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Chow-Chow [Sechium edule (Jacq.) Swartz] is used in many parts of Latin America, humid tropical regions of Central America and Southern Mexico. It is cultivated in South East Asia (India, Malaysia, Indonesia and Phillipines), Central and Western Africa, Central and South America (Brazil) and other tropical regions. (Dutta 1994). In India, local cultivars are commonly grown in coastal and low-hills (1000-2000m) of Maharashtra, Karnataka, and Tamilnadu. In Tamil, it is called “Seeme Kattrikkai” (Bailey, 1947). It is an important part of dietary system of tribals of  North East Regions. It is found in kitchen gardens of every tribal. It is found in almost all states and regions but maximum variability is found in Sikkim, Mizoram and Meghalaya (Yadav et al., 2005). Its variable fruits and roots, are important elements in diet of people. Chow-Chow is widespread and is an important export crop for  Latin American countries, much still need to be learned  about this crop (Rafael Lira Saade,1996). Chow-Chow is a single seeded fruit of  Cucurbitaceous family (MacGillivray, 1953). It is a perennial rooted vine that bears edible fruits (Thompson and Kelly, 1957). In subtropical and tropical regions, it produces large edible tuberous roots. It thrives under moderate temperature in  tropical or semi-tropical environment, though it can also be successfully grown under high temperature near sea level. Chow-Chow is a herbaceous perennial creeper (Choudhury, 1967) and is a robust grower in warmer months of year and during  cold weather of July and August  plant dies back temporarily. It has a viviparous type of germination (Patnaik, 1967). S.edule is called chayote, probably from  Greek ‘Sekos’ to  fatten in a fold because it was fed to hogs ( Bailey, 1963).

1. Introduction

Chrysanthemum is commonly known as ‘Guldaoudi’, “Queen of the East”, “Glory of East” or “Autumn Queen”. It is one of the most beautiful and widely cultivated flowers that can be grown for its aesthetic value as well as for its commercial potential. The word chrysanthemum is derived from two Greek words, viz. “Chrysos” means gold and “Anthemon” means ‘flower’ i.e. golden flower. Chrysanthemum is the only crop that offers a great genetic diversity of flower colour, shape, forms, size, easy to propagate, growing habit, longer flowering duration and excellent vase life. Based on the shape of flower heads and floret arrangement of petals it can be used as pot plants for indoors and outdoors decoration as well as exhibition purpose; as cut flowers for flower arrangements, bouquets making and vase decoration; loose flower for making garlands, worshipping purpose and for bedding and garden decoration. Tall cultivars are suitable for background planting in borders and the dwarf and compact can be planted in front rows. 

Chrysanthemum (Dendranthema spp.) belongs to family Compositae (Asteraceae). It was named by Carolus Linnaeus from the Greek prefix “chrys” means golden and “anthemon” means flower. Chrysanthemum morifolium is the modern florists chrysanthemum, which evolved as a result of endless variation and hybridization from C. sinensis, C. indicum and C. ornatum (Bailey, 1963). This group is also distinguished as C. hortorum. The name of C. morifolium Ramat has been changed to Dendranthema grandiflora Tzvelev (Anderson, 1987, Heywood and Humphries, 1977). Chrysanthemums are mainly herbaceous perennial and bear flowers in capitula. Chrysanthemum perennates in nature by means of stolons and is readily propagated through basal stem cuttings. It ranks second next to roses in importance among the cut flower crops in the world.

ORIGIN AND DISTRIBUTION

Chrysanthemum is originated in northern hemisphere (Europe and Asia). However, some workers reported that China is the native place of chrysanthemum (Carter, 1980). Most of the species in the lineage of present day cultivars are from China.

Chrysanthemum was first cultivated in China as a flowering herb and is described in writing as early as 15^th century B.C. As herb, it was believed to have the power of life. In 18^th century, they appeared in Japan as the crest and official seal of the Emperor. Japan also has a national chrysanthemum day, which is called the Festival of Happiness. In the western world, they are introduced in England, Japan, France and U.S. have developed a wide range of colours, shapes and sizes of flowers. Since the chrysanthemum was first introduced in the U.S. during colonial times, its popularity has grown such that mums now reign as undisputed ‘Queen of the Fall Flowers’. The Netherlands is the foremost importer of chrysanthemum cut flowers and is the centers for re-export to other parts of the world. In India, chrysanthemum is successfully grown under protected as well as open conditions in different states.

Chrysanthemum is an economically important flower crop cultivated extensively for cut flowers, loose flowers and ornamental purposes. This chapter presents its origin, taxonomy, genetics, botanical features and commercially important varieties. Production technologies include propagation, nursery management, planting, spacing, nutrient management, irrigation, pinching, disbudding, photoperiodic manipulation and protected cultivation. Major pests and diseases and their management are described along with harvesting, grading, postharvest treatment and yield. The chapter emphasizes the importance of crop regulation and environmental management for producing uniform, marketable stems. It provides practical guidance for growers and students studying commercial chrysanthemum production and floriculture. under diverse Indian production conditions.

Chrysanthemum is one of the important commercial loose flower crops in India, valued for its wide range of flower forms, colours, sizes and long-lasting florets. It is extensively used for religious offerings, garlands, Veni, bouquets and ornamental purposes. The chapter describes its origin, distribution, genetics, botanical characteristics and important annual and perennial types. It provides information on suitable varieties, climate, soil, propagation and field establishment. Production practices including nutrient management, irrigation, pinching and other cultural operations are explained systematically. The chapter also discusses important pests and diseases, harvesting, postharvest management and yield, providing a practical foundation for commercial chrysanthemum cultivation and floriculture teaching.

Chrysanthemum takes its name derived from the Greek word chryos meaning gold and anthos meaning a flower, as many species have yellow flower heads. The genus Chrysanthemum belongs to family Asteraceae. It is herbaceous perennial plant. The genus comprises some 200 species of annuals, perennials and shrubs from northern temperate zone (chiefly Europe and Asia), whereas some researchers claim it was originated only from China. Though botanists have retained only the annual species under the genus Chrysanthemum (Beckett, 1983; Dole and Wilkins, 1999).

Annual chrysanthemums which are propagated through seeds. Annual chrysanthemum comprise ofthree species viz, Chrysanthemum segtum (corn marigold), Chrysanthemum carinatum (tricoloured chrysanthemum) and Chrysanthemum coronarium (crown daisy or garland chrysanthemum). The crown daisy or garland chrysanthemum (C. coronarium) is a native from Southern Europe, branching annual with finely cut foliage reaching a height up to a metre, size of flowers varies from 2.5 to 4 cm and colour is usually in shades of yellow and white with cream zone at the center (Vishnu Swarup, 1967).

Importance and Uses

Chrysanthemum is the number one dollar earning flower in the United States and cultivars suitable for growing throughout the year have been evolved there. The members of National Chrysanthemum Society run into thousands in several countries. It ranks second (next to rose) in the international cut flower trade. In India, it occupies a place of pride both as a commercial flower, garden plant, pot plant and as a popular exhibition flower.

Large number of chrysanthemum cultivars which exhibit wide variation for characters like growth habit, size, colour and shape of blooms makes chrysanthemum suitable for varied purpose. Its erect and tall growing cultivars are suitable for background planting in borders and as cut- flowers. The dwarf and compact growing ones are suitable for front row planting or pot culture. The decorative and fluffy bloomed small flowered cultivars are ideal for preparation of garland and hair decoration. The extra large- bloomed cultivars are prized for their exhibition value. Certain species like Chrysanthemum cinerariifolium and Chrysanthemum coccineum are cultivated as sources of pyrethrum, a natural insecticide.

Chrysanthemum (Chrysanthemum morifolium) is a popular flowering plant grown for its magnificent flowers in wide range of colour. There are various size of flowers like mini, small and large. Forms of the flowers also vary from ball shape to spider type. In ornamental gardening, Chrysanthemum is used as bedding as well as pot plant. Cut-flowers are also very popular for vase decoration and commercially important. Flowers of the small-flowered cultivars are also used as loose flowers for making garland and floral ornaments.

Classification

There is huge diversity in the form and types of Chrysanthemum. Therefore, one has to know the various types of flowers, growth habit and their use in the gardens.

INTRODUCTION

The chrysanthemum is one of the most beautiful and perhaps the oldest flowering plant, commercially grown in different parts of the world. It is commonly known as Queen of East, Autumn Queen and Guldaudi. It is im ortant both as cut flower and as potted plant in the international market. In Dutch cut flower auction, chrysanthemum ranks second after rose. It is preferred practically due to vast range of shapes and sizes of flowers, brilliance of colour tones, long lasting floret life, diversity of height and growth habit of the plant, exceptionally hardy nature, relative ease to grow all the year round and versatility of use.

It is one of the most important traditional flowers of India mainly used as a potted plant, loose flower, cut flower and as border plant in the garden. Chrysanthemum cinerariifolium inflorescences are of considerable importance in the manufacture of pyrethrin insecticides. The leaves of Chrysanthemum balsamita become leathery on drying and can be used as bookmarks. Fresh young customary leaves can be used in salads and to add a balsam flavour in beer, soups and bread. Now programmed blooming of chrysanthemum all the year around is possible by environmental manipulations.

This chapter introduces chrysanthemum as one of the world's important commercial cut flowers, particularly suited to controlled production because flowering is strongly influenced by environmental conditions. It discusses standard and spray types, origin, genetics, botanical characteristics, varieties and greenhouse cultivation. Temperature, humidity, light regulation, carbon dioxide, nutrition, irrigation, pest and disease management, harvesting, grading and storage are covered. The chapter also highlights the use of modern breeding and protected environments for year-round production.

Chrysanthemum (chrysos =golden; anthos = flower) is a popular flower crop of commercial importance known as the “Queen of the East”. It ranks next only to rose among flower crops in the world.

Introduction

The chrysanthemum is one of the most beautiful and perhaps the oldest flowering plant. It is commercially grown in different parts of the world. Chrysanthemum is commonly known as Guldaudi. In Dutch cut flower auction, chrysanthemum ranks second after rose. It is preferred practically due to vast range of shapes and sizes of flowers, brilliance of colour tones, long lasting floret life, diversity of height and growth habit of the plant, exceptionally hardy nature, relative ease to grow all the year round and versatility of use.

It is one of the most important traditional flowers of India mainly used as a potted plant, loose flower, cut flower and as border plant in the garden. Chrysanthemum cinerariifolium inflorescences are of considerable importance in the manufacture of pyrethrin insecticides.

Abstract: Chrysanthemum, commonly known as Queen of East, is perhaps oldest flowering plant, commercially grown in different parts of the world in a wide range of floricultural product including potted plants, cut flowers and garden plant. Vast range of shapes and sizes of flowers, brilliance of colour tones, long lasting bloom, ease of production and cultivation all the year round, range of plant habits from pot mums to tall shrub, hardy nature, and versatility of use make this a versatile floriculture crop, wide range of polyploidy level (diploid to decaploid) is found in different cultivars and are almost exclusively asexually propagated. The crop arises from multiple species, its allopolyploid nature has complicated progress in crop development due to inbreeding depression, genetic load and aneuploidy. Precise genetic information and trait heritability has been established for this crop; plant breeding continues to produce new variants for commercial production. Currently, numerous varieties have been developed through complex interspecific crosses among elemental species, open pollination, indiscriminate Intervarietal hybridization, spontaneous and induced mutation, selection, and management of chimera. Number of traits targeted for genetic intervention have been presented and discussed. Crop idiotypes for product classes prescribe numerous traits for incorpotion by flower breeders and geneticists including compact framework to withstand bloom for pot mums, long lasting bloom colour with enhanced shelf life for cut flower and sweet scented blooms with extended blooming season for garland use.

Introduction
It was first introduced from Java by National Botanical Research Institute (NBRI), Lucknow in 1959. Later on Regional Research Laboratory (RRL) of CIMAP, Bangalore started research work from 1961. Presently, it is cultivated in Karnataka, Assam, Maharashtra, TN, WB, AP, Southern Gujarat and UP. Citronella oil is produced from two species, viz., Cymbopogon winterianus (Java type) and C. nardus (Ceylon type). About 300-350 tonnes of oil is produced annually in India, as against 7000 tonnes in the world.
Origin
It is reported to be originated from Borneo, Java and Sumatra
Uses
Despite production of synthetic isolates in large scale, there is still a widespread preference for natural citronella oil because of its unique olfactory and stable technical properties, which are vital in blending perfumes and compounding industrially important essences. The oil is mainly used in perfumery, soaps, detergents, industrial polishes, cleaning compounds, mosquito repellent products and other industrial products.

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.

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.

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.

2.1 INTRODUCTION

Owing to a varied agro-ecological and eco- edaphic condition prevalent in one or other part of the country, quite a large number of crops are grown in different parts of India. India is rich in bio-diversity with four hotspots out of twenty-five in the world. About 356 domesticated plant species having economic and botanical importance and 326 species with their wild relatives are found in Indian sub-continent. Besides the above, 9500 other plant species are also available. More than 50 different types of fruits, 50 different types of vegetables, 95 types of spices and condiments, medicinal and aromatic plants, plantation crops and ornamental crop plants have been recorded. To avoid confusion and identity, the horticultural plants are grouped into different categories based on similarity or dissimilarities. Grouping of the crop plants with similar characteristics is referred as classification.

Classification is system of placing an individual or a member in various groups or to categories them according to particular plan or sequence which is in conformity with the nomenclature. From time-to-time for purposes of convenience plants or fruits have been classified in various ways that makes possible to refer them to a large number of kinds under a group name without enumerating or specifying individually. The basis of these groupings varies according to the features of fruits or growth of the fruit plants that have been under classification at the time.

Knowledge of classification of horticultural plants is very useful to the horticulturists because it serves: (1) to identity and name them, (2) to afford at least some idea of the closeness of their relationship i.e. line of descent to other kinds, (3) to suggest with what other kind they possibly may or may not be interbred or crossed, (4) to suggest the kinds with which they possibly may or may not be inter-grafted, and (5) often to suggest certain soil and the cultural requirements, climatic adaptations etc. However, the classification of fruit trees or fruits and vegetables on the basis of consumer’s rating also gained attention in recent years. The consumers’ rating is mainly based on the size, shape, nutritive value and marketability of them. Each of these classifications is quite different from the other classification or groupings.

Basically, the fruit trees, as suggested by many authors, have been classified on the basis of their botany comprising of taxonomic ancestry, morphologic features, physiological functions, adaptability etc. or on the basis of agricultural and horticultural requirements. But the consumers’ rating has not been properly covered in the earlier classification. Generally based on botanical relationship the plants are classified as under.

Grouping plants in different categories on the basis of similarities and dissimilarities is referred to as classification, which helps for study of these crops in various perspectives. India is endowed with a rich diversity of horticultural plant wealth due to varied agro-climatic conditions. Number of fruits, vegetables, ornamental crops, spices, condiments, plantation crops, etc. is under commercial cultivation in different parts of the country under different sets of growing conditions.

The systematic study of all these crops becomes a difficult and more repetitive part. To avoid it; classification of horticultural crops on different aspects has been made to deal with all these plants separately. Classification of horticultural crops has been made in different groups on similarity or dissimilarity of attributes. Plants having similarity in either of the traits are placed under one group. The overall objective of the classification is to categorize the horticultural plants and make the recollections very easy and convenient.

5.1 Fundamentals of Plant Nomenclature
(A) Plant Nomenclature
5.1.1 Definitions
Assignment of definite names to plants is called nomenclature. In the present botanical world, the nomenclature involves the principles governed by rules formulated and adopted by International Botanical Congresses. The rules developed by IBC are listed formally in a code called International Code of Botanical Nomenclature (Voss et al., 1983), abbreviated as ICBN. The major goal of ICBN is to provide one correct name for each taxon. Taxa (singular, taxon) are the taxonomic groups of any rank. The ascending hierarachy of taxa include species, genus, family, order, class and division.
5.1.2 Who is a Nomenclaturist?
A nomenclaturist is a taxonomist who assigns names to new taxa, determines the right names for old taxa according to the rules of International Code of Botanical Nomenclature, and finalizes the right name for a specimen according to an established system of classification.