eChapters

In the soil environment plants are constantly exposed to a range of microorganisms which are likely to influence one another, as they occupy the same habitat. Phytonematodes are often considered as pathogens in their own right and are capable of producing a single, recognizable disease. Apart from this, they also get associated with other soil pathogens that result in the complex diseases, which are more devastating and cause huge crop losses. Phytonematodes are major predisposing factors for other potential soil pathogens, which deserve more attention. In the case of soil borne pathogens, further opportunities exist for interactions with other microorganisms occupying the same ecological niche. The significant role of nematodes in the development of diseases caused by soil borne pathogens has been demonstrated in many crops throughout the world. In many cases, such nematode–fungus disease complexes involve root-knot nematodes (Meloidogyne spp.), although several other endoparasitic (Globodera spp., Heterodera spp., Rotylenchulus spp., Pratylenchus \spp.) and ectoparasitic (Xiphinema spp., Longidorus spp.) nematodes have been associated with diseases caused by soil borne fungal pathogens (Back et al., 2002).

Vegetables are the largest important constituent of our daily diet as well as high value cash crops for small, marginal and large scale growers. These are rich in proteins, vitamins, minerals and dietary fibre which are essential for our normal body functions, prevention of malnutrition and deficiency diseases. Vegetables also play key role in neutralizing the acids produced during digestion of fatty foods and also provide valuable roughages which help in movement of food in intestine. Some of the vegetables are good sources of carbohydrates (leguminous vegetables, sweet potato, potato, onion, garlic and fenugreek) proteins (peas, beans, leafy vegetables and garlic) vitamin A (carrot, tomato, drumstick, leafy vegetables), Vitamin B (peas, garlic and tomato), vitamin C (green chillies, drumstick leaves, cole crops, leafy vegetables and leaves of radish) and minerals (leafy vegetables, drumstick pods etc.). As per dietician recommendation, our daily requirement is 75-125g of green leafy vegetables, 85g of other vegetables and 85 g of roots and tubers with other food (http://AgriInfo.in).

Vegetables are the largest important constituent of our daily diet as well as high value cash crops for small, marginal and large scale growers. These are rich in proteins, vitamins, minerals and dietary fibre which are essential for our normal body functions, prevention of malnutrition and deficiency diseases. Vegetables also play key role in neutralizing the acids produced during digestion of fatty foods and also provide valuable roughages which help in movement of food in intestine.

Plant parasitic nematodes are microscopic, thread like, soil-born organism, found in every conceivable environment. Severity of nematodes as plant pathogen is more a problem in tropical than temperate climate. These organisms are basically root feeders causing injury to the plants, which adversely affect the function of the root to absorb and translocate nutrients and water efficiently. This result into nutrient deficiency like symptoms, and as such nematode problems go unnoticed. Such symptoms are not corrected even after a dose of fertilizers.

Based on feeding habits, they are classified as migratory ectoparasitic, sedentary semi-endoparasitic or endoparasitic nematodes. They feed silently but constantly without killing the host producing debilitating symptoms and in the process reproducing to great numbers at the end of the crop season. Normally, nematodes complete their life cycles in a span of 20-25 days at temperature of 25-30 °C. They have a great egg laying capacity, which varies from 40-1000 eggs.

The most important nematode is root-knot nematode, Meloidogyne sp. distributed worldwide and can infest more than 2000 species of plants. Cereal cyst nematode, Heterodera avenae - an important nematode pest of wheat, barley and oat, citrus nematode, Tylenchulus semipenetrans associated with citrus dieback and slow decline, burrowing nematode, Radopholus similis causing spreading decline in plantation crops, the reniform nematode, Rotylenchulus reniformis in vegetables and cotton and the rice root nematode, Hirschmanniella spp in lowland rice are few other damaging nematodes.

Crossandra

Crossandra (Crossandra undulaefolia) is one of the important commercially grown flower crop in Tamil Nadu. In recent years there is a marked decline in the cultivation of this crop in Madurai, Dindigul, Coimbatore, Salem, Thiruvannamalai and Tiruchirappalli districts. The common problem with the crop is death of plants in patches during the second and third year. This is due to the nematode-fungal complex disease in the crop.

Investigations revealed the association of root-knot nematode, Meloidogyne spp. and the root-lesion nematode, Pratylenchus delattrei with the crop along with fungal patheogen, Fusarium solani.

Root-knot nematode

Both M. incognita and M. javanica are reported to cause damage and yield loss to the crop. The affected plants exhibit stunted growth, yellowing of leaves and also have chlorotic symptoms. The nematode in association with R. solani causes serious damage to the crop. The infested plants show root galls.

Crossandra (Crossandra undulaefolia) is one of the important commercially grown flower crop in Tamil Nadu. In recent years there is a marked decline in the cultivation of this crop in Madurai, Dindigul, Coimbatore, Salem, Thiruvannamalai and Tiruchirappalli districts. The common problem with the crop is death of plants in patches during the second and third year. This is due to the nematode-fungal complex disease in the crop.

Rice

Plant parasitic nematodes cause serious damage to rice crop. Thirty two species belonging to 13 genera were observed in association with the crop. Among them few are considered to be important. They are the rice white - tip nematode (Aphelenchoides besseyi), rice stem nematode (Ditylenchus angustus), rice root nematode (Hirschmanniella oryzae), root-knot nematode (Meloidogyne graminicola) and the cyst nematode (Heterodera oryzicola).

The white-tip nematode (Aphelenchoides besseyi)

The yield loss due to the white-tip nematode is estimated to be as much as 17.4 to 54.1 per cent. The nematode is distributed in India, Bangladesh, Sri Lanka, Japan, Indonesia, Taiwan, Former USSR, Italy, Cuba and Madagascar.

Plant parasitic nematodes cause serious damage to rice crop. Thirty two species belonging to 13 genera were observed in association with the crop. Among them few are considered to be important. They are the rice white - tip nematode (Aphelenchoides besseyi), rice stem nematode (Ditylenchus angustus), rice root nematode (Hirschmanniella oryzae), root-knot nematode
(Meloidogyne graminicola) and the cyst nematode (Heterodera oryzicola).

Introduction

Plant parasitic nematodes occur wherever plants grow. These nematodes are referred to as plant pathogenic when they cause crop losses by direct injury to roots, stems, leaves and seeds. A large number of plant parasitic nematodes have been found associated with fruit crops in all over India but pathogenisity has not been proved for all. Most of commonly occurring nematodes belong to genera Meloidogyne spp., Pratylenchus spp., Rotylenchulus spp., Hoplolaimus spp., Tylenchulus spp., Xiphinema spp., and Radopholus spp. etc. The nematodes damage the crops not only by feeding on plants but also by interacting with various other organisms like fungi, bacteria and viruses etc. Estimated overall average annual yield loss of the world’s major crops due to damage by plant parasitic nematodes was 12.3%. Estimated annual crop losses in India have been accounted to Rs. 242.1 billion. The crop losses due to nematode pests are not only in the form of reduced plant growth and yield but are also in the marketable quality of the produce.

Most of the plant parasitic-nematodes (PPNs)are worm-shaped microscopic animals. They are virtually invisible through naked eyes when present in soil or plant materials. It has been estimated that of the known nematode species, approximately 50% are free-living found in soil and fresh water, 25% are marine (found in sea water), 15% are animal parasites, and 10% are plant-parasites (Walia and Bajaj, 2004; Sasser and Freckman, 1987). Free living nematodes contribute to maintain the soil bio-dynamic system, by influencing microbial colonization of substrates and mineralization of nutrients (Neher, 2001), whereas PPNs feed on plants and reduce crop growth and yield efficiency. Among the PPNs, a few nematode species feed on aerial plant parts (leaves, stems, flowers and seeds), but the majority of feed on underground plant parts (roots, bulbs, and tubers).

Citrus (Citrus spp.)

Citrus is an important fruit crop and ranks third in area which is followed by mango and banana. They are grown in 105,396 hectares in India. Among the oranges, mandarin oranges, limes and sweet oranges are very popular while lemons, grape fruits, pummelos, sour and bitter oranges are of minor importance. The Citrus spp. are grown in larger extent in the states of Maharashtra, Karnataka, Kerala, Tamil Nadu, Andhra Pradesh, Punjab, Haryana, Rajasthan, Assam, Orissa and Bihar.

Nematode menace in citrus gardens are very much realised. In 1912 the citrus nematode, Tylenchulus semipenetrans was reported from California and found to cause ‘slow decline’ disease. More than 30 genera of plant parasitic nematodes are associated with the Citrus spp. Among them, Tylenchulus semipenetrans, Radopholus citrophilus, Meloidogyne spp. Pratylenchus spp. Xiphinema spp. and Hoplolaimus spp. are often associated with the crop.

Citrus is an important fruit crop and ranks third in area which is followed by mango and banana. They are grown in 105,396 hectares in India. Among the oranges, mandarin oranges, limes and sweet oranges are very popular while lemons, grape fruits, pummelos, sour and bitter oranges are of minor importance. The Citrus spp. are grown in larger extent in the states
of Maharashtra, Karnataka, Kerala, Tamil Nadu, Andhra Pradesh, Punjab, Haryana, Rajasthan, Assam, Orissa and Bihar.

Crop productivity is largely affected by the several factors; however, biotic stress factor is one of the major concerns. Horticultural crop productivity is low in India as compared to other countries for many reasons including pest problems. Plant parasitic nematodes is one of the potential threat for cultivation of some important crops- root knot and reniform nematodes in vegetables; burrowing nematodes in banana, spices and plantation crops; citrus nematode in citrus; cyst nematodes in potato, foliar and lesion nematodes in flowers etc.

Black Pepper

Black pepper (Piper nigrum) is indigenous to the tropical forests of Western Ghats of South India. The crop is grown in Kerala, Karnataka, Tamil Nadu, Andra Pradesh and Assam.

The root-knot nematode, Meloidogyne incognita and the burrowing nematode, Radopholus similis are important pests of this crop. The root-knot nematode infested vines show yellowing of lower leaves and the leaves loose natural luster. The yellowing of leaves gradually progresses upwards. The affected vine leaves become flaccid and wither. The infested plant root show root galls of varying sizes.

The burrowing nematode also causes serious damage to the vine. Var der Vecht (1950) first reported slow wilt in this crop due to R.similis infestation in Indonesia. The nematode in association with Fusarium and Rhizoctonia causes serious damage to the crop.

Black pepper (Piper nigrum) is indigenous to the tropical forests of Western Ghats of South India. The crop is grown in Kerala, Karnataka, Tamil Nadu, Andra Pradesh and Assam.

Potato

Potato is one of the most important vegetable crop grown in India. It thrives best in cool climate. Therefore it is a summer crop in the hills and a winter crop in plains.

Twenty seven species of nematodes have been reported on potato among them the cyst nematodes (Globodera rostochiensis and G. pallida) and the root-knot nematodes (Meloidogyne incognita, M. javanica and M. hapla) are important in India.

Cyst nematodes (G.rostochiensis and G. pallida)

In India, the cyst nematode menace on potato was first reported by Dr. Jones during 1961 from Nilgiri Hills.

Geographical distribution

The potato cyst nematode is distributed in Central, South and North America, Europe, Iceland, Western USSR and South Africa.

In India it is distributed in Nilgiri and Kodai Hills and in New Delhi.

Potato is one of the most important vegetable crop grown in India. It thrives best in cool climate. Therefore it is a summer crop in the hills and a winter crop in plains.

Introduction

Agricultural soils harbour a rich variety of nematode fauna, where they coexist with a myriad of other microorganisms. It has been estimated that one cubic meter soil of highly fertile field may contain as many as 3×10¹⁴ bacterial cells (300 g), 5×10⁸ protozoa (39 g), 1×10⁷ nematodes (12 g) and fungi (400 g), besides other organisms. The nemic fauna comprises of free-living (saprophagous and microbivorous), predatory forms and plant parasites (phytophagous). In addition, certain animal and insect parasitic forms may spend a part of their life cycle in soil. Plant parasitic nematodes (PPNs) exist in poly-specific communities and attack all types of plants- cultivated or wild. They possess a needle-like stylet or spear at their anterior end, which is used to puncture the plant cells and ingest the cell contents. Majority of PPNs dwell in soil and draw their nutrition from plant roots. Only a few forms attack the above ground plant parts such as stem, leaves, inflorescence and seeds. PPNs may be ectoparasites (feed from outside and do not enter plant tissues) or endoparasites (enter inside the plant tissues). The endoparasites spend a part of their life cycle in soil or may come out into the soil to re-infect the other roots. These may be further categorized into migratory or sedentary types. The migratory forms keep on moving, feeding and laying eggs that are scattered in soil or plant tissues. The sedentary nematodes are more harmful and a particular stage of their life cycle infects the plant and establishes a feeding site by modifying plant tissues by their enzymatic secretions. The females of sedentary nematodes usually attain swollen shapes upon maturity and lay hundreds of eggs in clusters.

Plant parasitic nematodes are ubiquitous, and so far, more than 1800 species have been recorded. They are obligate parasites and must feed upon plant hosts, thus, debilitating the plants to some extent. The extent of direct damage by the nematodes to plants depends on several factors viz., nematode density in soil, nature of parasitism (ectoparasite or endoparasite), host susceptibility, cropping pattern, edaphic factors (mainly soil texture and moisture) and ambient climatic conditions (like temperature and relative humidity). Nematodes, by themselves, rarely kill the plants to ensure their own survival. Nematodes also inflict considerable indirect damage to crops by interacting with other plant pathogens (fungi, bacteria and viruses) to cause disease complexes in which nematodes act as incitants, aggravators, or vectors.

Introduction

Seed spices have prominent place in India’s national economy because of their very high domestic consumption and growing demand for export. This group of spices, being consisting of mostly annual crops, is grown extensively in rotation with food and cash crops and also as inter crops under rain fed as well as irrigated conditions.

There are about 20 seed spice crops grown in India. Out of which nine are important in terms of production and export. The most important ones are coriander, cumin, fennel and fenugreek (major seed spices) and ajowain, aniseed, black cumin, celery and dill (minor seed spice crops). Although these crops are grown all over India but Haryana, Rajasthan, Madhya Pradesh, Uttar Pradesh, Orissa, Tamil Nadu and Andhra Pradesh are the main seed spice growing states.

Nematodes are invertebrate roundworms that inhabit marine, freshwater and terrestrial environments. They comprise the phylum Nematoda or Nemata, which includes parasites of plants and of animals, including humans, as well as species that feed on bacteria, fungi, algae, and on other nematodes. Four out of every five multicellular animals on the planet are nematodes. All nematodes may look alike, the smallest being scaled down versions of the largest. The phrase tube-within-a-tube is a convenient way to think of nematode body structure and also a term used to refer to a major trend in the evolution of triploblastic metazoa. It refers to the development of a fluid-filled cavity between the outer body wall and the digestive tube. The nature of this body cavity has led to the grouping of metazoa into three grades, acoelomate, pseudocoelomate and eucoelomate. Nematodes together with Rotifera, Gastrotricha, Kinorhyncha, Nematomorpha, Acanthocephala and Entoprocta are traditionally grouped together as pseudocoelomates on the basis of possessing a body cavity that is not formed from the mesoderm or fully lined by peritoneum.

Introduction

A. Common species of nematodes encountered in poultry are:

1. Syngamous trachea (in the respiratory tract) large 2.00cm size live in the trachea and larger bronchi. Many species of domestic and wild birds are affected. Dyspnea, gasping and head shaking are main clinical signs. Treatment is difficult.
2. Ascaridia galli (in the intestine) They parasitize chicken, turkey, pigeon, quail and guineas. In younger birds parasites cause enteritis. In heavily infected birds clinical signs are emaciation and diarrhea.

2.1. Rice

2.1.1. Rice root knot nematode (Meloidogyne graminicola)

1. Symptoms

6.1 Nematodes as Biological Models
A model organism can be a non-human species (e.g., microbe, plant, or animal) with extensive genomic research data. These organisms are used to study and understand specific biological phenomena, with the expectation that discoveries made in these models will provide new insights into “big biological questions” (Semprucci et al., 2025). Model organisms are widely employed to explore potential causes and treatments for human diseases when direct experimentation on humans is unfeasible or ethically problematic. This approach is supported by the common descent of all living organisms, as well as the conservation of metabolic and developmental pathways and genetic material over the course of evolution. The use of model organisms is not confined to biomedical research. Significant advancements in developmental biology, eco-toxicology, fertilization processes, speciation, symbiosis, and sexual selection have been achieved using these models. Furthermore, emerging animal models—species with less neurological complexity than those protected by legislation—are increasingly recognized as a valid application of the Three Rs principle (Replacement, Reduction, and Refinement). To support this approach, databases of invertebrate species currently used or with potential applications in biomedical research are continually being developed and updated.
Nematodes, particularly Caenorhabditis elegans, are widely used as model organisms in biological research due to their simplicity, ease of study and shared biological processes with other animals, including humans. C. elegans, a small, free-living nematode, has a short life cycle, a known number of cells and a well-mapped genome, making it an ideal system for studying developmental biology, genetics and other aspects of animal biology.

6.1 Nematodes as Biological Models
A model organism can be a non-human species (e.g., microbe, plant, or animal) with extensive genomic research data. These organisms are used to study and understand specific biological phenomena, with the expectation that discoveries made in these models will provide new insights into “big biological questions” (Semprucci et al., 2025). Model organisms are widely employed to explore potential causes and treatments for human diseases when direct experimentation on humans is unfeasible or ethically problematic. This approach is supported by the common descent of all living organisms, as well as the conservation of metabolic and developmental pathways and genetic material over the course of evolution. The use of model organisms is not confined to biomedical research. Significant advancements in developmental biology, eco-toxicology, fertilization processes, speciation, symbiosis, and sexual selection have been achieved using these models. Furthermore, emerging animal models—species with less neurological complexity than those protected by legislation—are increasingly recognized as a valid application of the Three Rs principle (Replacement, Reduction, and Refinement). To support this approach, databases of invertebrate species currently used or with potential applications in biomedical research are continually being developed and updated.
Nematodes, particularly Caenorhabditis elegans, are widely used as model organisms in biological research due to their simplicity, ease of study and shared biological processes with other animals, including humans. C. elegans, a small, free-living nematode, has a short life cycle, a known number of cells and a well-mapped genome, making it an ideal system for studying developmental biology, genetics and other aspects of animal biology.

14.1 Model Organism: A model organism is a species that has been widely studied, usually because it is easy to maintain and breed in a laboratory setting and has particular experimental advantages. Model organisms are non-human species that are used in the laboratory to help scientists understand biological processes. They are usually organisms that are easy to maintain and breed in a laboratory setting. For example, they may have particularly robust embryos that are easily studied and manipulated in the lab, this is useful for scientists studying development. They may occupy a pivotal position in the evolutionary tree, this is useful for scientists studying evolution.

Introduction

Nematodes are cosmopolitan and ubiquitous in occurrence. These have been reported in all kinds of ecological niche. Accordingly, different kinds of nematode fauna had evolved with distinct morphological features and physiological variability. However, development and perception keep changing with the ambient environment. Agriculture has progressed with leap and bounce as human being has managed this to its maximum utility. The fast changes in agriculture definitely influenced the ecological niche and affected the flora and fauna. Consequently, specific and unspecific kind of relation evolved between host and parasite. With the thumb rule of ecological balance or homeostasis. In the dynamic Mother Nature, multispecies heterogeneous complex is sustained and nature do not perpetuate homogeneity.

Introduction

Plantation crops are high value commercial crops which are broadly classified as estate crops consisting of crops like tea, coffee and rubber and small holders plantation crops like coconut, cashew, arecanut, cocoa etc. Spices especially black pepper, cardamom, vanilla, tree spices like clove, nutmeg, cinnamon and allspice are generally grown as mixed crops in perennial cropping systems. In India, plantation crops including spices are grown in an area of three million hectares and generate an annual income of more than Rs, 5,53,630 million. They are valued for multifarious uses to meet the human needs such as food, oil, industrial raw materials, beverages and confectionary items. Pests and diseases are the major limiting factors in increasing the productivity of these crops. Among the pests, nematodes have got a major role in devastating the pepper plantations by the involvement in slow wilt disease, nematode diseases of cardamom nurseries, root-knot nematode infestation in ginger, turmeric, clove, nutmeg, allspice, lesion nematode infestation in tea, coffee, etc.

Sampling for nematode population estimation

Sampling for nematode communities has been the basis for the development of appropriate control strategy. The major purposes of sampling for nematodes include population estimation for general detection, advisory or predictive programme, disease diagnosis and also for research purposes.

Plant parasitic nematodes are usually confined to top 20-25 cm soil and may vary depending upon the soil type, moisture content, host plant and climatic condition. Surface soil do not harbour any nematode. The roots and rhizosphere of severely infested plants do not harbour numerous nematodes as the nematodes tend to move to adjacent healthy plants. Hence soil and root samples need to be collected from plants showing partial symptoms. Samples should not be collected from dead or wilted plants.

Sampling for nematode communities has been the basis for the development of appropriate control strategy. The major purposes of sampling for nematodes include population estimation for general detection, advisory or predictive programme, disease diagnosis and also for research purposes.

‘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.

To tackle modern-day challenges and attain a sustainable growth while managing farm enterprises, the farmers have to undergo rigorous behavioral change to transform themselves as entrepreneur. Thus, the present chapter deals with incorporating an understanding about the idea of an entrepreneur and entrepreneurship and the organization level, present status and promotional opportunities of FPOs.

2.1 Who is an Entrepreneur?

An entrepreneur is someone or a group of individuals who conceptualize, start, and sustain for a long enough period of time a social organization that provides financial rewards, or, to put it another way, who see a business opportunity and create a firm to pursue it. (Cole,1968)

Abstract

Satellite imagery interpretation has shown the existence of a major Palaeochannel system in the Great Indian desert. These palaeochannels belong to the mythological Sarasvati river, which seems to have flowed southwesterly close to the Aravalli hill ranges and joined the sea in the Great Rann of Kutch. Subsequently it seems to have shifted northwesterly, and more precisely in an anti-clockwise direction and got buried in the desert in Anupgarh plains. While its oldest course is the now misfit Luni river, its final trace is now represented by Ghaggar river. Whereas its overall northwesterly migration is attributed to NE-SW trending cymatogenic arching along the Great Rann of Kutch in the southwest to the Siwalik hills in the northeast, its multivariate palaeodrainage is attributed to block faulting and land subsidence in the Bikaner sector.

Introduction 
NEP was announced by Sri Narendra Modi, the PM of India on July 29,2020. The system was introduced after the debates by experts from various fields. The earlier education system was 10+2+3 which changed to 5+3+3+4.The NEP 2020 have less curriculum contents and increases learning, reasoning and logical skills. After the completion of UG courses in the higher education they may opt for the Research Methodology. The 5+3+3+4 design is equivalent to the age groups 3-8 years, the foundational stage which is mainly based on play or activity based learning, 8-11 years, the preparatory stage which is based on play, discovery, activity based and interactive classroom learning, 11-14 years, the middle stage is based on experiential learning in Science, Mathematics, Arts, Social Science and Humanities and 15-18 years, the secondary stage emphasized on multidisciplinary study, greater critical thinking, flexibility, student choice of subjects. Government will constitute a Gender Composition plan to provide equal and standard education to all girls and third gender learners. 10th and 12th standard students are no longer to sit for board exams which will be accessible to test core competencies rather than memorised facts with all students allowed to take the exam twice. Internships will be started from 6th standard. The teaching upto 5th standard will be in regional languages and mother tongue. The assessment covers reforms with 360 degrees overall progress report tracking the progress for achieving learning outcomes. Within 2030, the B.Ed degree duration will be 4 years. The holistic U.G education will be having several exit options and certification will be provided.

1. Introduction to Nepal and its Agriculture

1.1. Geography

Nepal is a country of enormous geographical diversity, and is situated in the southern slopes of the central Himalayas, which spreads over an area of 1,47,181 square kilometers. Sandwiched between India on three sides- east, west, and south – and China to the North, Nepal is a land-locked country (CBS,2003).
 
Geographically, the country is broadly divided into five roughly parallel east-west regions (ecological belts), which from north to south are known as High Mountains, Mountains, Hills, Siwaliks  and Tarai. With altitudes ranging from less than 100 m in the Tarai to 8,848 m in the High Mountains, there exist different climates and different types of farming systems within Nepal. As a result of these diversities, a wide variety of crops, vegetables and fruits are produced.
 
For administrative and developmental purposes, Nepal is divided  into 75 districts. Each district is further divided into Village Development Committees (VDCs) in rural areas and municipalities in urban areas. At present, there are 3,913 VDCs and 58 municipalities in Nepal.

Nerium oleander

? (Oleander, kaner, rose laurel)

? An ornamental plant and grown in lawns and gardens.

? Other species are Nerium indicum (kaner) & Thevetia peruviana (yellow oleander).

Sources

? Almost all animal species are poisoned.

? Ingestion of branches, stem or leaves during drought or periods of food scarcity or consumption of contaminated water by ruminants or horses.

? Chewing of leaves may be responsible for toxicity in dogs.

? Ingestion of 30-60 gram fresh leaves of oleander is fatal for horses, cattle and sheep.

? All parts of plant are toxic, the leaves and flowers may be less toxic than the seeds.

Nerium (Nerium oleander L.) belongs to family Apocynaceae is a Mediterranean evergreen shrub characteristic of watercourses, gravely places and damp slopes (Portis et al., 2004 and Herrera, 1991). The first Oleanders came to subtropical Galveston in 1841. Joseph Osterman, a prominent merchant, brought them from Jamaica. After distributing these oleanders, these new plants were growing throughout the city. Later as early as 1908, an editorial in the Galveston Tribune observed that the oleander was emblematic of Galveston. In 1910, The Galveston Daily News also reported that Galveston was known throughout the world as “The Oleander City” and in 1916, an article named it one of the most beautiful cities in the South. It is widely grown as an ornamental in warm temperate and subtropical regions, due to its abundant and long-lasting flowering and moderate hardiness. It is used for screens, hedging along highways, planting along beaches and in urban areas as, by removing suckers and leaving just a few stems, it can also be formed into very attractive small trees (Portis et al., 2004). Nerium oleander is among the most toxic of all ornamental plants. More than fifty toxins have been isolated, including cardiac glycosides, general cell toxins and the strychnine-like compound rosagenin. The ancient city of Volubilis in Morocco took its name from the old Latin name for the flower.

Nerium (Nerium oleander L.) belongs to family Apocynaceae is a Mediterranean evergreen shrub characteristic of watercourses, gravely places and damp slopes (Portis et al., 2004 and Herrera, 1991). The first Oleanders came to subtropical Galveston in 1841. Joseph Osterman, a prominent merchant, brought them from Jamaica. After distributing these oleanders, these new plants were growing throughout the city. Later as early as 1908, an editorial in the Galveston Tribune observed that the oleander was emblematic of Galveston. In 1910, The Galveston Daily News also reported that Galveston was known throughout the world as “The Oleander City” and in 1916, an article named it one of the most beautiful cities in the South. It is widely grown as an ornamental in warm temperate and subtropical regions, due to its abundant and long-lasting flowering and moderate hardiness. It is used for screens, hedging along highways, planting along beaches and in urban areas as, by removing suckers and leaving just a few stems, it can also be formed into very attractive small trees (Portis et al., 2004). Nerium oleander is among the most toxic of all ornamental plants. More than fifty toxins have been isolated, including cardiac glycosides, general cell toxins and the strychnine-like compound rosagenin. The ancient city of Volubilis in Morocco took its name from the old Latin name for the flower.

Nerium (Nerium oleander), commonly known as oleander or Kaner, is an evergreen flowering shrub cultivated for loose flowers, landscaping and religious uses. Its flowers are widely used for garlands and temple offerings, while the plant is valued in landscaping because of its drought tolerance and adaptability to poor soils. The chapter presents its origin, distribution, genetics, botanical description and important varieties. It explains climate and soil requirements, propagation, planting, nutrient management, irrigation, pruning and other cultural operations. Pest and disease management is also covered. Special attention is given to harvesting fully open flowers, postharvest handling and shelf-life improvement. The chapter also discusses yield and the plant’s toxic nature.

Brachial plexus (FIG. 5-5 A)

The fore limb is supplied by nerves that extend from the brachial plexus. The brachial plexus is a large wide, flat and thick fascicular anastomosis of nerves formed by the convergence of ventral branches of last three cervical and first two thoracic spinal nerves in ox. It is placed between the scalenus muscle on the lateral wall of thorax and subscapularis and deep pectoral muscles on the costal (medial) surface of the scapula. From this plexus extend the following eleven branches (nerves) which are distributed mainly to the fore limb (thoracic limb) and most of the muscles of the thoracic girdle.

The nerves of the head connect the central nervous system i.e. brain with the structures like skin, muscles, glands, blood vessels, organs of special senses etc. so as to monitor or control their functioning. These nerves are the cranial nerves and their branches. There are twelve pairs of cranial nerves.

Olfactory nerve (Cranial nerve I)

The olfactory nerve is the first cranial nerve and is known as the nerve of sense of smell. It consists of fibres which are the axons of olfactory cells of olfactory part of nasal mucous membrane. These fibres are nonmedulated and they form number of small bundles which are enclosed into connective tissue sheaths derived from the meningeal layers of the brain. These nerve fibres bundles pass caudally upward through the cribriform plate of the ethmoid bone and enter the cranium to join the olfactory bulbs of the brain. Besides the olfactory nerve bundles there are two more nerves that extend from the nasal mucous membrane, traverse through the cribriform plate and join the parts of the brain. These include the vomeronasal nerve that is formed by the nerve fibres arising on the vomeronasal organ and terminating on the accessory olfactory bulb of the brain. The other one is the terminal nerve that after reaching the brain joins the olfactory trigone.

Pelvic (Lumbosacral) plexus

The hind limb is supplied by the nerve branches extending from the Pelvic (lumbosacral) plexus (Fig. 6-4 A and B) which is formed by the convergence of the ventral divisions of the last three lumbar and first two sacral nerves. It is formed in two parts, the cranial and caudal. The two parts are connected by anastomotic branches. The cranial (lumbar) part is formed by the fourth and fifth lumbar nerves and lies between the psoas major and psoas minor muscles while the caudal (sacral) part is formed by the sixth lumbar and first and second sacral nerves. Some times a root from third sacral also joins this part. It lies on the pelvic surface of the sacrosciatic (ischial) ligament. The nerves extending from the cranial part of the plexus are the lateral cutaneous femoral, the femoral and the obturator. The nerves extending from the caudal part are the cranial gluteal, caudal gluteal and the sciatic (ischiatic).

Lateral cutaneous femoral nerve

The lateral cutaneous femoral nerve while leaving the cranial part of the plexus, receives fibres from the fourth lumbar nerve, passes caudally between the psoas major and psoas minor muscles and reaches the tuber coxae. Here it perforates the obliquus abdominis externus muscle in company with the circumflex iliac artery and reaches the skin of the lateral aspect of the thigh. In this course, the nerve supplies the psoas major, psoas minor, iliacus and external oblique muscles of the abdomen and the skin and cutaneous muscle on the lateral face of the thigh.

There are eight pairs of cervical spinal nerves in ox. The first of these emerges out through the lateral vertebral (alar) foramen of the atlas vertebra. The second through the lateral vertebral foramen (at the cranial border of the arch) of the axis vertebra and the eighth nerve emerges through the intervertebral foramen between the last cervical and first thoracic vertebra. The third to seventh nerves emerge through the corresponding intervertebral foramen. Each of these nerves divides into dorsal and ventral branch immediately after their exit from the vertebral canal through respective foramina. The dorsal branches are larger than the ventral except for the first and last two and most of them divide in to medial and lateral branches. They supply the dorsal (dorsolateral) cervical muscles, skin and the cervical part of the nuchal ligament. The ventral branches are distributed to the ventral cervical muscles and skin, The ventral branches of the last two cervical nerves are large.

Lumbar nerves

There are six pairs of lumbar spinal nerves. Each of these, after emerging out of the intervertebral foramen, gives out firstly a meningeal branch which reenters the vertebral canal through the intervertebral foramen and supplies the meninges. Next to this it furnishes the ramus communicans to the sympathetic chain ganglion. After this, the lumbar spinal nerves divide into dorsal and ventral branches. The dorsal branches are smaller and they supply the muscles and skin on the loins and croup. The ventral branches are larger and they slightly differ from each other in their course and distribution. In their initial course, they pass under the psoas minor and psoas major muscles emerge at the lateral border of the psoas major and supply branches to the sublumbar muscles. Hereafter, they differ in their course and distribution.

The ventral branch of the first lumbar nerve passes on the medial face of the quadratus lumborum, runs down the medial face of the transversus abdominis, the obliquus abdominis internus and externus and finally reaches the rectus abdominis, supply all these muscles and the skin on the lateral wall and the floor of the abdomen.

The ventral branch of the second lumbar nerve has two divisions. The cranial division passes ventrally and caudally to reach the external angle of the ilium, supplies branches to the oblique muscles of the abdomen and the skin over this region and terminates in the rectus abdominis muscle. The caudal division passes caudally and laterally under the quadratus lumborum, supplies branches to the muscles and skin at the flank region and then crosses the circumflex iliac vessels. Here it joins a similar branch of the third lumbar nerve and forms the genitofemoral nerve.

Spinal nerves

The thoracic spinal nerves are thirteen pairs in ox. These are named and numbered according to the vertebra caudal to which they emerge from the vertebral canal. They emerge from the vertebral canal through the respective lateral vertebral (intervertebral) foramina. Each nerve, after its emergence, divides into dorsal and ventral branches. Each dorsal branch passes up dorsally between the transverse processes of the vertebrae and divides in to medial and lateral branches. The medial branch passes upward and supplies the dorsal muscles of the back. The lateral branch passes laterally on the deep surface of the longissimus dorsi muscle. At the lateral border of this muscle it passes between this and longissimus costarum muscles and becomes a cutaneous nerve which divides into ascending and descending branches supplying the muscles and the skin of this region.. Before its division, the lateral branch supplies muscular branches to the longissimus dorsi and longissimus costarum muscles.

The ventral branches continue ventrally as intercostal nerves. The first and second thoracic nerves, before their continuation as intercostal nerves, give out a branch to the brachial plexus. At a short distance from the spinal nerve, the ventral branch of each of these nerves is connected to sympathetic trunk by a ramus communicans containing preganglionic and postganglionic sympathetic fibres. The intercostal nerves run down ventrally through the intercostal spaces, lying between the external and internal intercostal muscles close to the caudal border of the respective rib and in company with the intercostal vessels. Along this course they supply these muscles. After a variable distance, the intercostal nerves and vessels traverse through the internal intercostal muscles and become subpleural in position. The second to eighth nerves end in the transversus thoracis muscle. The rests behind these end in the rectus abdominis and other abdominal muscles and the skin in this region.

25.1 Introduction

All fishes have a similar nervous system organisation. Meninx primitive is a single protective covering that covers the brain and spinal cord. The brain varies in size about the body in different species and does not occupy the entire cranial cavity (Fig. 25.1).

25.2 The Brain

Except for elasmobranchs, which have larger brains, the relative ratio of the brain has been observed to be fairly constant in all fishes. The brain-body weight ratio, also known as the cerebro-somatic index (CSI), is calculated as follows. 

Various activities of the body in different external environmental conditions are co-ordinated by the appropriate message from the neurons due to the stimuli from the environment. These messages pass in the form of impulses through the co-ordinated links between a number of neurons or nerve cells. The constant passage of messages require a very little energy but high level of O₂ .There is interaction between the nervous and endocrine system with the areas of interchange among the two systems. Some neurons show the action of both the systems and thus termed as neurosecretory or neuro-endocrine. Fishes have a well-developed nervous system. Broadly the nervous system can be divided into central nervous system (CNS) and peripheral nervous system (PNS).The brain and spinal cord are the parts of the CNS. The motor and sensory nerves link the receptor and effector organs. All nerve tissues other than brain and spinal cord are grouped under PNS. Peripheral nervous system consists of nerves, ganglia and receptors. The nerves carry sensory information from special receptor organs like eyes, internal ear etc. to the integrating centers of the brain and spinal cord. The PNS also carries information via different nerve cells from the integrating centers of the brain and spinal cord. This coded information is carried to the various organs and body systems, such as the skeletal muscle system for appropriate action in response to the original external and internal stimulus. The PNS can be divided into somatic and visceral. The term visceral is sometimes used in referring to the autonomic or involuntary nervous system (ANS), controlling visceral functions. The ANS helps to co-ordinate the activities of many glands and organs, and it is closely connected to the integrating centers of the brain.

All animals, including domestic animals and humans, depend entirely on their sense organs and nervous system for information about external environment and the internal status of their bodies. Sensory inputs, together with the genetically inherited organization and properties of the nervous system is responsible for the all knowledge and determines how each animal behaves.

Nervous system may be viewed as an anatomical arrangement of neurons with a large number of different kinds of synapses through which sensory information from the periphery of the body is transmitted through numerous sensory neurons to a set of neurons in a central region of the body, where the information is integrated and from which impulses are then directed out through numerous motor neurons to effectors.

The central nervous system is distinguished from the peripheral nervous system in that it is made up of a concentration of tracts, ganglia and nuclei. Thus nervous system is a structural and functional mechanism involved in the coordination of an animals responses to internal and external environment.

Neurons : The central and peripheral portion of the nervous system are comprised of nerve cells (neurons) and supporting tissues.

Supporting tissues : The supportive tissues of the peripheral nervous elements consist primarily of connective tissue and specialized cells called neurolemma or Schwann cells. The supportive tissues of central nervous system are glia cells or neuroglia. These cells have functional and nutritive roles in addition to their roles as supportive tissue.

Towards the end of the third week of embryological development, the notochord induces the overlying columnar ectodermal cells of the embryonic disc to become pseudostratified neuroepithelial cells and form a spoon shaped thickening of dorsal ectoderm called the neural plate. The cranially expanded region of the neural plate forms the primordium of the brain, while the narrower region caudal to the brain gives rise to spinal cord.

The raised lateral edges of the neural plate form the neural folds while the depressed midline region of the plate forms the neural groove. Cellular proliferation at the medial aspects of the neural folds causes these structures to gradually approach each other in the midline, meet and fuse, forming the neural tube which encloses a central neural canal.

A neuron is the basic unit of nervous tissue. It is specialized for the function of reception, integration and transmission of information in the body. The nerve cells are excitable, i.e. capable of generation of electrical impulses at their membranes. The electrical impulses generated in the excitable tissues, in most instances, can be used to transmit signals along the membranes.