eChapters

Medicinal plants are non-food non-plantation crops.

These are rich in secondary metabolites viz. alkaloids, glycosides, coumarins, flavonoides and steroids, etc.

Union government of India has started a project on 'Traditional Knowledge Digital Library' under which it is documenting all Ayurvedic formulations in a digital form to avert patent threats from companies in the developed world

Spices: It is defined as vegetable products (non-leafy parts) or mixture thereof, used for flavouring, seasoning and imparting aroma in food. It may be whole form or in ground form e.g. Pepper, Cardamom, Clove, Cinnamon, etc.

These crops are cultivated in an extensive scale in large contiguous areas, owned and managed by an individual or a company and whose produce is utilized only after processing e.g. Coffee, Tea, Rubber, Coconut, Cocoa, etc.

USA ranks 17th in per capita cut flowers consumption.

India ranks 2nd in flower cultivation next to China.

India stands 14th in the world in exporting floricultural products, while the Netherlands and Columbia rank 1st and 2nd, respectively

Olericulture is Latin term ‘Olerus’ meaning ‘pot herb’ and ‘Cultra’ meaning ‘cultivation’.

Definition: Vegetables are those plants wherein parts such as leaf, stem or root can be used for food.

Herbs: Are those plants that are used for food, medicine, scent or flavour.

GENERAL POMOLOGY

Word pomology: Derived from Greek word ëpomeí means ëdevelopment of fruit from inferior ovaryí and ëlogosí means ëto studyí.

Father of systematic pomology: De Candolle.

T. A. Knight attempted 1st artificial hybridization in fruit crops

Definition of farmer (National Policy for Farmers, 2001): A person actively engaged in the economic and/or livelihood activity of growing crops and producing other primary agricultural commodities and will include all agriculture operational holders, cultivators, agriculture labourers, share croppers, tenants, poultry and livestock rearers, fishers, beekeepers, gardeners, pastoralists, non-corporate planters and planting labours, as well as persons engaged in various farming related occupations such as sericulture, vermiculture, and agroforestry. It also includes tribal families/ persons engaged in shifting cultivation and in the collection, use and sale of minor and non-timber forest produce.

Powdery mildew

Sphaerotheca pannosa var. rosae (Sphaerotheca pannosa)

Diagnostic Symptoms

• A white, powdery fungal growth on the upper, lower or both leaves and shoots.

Botrytis Gray Mould

Diagnostic Symptoms

• Appearance of a gray, fuzzy mold on flowers, leaves or stems of or plants. Also called, “gray mold”.

Stem gall

Diagnostic Symptoms

• Symptom appears in the form of tumor-like swellings of leaf veins, leaf stalks, peduncles, stems as well as fruits.

• Infected veins show a swollen hanging appearance to the leaves.

Leaf spot

Colletotrichum capsici

Diagnostic Symptoms

• Initially oblong brown spots having about 4-5 cm in length and 2-3 cm in width with grey centres surrounded with yellow hallo are found on the leaves .

Anthracnose or Fruit Rot and Die Back

Colletotrichum capsici

Diagnostic Symptoms

Dieback symptoms

• Small, circular to irregular, brownish black scattered spots appear on leaves .

Purple blotch

Alternaria porri

Diagnostic Symptoms

• Disease symptoms occurs on leaf and flower stalks.

Downy mildew

Pseudoperonospora cubensis

Diagnostic Symptoms

• Yellow, angular spots restricted by veins resembling mosaic mottling appear on upper surface of leaves .

Late Blight

Phytophthora infestans

• Phytophthora in Greek means “plant destroyer”(phyto=plant, phthora= destroyer).

Leaf Spot

(Mycosphaerella fragariae teleomorph, Ramularia brunnea Peck anamorph)?

Disease Symptoms

• Older leaves usually show purple spots (3-6 mm in diameter) on the upper surface, sometimes with a slightly darker halo

Leaf Curl

Taphrina deformans

Disease Symptoms

• Initially yellowish to reddish areas appear on leaf blade of young leaves in the spring.

Scab

Ventruia inaequalis (Spilocaea pomi Fr?)

Diagnostic Symptoms

• Symptoms generally noticed on leaves and fruits.

Downy Mildew

Plasmopara viticola

• Downy mildew of grapes was catastrophic in France in 1878.

Gummosis

Phytophthora spp

Diagnostic Symptoms

• Dark water soaked large patches appear on the basal portions of the stem near the ground level.

Anthracnose

Colletotrichum gloeosporioides (Glomerella cingulata)

Diagnostic Symptoms

• Disease produces symptoms like leaf spot, blossom blight, withertip, twig blight and fruit rot

• Symptoms on leaves show as gray to brown spots with dark margins and a yellow halo. The spots later enlarge and coaleasce to form sizable necrotic areas.

Powdery Mildew

Erysiphe polygoni

Diagnostic Symptoms

• At first symptom appears on leaves.

• White floury patches appear on both surface of leaves as well as tendrils, stem and pod.

Wilt

Fusarium oxysporum f.sp. vasinfectum

Diagnostic Symptoms

• Disease affects the crop at all stages.

Diagnostic Symptoms

• Symptoms can occur at both the seedling and plant developmental stages and appear as patches in the field

• It usually occurs near or at the reproductive stages (flowering to podfilling) of crop growth

Diagnostic Symptoms

• At first pale-green chlorosis, typically appear on lower leaves and extending up the plant.Leaves eventually take on a dull-yellow colour, wilt and the plant collapses and dies.

Diagnostic Symptoms

• Intially chlorotic (yellowed) lesions and sometimes galls appeared on the upper leaf surface.

• There are corresponding white blister-like dispersal pustules of sporangia on the underside of the leaf.

Diagnostic Symptom

• Circular to oval, dark brown to black spots appear on the leaves.The spots enlarge into round to irregular spots with concentric rings and coalesce causing blighting and withering of leaves.

• These are surrounded by chlorotic zone with grey white necrotic center.

Diagnostic Symptoms

• Practically all above ground parts are affected, but stalks are the main targets of stack.

• Spindle leaves (third or fourth) starts drying.

• Further stalks becomes discolored and hollow.

Rust

The rust of wheat has been studied more than any other disease in the world. In India, K.C Mehta and his associates studied this disease with exemplary zeal. Three rusts of wheat are known. These are Black stem rust, caused by Puccinia graminis tritici, Brown rust (leaf rust), caused by Puccinia recondita, and Yellow rust, caused by P? striiformis. Brown and yellow rusts cause more damage thant the black rust, because of early appearance in the season.

The results pertaining to the present investigation, “Diagnostic Study of Farmers in context of Price spread analysis, marketing pattern and Potential assessment of agricultural diversification in Chenani Block of Udhampur district” have been presented in this chapter.

4.1 Cost and return analysis of cereals, vegetables and fruit crops

For financial analysis of different enterprises, it is necessary to workout costs of various inputs, which needs to be deducted from the value of inputs. The cost and return analysis of cereal crop and vegetables in Mantalai village of Chenani block is presented in Table 4.1. Per hectare Cost A which included all the variable costs excluding the family human labour were found to be highest (?55416.38) for the cultivation of garlic followed by tomato (?54260.75) whereas raddish incurred lowest of ?29361.33. The cost B which included the fixed costs in addition to cost A were ?39020.89 for maize, ?59074.66 for tomato, ?37280.11 for cucumber, ?33361.33 for raddish, ?41053.97 for beans and ?59416.38 for garlic. The cost C i.e. total item wise per acre operational costs which also included the imputed value of family labour were found to be highest (?149074.66/ha) in tomato and lowest of ?39361.33/ha in raddish. The cost C increases in case of tomato to such an extent only because of the addition of family labour. Cost C* was also calculated by adding 10 per cent of cost C as management cost to total cost.

The present investigation entitled “Diagnostic Study of Farmers in context of Price spread analysis, marketing pattern and Potential assessment of agricultural diversification in Chenani Block of Udhampur district” was carried out during the year 2015. The sampling structure, experimental procedures and techniques adopted during the course of investigation have been described in this chapter.

3.1 Locale of study

The present study was conducted in Chenani block of Udhampur district in Jammu and Kashmir state. Mantalai, Kosar, Bupp and Bashath villages were randomly selected.

3.2 Climate and rainfall

The Jammu and Kashmir state is situated between 32⁰.17'–36⁰.58' North latitude and 37⁰.26´–80⁰.30´East longitude. The state is the northern most part of the India is girdled by Tibet to the east, China and Afghanistan to the north, to its west is Pakistan. To its south lies the states of Punjab and Himachal Pradesh and have been divided into three agro climatic divisions’ viz. outer plain and outer hills, middle mountains and Kashmir valley and inner Himalayas (Ladakh). The outer plains and outer hills includes Kathua and Jammu districts, extends up to Shivalik hills in the north. According to NARP (National Agricultural Research Project) classification this state has been divided into four agro-climatic zones: Temperate, Sub-tropical, Intermediate and Cold-Arid zone. In summer hot dry winds from plains of Punjab make it very hot, dust storms are common with occasional rain. Rainfall occurs from July to September. Average rainfall is 1143 mm and temperature shoots up to 46⁰C during May to June. During December to February temperature is between 13.5⁰C to 20⁰C, rainfall is 150 mm and in upper reaches there is snow. In the region of middle mountains and Kashmir valley winters are very cold. There is snowfall during winter and subzero temperature. In valley, winters are long and summers are short but pleasant. Average rainfall is 732 to 854 mm. The maximum temperature hardly ever goes beyond 35⁰C. In region of inner Himalayas, days are hot and there are no clouds in the sky. Winters are very cold. Temperature falls as low as minus 23⁰C. The average rainfall is 976 mm and humidity level is very low.

Globalization of economies and liberalization of trade has led an urgent need for prioritizing the potential areas for investment in order to earn handsome amount of income. Even the entrepreneurs, small as well as marginal farmers aspire to take advantage of global opportunity. Diversification to horticultural crops has been found to be best option as they make more profit, generate additional employment for rural masses and conserve natural resources. Agriculture plays a vital role in the Indian economy. Over 52 per cent of the rural households depend on agriculture as their principal means of livelihood. But unfortunately Indian farmers in general are small and marginal land holders with poor resources and realizing income mainly from cereal based production system, which is insufficient to improve their living standards. Agriculture, along with fisheries and forestry, accounts for one-third of the nation’s GDP and is its single largest contributor (www.indianbusiness.nic.in). GVA at Basic Prices for 2019-20 from ‘Agriculture, Forestry and Fishing’ sector is estimated to grow by 2.8 per cent as compared to growth of 2.9 per cent in 2018-19. The GVA estimates of this sector are based on 1^st advance estimates of agricultural production during Kharif season of 2019-20 obtained from the Ministry of Agriculture & Farmer Welfare. For Livestock sector, estimates of production of major livestock products (i.e. Milk, Egg, Meat and Wool) obtained from the Department of Animal Husbandry & Dairying and Fish production data obtained from Department of Fisheries have been used. The crops including fruits and vegetables account for about 56 per cent, the livestock products 30 per cent and forestry & fisheries 14 per cent share of GVA in total GVA of ‘Agriculture, Forestry and Fishing’ sector [As per the estimates released by National Statistics Office, Ministry of Statistics and programme Implementation, GoI, 2020]. Agricultural exports constitute a fifth of the total exports of the country. In view of the predominant position of the Agricultural Sector, collection and maintenance of Agricultural Statistics assume great importance. In 2018-19, India achieved a record food grain production of 285.17 million tonnes beating the previous year’s (2017-18) 285.01 million tonnes, according to data provided by Department of Economics and Statistics (DES). Also, agricultural profitability has increased over the last decade with record increases in MSPs (minimum support prices) for agricultural produce for all covered crops.

Bhatia, (1965) in his study on “Patterns of Crop Concentration and Diversification in India” has observed that physical, socio-economic and technological factors have affected the magnitude of crop diversification. Variations in above mentioned factors are responsible for variations in patterns of crop diversification in India. He has also evolved a new technique for measuring crop diversification in India. He has taken all the crops which are having 10 per cent or more than 10 per cent of the cropped area. He summed up the total area under these crops and divided the sum by the number of crops. According to his method, higher the index, lower is the magnitude of crop diversification and vice-versa.

Ayyar, (1969) in his study “Crop Regions of Madhya Pradesh: A Study in Methodology” has evolved a new technique for measuring crop diversification regions. He has taken all the crops which were having 1 per cent or more than 1 per cent of the total cropped area. Then he divided the sum of crops by the number of crops which are having 1 per cent or more than 1 per cent of the total cropped area. His method is an improvement over Bhatia’s and Singh’s methods for measuring crop diversification.

Patel and Pawar (1980) studied the marketing of fruits in Mahatma Phule market, Bombay. The study showed that there was close relationship between wholesale prices and supply position, whereas there was no such pattern in case of retail prices. The producers’ share in consumers’ rupee was 33.07 per cent for sweet oranges. In case of apples, mangoes and grapes, the share of the producer in consumers’ rupee varied according to the varieties and ranged from 33 to 54 per cent. The study also made some suggestions as standardization and grading, and establishment of cooperative marketing societies for getting better prices for the producers.

29.1 Introduction

An environmental factor that interferes with the complete expression of genotypic potential of a crop is called stress. The stresses may be biotic (pathogens, insect-pests, etc.) or abiotic. The main abiotic stresses are drought, mineral deficiency/toxicity and heat or cold. The losses due to abiotic stresses can be minimized by:

Crop management: The degree of stress can be reduced by suitable agronomic/soil management practices, e.g., irrigation to relieve drought stress, soil amendments to reduce salinity.

Development of resistant cultivars: This offers the cheapest, easiest to apply and most eco-friendly approach to reduce losses due to any stress.

Indirect breeding: Evaluation of materials under stress often helps in identification of a resistant line that may become an important commercial cultivar.

???????Direct breeding: It is deliberate breeding of materials for stress resistance. When a genetically variable material is grown under the stress environment, selection can be based on survival, yield and other traits contributing to stress resistance.

28.1 Introduction

The stress that is caused by biological agents or factors such as diseases, insect-pests and parasitic weeds is called biotic stress. The term disease can be broken into two words: “dis” (means negative, reverse or opposite) and “ease” (means comfort, or freedom from pain or discomfort). Hence, plant disease can be defined as any harmful alteration from the normal functioning of physiological processes. Diseases may be bacterial, fungal or viral. A wide range of insects infests various crop plants. The extent of damage caused to crop plants by various organisms is usually in the order fungi > bacteria > viruses > nematodes = insects. But the relative importance of these organisms varies to a great deal in different crops. Breeding of cultivars resistant to diseases and/or insect-pests is the cheapest, safest and most dependable means of limiting the losses due to them. Resistant cultivars form an important component of integrated management of diseases and insect-pests.

28.2 Breeding for Resistance to Biotic Stresses-Diseases

Agrios (1970) has defined disease as: “Disease is a series of invisible and visible responses of plant cells and tissues to a pathogenic microorganism or an environmental factor that result in adverse changes in form, function or integrity of plant and may lead to partial impairment or death of the plant or its parts.” The organism causing disease is called pathogen, while the plant affected by the disease is called host.

The principles underlying breeding for resistance to diseases are much the same as for other characters, except for one important difference, i.e., the diseases caused by pathogens are the product of interaction between two genetic systems, that of the host and that of the parasite. Both systems are capable of variation and evolution and affect the interaction between host and pathogen. Here the breeder is required to deal with the heritable traits of both the host plant and the pathogens invading it.

27.1 Introduction

Crop improvement depends on genetic variation present in nature or created by hybridization followed by segregation and recombination. Again, gene transfers are possible only from the lines and species that are sexually compatible with the concerned species. Interspecific gene transfers pose many problems, including the loss of F₁ hybrids during embryo development due to abortion of the endosperm in the developing hybrid seeds. Embryo rescue technique was developed to rescue such interspecific hybrid embryos, and it has been widely used for this purpose. It is to be mentioned that embryo rescue can be used only in such cases where sexual hybridization is successful in producing zygotes that begin to develop into embryos.

Besides, the technique of somatic hybridization by protoplast fusion was developed to enable gene transfer from the species that do not produce zygotes on hybridization. This method has been extensively used and some useful lines have been derived. But this method is limited to utilization of genes present in plant species. Again, the results of somatic hybridization are unpredictable since many somatic hybrids fail to regenerate complete plants and the transfer of specific genes or groups of genes depends entirely on chance.

The recombinant DNA technology (also called genetic engineering) has permitted the transfer of genes from any organism into any organism. Besides, chemically synthesized genes can be transferred and integrated into genomes of various organisms to enable the expression of these genes. A gene transferred into an organism by genetic engineering is called a transgene. 

26.1 Introduction

We have already discussed the basics of tissue culture techniques in Chapter 2. Plant tissue culture techniques in combination with recombinant-DNA technology are essential requirements for development of transgenic plants (will be discussed in next chapter). However, tissue culture techniques like anther, pollen, ovule and meristem culture can themselves be used for improvement of different traits or as an aid to conventional breeding methods. In recent years, isolated microspore culture has been preferred as a breeding tool and an experiment system for various genetic manipulations. Besides, using protoplast fusion and hybrid embryo rescue, distant hybridization has been successfully achieved in many crops. Protoplast fusion technique can be used for the transfer of cytoplasmic male sterility from one species to another in very short duration. Somaclonal variation generated during tissue culture can also be utilized for recovery of variants showing disease resistance or other desirable characters.

25.1 Introduction

The method of selection in which a gene/QTL (Quantitative Trait Locus) is selected on the basis of the genotype of the molecular marker (also called DNA marker) linked to this gene/QTL is known as marker-assisted selection (also called marker-aided selection). The idea of marker-assisted selection (MAS) was first advocated by Tanksley (1983). MAS can be used in combination with the conventional breeding methods or novel breeding schemes could be devised to take full advantage of the marker data. MAS has been widely used for introgression of the desired genes and QTLs using backcross programmes.

25.2 Marker-Assisted Backcrossing (MABC)

The backcross programme based on molecular marker is usually called marker-assisted backcrossing (MABC). MABC has three activities: (a) foreground selection, (b) background selection and (c) recombinant selection.

25.2.1 Foreground Selection

The use of molecular marker to select the gene/QTL being introgressed is known as foreground selection. The objective of foreground selection is to select the target gene, i.e., the gene being introgressed, without phenotypic evaluation for the trait governed by the target gene. Foreground selection for a gene/QTL will be highly desirable in a variety of situation, some of which are listed below:

24.1 Introduction

When crosses are made between two different species of a genus or between two different genera, they are known as distant hybridization (also called wide hybridization). It includes both interspecific and intergeneric hybridization. Thomas Fairchild (1717) was the first man to do distant hybridization. He produced a hybrid between two species of Dianthus, viz., D. caryophyllus and D. barbatus (Carnation and Sweet William). Intergeneric hybrid produced by Karpechenko, a Russian scientist, in 1928 is Raphanobarssica. It is the amphidiploid of cross between radish (Raphanus sativus) and cabbage (Brassica oleracea var. capitata). Unfortunately, it had roots like cabbage and leaves like radish. Triticale was produced by Rimpau in 1890 itself. It is an amphidiploid obtained from a cross between wheat and rye (Triticum and Secale). Another example is Saccharum nobilisation involving Saccharum officinarum, S. barberi, S. sinensis, S. spontaneum. Wide hybridization has been used in the genetic improvement of some crops. It is an effective means of transferring desirable genes into cultivated plants from related species and genera.

23.1 Introduction

An organism or individual having more than two basic sets of chromosomes is called polyploid and the condition is known as polyploidy. Polyploidy is an important tool to increase genetic diversity by altering the chromosome number (2x) and consequently the number of genes within a single cell. Polyploidy has been one of the important mechanisms in the evolution of many cultivated crop plants.

23.2 Types of Polyploidy

23.2.1 Autopolyploidy

The condition that arises due to multiplication of the same chromosomes of a single species is known as autopolyploidy (also called ‘simple polyploidy’ or ‘single species polyploidy’). Autopolyploids have generally larger leaves, stem and other vegetative parts and flower, fruit and seeds than their normal diploids.

22.1 Introduction

Mutations are sudden heritable changes in the genotype of an organism. De Vries (1900) for the first time used the term mutation (mutare in Latin means ‘to change’) for the appearance of new types in evening primrose (Oenothera) plant. In 1901 he put forth the idea of producing mutations artificially for use in crop improvement. Alberto Pirovano (1922) was first to use X-rays and ultraviolet rays for inducing mutations in plants, but his work remained unknown. So, Muller (1927) became the first known to induce mutation in Drosophila fly using X-rays. Though Stadler (1928) had started working simultaneously on barley and maize and induced mutations, he was late in reporting mutation due to longer life cycle of these plants compared to Drosophila. Mutation may be gene mutation (the result of change in the nuclear gene or plasma gene) or chromosomal mutation (change in chromosome number, structure or chromosomal aberrations of various types).

21.1 Introduction

There are a number of field, vegetable, fruit and ornamental crops that are cultivated using asexual or vegetative parts such as stems, roots, modified flower etc. This is a heterogeneous group of plants and can be further categorized into four groups for ease in understanding the breeding methods applied to them. They are:

Group 1: Flowerless or Sterile

This group either does not bear flowers or if bears, they are sterile and do not set seed, e.g., ginger, mango ginger, turmeric, garlic, betel, many yams, etc.

Group 2: Apomicts

Apomixis has been reported in over 300 genera. But stable apomixis has been reported only in a few cultivated plants like meadow grass, citrus, mango, raspberry, etc.

Group 3: Flowers but Seed-Set Rare

In this group flowering takes place under specific situations but seed-set is limited, e.g., potato, sweet potato, sugarcane, etc.

20.1 Introduction

A hybrid cultivar (also called hybrid) is the F₁ progeny of a planned cross between inbreds, cultivars, clones or populations. Depending upon the breeding approach, the hybrid cultivar may involve two or more parents. A critical requirement of hybrid production is that the parents are divergent. This divergence is the cause of superior performance of hybrids. The outstanding performance of crops is due to the exploitation of the phenomenon of heterosis (hybrid vigour) which is high when parents are divergent. Much of what we know about heterosis breeding (also called hybrid breeding) came from the work on maize hybrid cultivar development. However, commercial hybrids are now available in many crops including self-pollinated crops.

19.1 Introduction

In self-pollinated crops, the methods of selection aim at improving individual plants. On the other hand, in cross-pollinated crops they aim at improving a population of plants. A population is a large group of interbreeding individuals. Hence, selection is called population improvement in cross-pollinated crops. Selection in self-pollinated crops results in isolation of pure breeding lines which is the end product. But in cross-pollinated crops, it results in an improved population which is used as the commercial cultivar. Improved inbred lines (also called inbreds) for producing hybrids can be obtained from such populations. Again, like many rounds of selection being practised in different inbreeding generations in self-pollinated crops we are also practising many rounds of selection in cross-pollinated crops. But, unlike self-pollinated crops selection in cross-pollinated crops is followed by intermating to develop a new population before starting another round of selection. One cycle of selection consists of selection of individual/family and intermating of the selected units. Such cycle is repeated till we get the improved population. This method of practising the cycles of selection and recombination in a population is called recurrent selection or population improvement. Frey (1983) prefers the use of recurrent selection for closed populations where no new germplasm is added to the population during selection. Population improvement was used for a group of breeding techniques where all aspects are similar to recurrent selection but with the provision of adding new sources of germplasm whenever feasible. It is only a matter of coincidence that past history of application of recurrent selection has been limited to closed populations, but its basic aim has always been the accumulation of favourable genes, without any restriction on the migration of new genes during the course of selection. Apart from a slight nuance, population improvement and recurrent selection are two titles of the same principle and procedure of manipulating the genetic potential of populations. Recurrent selection can also be applied in self-pollinated crops.

18.1 Introduction

The genetic variability present in populations of self-pollinated vegetable, spice and ornamental crops is rapidly exhausted by pureline selection. For further improvement, genetic variability must be created. This is generally achieved by hybridization. After the cross has been made, F₁ is grown and seeds set on it are harvested. This makes the seed source for raising F₂ population, and so on. The segregating populations from crosses are handled according to a suitable method. The three basic methods available for this purpose are: (1) pedigree method, (2) bulk method, and (3) backcross method. There are also certain modifications of these methods.

18.2 Pedigree Method

Pedigree method is developed from the pureline system and widely used method of plant breeding for self-pollinated crops. A main difference between pedigree selection and mass selection or pureline selection is that hybridization is used to create variability for the base population in case of the former, whereas in mass and pureline selections variability is naturally present in the base populations. The pedigree method was first described by H.H. Lowe (1927). This method predominated the crop improvement programme throughout the world until 1980s. Pedigree method is common in horticultural crops, especially where readily identifiable qualitative traits are involved. Vegetable crops in which pedigree system is used include tomato, cucumber, pepper, pea, lettuce, snap and field beans, all self-pollinated crops. In general, selection is done on F₂ plants. Yield is important in many horticultural plants, but quality is equally or even more important. Quality may be associated with identifiable traits, making the pedigree system ideal for self-pollinated vegetable crops.

17.1 Introduction

Self-pollinated vegetable, spice and ornamental crops may be heterogeneous. It is exemplified by landrace cultivars. They may have originated from single plant selections but have been grown over a long period of time. Landrace cultivars are a mixture of genotypes, perhaps because of breeders’ lack of appreciation of selection techniques to produce a pure line, spontaneous mutations, chance hybridization, or a combination of factors. Natural selection in landraces has resulted in a cultivar that is well adapted to the local environment. Depending on amount of human selection, differences among genotypes in a landrace cultivar may be small and inconspicuous. On the other hand, a lack of human intervention may mean that differences among plants in a landrace cultivar will be conspicuous. After years of self-pollination, individual plants are homozygous. Selection of such individuals would result in a true-to-type reproduction of their phenotype within the limitations imposed by the environment.

16.1 Introduction

Plant introduction is the process of introducing plants from their growing locality to a new locality. Introduction of plants from a foreign country is called foreign introduction or exotic collection. Introduction from one state to another within a country is called indigenous collection or indigenous introduction. With introduction, the process of acclimatization is associated. Acclimatization is the adaptation or adjustment of an individual plant or population of plants under the changed climate for a number of generations. Plant introduction is an oldest method of plant breeding. It is used in self-pollinated, cross-pollinated and asexually propagated crops. The material of seed-propagated crops is introduced in the form of seed and that of vegetatively propagated crops in the form of cuttings or propagules. The introduced material may be a new crop, a wild relative or a new cultivar of a crop already grown in the area. There are five important sources of plant collection, namely, (1) centres of diversity, (2) gene banks, (3) gene sanctuaries, (4) seed companies, and (5) farmers’ fields.

15.1 Introduction

Plant breeding aims at developing genetically improved crop cultivars with economic benefits for small-scale and commercial farmers. Population growth, dwindling agricultural land and global climate change present increasing risk to crop production. Consequently, plant breeding aims to constantly develop crop cultivars with improved yield and quality and tolerant to drought, diseases and pests. Use of genetically improved crop cultivars and better management practices are among the best strategies to increase food production and meet a projected doubling of food demand in the next 40 years. Both the public and private plant breeding sectors face several constraints, including a shortage of professional plant breeders and breeding technicians, limited budget, inadequate facilities and lack of access to information. Successful plant breeding requires adequate infrastructural investment, in addition to the actual breeding activities. The benefits of plant breeding research and development can only be realized on a long-term basis because of the inherent nature of the crops and the eminent breeding procedures involved. Plant breeding involves two main activities, i.e., pre-breeding/ germplasm enhancement and cultivar development per se. These interdependent activities are the controlling factors that determine the pace at which cultivars are released timeously and consistently to farmers. The two phases, in turn, depend upon various factors, e.g., breeding goals, genetics and agronomy of the crop, breeder’s long-term objectives, availability of testing facilities and national cultivar-registration requirements. Despite these factors, there are certain clear steps and breeding procedures found in any conventional breeding programme. These include choice of parents, making crosses among chosen parents, and selection from recombined parents followed by extensive field testing of the candidate cultivars. Maintenance, multiplication and distribution of the seed are the ultimate stages of a breeding programme. Systematically outlined conventional breeding procedures, timeframes and estimated breeding generations are essential to objectively consider the ultimate timescales required to release new and improved cultivars of all crops. The information may assist plant breeding- students, educators, researchers, project advisors, administrators and funding agencies. Dear students, in this chapter we outline the timeframes of conventional breeding procedures of clonally (also called vegetatively) propagated, self-fertilizing (also called self-pollinated) and cross-fertilizing (also called cross-pollinated) crops.

14.1 Introduction

The mating or crossing of genetically dissimilar individuals is called hybridization. Hybridization results in recombination that in turn widens the spectrum of variation among individuals. So, the reason for genetic diversity in progenies of crosses is the formation of new combinations of genes. This newly created variability is then channelized into development of better cultivars.

The importance of pure line selection as a method of breeding started decreasing when plant breeders felt that the genetic variability existing in the land races of self-pollinated crops had been almost completely exploited and there was little chance for further improvement in these crops by using pure line breeding. Therefore, no option was left for plant breeders except to cross diverse individuals and combine together desirable characters in a single genotype from two or more parents. The planned hybridization which could avoid self-pollination and chance cross-pollination, soon became the main feature of almost all plant breeding programmes.

13.1 Introduction

F₁ plants produced by crossing two parents with contrasting characters are called hybrids. Hybrids generally exhibit increased vigour and fitness over the parents. This phenomenon is called hybrid vigour or heterosis. Thus, heterosis is the phenomenon in which the hybrid of two genetically dissimilar parents shows increased vigour at least over the mid-parental value. Heterosis is just the reverse of inbreeding depression, which results after selfing the plants of the cross-pollinated crops. Kolreuter (1761-66) was the first to report hybrid vigour in the hybrids of tobacco, Datura, etc. Most of the early plant hybridizers including Mendel (1865) had noticed this phenomenon. Shull (1914) coined the term heterosis from two Greek words, hetero (different) and osis (condition), to replace his own earlier word ‘stimulus of heterozygosis’. In current usage, heterosis and hybrid vigour are used as synonyms and interchangeable.

13.2 Types of Heterosis

Depending on the nature, origin, adaptability, reproducibility and non-reproducibility, heterosis can be categorized into two: (1) euheterosis (true heterosis) and (2) pseudo-heterosis (false heterosis, i.e., luxuriance).