminated with excretions. Crates, feed bags and utensils serve as a mechanical carrier of the organism.

Etiology

There are 18 species in genus Campylobacter. Campylobacter species in poultry include C. jejuni, C. coli and C. lari. The most predominant species is C. jejuni.

Epizootiology

The infection has been reported in chicken, but the organisms have been isolated from ducks, turkeys, black birds, sparrow and pigeons.

Transmission

Possibly through faeces, as organisms are in the intestinal tract. Egg transmission of bacteria on or in the egg through hatchery is strongly suggested.

In avian species following diseases are caused by Clostridium bacteria.

1. Ulcerative enteritis
2. Necrotic enteritis
3. Gangrenous Dermatitis
4. Botulism
5. Yolk sac infections.

Clostridia infections are not common in birds and are not a significant source of infection for man and animals.

Etiology

Genus Mycobacterium contains many pathogenic species that can cause disease in birds (M. avium, M. tuberculosis, M. genavenes, M. gordonae). Within M. avium, organisms are divided into four sub species. M. avium sp avium, M.avium sp silvaticum, M. avium sp homnissuis and M. avium sp paratuberculosis. Mycobacterium avium sp avium - has wide host spectrum; poultry, pigeons, raptors, ratites and wild birds. M. genavense- affects Psittacines and passarines. M. tuberculosis- psittacines and other cage birds, and wild birds in captivity. M.bovis- Psittacines and others.

Under natural conditions, M. avium sp avium does not cause severe disease in mammals except in rabbit and pig. Majority of mycobacteriosis in pigs is by M. avium sp avium. In cattle and other mammal infection by M. avium remain localized and is known to give positive reaction to mammalian tuberculin. The disease in caged and wild birds in captivity is common with M. tuberculosis, because of its close contact with humans. Tuberculosis is a serious problem in zoological gardens. M. avium is being isolated in increasing number of immunocompromized human patients.

Etiology

The subfamily Pneumovirinae includes two genera: Pneumoviruses and metapneumovirus. The later consists of both human and avian metapneumovirus (aMPV). aMPV produces turkey rhinotracheitis (TRT) in turkey and Swollen head syndrome (SHS) in chickens. aMPV has been detected in other species of birds, but the disease in those birds are not well defined.

Occurrence Species

A new disease of turkeys (in the UK since 1985) which is suspected to cause some lesser problems in chickens.

ILT is an acute viral disease of chickens, pheasants and peafowl characterized by marked dyspnea, coughing, gasping and expectoration of bloody exudate. The disease is worldwide.

Hosts

Chickens particularly susceptible; reported to occur in pheasants and peafowl.

Age Range

All ages susceptible but is most often found in adult (mature or nearly mature) commercial chicken layers.

This ‘virus’ is widespread in commercial flocks worldwide, but its taxonomic position is not determined. The disease is characterized by aplastic anaemia and generalized lymphoid atrophy with a concomitant immunosuppression. Consequently, infectious anaemia is frequently complicated by viral, bacterial, or fungal infections.

Occurrence

Chickens up to 3 weeks of age are most susceptible.

IBH is an adenovirus infection of young chickens characterized by sudden onset and sharply increased mortality, short course, anaemia, and hepatitis often accompanied by intranuclear inclusion bodies. It is described in Canada, USA and many other countries.

EDS 76 is an infectious disease of laying hens caused by hemagglutinating adenovirus and characterized by failure to achieve production targets or by the production of thin-shelled or shell-less eggs in otherwise healthy birds.

This important disease caused loss of egg production for several years - vaccination introduced the disease and a new vaccine virtually eradicated it.

(Tenosynovitis; Ruptured gastrocnemius tendon; Reovirus infection)

Viral arthritis is a reovirus infection primarily of broilers characterized by arthritis and tenosynovitis (primarily of the tarsus and metatarsus, the digital flexor and tarsometatarsal extensor tendons) and, occasionally, by rupture of the gastrocnemius tendon(s) resulting in lameness and condemnations at slaughter. The disease is reported worldwide.

Fowl pox is a slow spreading viral disease of chickens, turkeys and other birds characterized by cutaneous lesions on the un-feathered skin of the head, neck, legs and feet and/or by diphtheritic lesions in the upper digestive and respiratory tract. The disease is worldwide in distribution.

Occurrence

Among poultry chicken and turkey are more susceptible. Other birds include pigeons, canaries, psittacines and wild birds. Fowl pox has been reported from more than 200 species of birds. The incidence is severe in multiple age groups and intensive poultry farming areas.

AI is a viral disease affecting the respiratory, enteric or nervous system of many kinds of birds. The most virulent form is an acute, generalized disease characterized in poultry by a short course and extremely high mortality.

(AE; Epidemic Tremor; Infectious Avian Encephalomyelitis)

AE is a viral infection of chickens, turkeys, pheasants and cortunix quail characterized in young birds by ataxia progressing to paralysis and, usually, by tremors of the head and neck. Infected adults usually show no signs. AE is world wide in distribution.

Etiology Herpes Virus

Variation in pathogenicity of virus strains has been reported, but all strains appear identical immunologically.

Occurrence

The disease was first reported in the Netherlands in 1923. The disease has been confirmed in France, Belgium, Canada, India, Thailand, England, Hungary, Austria, Denmark and Vietnam, and suspected in China.

DVH is a highly fatal infection of young ducklings. Lesions are primarily in the liver.

It is an acute disease of pheasants, chukars, partridges, turkeys, ducks, pigeons and wild birds. The viruses of EEE and WEE are of public health importance as they infect humans and occasionally cause fatal disease. The disease is further significant because of its link to disease in horses.

Etiology

The arboviruses are grouped into 12 different families. The five arboviruses causing disease in birds are Eastern equine encephalitis (EEE) virus, Western equine encephalitis (WEE) virus, Highland J (HJ) virus, Israel turkey meningoencephalitis (IT) virus and West Nile Virus WNV. The first three are in Togaviridae, and IT and West Nile Virus (WNV) are in Flaviviridae.

Introduction

This is a disease mainly of the respiratory system affecting domestic poultry, wild birds and zoo birds. Systemic aspergillosis affecting visceral organs and other tissues of the bird’s body is also reported. Reports are also available on eye and brain infections.

LICE

Introduction

Lice are common ectoparasites of birds. There are many species of bird lice and are found on chicken, turkey, guinea fowl, duck, goose and pigeon. Lice species prefer a different part of the body. Most of them are straw colour and measure 1-10 mm. Lice from one host can parasitise another host if they are in close contact. For example, a louse from chicken can parasitise guinea fowls kept on the same premises. Hence, the species of lice is determined if cross contamination from another species is suspected. Lice are not highly pathogenic to mature birds. However, severe lousiness may lead to weight loss, as well as low production and death.

CALCIUM & PHOSPHORUS

Source of mineral

Soluble grits (Limestone grits containing chiefly CaCo3) which is soluble in acid medium of crop. It differs from insoluble grits (gravel, granites, sand etc.) which acts only mechanically in the gizzard.

Seen in mature chickens. Condition results from myocardial degeneration which causes bilateral ventricular hypertrophy and dilation. Etiology is not known.

Round heart disease in turkey causes mortality in 1-4 weeks of age. Lesions are severe cardiomyopathy, ascites, hydropericardium and generalized congestion of tissues. No aetiology is known.

Although the Dacron bag technique for protein degradation measurement is relatively simple and not too expensive as compared to in vivo measurements, the technique is not easily adaptable in laboratories that are not fully equipped to maintain cannulated animals. Therefore, different alternative approaches such as measurement of protein solubilities in buffer, enzymes and detergent solutions have been tried (Pichard and Van Soest, 1978; Krishnamoorthy et al., 1982, 1983, 1995; Aufrere et al.,1991; Prabhu et al., 1996; Licitra et al., 1996 and 1998). The advantages of these approaches are that, they are simple, rapid, economical and repeatable. However, since the enzymes used are not of rumen microbial origin, degradation obtained from these enzymes may not be a true .reflection of degradation occurring in the rumen. Nevertheless, because of their simplicity and rapidity, in situations where large number of samples are to be compared, in vitro techniques serve as useful tools.

Different enzymatic methods have been proposed as potential alternatives to rumen inoculum studies to determine dry matter digestibility and protein degradation. However, the type of enzyme used and the procedure adopted differ (Marten and Barnes, 1979). The enzyme methods offer distinct advantage under circumstances of the difficulties in maintaining rumen fistulated animals as a source of rumen inoculum. Since, the enzymes used in these techniques are commercially available enzyme preparations, and are not of rumen microbial origin, the digestibility obtained from these techniques are related to in vivo digestibility by means of mathematical equations. Therefore, equations developed to predict energy content using enzyme techniques differ with the type of feedstuff and type of enzymes used in the technique (Table 5.1.) (Martens and Barnes, 1979). The enzyme methods are popular among the feed compounding industries to evaluate raw materials and compound feeds.

The method used by DeBoever et al. (1986) to determine digestibility of mixed feeds is given below.

Neem seed cake (NSC) despite of being rich in protein is not used as animal feed due to the presence of large number of toxic/bitter compounds in it. Studies have shown that NSC can be safely included the ration of animals after water washing / alkali/ urea treatment. These treatment methods appear to remove / reduce or largely inactivate the toxic principles present in NSC. In order to assess the quality/safety of the treated product, quantification of the residual toxic compounds is essential. One such compound is azadirachtin. It has been reported to be biologically most active.

One of the best techniques for the estimation of azadirachtin is by using high performance liquid chromatography (HPLC).

In spite of its high protein (CP, 34-36%) content, castor bean meal as such is not used as livestock feed due to the presence of toxic factors viz., ricin, ricinine and allergen. Of the three, ricin is the most detrimental to animals. In order to detoxify the castor cake, a number of physical and chemical methods are employed. The efficacy of the treatments is assessed, based on the qualitative and quantitative changes in ricin content. Of all the detoxification methods, autoclaving (15 p.s.i., 60 min) and lime (4% w/w) treatments completely destroy the toxin. (Anandan et. al., 2005).

Estimation of Ricin

The raw and detoxified samples can be analysed for the toxin, ricin as per the method of Kabat et al. (1947) with modifications as suggested by Waller and Negi (1958).

Extraction of Ricin

The solvent extracted castor cake sample of 500 g is extracted with 2.5 l of water acidified with HCl to a pH of 3.8 by shaking the contents in a conical flask for 6 h. The contents are allowed to settle and are then filtered trough Whatman filter paper No.1 . The residue is treated with 1.5 l of distilled water, shaken for 3 h and filtered through the same paper. A second treatment with water is given to the residue and filtered again through the same filterpaper.

This filtrate contains all the ricin and portions of ricinine that are soluble in cold, dilute HCI. It is evaporated to a small volume by vacuum distillation below 40 °C. The filtrate is saturated with sodium chloride and centrifuged at 4000 rpm for 20 min. to separate the precipitate containing only ricin.

Determination of True Protein

Apparatus

Wide mouth stoppered bottle, water bath plus those used for total nitrogen (crude protein) determination.

Reagents

1. Saturated solution of potash alum.
2. Stutzer reagent-Dissolve 40g of CuSO₄ in 2 litres of water in a wide mouth stoppered bottle. Add 10ml of glycerine and sufficient quantity of 30 % NaOH to make the solution alkaline (Litmus paper). Shake the contents and allow to settle. Discard the supernatant liquid. Collect the precipitate on a filter paper and transfer it to glass mortar with the help of spatula. Add 3ml of glycerine and a little water in the mortar and triturate the precipitate with a glass pastle. Transfer the triturated material to a wide mouth stoppered bottle, add 600ml of water, shake well and filter. Repeat the process till the precipitate (filtrate) is free from alkali and sulphate. Collect the precipitate and add 30ml glycerine. Dilute the emulsion to 320ml with water and preserve in a container.

18.1. Basic for Government Intervention in the Economy

One of the most powerful arguments to justify government intervention in the economy in the economy is the so-called concept of market failure. In a typical free enterprise system where demand and supply forces operate, the efficiency which results only relates to economic welfare. The social cost implications of economic activities tend to be ignored. Governments therefore intervene in the economy with the social welfare objective in mind. One popular way by which governments have intervened in the economy is through ownership of particular industries or outright nationalization of some private enterprises. The advantages usually claimed for such an action are as follows:

Aim

To synthesize chitosan/nanosilica coating solution for fruit coating aiming at increasing shelf life.

Introduction

Application of edible coatings is promising to improve the quality and extend shelf life of fruits and vegetables (Lin et al., 2011). Chitosan, a versatile biopolymer derived from deacetylation of chitin had been widely applied in the fresh-keep field owing to its good biocompatibility, biodegradability, antibacterial activity and capacities to form film (Lin et al., 2011).

Zerovalent (nZVI) Ionic Compounds

Although Ag⁺ contains a filled d¹⁰ shell, the structures of Ag compounds can in many instances be understood only if one assumes the existence of weak attractive Ag⁺ - Ag⁺ interactions. Similar attractive forces have been shown to be responsible for the formation of gold cluster compounds. In Ag⁺ solid state compounds the unoccupied 5s and 5p orbitals give rise to empty bands which may be partially occupied thus resulting in subvalent Ag compounds; examples are Ag₃O and Ag₂F. The compound Ag₅SiO₄ prepared from Ag and Si0₂ at 350 °C under a high pressure of oxygen, contains [Ag₆]⁴⁺ clusters (average oxidation state 2/3) and should be formulated at [Ag₆]⁴⁺ (Ag⁺)₄ (SiO₄ ^{4 -})₂.

Ag and Au forms numerous cluster compounds in which the metals are zero valent or subvalent. Examples are Ag₆ Fe₃ (CO)₁₂ {HC(PPh₂)₃} and paramagnetic cluster ions [Ag₁₃ Fe₈ (CO)₃ ²]^4-.

Polymer Clay Nanocomposites

Polymer clay nanocomposites has been used as to affect permeability of the maternal to gases and vapours. Majority of papers on nanocomposites have been focused on the use of smectitic type clays as nanoparticles. They are a group of swelling type of clay minerals including montmorilonite, nontronite, saponite, sauconite and hectorite.

A number of polymer-layered silicates (PLS) preparation methods has been reported in literature. The three most common methods to synthesize PLS nanocomposite are intercalation of suitable monomer and subsequent in situ polymerization, intercalation of polymer from solution and polymer melt intercalation.

In general, layered silicates have layer thickness on the order of 1 nm and a very high aspect ratio (e.g. 10–1000). A few weight percent of layered silicates that are properly dispersed throughout the polymer matrix thus create much higher surface area for polymer/filler interaction as compared to conventional composites. Depending on the strength of interfacial interactions between the polymer matrix and layered silicate (modified or not), three different types of PLS nanocomposites are thermodynamically achievable (Fig. 1 and 2 ) as outlined by Sinha Ray and Okamoto (2003). They are as follows:

Biological synthesis of Zinc Oxide (ZnO) nanoparticles

Aim

To synthesize nano ZnO particles using fungal isolates.

Introduction

The ZnO nanoparticle are effective anti-bacterial and antiodur agent. Biological synthesis of ZnO nanoparticle is a new approach for environmentally benign protocol in context to green nanotechnology, (Raliya and Tarafdar, 2013).

Aim

To synthesize phosphorus (P) nanoparticles from tricalcium phosphate using fungal mycelium.

Introduction

Green nanotechnology includes a range of processes that reduce or eliminate toxic substances to restore environment. Microorganisms like fungi and bacteria having naturally bestowed property of reducing and oxidizing nanoparticles, are used for synthesis.

Aim

To synthesize gold (Au) nanoparticle using fungal mycelium.

Introduction

Biosynthesis of nanoparticles is a kind of bottom up approach where the main reaction occurring is reduction/oxidation. The fungal enzymes are usually responsible for reduction of metal compounds into their respective nanoparticles.

Aim

Phytosynthesis of silver (Ag) nanoparticles using Cassia roxburghii aqueous leaf extract.

Introduction

The Ag nanoparticles constantly exhibit adverse effects on microbes such as inhibition and inactivation (Nasrollahi et al., 2011). The Ag nanoparticles synthesized by using various biological sources such as herbs, plants and biological organisms display excellent properties in various fields i.e., non-linear optics and intercalation materials for electrical batteries as optical receptors, catalysts in chemical reactions biolabelling and as antibacterials (Sanghi and Verma, 2009).

Chemical Synthesis Methods

Several methods can be used for the production of these nanoparticles, namely: (i) top-down methods (Li et al., 2006) such as vacuum sputtering (Kuhn et al., 2002) or the decomposition of iron penta carbonyl (Fe(CO)5) in organic solvents (Karlsson et al., 2005); and (ii) bottom-up methods that promote the ‘growth’ of the nanostructures via chemical synthesis, for example through the reaction of iron(II) or iron(III) salts with sodium borohydride (Wang and Zhang, 1997). However, these methods present several limitations and problems; the top-down methods are generally expensive and require specific and costly equipment while the drawbacks of the bottom-up approaches are related to safety issues due to the toxicity of sodium borohydride, the production of flammable hydrogen gas during the process (Li et al., 2006), and the tendency to form large agglomerates, very fast and at a high extent, and therefore have a reduced reactivity and degradation efficiency.

Characterization Tools: Microscopy

Agriculture is dependent directly on weather and indirectly on the consequences of climate change. Changes in temperature, precipitation, incoming solar radiation and CO2 concentration are expected to impact crop growth to a greater extent. The overall impact of climate change on worldwide food production is considered to be low to moderate only when there is successful adaptation strategies towards climate change (IPCC, 1998). Global agricultural production could be benefited by the doubling CO2 concentration. All sectors including agriculture will be impacted by the adverse effect of climate change imposed on water resources (Gautam and Kumar, 2007; Gautam, 2009). India is expected to face more seasonal variation in temperature with more warming in the winters than summers (Christensen et al., 2007; Cruz et al., 2007). The frequency of drought occurrence is increasing due to variations in the monsoonal rainfall. Climate change is posing a great threat to agriculture and food security. Water is the most critical agricultural input in India, as 55% of the total cultivated areas do not have irrigation facilities.

Even with the variations in climate conditions, food accessibility for the present generation is assured, but as far as the future is concerned there is still the uncertainity of agricultural production. All climate models predict that there will be more extreme weather conditions, with more droughts, heavy rainfall and storms in agricultural production regions. Such extreme weather events will inf luence pest and disease occurance, imposing severe risks of crop failure. In India, climate change could be a potential threat towards food security due to population growth, industrialization and economic development. India’s climate could become warmer under conditions of increased atmospheric carbon dioxide.

Communication is a key to understand things between two people. Today’s communication is entirely different from pre-historic era and has taken many evolution throughout the years. Before alphabets, signs, symbols, letters and telephone evolved, communication was restricted to interpersonal interaction (i.e.) from one person to another in the form of gestures. It is in other terms called non-verbal communication. Today, communicating between two or more people has become too easy that one can communicate with more than 10 members at a time which is in technical means called conferencing.

The growth of internet has paved way for innumerable means of communica- tion. In other words it can be told as, communication is re-defined by technol- ogy. Texts, email, tweets, tele and video conferencing have widely saved much time of people and made them recipients of today’s fast moving world.

Fidelity

Fidelity is said to exist in a communication situation when there is no distortion of the message from the time it leaves the source until it is received. The most effective communication occurs when the message transmitted and the message received are identical i.e., when complete fidelity is there. Some communication theorists believe that complete fidelity can never be achieved that no message is ever received exactly as it was intended by the source. This seems likely, since the source and receiver always have different frames of reference. It is clear, however, that the fidelity of any communication can be vastly improved by several methods.

Feedback

Feedback’s influence on learning is indisputable and undeniable and feedback’s varying roles in instruction are heavily researched concepts (Mory, 1992). Understanding how feedback facilitates, and, in some cases, hinders transfer of knowledge is essential to creating effective instruction.

Researchers have focused on the many aspects and roles of feedback in hopes of developing some synthesis that will increase learner performance and improve instruction. Researchers such as Bangert - Drowns, Kulik, Kulik and Morgan (1991), Brinko (1993), Clariana, R.B. and Lee, D. (2001), Clariana, R.B., Wagner, D. and Rohrer-Murphy, L.C. (2000), Kulhavy (1976), Kulhavy and Stock (1989), Kulik and Kulik (1988) and Mory (1992) to name only a very few, have sought to discern the complex role feedback plays in learning. While many studies have been convincingly conducted trying to ascertain how feedback best works in certain circumstances, a consensus has yet to be reached in most, if not all, areas and as Clariana (2000) writes, “There are a number of unanswered questions and perhaps even more unquestioned answers”.

ABSTRACT

Solanum trilobatum Linn. (Solanaceae) was investigated for the induction of tumor using a soil borne bacterium, Agrobacterium tumefaciens. Explants like stem segments and nodes were infected with bacterium. Tumors were induced from nodal explants within 10 days of infection. These explants were then transferred to MS basal medium and their growth was observed to be independent of exogenous supply of phytohormones. The growth rate of transformed callus was 10-fold as compared to control. They are used as a promising source of secondary metabolites of medicinal significance.

ABSTRACT

Albizzia lebbeck is commonly called as “vagai” in Tamil belonging to family Mimosaceae, is a large deciduous tree commonly seen throughout India. Our present aim, was to study the CNS depressant activity of Albizzia lebbeck in wistar albino rats. The bark and leaves of Albizzia lebbeck were shade dried and coarsely powdered. About 500 gm of powder was extracted using petroleum ether, chloroform and alcohol by cold maceration process. The depressant activity was accessed using actophotometer. It was claimed that in indigenous system of medicine the drug has anti-inflammatory, opthalmopathy, leucoderma, leprosy, wounds, ulcers and CNS depressant activity.

India is a varitable emporium of herbs. The medicinal use of plants was known to the inhabitants of India from time immemorial. As per Indian Materia Medica, a large number of vegetables, different parts and products of flora and fauna came into use for the treatment of diseases by ancient Hindus. Generally the practitioners, of various Indian system of medicines used to utilise the flora and fauna found in their environment and accept those which were found useful after trial.Ayurved comes from Atharvaveda. There are hundred fourteen hymns which describe some diseases and medicinal practices. This was the era around 2000 B.C. The books written on Ayurved were rewritten by ‘Charak’. It is known s ‘Charak Sanhinta’. They were written in eight volumes having hundred twenty chapters in Sanskrit Sushrut wrote in similar way under the name of ‘Sushrut Sanhita’ having ten thousand verses in six-volumes under one hundred eighty six chapters. He described ‘Surgery’. Kashyap wrote on ‘Paediatrics’ and Vatsayana wrote on ‘Sexology’. Hence, very rich and old heritage of Ayurved is prescribed and documented in Hindu Vedas. This was the age when art of ‘Pharmacy’ was introduced. There after came the ‘Creative age’, when the active principles of medicinal drugs were adopted. According to Charak, in the Chapter ‘Kalpasophan’, the drugs differ with respect to land, season, source, flavour, taste, potency, post digestive effects and specification and also with respect to their body, morbid tendency, constitution, age, vitality, gastric fire, proclivities, homologation and stage of diseases.Accepting those ideas in 1864 with the help of the then king of ‘Jamnagar’ the famous Baidya, Jandu started a small factory (Rasasala) in Jamnagar. Then in 1910 Jandu Pharmaceutical works was established in Bombay to manufacture Ayurvedic medicines in large scale. Thereafter many small factories were started in different parts of India. The vedic period around 1800 B.C. The classic period of the Indian medicine begins about 600 B.C., where the treatments of various types of ailments have been indicated. Due to Industrial evolution and general economic growth in Eastern countries, there was growth of a systematic Eastern Medicine. Gradually people started to develop confidence in allopathic and ayurvedic medicines were neglected.Many allopathic medicines which were established as life saving drugs, were later found to be harmful to humans. Such medicines have been proved to have side effects which cause damage to health. The modern man of scientific C1ptitude again tries to rotate the wheel of history in search of an alternative source/truth from natural resources. With this view many attempts have been made in India and abroad to unravel the truth, described in Vedas with regards to medicinal effects of flora and fauna. Although the Allopathic medicines are found to dominate over the Ayurvedic medicines, many remote areas of tribals are still continuing the traditional practice of using medicine from their natural surroundings.

Agriculture plays a key role in the overall economic and social well being of the country. Though the share of Agriculture in both GDP and employment has declined overtime, Agriculture still forms the backbone and occupies a pride of place :

1. Agriculture contributes 24 per cent to the Gross Domestic Product. GDP was declined from 39 per cent in 1983 to 25 per cent during 1999-2000 and now it 17.32 per cent.
2. Provides livelihood support for more than half of the population in the country. The sector provides employment to 56.7 per cent of the India’s work force.
3. Agriculture has been the source of raw material for industries. Majority of the industries depending on agriculture for their raw materials. Ex: Textile (Cotton, Jute), Sugar (Sugarcane, Sugar beet), Small & medium scale industries like soaps, dyes, medicines, vitamins, preservation of fruits and vegetables, dhal milling, rice husking, Jaggery making, oil crushing, handlooms etc.
4. It provides large part of market for industrial goods viz., seeds, fertilizers, pesticides, implements, machines like pump sets, trucks, tractors, power tillers, sprayers etc.
5. Support roadways, railways, airways and shipways for transport of inputs & produce.

Crop density is nothing but number of plants or seedling per unit area. Crop density per unit area depends on the soil, climate and type of crop being planted. For example under extreme conditions, in poor soils and in semiarid regions with no irrigation planting at low density is best. Otherwise crop plants will be thin and weak. In such conditions not only produces low yield but also is the ideal condition for pest and diseases. Crop unit area depends on :

1. Soil fertility: In poor soils, plant density should be lower than in fertile soils.
2. Availability of water: In areas where water is a limiting factor, planting should be done at a lower density.
3. Tillering capacity of the crop: Small grains and other cereals are planted at lower densities due to tillering capacity and elasticity of the crops.

Harvesting is the act of removing crop from where it was growing and moving it to a more secure location for processing and storage. Some root crops and fruits trees can be left in the field or orchard and harvested as needed, but most crops reach a period of maximum quality that is they ripen or mature and will deteriorate if left exposed to the elements. While the major factor determining the time of harvest is the maturity of the crops and other factors such as weather, availability of harvest equipments, packing, drying, transport and storage facilities.

Economic and marketing issues are often even more important to consider when to harvest commodity. Before harvesting of crop, grower must be sure about demand of the produce.

Harvesting the crop at optimum maturity is critical for reaping the benefits of season long efforts on crop production. After final decision on crop maturity, care must be taken to avoid losses during harvest, threshing, transport and storage. Processing is equally important to keep the produce in good condition for realizing good price.

Crop maturity: There are different types of maturity namely physiological maturity, harvest maturity and storage maturity.

Physiological maturity: It is the stage of development in the life cycle of plant when the plant reaches maximum dry weight. At this stage any further increase in inputs does not produce any gain in yield. There is cessation in growth and grain filling at this stage. Grain at this stage has 40 per cent moisture and 90 per cent produce is matured and this remaining 10 per cent still immature. So farmers should harvest at stage to get maximum benefit.