eChapters

3.1. Origin and distribution

• Originated from Sri Lanka.

• Cultivated throughout tropics.

• Presently maj or producers - China, Vietnam, Indonesia, Argentina, Taiwan, Sri Lanka, Brazil, Madagascar and India.

3.2. Economic importance

• Two types of citronella oil: Java citronella oil obtained from Cymbopogon winterianus which is superior.

• Another is Ceylon citronella oil which is obtained from Cymbopogon nardus inferior type oil.

• Citronella oil - essential oil containing citronellal, geranial and hydroxy citronellal and high value perfumery bases obtained on steam distillation of citronella grass.

• Used for perfuming soaps, detergents, cosmetics, agarbattis and for making mosquito repellent creams.

Scientific name: Cymbopogon spp.
Family: Poaceae
Citronella was first introduced in India in 1959 from Indonesia, specifically from Java Island, which is why it is also known as Java citronella. This fragrant grass, belonging to the Poaceae family, yields essential oils when steam-distilled. The resulting citronella oil (Cymbopogon winterianus Jowitt) is widely used globally in various industries, including flavoring, soap, perfumery, and cosmetics. There are two main types of citronella: Ceylon and Java. The species C. nardus yields Ceylon-type oil, while C. winterianus yields Java-type oil. Java-type oil
is preferred over Ceylon-type oil due to its higher citronellal content, ranging from 30-38% compared to 20-25% in Ceylon-type oil.
Origin and distribution
Citronella originated in tropical Asia, specifically in Indonesia (Java Island) and Sri Lanka. Today, it is cultivated in many tropical and subtropical regions worldwide. In India, citronella is grown in several states, including Maharashtra, Uttar Pradesh, and Madhya Pradesh. It is also cultivated in other parts of Southeast Asia, such as Malaysia, the Philippines, and Thailand. Citronella is also grown in Africa, Central and South America, and the Pacific Islands, where the warm and humid climate provides ideal conditions for its growth.

Introduction

Citrus is one of the most important fruit crops in the world. Citrus fruits are grown in the tropical and subtropical regions of the world. Some of the important countries where these fruits are grown include USA, Brazil, Spain, Israel, South Africa, Australia, China, India, Mexico and Morocco. Citriculture as a garden industry dates back to less than one hundred years. Indian citrus industry is the third fruit industry after mango and banana. The important groups of crops in citrus are sweet oranges, mandarins, limes, lemons, grapefruits and pummelo (Singh, 2001). Total world citrus production is about 115525.2 thousand tonnes, whereas in India, the production of citrus fruits is 8267.2 thousand tonnes (Anonymous 2012). The most important commercial Citrus species grown in India are the mandarin (Citrus reticulata Blanco), followed by sweet orange (Citrus sinensis Osbeck) and acid lime (Citrus aurantifolia Swingle). The main cultivars in the mandarin group are the Nagpur mandarin, Coorg mandarin, Khasi mandarin, Hill mandarin and the Kinnow mandarin. Maharashtra, Karnataka, Andhra Pradesh and Punjab are the major citrus producing states, while in Haryana, Uttar Pradesh, Madhya Pradesh, West Bengal, Tamil Nadu, Gujarat and Bihar, the fruit is grown to a limited extent. In Rajasthan new plantation of citrus are coming up very well and the main cultivars are Nagpur and Kinnow mandarins.

1. Gummosis.
Diagnosic Symptoms
• First symptoms are dark staining of bark which progresses into the wood.
• Bark at the base is destroyed resulting in girdling and finally death of the tree.
• Bark in such parts dries, shrinks and cracks and shreds in lengthwise vertical strips.
• Later profuse exudation of gum from the bark of the trunk (characteristic symptom).
• The infection spreads both upward to the leaves and even fruits and downward to the roots causing fibrous root rot.
• The fibrous root rot destroys a major portion of the root system.
• However, the trunck and root infections may usually result in ultimate drying of the tree (Fig-1).
Etiology
Scientific Classification
Kingdom : Fungi
Division : Eumycota

Cultivation of citrus holds promise in arid irrigated tracts. The major citrus fruits under cultivation in arid regions are acid lime , lemon, Kinnow, Mandarin hybrid, sweet orange and grapefruit .Acid lime and kinnow are widely grown. Citrus fruit are grown  through out country for its  nutritive and medicinal value (Chadha, 2001) . Citrus is world’s leading fruit crop. In India, it is cultivated in the states of Maharashtra, A.P., Punjab, Rajasthan, H.P., U.P., M.P., Karnataka, T.N., J&K., Odisha, Gujarat, Assam, & Sikkim, For obtaining quality plant material, propagation is an important aspect. Citrus is largely propagated   by budding except kagzi lime which is raised from seeds because of occurrence of polyembryony and sweet lime which is  commercially  propagated by stem cuttings. Kagzi lime and lemon can also be propagated by layering. In case of citrus the availability of proper plant material is very much essential.

SUMMARY

Citrus is third most important fruit crop in India after banana and mango. Citrus crops have occupied an area of 8.43 lakh ha with total production of 75.7 lakh tons and the productivity of 9.9 tons/ha in India. Such a quantum of citrus production contributes 13 per cent of total fruit production demonstrating the significance of citrus in horticultural research and development in India. Rootstocks are known to have profound effect on the vigour, precocity, productivity, internal quality, and longevity of the scion varieties grafted on them. They are also known to influence the susceptibility of trees to various diseases and insects. Furthermore, it is recognized that optimum performances depends on the proper selection of rootstocks for a given set of growing conditions. The most commonly and widely used citrus rootstocks in India are Rough lemon, Cleopatra and Pectinifera. Rough lemon (Jatti Khatti) is the most important and widely used rootstock in the country for most of the scions followed by Kharna Khatta being more popular in Uttar Pradesh. While the problem of rootstock selection is important in all major fruit crops, it is of even greater importance in citrus due to tristeza virus disease now present in many areas of the world. It is also possible that citrus decline in India may be due partly to stionic incompatibilities. This chapter deals with problems and prospects of rootstocks in citrus in India, particularly related to horticultural aspects, insect-pests, diseases, nematodes, physiological disorders, post harvest quality, aspects related to tissue culture and rootstock breeding.

The research work carried out throughout citrus growing countries of the world including India showed utility of different rootstocks for citrus plants, which varies greatly with scion variety and agro-climatic condition. A wide range of citrus rootstocks are available, each having desirable attributes. The success of a rootstock is determined by its tolerance to prevailing conditions of soil, climate and diseases. Citrus plants are unusual in that many species and cultivars including the commercial rootstocks reproduce true to type from seed. Commercial citrus rootstocks are usually highly polyembryonic but there can be 1-40 zygotic seedlings in the seedbed.

Citrus fruits are originated in the tropical and sub tropical regions of South East Asia, particularly in India and China. North East India is the native place of many citrus species. Citrus fruit has been cultivated in an ever-widening area since ancient times. Although oranges are the major fruit in the citrus fruits accounting for about 70 per cent of citrus output, the group also includes small citrus fruits (such as tangerines, mandarins, clementines and satsumas), lemons, limes and grapefruits. Citrus fruits are consumed as fresh fruit or utilized for preparing processed citrus products. Approximately one third of total citrus production is utilized for processing. India ranks sixth in the production of citrus fruits in the world. In India, it is primarily grown in Maharashtra, Andhra Pradesh, Punjab, Karnataka, Uttaranchal, Bihar, Orissa, Assam and Gujarat. Citrus fruits have several beneficial health and nutritive properties. They are rich in Vitamin C and folic acid, as well as a good source of fiber. In addition they contain potassium, calcium, folate, thiamine, niacin, vitamin B6, phosphorus, magnesium and copper.

Citrus butterfly: Papilio demoleus, P. polytes : Papilionidae

The pest is distributed all over the world and has a host range that includes citrus and other rutaceae plants like Aegle marmelos. Adult has the head and thorax black with a creamy-yellow coloration on the underside of the abdomen. Wings are dull black, orna-mented with yellow markings and a distinct red patch on the hind wing. The underside is orange and yellow coloured and can be seen when it flirts for honey collection or just before egg laying. The Antenna is black and clubbed.

Genus : Citrus
Species : Sinensis aurantium, limon, medica grandis L. paradisi Macf. reticulata Blanco
Family : Rutaceae
Chromosome No. : 2n = 18

Citrus is one of the most important and popular fruit of the world which is widely cultivated in almost all of the tropical and subtropical parts of the world. Amongst the subtropical fruits in respect of average it occupies the third position. In India too it is next to mango and banana in commercial perpective. Citrus fruits on account of extensive adaptability are successfully cultivated in tropical, subtropical and even in the marginal temperate regions where the condition are somewhat favourable with its attractive appearance (foliage) distinct flavour and above all its excellent fruit quantity, citrus is liked by one and all. Fruits are not only refreshing and delicious but are also very rich in vitamin C and is good source of A and B, with fruit sugar acids, minerals like Ca, P, Fe. They are essential and play significant role in health promoting constituents in human diet, significance of citrus fruits in diet is very well established. Limes and lemons

Origin and history: Citrus is the leading fruit crop in the world. In India, citrus ranks second in area sharing 12.8% of the total area under fruit crops with 9.6% share in production. Under citrus group, mandarins are the most important, occupying 50% of the total area under citrus followed by sweet orange and limes. Citrus fruits are grown mainly in Maharashtra, Andhra Pradesh, Punjab, Karnataka and North-Eastern region. 

1.    Nagpur mandarin was introduced in India in 1894 by Shriji Raja Bhosle. 

2.    Kinnow can be grown in high density planting by using the cultivar  Troyer Citrange'  as a root stock by spacing the plants at 1.8 x 1.8 m2. 

3.    Classification of citrus was given by Tanaka and Swingle. 

4.    Grape fruit is also known as Forbidden fruit, Breakfast food.

Genus Citrus (Citrus spp.) belongs to family Rutaceae and subfamily Aurantioedae. Citrus fruits are cultivated over a wide range of agroclimatic conditions because of their ability to adapt to different situations. Citrus is considered to be one of the most remunerative fruit crops in India, having a lasting niche in the international trade and world finance. Most of the Citrus species are believed to be native to tropical and subtropical regions of southeast Asia, particularly, northeastern India and the region between China and India (Ghosh, 2007). Trees belonging to genus Citrus are comparatively small in size (other perennial fruit crops) and evergreen in nature that are grown in tropical, subtropical and even mild temperate climates. Citrus fruits are nonclimacteric so they do not ripen further once removed from the trees. So it is important that they are picked at the right stage of maturity.

Citrus is one of the most important fruit crops of the world. The most important commercial citrus fruits in India is mandarin oranges followed by sweet oranges, lemons and acid limes. Citrus fruits are used for fresh fruit juices, processing into squashes, marmalades and its essential oils from peel are widely used in flavouring, perfumery and cosmetic industry. The citrus peel is one of the important sources for manufacture of pectin.

It is believed that most of the species under the genus citrus are native to tropical and subtropical regions of South-East Asia, particularly India, China and in the region between these two countries. The north-eastern region of India is considered as one of the natural homes for few species of citrus. The other major citrus producing countries of the world are Brazil, USA, India, China,Mexico, Spain, Egypt, Italy, Indonesia and Trukey.

Sweet Orange (Cirus sinensis Osbeck) or Mosambi

Sweet orange is one of the most widely favored citrus fruit of of the world. Its scientific name is Citurs sinensis Osbeck. The sweet oranges are generally round to oval in shape; tight skinned with solid central core. The skin is yellow to orange in colour, smooth and pulp is yellow to orange or reddish. The segments are tightly attached to one another. The commercially important varieties are Malta (Blood Red), Mosambi and Satgudi. Other exotic varieties like Valencia, Washington Navel of USA and Shamouti of Isreal.

Citrus is a major fruit crop grown all over the tropical and subtropical region of the world. Maximum citrus species are native of tropical and subtropical regions of South East Asia specially India, China in the area between these two countries. It is mainly cultivated in China, Brazil, India, USA, Mexico, Spain and Egypt in the world. China is the leading producer country in the world followed by Brazil, India and USA. India is the third largest citrus producer which has 4.8 per cent of the world’s total citrus production.

Citrus crop includes lime, lemon, sweet orange, mandarin orange, Kamala orange, grapefruit, malta and pomelo etc. The disease which attacks one species of citrus mostly attacks other species also.

Subtropical and Tropical Fruits

Most of the area of India experience subtropical and tropical climate. Subtropical and tropical fruits contribute maximum to the overall fruit production. Major fruit crops cultivated in subtropical and tropical region are citrus, mango, litchi, guava, sapota, pomegranate, banana, ber, sapota, grapevine, papaya etc. Various pests affect the fruit production by infesting at various stages of the tree growth quantitatively as well as qualitatively. The pests of these crops are described fruit wise.

Citrus

Most of the area of our country is tropical and subtropical, where the citrus, Citrus spp. cultivation is practiced and main citrus growing areas are in Maharashtra, Andhra Pradesh, Punjab, Karnataka, Uttarakhand, Bihar, Orissa, Assam and Gujarat. As for as the ranking in the world

The prime objective of any plant breeder is to develop high yielding varieties and make the quantity of quality seed of those varieties to farmers for commercial cultivation to realize the benefits of superior varieties. This necessitates, the production of seed of improved varieties in large scale in order to make them available to farmers without losing their genetic purity. Seed production is a continuous process. The seed of improved varieties are produced in several stages, each class producing a special class of seed. The various classes of improved seeds are recognized in order to facilitate seed production and to ensure continuous supply of quality seed. A seed production programme for the production of quality seed has different classes of seeds viz; nucleus seed, breeder seed, foundation seed, registered seed and certified seed. The Association of Official Seed Certifying Agencies (AOSCA) has defined these seed classes as follows:

1. Nucleus Seed

Basic or nucleus seed is the original seed of a released and notified variety. Nucleus seed is multiplied by single plant progeny system, using the concept of maintenance breeding, where purity of the original parental stock is maintained. It is available in very limited quantities and taken from the individual plant of a variety for purification. It is directly under the controlled of concerned crop breeder. This seed has hundred percent genetic and physical purity. Breeder seed is multiplied out of this material and about 500-1000 plants are kept for continued multiplication of nucleus seed.There is no need of any type of tag on nucleus seed but concerned breeder issue a certificate for purity.

3.1 Introduction

Genetics deals with genes and cytogenetics with chromosomes that harbour genes. On the other hand, plant breeding strives to upgrade the genotypes of crop plants. So, the plant breeding methods should be based on genetic principles. Dear students, you should have clear understanding of genetics in broad sense so that you can appreciate the applicability of breeding methods. As I have already pointed out that you have been taught the course ‘Principles of Genetics and Cytogenetics’ in the first semester, only a brief discussion is followed for your review and better understanding.

3.2 Character

When we call ‘character’ or ‘trait’ in genetics, we mean any morphological, anatomical, biochemical or behavioural feature of an organism. For instance, flower colour, blooming period, leaf size, size of guard cells in stomata, vitamin C content, disease resistance etc. A single gene or a number of genes may govern the development of a character and, often it is influenced by the environment. Characters may be qualitative or quantitative.

6.1 Introduction

Plant breeding is the indispensible component of elevating production and productivity of spices by evolving high yielding and/or with good quality type. Thereby, the practice of identification and selection of desirable traits and introgression of those characters in a single plant is being done since the beginning of organized agricultural activities by humankind. The act of plant breeding was reshaped and got a momentum with a scientific basis after the discovery and rather rediscovery of Mendel’s laws. Worldwide, humankind could enjoy the direct benefits of methodical plant breeding during green revolution. Manipulation of genetic architecture for creating variation in the population and successive selection is the basic of all kinds of crop breeding. But the process of creation of variability and selection differs from crop to crop depending on their mode of reproduction. It is comparatively easier to get a new homogeneous population in self pollinating plants. Therefore, segregating generations are handled differently in these two categories of self and cross pollinated crops.

4.1. Agricultural production economics

An applied science, wherein principles of choice are applied to use of land, labour, capital and management in farming.

Explains conditions under which profit and output can be maximized and cost and use of physical inputs can be minimized.

Synonyms : Hog eholera, European swine fever

It is an acute highly infectious viral septicaemia of swine of all ages characterized by rapid and sudden onset, high morbidity and mortality and generalized  haemorrhages. A chronic course  followed by recovery after treatment has been reported in older pigs and appearance of new born pigs with congenital defects.

Etiology : The etiological agent causing hog cholera is a linear  single stranded positive sense RNA virus under the genus Pestivirus and family Flaviviridae. The virions are spherical, 40-50 nm in diameter  and consist of a tightly adherent lipid bilayer envelope covered with glycoprotein peplomers surrounding an icosahedral capsid of 28-35 nm in diameter. The genome is 12 kb in length with 5’end capped but  3’end  not  polyadenylated. The genes for structural proteins are located at 5’ end of genome. The virus replicates in the cytoplasm and matures within cytoplasmic vesicles. Though there is only one antigenic type of the virus, a number of strains of variable virulence and antigenicity has been reported. The causative agent was first thought to be a gram negative bacterium named Salmonella cholera suis. Later, it was confirmed that the disease is caused by a  virus.

History on Classification of Herbicides

Copper sulphate (CuSO₄) was the earliest inorganic salt used as selective herbicide for controlling dicot weeds in cereal crops during 1896 in France, Germany, and USA. Sulphuric acid (H₂SO₄) was used as herbicide in cereals during 1909. In selective killing action depends on the fact that it runs off the leaves of the cereals and scorches rough surfaces of certain seeds. Sodium chlorate (NaClO₃) under the name mort-herbs is used in France for killing deep rooted perennials. Another non-selective herbicide, ammonium sulphamate (NH₄SO₃NH₂) was introduced in 1945 as ammate for the control of woody plants. Organic herbicides are more effective and selective.

Classification of Herbicides

Classification of herbicides is modified periodically as and when new herbicides are developed. Herbicides are classiûed based on their method of use (soil and foliage applied), mode of action (systemic or translocated and non-systemic or contact herbicide) and chemical key structure (aliphatic-aromatic, dinitrophenal, etc. Some herbicide molecules contain more than one classifying key structure and they are put into the group most likely to be contributing activity.

Any approved herbicide is known by three names: common name, chemical name and trade name. Common name of herbicide is a technically accepted abbreviation of its chemical name. Chemical name reads out its full molecular structure. Trade names refer to their formulations offered by the chemical companies for the consumers.

The modern breeds of chicken have known to be descended from the wild jungle fowl. India, Nepal, Bangladesh, Myanmar, Thailand, Sri Lanka and Malaysia are the homeland to these jungle fowls. There are four known species of jungle fowl viz. Gallus gallus (Red jungle fowl), Gallus lafayetti (Ceylon jungle fowl), Gallus sonnerati (Grey jungle fowl) and Gallus varius (Java jungle fowl). The domestic breeds of chicken/fowl have originated from Gallus gallus.

Introduction
A biogas plant is an engineered system designed to generate biogas through the anaerobic digestion of organic materials rich in cellulose, such as cow dung, agricultural residues, poultry waste, and other biodegradable biomass. In the absence of oxygen, microorganisms decompose these materials, producing a mixture of methane (CH4), carbon dioxide (CO2), and traces of hydrogen sulfide (H2S). This biogas can be utilized as a renewable energy source for cooking, heating, and power generation.
In India, cow dung has traditionally served as the primary substrate, and such systems were popularly known as Gobar Gas Plants. The early designs were promoted by the Khadi and Village Industries Commission (KVIC)
Components of a Biogas Plants
A typical biogas plant consists of the following major components:
• Foundation: Provides structural support to the digester and gas holder.
• Digester (Fermentation Tank): The main chamber where anaerobic digestion occurs.
• Gas Holder (Masonry Dome or Drum): Collects and stores the biogas produced.
• Mixing Tank: Used to prepare the slurry by mixing feedstock with water (commonly 1:1 ratio).
• Inlet Chamber/Pipe: Feeds the prepared slurry into the digester

This chapter introduces the principles used to classify and grade wool according to fineness, length, colour, strength, purity and suitability for end use. It explains traditional count systems and modern micron-based classification, including the relationship between Bradford count and fibre diameter. The chapter discusses breed and fleece-type differences, objective measurement and the importance of representative sampling. It also explains how grading converts variable biological material into commercially meaningful categories that support fair pricing and appropriate processing decisions.

CMTs can be classified on the basis of morphologic features, tissue of origin (epithelial, myoepithelial or mesenchymal tissue) or prognosis. The World Health Organization (WHO) classification of canine and feline mammary tumors has categorized CMT into three major categories i) malignant, ii) benign and iii) unclassified tumors. On the basis of histological characteristics, the mammary tumors have been classified into fibroadenomas, adenomas, solid carcinomas (with transformed epithelial cells), tubular adenocarcinomas (with tubule like arrangements), papillary adenocarcinomas (having papillary like projections), anaplastic carcinomas (with highly pleomorphic cells), sarcomas (involvement of connective tissue) and malignant tumors (Fig. 2). Fibroadenomas and adenomas are the types of benign mammary tumors the former contains some connective tissues component in between, and carcinomas, adenocarcinomas and sarcomas come under malignant tumors.

Classifications and Nomenclature

Plants can be classified according to the following criteria: (1) botanical, (2) descriptive and (3) agricultural. Botanical classification is based on the morphological characteristics of plants as well as on their anatomy, physiology and DNA sequences. Descriptive classification is based on the environmental adaptation, growth habit and other observable features. In agriculture, plants can be broadly classified as either useful or useless. Those which are useful are called crops while those which are not useful are called weeds.

A common, well-defined system of crop classification is important in crop science and agriculture. Grouping of plants following established systems will simplify plant collection initiatives, research and breeding specialized development efforts. Having standardized botanical names will also facilitate efficient communication, dissemination and retrieval of scientific information. Additionally, the grouping of crops will indicate that these crops may have similar uses, adaptation, growth habits and methods of culture. Classifying crops by family is likewise important in intergeneric grafting. To students of crop science, a list of crops under the various agricultural classifications will be a useful reference in crop names and identification and as a review guide. To the farm manager himself, the same list will offer innumerable benefits in finding alternative crops for specific uses.

Despite these advantages, however, classifications of crops in agriculture vary from place to place and from one country to another due to differences in the primary usage of certain crops, intensity of care, extent of cultivation and other criteria under consideration. It is not uncommon to find crops having two or more classifications, used simultaneously, alternatively or sequentially. FAO(2010) in its report entitled “Crops Statistics - Concepts, Definitions and Classifications”, expressed its difficulty in the collection and presentation of statistical data due to differences in the concepts, definitions, coverage and classifications” of crops which are grown in different countries.

Taxonomy (biological systematics) is the branch of science which deals with classification of units or individuals on the basis of similarities and differences. The classification, nomenclature, and identification are three interrelated components of bacterial taxonomy (Cowan, 1965).

Classification: Classification is the arrangement of bacteria into groups (taxa) based on the similarities of certain characteristics. Presently 11,000 bacterial species is classified. At the current rate of 600 bacterial species / year it is estimated to take 1000 years to classify all the bacteria!

Nomenclature: It is the assignment of specific names to the taxonomic groups following the regulations mentioned in ‘International Code of Nomenclature of Bacteria’ (Euzeby, 1997). International committee on systematic bacteriology (International committee on systematics of prokaryotes, ICSP) standardizes the code. The committee is helped by a number of taxonomic subcommittees on different groups of bacteria. The Code can be amended by the Judicial Commission. The Code contains general considerations, principles, rules and recommendations on the naming of prokaryotes (bacteria) up to the rank of ‘Class’.

Classification of Organisms
Over the years, scientists have developed several systems for the classification of organisms. Greek phlosopher Aristotle (384-322 BC) grouped life forms as either plants or animals. Microscopic organisms were unknown at that time. Fungi were included in plants. Aristotle’s system distinguished only between plants and animals on the basis of movement, feeding mechanism, and growth patterns. In 1735, Carolus Linnaeus formalized the use of two Latin names to identify each organism, a system called Binomial nomenclature. He grouped closely related organisms and introduced the modern classification groups: kingdom, phylum, class, order, family, genus, and species. At that time singlecelled organisms were observed but not classified. This classification had two kingdoms.
Plantae: containing Plants and Fungi
Animalia: containing Animals
In 1866, Ernst Haeckel proposed a third kingdom- Protista, to include all single-celled organisms like amoebas and diatoms. Some taxonomists also placed simple multicellular organisms, such as seaweeds, in Kingdom Protista.
In 1938, Herbert Copeland proposed a fourth kingdom, Monera, to include only bacteria. This was the first classification proposal to separate prokaryotes from eukaryotes, at the kingdom level.
In 1957, Robert H. Whittaker proposed a fifth kingdom –Fungi.Fungi do not ingest food as animals do, nor do they make their own food, as plants do. They secrete digestive enzymes around their food, breaking it down before absorbing it into their cells.

Abstract

Classification of the hundreds of possible dryers is essential to the logical selection of appropriate dryer for a given application. Diverse criteria for classification as well as selection of dryers are presented and discussed briefly. The advantages and limitations of different dryer types must be taken into consideration. Initial capital cost is often the key deciding criterion in industrial dryer selection. This is not a good strategy as the user must pay for the operating costs over a long period of life of the dryer. In general several different dryer types are suitable for a given product. Careful selection is essential for cost-effective operation of the dryer.

2.1 What is a frequency distribution?

A frequency distribution shows the frequencies of occurrence of the observations in a data set. Often the distribution of the observed data is called an empirical frequency distribution, in contrast to the theoretical probability distribution determined from a mathematical model.

The class interval is a term used in statistics when we are given a continuous series. Class means a group of numbers in which items are placed such as 0-10, 10-20, 20-30, etc. Class interval refers to the numerical width of any class in a particular distribution.

2.2 Relative frequency distributions

Although creating a frequency distribution is a useful way of describing a set of observations, it is difficult to compare two or more frequency distributions if the total number of observations in each distribution is different. A way of overcoming this difficulty is to calculate the proportion or percentage of observations in each class or category. These are called relative frequencies and each is obtained by dividing the frequency for that category by the total number of observations (column 3 of Table 2.1). The sum of the relative frequencies of all the categories is unity (or 100%) apart from rounding errors.

1.1 Classification

The raw or ungrouped data are in unorganized form and need be organized in meaningful and readily comprehensible form in order to facilitate further statistical analysis. Classification of data is the first step in this direction. It is the process of arranging thing in groups according to their resemblance and affinities. There are two basic types of classification namely-qualitative and quantitative. In qualitative classification, the basis of classification is some attribute or quality like: sex, literacy, religion, etc. A qualitative classification may be simple or manifold. The classification done with respect to one attribute is termed as ‘Simple Classification’. The classification in which two or more attributes are considered and several classes are formed is called ‘Manifold Classification’. In quantitative classification, the collected data are grouped in respect of characteristics, which can be measured and numerically expressed such as height, weight, etc.

Statistical Series: When observations of any characteristic present in the individual of a group are recorded and arranged one after the other in a systematic order, they form a series, known as statistical series. For example: milk yield of 20 cows, height of the students in a class in a systematic order, etc. These are some important types of series:

• Discrete series: In this series, observations can take up only exact values and not any fractional values, is called discrete series. That means, this type of series has whole number of counting. For example: number of the students in a class, members of a family, number of births in a certain year, etc

• Continuous series: A series which can take up any numerical value (integral/ fractional) within a certain range is called continuous series. For example: milk yield of 20 cows, height, weight, temperature, etc.

• Array series: When we arranged the observations of a series either in ascending order of their magnitude or descending order of their magnitude, then it becomes an array series.

• Spatial series: When items of a series are given according to space or place or time, then such type of series is known as spatial series. For example: month wise milk yield of a herd of cows, month wise income or expenditure of an industry, population of a country according to states, etc.

In broad perspective, plants and crops of agriculture can be classified mainly based on three criterions namely descriptive, ecological and agronomical. Understanding these basic classifications will help us to study the characteristics of each plant in detail.

Descriptive Classification

In descriptive approach, plants and crops can be classified based on the mode of reproduction, mode of pollination, life span, growth habits and leaf retention property. Sexual and asexual reproducing plants are the two groups based on the mode of reproduction. The sexual reproducing plants are developed from a seed after the union of male and female gametes and asexual plants reproduces through vegetative means and not by male and female gametes.

It is vital to categorise agroforestry and its many systems in accordance with certain contemporary standards in order to have a thorough grasp of them and to enable future progress. Since each agroforestry system refers to a different set of agroforestry practices involving agriculture (crops), forestry (trees), and pasture (animals), the various uses of land are combined either temporally or spatially. Each agroforestry system has its own unique arrangement of various components, such as crops, animals, perennial trees, etc., and degree of interaction between the components. In terms of structure, composition, age intensity, technology, inputs, etc., one system varies from the other.

Creating a useful framework for the synthesis and analysis of data on current systems as well as the creation of new, promising ones should be the primary goal of classification. For this reason, every categorization system needs to have the accompanying the following standards.

Though more than 1500 species contain volatile aromatic principles, only around 50 species serve as commercial source of essential oil and aroma-chemicals. Among these, aromatic crops under large-scale cultivation hardly exceeds two dozens. Important aromatic plants of world are classified according to economic part used, growth habit, habitat, crop duration and propagation method besides usual botanical classification.

"Bacteria” = Plural form, “Bacterium” = Singular form

Bacterium is a single-celled microorganism that do not have cell organelles (mitochondria, endoplasmic reticulum, chloroplast etc.) or a true nucleus. Bacteria are microscopic, unicellular organism that belongs to the kingdom prokaryotes.

Morphology of Bacteria

Bacterial morphology deals with size, shape, and arrangement of bacterial cells.

Size of Bacteria

Bacteria are microscopic organisms that are less than 3 micrometeres (μm) in size. Size of cocci range from 0.5 to 3 μm, and the size of a rod shaped bacteria range from 0.15 to 2 μm (width) to 0.5 to 20 μm (length).

Biofertilizers can be defined as the preparations containing strains of micro-organisms which can augment the microbiological process viz. nitrogen fixation, phosphate solubilization or mineralization, excretion of plant growth promoting substances or cellulose or lignin biodegradation in soil, compost or other environments. Biofertilizers can be divided into nitrogen fixing bacteria, phosphate solubilizing and mobilizing microorganisms and organic matter decomposers as (Table 3.1 and Fig. 3.1):

On the basis of Nitrogen Fixation: On the basis of N₂ fixation, they are divided in to two sub categories as

1. True bone tumours. Neoplasms arising from cells of mesenchymal origin, derived from a common ancestry and whose function is primarily skeletal boen formation. These tumours fall into four main groups according to the predominant cell type present. By reason of the mutability of the cells metaplasia is common and intermediate stages are found.

Characters

1) They are called true flies.

2) It is one of the largest orders in the class Insecta, having more than 1, 20, 000 described species.

3) On thorax, there is only one pair of wing (Di = two; ptera = wings) i.e. Mesothoracic wing. Metathoracic pair of wings are modified into structures called “Halters or balancers.” Halter is a rod like structure having knob at distal end. During flight, this halter goes on vibrating @ 300 vibrations/sec. Its main function is to keep fly balanced during flying/flight.

4) One pair of compound eyes is present which is dichoptic in female and holoptic in male.

5) Larvae are apodous which is called maggots.

6) The order Diptera is divided into suborders, Orthorrhapha and Cyclorrhapha. These sub orders are distinguished morphologically by wing venation and structure of antennae.

Climatic classification is the method of identifying climatologically homogenous regions. The systematic study of climate and its analysis and processing, which is referred as climatology plays an important role in national weather, planning activities and decision making in human activities. Iso climatic regions are those regions which have same climatic conditions.

Specific objectives of climatic classification

To identify the climates for transfer of production technology developed at particular center.

To provide adequate indices of moisture availability for successful crop production in drylands.

To quantify the risk levels associated with production constrains to agriculture production.

Climate classification systems are ways of classifying the world’s climates. One purpose of climatic classification is to group together places with similar climatic characteristics. That means if an area or region is categorised under a particular climatic type, it possesses broadly uniform characteristics with respect to climate. Classifications have been based on climatic elements such as temperature and precipitation, which are measurable, and on differences in tree species, soil characteristics, topography, etc. The varied nature of earth’s surface and the many interactions that occur among atmospheric processes give every location on the earth a distinctive climate.

Although the delineation of distinct climates may seem likely a very straightforward job, establishing the criteria by which climates are delineated requires considerable subjectivity. There are many ways of classifying the climate depending on the user and the level of understanding of the climate system at a given time. Different regions of the same climate type constitute isoclimatic regions. Identification of isoclimates helps in the transfer of agro-technology and suggesting new cropping pattern. Climatic classification is based on two approaches, viz., generic or empirical approach and genetic approach. In the generic approach the classification is based on the observed climatic elements or their effects on the phenomena, usually vegetation or humankind. The genetic classification is based on climatic controls such as general circulation, net radiation and moisture fluxes.

The concept of climate classification was originally brought out to delineate natural vegetation, which is dependent on rainfall and temperature. Climate classification is unique tool to find out different climate types across the globe, out of which isoclimates or homoclimates can be traced out.

The climate of a particular place is the function of a number of factors such as latitude and its influence on solar radiation received, air mass influences, location of global high and low pressure zones, heat exchange from ocean currents, distribution of mountain barriers, pattern of prevailing winds, distribution of land and sea, and altitude.

The classification of crop diseases is a fundamental aspect of plant pathology, as it provides a framework for understanding the causes, symptoms, and management of diseases that affect crops. Classification is the process of grouping organisms or diseases into categories based on their shared characteristics, and it is essential for developing effective disease management strategies. Crop diseases can be classified in various ways, including by their causes, symptoms, hosts, and environmental factors. Understanding the classification of crop diseases is crucial for farmers, agricultural professionals, and researchers, as it enables them to identify diseases accurately, select appropriate management strategies, and develop new control methods. One of the primary ways to classify crop diseases is by their causes, which can be broadly categorized into infectious and non-infectious diseases. Infectious diseases are caused by living organisms, such as fungi, bacteria, viruses, and nematodes, while non-infectious diseases are caused by environmental factors, such as temperature, moisture, nutrient deficiencies and some substances toxic to plants. Another way to classify crop diseases is by their symptoms, which can include visible changes in plant growth, color, or texture, as well as reductions in yield or quality. Symptoms can be categorized into different types, such as leaf spots, blights, wilts, and tumors, each of which is associated with specific diseasecausing agents. Classification of crop diseases can also be based on the host plant, with diseases being grouped according to the specific crop or plant species they affect. This type of classification is useful for developing crop-specific disease management strategies. In this chapter, we will explore the different classification systems used for crop diseases, including their causes, symptoms, hosts, and environmental factors. We will also discuss the importance of accurate disease classification for effective disease management and the development of new control methods. The broad classification of crop diseases followed uniformly throughout the world is based on the nature of the causal agent, and it categorizes diseases into two main groups: infectious diseases and non-infectious diseases.
5.1 Infectious diseases
These are caused by living organisms, such as fungi, bacteria, viruses, and nematodes, which can spread from plant to plant. These diseases can be further subdivided into several categories, including:

The agricultural sector is a complex and dynamic system, influenced by a
multitude of factors, including weather, soil, and market conditions. To provide effective support to farmers, it is essential to have a comprehensive understanding of the diverse range of crops and farming systems that exist. Classification of crops and farmers is critical components of this understanding, as it enables the development of targeted and customized Agromet advisories that take into account the specific needs and circumstances of different farming communities.
9.1. The Importance of Classification
Classification of crops and farmers is a fundamental concept in agriculture, as it allows for the identification and grouping of similar crops and farming systems. This, in turn, enables the development of tailored recommendations and advisories that are relevant to specific farming contexts. By classifying crops and farmers, agricultural researchers, extension agents, and policymakers can better understand the diverse range of agricultural practices and systems, and develop targeted interventions that address the unique needs and challenges of different farming communities.
9.1.1. Customized Agromet Advisories
Agromet advisories are critical for supporting farmers in making informed decisions about their agricultural practices. By providing timely and accurate weather forecasts, advisories can help farmers to optimize their crop management, reduce losses due to weather-related events, and improve their overall productivity and income. However, to be effective, Agromet advisories must be customized to take into account the specific needs and circumstances of different farming communities. This requires a comprehensive understanding of the diverse range of crops and farming systems that exist, as well as the specific challenges and opportunities faced by different farmers.
9.1.2. The Role of Classification in Customized Agromet Advisories
Classification of crops and farmers plays a critical role in the development of customized Agromet advisories. By grouping similar crops and farming systems together, researchers and extension agents can identify patterns and trends that inform the development of targeted advisories. For example, advisories for farmers growing wheat in a particular region may focus on issues related to soil moisture, temperature, and pest management, while advisories for farmers growing rice in a

Crops: Is a cultivated plant that is grown on large scale commercially, especially cereal, pulses, fruits or vegetables.

Classification of crops : Several crop plants are alike with respect to ontogeny (Development), morphology, anatomy, physiology and requirement of environment. Classification is done to generalize similar crop plants as a class for attaining better understanding of them. Field crops are classified in several ways.

Textile and apparel defects are commonly classified according to their severity, effect on product performance and influence on visual appearance. Accurate classification supports inspection decisions, corrective action and cost management. Critical defects create safety hazards, breach legal or compliance requirements, or make a garment unusable; affected products must be rejected immediately. Major defects significantly reduce appearance, durability or functionality and ordinarily require correction before sale, although they may not endanger the wearer. Minor defects are small departures from specifications that do not substantially affect usability but may lower perceived quality. Consistent classification enables inspectors to apply AQL criteria objectively and communicate appropriate acceptance, rejection or rework decisions.

Plant diseases are caused by different etiological agents like Fungi, Bacteria, Viruses, Viroids, Phytoplasmas, Rickettsia like bacteria, Nematodes, Algae and Protozoan parasites. To control these specific pathogens and the diseases caused by them, a specific group of medicine/chemical molecule is required.

Droughts are intricate and multifaceted phenomena that can have far-reaching impacts on the environment, economy, and society. The complexity of droughts arises from the interplay of various factors, including climate variability, water availability, land use, and human activities. Given the varying characteristics and consequences of droughts, classification becomes a crucial step in understanding and managing these events. By categorizing droughts based on their severity, duration, and impact, researchers and policymakers can better grasp the intricacies of drought dynamics and develop targeted strategies for mitigation and adaptation. The classification of droughts is necessary for several reasons

Introduction

Drought occurs when a region experiences below average precipitation, resulting in prolonged shortages in its water supply, which can have a significant impact on agriculture and the ecosystem. To reduce the effect of drought on farm production and stabilize farm income, farmers must take systematic measures called drought coping mechanisms. These measures can be categorized into two broad categories: Ex-ante coping mechanisms, which are taken before the occurrence of drought, and Ex-post coping mechanisms, which are taken after the occurrence of drought. Ex-ante coping mechanisms include activities such as crop, spatial, and varietal diversification, income diversification, and the use of savings. Ex-post coping mechanisms include changing consumption patterns, borrowing money, liquidating assets, seeking government drought relief funds, and migration. Drought can have a significant impact on crop and livestock production, causing farmers to adopt drought coping mechanisms to stabilize their farm income. This study goals to identify the factors that determine the adoption of such coping mechanisms, to mitigate the effects of drought on the livelihoods of farmers.

Rural Economy and Agriculture

It is being progressively recognized that the globalized nature of economies across the world is affecting the economic security of all nations. Particularly, in this present era when globalization, liberalization and privatization are rapidly budding and creating new threats and opportunities, it is established that farmers need to be organized to participate and proliferate in the development processes. The phenomenon has triggered substantial debate as to whether globalization is positive evolution of economic action or detrimental to the interests of certain countries or specific groups (Kaplinsky, 2004; Nadvi, 2004).