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All living organisms are basically made up of chemical components. The chemistry, composition and energy management of living organisms is what we call biochemistry. It tries to explain life processes at the molecular level. Although different organisms differ outwardly in their life processes, there are striking similarities in executing the different tasks. Genetic code, metabolic pathways, enzymes, coenzymes and even regulatory mechanisms are similar to a large extent in all the living organisms. Living organisms have certain extraordinary properties. They can grow, respond to stimuli and replicate themselves with high fidelity. All these activities are ultimately interpretable in chemical terms. The components that constitute organisms are all inanimate. The lifeless organic molecules with appropriate complexity and properties make a living being.

Biochemistry helps us understand how the inanimate molecules that constitute living organisms interact with each other to maintain life. The basic life processes or the biochemistry remains broadly the same in either the unicellular microorganism or the higher organisms such as the plants or the human beings. Life is nothing but thousands of ordered chemical reactions. In other words, chemistry is the logic of all biological phenomena.

Carbohydrates are the most abundant biomolecules on earth. They occur in nature as glucose, starch and cellulose etc. Each year, photosynthesis converts more than 100 billion metric tonnes of carbon dioxide and water into starch, cellulose and other plant products. Carbohydrates are polyhydroxy aldehydes or ketones and their derivatives. They provide 4k calories energy per gram. They promote utilization of lipids and reduce wastage of proteins. They are readily available in roots, tubers, cereal grains, sugarcane and sugar beet.

Carbohydrates have the general formula C_n( H₂O)n, indicting that they are the hydrates of carbon. Some carbohydrates also contain nitrogen, phosphorous or sulfur. They are characterized by the number of carbon atoms they contain. If n=3, they are trioses, n=4 tetroses, n=5 pentoses, n=6 hexoses and n=7 heptoses. The most common sugars in plants are the hexoses. Two or more simple carbohydrates condense together to form polymer sugars like sucrose, starch and cellulose etc. The basic condensing bond is glycosidic bond.

Lipids are non polar substances of biological origin that are sparingly soluble in water, but soluble in organic solvents like chloroform, hexane, benzene etc. The word lipid comes from the Greek word lipos meaning lard or fat. The lipids present in biological systems are either hydrophobic (non polar) or amphipathic (both polar and non polar). Lipids like fats, oils or glycerophospholipids can be hydrolyzed to get fatty acids and other products. Hydrophobic nature is useful in making lipids as membranes which act as effective barriers to more polar molecules. Steroids are also considered lipids, but cannot be hydrolysed and are components of non-saponifiables in fats. Waxes, which are esters of fatty acids with long chain alcohols are also considered as lipids.

Amino acids are the building blocks of proteins. They occur in all living plant cells as constituents of proteins and as free acids or amides. More than 200 naturally occurring amino acids have been identified in higher plants. Around 20 different amino acids have been observed to be incorporated into proteins. They have two functional groups, an amino group (-NH2) and a carboxylic group(-COOH). Both these groups are attached to the a carbon atom only. Amino acids with this structure are called a amino acids or 2-aminoacids. The unique characteristics of the 20 amino acids are due to the side chain (R), which can be an alkyl, hydroxyl, thiol, amino, sulphide, aromatic, or heterocyclic group.

Amino acids have the general formula, R-CH(NH₂)-COOH. The R represents a side chain. If R=H, the simplest amino acid glycine (NH₂ -CH₂ –COOH) results. Amino acids are alpha (a ) amino carboxylic acids. The carbon atom is tetrahedral in shape. The various groups attached to it are placed in different positions. Since the valence of the carbon atom is four, four groups can be attached to the carbon atom. Based on the groups attached to the carbon atom it may be of two types.

An amine reacts with a carboxylic acid to form an amide. Similarly, the amino group  on one amino acid molecule reacts with the carboxyl group of another amino acid  to form a compound called peptide. A peptide bond is an amide bond that forms when the –COO- group of one amino acid reacts with the -NH₃+ group of another amino acid. The resulting compounds are called peptides. Even after this there is a reactive amino group and a carboxyl group in the peptide. If these groups react further a poly peptide can form and later a polymer called protein can form.

The word protein was first coined in 1838 to emphasize the importance of this class of molecules. The word is derived from the Greek word proteios which means “of the first- rank”. Proteins are polymers/macro molecules made up of several amino acids. When there are more than 50 amino acids in a chain, the polypeptide is normally called a protein. Each protein in the cells of living beings has a unique sequence of amino acids that determines its biological function. The proteins are folded into specific defined structures, which are maintained by a large number of relatively weak bonds. The  three  dimensional structure is well defined and suited to it’s specific function.

Very small changes in the structure can modify the function. Hence, it is important to know the structure of proteins to understand their behavior and function. The biological activity of proteins depends on maintenance of folded conformation. Proteins fold into well defined three dimensional shapes and they are able to recognize their corresponding substrates or antigen molecules and bind them tightly. The protein structure has been classified into four different levels based on the folded conformation of the protein.

Enzymes are organic catalysts produced by living organisms. They make possible biochemical reactions. Hence they are called biocatalysts. They are mostly a specialized class of proteins. However, there are some non-protein enzymes like ribozymes, which are RNAses. Enzymes speed up reactions at ambient temperatures. This is in contrast to chemical reactions like saponification of lipids which take place when lipids are boiled for a few hours with concentrated alkali.  Enzymes, namely, lipases, hydrolyze lipids at body temperatures in minutes. They are superior to chemical catalysts by a factor of 107 to 1014 .  An enzyme may be a simple protein or a complex protein. They are produced by cells and are mostly globular proteins. Each cell contains an estimated 3000 different enzymes.

Nucleic acids were first discovered in 1868 by Friedrich Meischer. Nucleic acids are high molecular weight polymers that are present in our cells. They  store and transfer genetic material from generation to generation. Knowledge of how genes are expressed and how they can be manipulated is becoming increasingly important for understanding   of nearly every aspect of biochemistry. These macromolecules pass on information for cellular growth and reproduction.  All the genetic information in the cells is called the genome. Every time a cell divides, the information is copied and passed on to the new cells.
 
Nucleic acids fall into two main classes according to the type of sugar they contain: the Deoxyribonucleic acids (DNA) and Ribonucleic acids (RNA). Some sections  of  the  DNA  called  genes contain the information to make a protein. RNA translates the genetic information in the DNA to the ribosomes, where the synthesis of proteins takes place.

Plants are responsible for highly useful molecular reactions. All the enzymatic  reactions  that  occur in the cell are  termed  as metabolic reactions.  They  take place within organisms in an orderly and regulated way.  They  are  the  metabolic pathways and the compounds  resulting from the process, namely,  metabolism are called  the metabolites. Metabolism in Greek means change. It is the set of life sustaining chemical transformations within the cells of living organisms. These enzyme-catalyzed reactions allow organisms to grow and reproduce, maintain their structures, and respond to the environments around them.
 
Metabolism is a highly organized,   coordinated and purposeful enzymatic activity inside a cell. Metabolism has four functions: 1. To obtain energy from the environment, 2. To convert molecules into building blocks, 3. To convert the building blocks into proteins, lipids, sugars, nucleic acids and other cell components and 4. To synthesize and degrade organic molecules for specific needs of the cell.

Carbohydrate metabolism in the cell is essentially the metabolism of glucose and other substances related to glucose in their metabolic processes. The chemical reactions involved in carbohydrate metabolism represents complex groups, sequences, and cycles of reactions which integrate at various points with the reactions concerned in the metabolism of lipids and proteins. The major types of chemical processes involved in carbohydrate metabolism may be grouped as follows: a) Anabolism of starch – Photosynthesis, b) Catabolism of starch, c) Catabolism of glucose – 1. Glycolysis and TCA cycle and 2. Oxidative pentose   phosphate pathway.
 
Plant cells “burn “ glucose for energy. Plants also produce sugars through photosynthesis. This is roughly the reverse of the burning process.

The importance of lipids have already been elaborated. They play a major role as source of energy and as components of membranes which have implications in plant growth regulation. The complete metabolism of fat leads to oxidation, the final products being CO₂ and water. The burning of one mole of palmitic acid gives 2340 kcal.  The molecular weight of palmitic acid is 256. This works out to approximately 9 kcal/g of palmitic acid. This energy is twice that derived from either sugars or proteins. Fats and oils are thus better and more efficient forms of storage of energy in living beings.

Plants can synthesize all the 20 amino acids, which include essential and non-essential amino acids. They can be degraded by removal of the amino group and conversion of the remaining skeleton to useful metabolic intermediates which participate in the synthesis of glucose and other ketone bodies.
 
Biosynthesis of amino acids
 
The biosyntheses of amino acids have an important feature. Their carbon skeletons come from intermediates from glycolysis, pentose phosphate pathway and citric acid cycle etc. The biosynthetic pathways depend on the intermediates from which they are derived. The primary amino group normally comes from the transamination of glutamate. Glutamine synthetase is a central control point in nitrogen metabolism, since glutamine is the amino group donor in the formation of many biosynthetic products as well as being a storage form of ammonia. Glutamate is the precursor of proline, ornithine, and arginine. Serine, cysteine, and glycine are derived from 3-phosphoglycerate. Glycine is synthesized from serine by removing CH2OH group. Tyrosine is synthesized from phenylalanine. Asparagine and glutamine are amides that are synthesized from aspartate and glutamate.

Amino acids serve as the building blocks of proteins and as precursors of many other important biomolecules such as hormones, purines, pyrimidines, porphyrins and some vitamins. They also serve as sources of energy when present in excess amounts and when they are used as fuel, amino acids undergo deamination reactions. The remaining carbon skeleton will either convert itself into glucose or undergoes oxidation to CO₂ via TCA cycle.

Central dogma: The Central dogma of molecular biology, which has been formulated as a simple linear progression of information from DNA to RNA to Protein, is summarized in the illustration. The replication process on the left consists of   passing  information from a parent DNA molecule to daughter molecules. The middle  transcription process copies this information to a mRNA molecule.  Finally, this information is used by the chemical machinery of the ribosome to make polypeptides.

Primary metabolism in a plant comprises all metabolic pathways that are essential to the plant’s survival. Primary metabolites, namely, carbohydrates, lipids and proteins are compounds that are directly involved in the growth and development of a plant whereas the secondary metabolites are compounds produced in other metabolic pathways that, although important, are not essential to the functioning of the plant. However, secondary plant metabolites are useful in the long term, often for defense purposes, and give plants characteristics such as color.
 
Secondary plant metabolites are used in signalling and regulation of primary metabolic pathways. Plant hormones, which are secondary metabolites, are often used to regulate the metabolic activity within cells. Secondary plant metabolites help the plant maintain an intricate balance with the environment, often adapting to match the environmental needs. Plant metabolites that color the plant are a good example of this, as the coloring of a plant can attract pollinators and also defend against attack by animals. Terpenes, alkaloids, sterols, pigments, growth regulators, and phenolics are the important secondary plant metabolites.

Phenol is normally a benzene ring containing an –OH group, and hence an aromatic alcohol. The term phenolic refers to similar aromatic compounds with one or more -OH groups. Phenolics constitute one of the most widespread classes of secondary metabolites. Commonly talked about class of compounds like anthocyanins, flavonoids, lignins, tannins, coumarins and chalcones are all phenolic substances. Phenolics are water insoluble substances. However, the water solubility increases with the increase in the number of -OH groups. Phenolics absorb electromagnetic radiation strongly. Many of the phenolics absorb in the visible part of the spectrum (Ex. anthocyanins) and are coloured. Phenolics are produced in plants by 1. Shikimate pathway through phenylalanine (C6.C3)  and 2. Acetate/ malonate pathway.

Plant pigments impart colour to the different components like leaves, flowers, fruits etc. They in turn are responsible for the colour of raw food, we eat. Pigments like chlorophyll, anthocyanins, flavonoids, tannins, xanthones etc. are the different pigments that are present in plants. The primary function of pigments in plants is photosynthesis, which uses the green pigment chlorophyll along with several red and yellow pigments that help to capture as much light energy as possible. Other functions of pigments in plants include attracting insects to flowers to encourage pollination.

Sterols are derivatives of a complex ring system called cyclopentano perhydro phenanthrene. The term sterol means solid alcohol. Sterols, though alcohols, are solids with a M.P. of 100-120^ºC. The 27 carbon atoms impart hydrocarbon character, namely, solubility in non-polar solvents. Free sterols in plants are mono hydroxy  secondary alcohols varying in the constitution of methyl or ethyl group and in double bonds. Cholesterol, ergosterol, bile acids, sex harmones, cortical harmones and D-vitamins are some of the sterol derivatives.
   
The most widely distributed sterols in higher plants are the C₂₉ sterols, stigmasterol, β sitosterol and g sitosterol. Together, they are called steroids. In plants, steroids are present as glycosides. Cholesterol was first isolated from gall stones. The word cholesterol means “solid alcohol from bile”. Bile is a fluid which is formed and stored in the gall bladder. It aids in the digestion of fats in the digestive tract. Sterols form an important group among the steroids. Unsaturated steroids with most of the skeleton of cholestane containing a 3β-hydroxyl group and an aliphatic side chain of 8 or more carbon atoms attached to position 17 form the group of sterols.

Alkaloids are naturally occurring substances of plant origin that are alkaline in reaction. They are optically active, contain nitrogen as part of a heterocyclic ring and have varying degrees of psychological responses in man and animals. They exhibit significant pharmacological activity. Alkaloids are mostly basic in character but also includes some related compounds with neutral and even weakly acidic properties. Presently more than 2000 alkaloids are known.

Nomenclature of alkaloids
Alkaloids are named by adding the suffix ‘ine’ to various distinguishable features such as sources, physiological action in animals, their properties etc. Thus, 1. The name of the genera of the plants containing them Ex. Atropine (Atropa), nicotine (Nicotiana) etc. 2. The names of the species of the plants producing them Ex. Cocaine (Erythroxolon coca). 3. The common name of the organism producing them Ex. Ergotamine (ergot fungus). 4. The specific physiological activity observed in animals Ex. Emetine (emetic – causing vomiting), narcotine (narcotic-alters mind).

Vitamins are essential organic nutrients required by an organism in small quantities. They are essential since they cannot be synthesized in sufficient quantities by an organism, and must be obtained from the diet. The term vitamin does not include other essential nutrients like dietary minerals, essential fatty acids, or essential amino acids which are needed in larger quantities than vitamins. The term vitamin is derived from “vitamine,” coined in 1912 by the Polish biochemist Funk. The name is from vital and amine, meaning amine of life. Thirteen vitamins are generally recognized presently. Vitamins are used in small quantities by an organism to keep it in a healthy condition.

Vitamins are given letters of alphabet (A,B, C, D, etc.) in the order in which they have been discovered. The letters do not bear any relation to their structures or their importance. Vitamins are classified by their biological and chemical activity and not by their structure. Thus, each “vitamin” refers to a number of vitamer compounds that all show the biological activity associated with a particular vitamin. Vitamin A includes the compounds retinal, retinol, and four known carotenoids. Vitamers by definition are convertible to the active form of the vitamin in the body, and are sometimes inter-convertible to one another, as well.

Plant hormones (phytohormones) are chemicals that regulate plant growth and are termed as ‘plant growth substances’. Plant hormones are signal molecules produced within the plant, and are present in extremely low concentrations. Hormones regulate cellular processes in targeted cells. Hormones also determine the formation of flowers, stems, leaves, the shedding of leaves, and the development and ripening of fruit. Every cell is capable of producing hormones in plants. They shape the plant, affecting seed growth, time of flowering, the sex of flowers, senescence of leaves, and fruits. Plant hormones affect gene expression and transcription levels, cellular division, and growth.They direct which tissues grow upward and which grow downwards. Hormones are vital to plant growth. Hence, they are also known as growth factors or growth regulators.

Before the invention of N fertilizer, mineralization of organic N ( present in dead plants and animals or manure) was the main method used to obtain ammonium and nitrate nitrogen. Mineralization is conducted by soil microbes resulting in ammonium ion. Most Nitrogen is absorbed by plants in the form of Nitrate (NO-₃). Ammonium is converted to Nitrate with the help of  soil bacteria. Nitrogen is a very mobile element and is easily lost from the soil. Ammonium (NH₄+) can be converted to Ammonia (NH₃). The gaseous ammonia can be lost to the atmosphere.  Nitrate can be lost through denitrification. Nitrate nitrogen is reduced to nitrous oxide (N₂O), elemental nitrogen (N₂) and nitric oxide (NO). All are volatile. Denitrification occurs under conditions of high water availability and temperatures higher than 10^ºC.

The word cell was coined by Robert Hooke with the help of compound microscope. Cell is the basic unit of life. A plant cell has three distinct components a). Cell wall b). Protoplasm and c). Vacuole. Cell wall  and  vacuole are considered as non-living substances. The protoplasm which is living is  composed of 1. Cytoplasm and 2. Nucleus. The cytoplasm contains several organelles such as mitochondria, chloroplast, ribosomes, endoplasmic reticulum, golgi complex, lysosomes, plastids etc.

Seed technology is defined as “that discipline of study having to do with seed production, maintenance quality and preservation (Cowan, 1973).

Feistritzer (1975) has defined seed technology as the method through which the genetic and physical characteristic of seeds could be improved. It involves such activities as variety development, evaluation and release, seed production, seed processing, seed storage, seed testing, seed certification, seed quality control and seed marketing etc.

So seed technology in widest sense, includes development of superior crop plant varieties, their evaluation and release, seed production, seed processing, seed storage, seed testing, seed certification, seed quality control, seed marketing, seed distribution and the related research on these aspects,

The major goal of seed technology is to increase agricultural production through the spread of good quality seeds of high yielding varieties. To achieve this goal, the quality seeds must be rapidly multiplied and supplied to the farmers at proper time with the reasonable price.

Seed

A true seed is defined as a fertilized mature ovule consisting of embryo, stored material and protective coats. The seed strictly speaking is an embryo a living organism embedded in the supporting or the food storage tissue.

A seed stands for any of the following used for sowing or planting.

1.    Seeds of food crops including edible oil seeds and seeds of fruit and vegetables.
2.    Cotton seeds
3.    Seeds of cattle fodder
4.    Jute seeds
5.    Seedlings, tubers, bulbs, rhizomes, roots, cuttings, all type of grafts and other vegetative propagated material for food crops or cattle fodder.

Multiplication and distribution of high quality seed of improved varieties is a crucial step in agricultural production of any country.

When an entry is identified by the workshop of the concerned project, the breeder begins the seed multiplication of the strain in the following crop season. The seed produced by the breeder after a strain is identified, but before it is released as a variety is termed as the “stock seed”. This seed is known as breeder seed after it is released and notified. In the crop season following notification foundation seed of newly released variety is produced. In the second crop season following the release of variety, certified seed of the variety is produced. Thus the farmer is able to obtain certified seed of a newly released variety for commercial cultivation only in the third crop season following in the notification of the variety. However the seed of such variety reach the farmer even before its release through mini-kit trials. Many other farmers would obtain the seeds from those farmers who conducted the mini kit trials and so on in the next two years. Thus an outstanding variety is likely to reach many farmers even before its certified seeds have been put on sale.

The degree of excellence in regard to the physical and genetical characterstics of seeds is called as Seed quality. Seed lots having high genetic purity and high germination percentage and minimum inert, weed and other crop seed and are free from diseases and pest attack, it is said to be a high quality seeds. If it is lacking in any of these qualities, it is said to be low quality seed lots. Only good quality seeds expected to respond well for fertilizers and other inputs used.
 
Viability: It is the ability of embryo to live, grow and develop into a seedling under favorable conditions. The seeds attained maximum viability at physiological maturity stage. Later on seeds start to loss viability.

Seed Production Technology

1.    Paddy
2.    Sorghum
3.    Bajra        
4.    Maize              
5.    Blackgram    
6.    Soyabean                
7.    Cowpea             
8.    Redgram 
9.    Groundnut
10.    Sunflower
11.    Castor       
12.    Gingelly
13.    Tomato
14.    Brinjal
15.    Chilli
16.    Bhendi

A hybrid is the first generation progeny of a cross between two genetically different identical inbred lines. The individual lines are known as inbreds.  Ineffective cross-pollination is a major constraint in a commercial production of hybrid seeds in many crop species. In such crops manual pollination is the way to produce hybrid seeds. Eg. Cotton. In the case of rice it is highly self-pollinated crop and cross-pollination is a big problem. The increased vigour, uniformity and yield of F1 hybrid have been exploited in most crops where the pollination system allows for convenient and economic cross hybridization.  This system is called breeding tool in exploiting the hybrid vigour.

The term heterosis from Greek means hetero different, osis-condition was coined by skull (1914).

Heterosis or hybrid vigour, refers to the increase or decrease in vigour of off spring (hybrid) over parents. Usually, theses two terms are used synonymous.   But hybrid vigour refers to increased vigour; Heterosis both increased and decreased vigour.

Superiority of the hybrid as hybrid vigour and the mechanism by which this superiority is developed is heterosis (Rangaswamy, 1998).

Need to know Physiological maturity (PM), Harvestable maturity (HM) and harvesting method

·    If these factors are considered, the harvest produce will have the maximum seed quality characters in terms of germination, vigour and storability.

 The maturity is of two types depending on the purpose. If the crop is for grain production it is enough to harvest the crop during harvestable maturity. But when the crop is meant for seed purpose it is advisable to harvest the crop during physiological maturity.

Seed processing, drying, cleaning and upgrading

Seed processing refers to all the steps necessary for preparation of harvested seed for marketing namely handling, drying, shelling, preconditioning, cleaning, size grading testing, and packaging etc.

Layout for seed processing plant

Layout plan for construction of seed processing plant should be carefully planned to ensure that thorough seed cleaning, upgrading, seed treatment and other seed processing operations are carried out efficiently without mixing and damaging seed lots with minimum equipment, personnel, time and at minimum cost.

The following factors should be considered while planning and designing the processing unit:

Seed Testing
1.    Sampling

2.    Determination of Heterogeneity

3.    Purity analysis

4.    Germination Test

5.    Seedling Evaluation

6.    Quick Test for Viability

7.    Estimation of Seed Moisture

8.    Grow Out Test

9.    Seed Health Test

Seed Storage is an essential process during seed production programme. The purpose of seed storage is to preserve planting stocks from one season to next planting season.Seed storage starts from the moment of maturity and extend until its planting, in the next season.
 
PRINCIPLES OF STORAGE

Primary aim of storage is simply to prevent deterioration of quality seed. The management objective during the storage period is to reduce metabolic activity to such a low level that the seed is sufficiently stable with minimal deterioration. The two alternative methods are

1.    Reduction of moisture content to a safe level and cooling of the seed.
2.    Modification of atmospheric condition of the storage system.

Types of storage

There are four types

1.    Storage of commercial,  truthfully labelled and certified seed.

2.    Storage of carry-over seeds.

3.    Storage of foundation seed stocks and enforcement seed samples.

4.    Storage for germplasm seeds.

Seed multiplication and production was controlled by a legally sanctioned system called Seed Certification. Seed certification procedures and designed to ensure physical and genetic purity, freedom from weed seeds and diseases and good germinability of the certified seed. Seed certification is done by the Seed Certification Agency (SSCA) of the concerned state or by NSC.
 
Objectives of Seed Certification

The objective of seed certification programme was formulated by Douglas, 1971
 
i)    to ensure genuineness and quality of seed.
ii)    The identification and their rapid increase of new varieties under accepted names.
iii)    The systematic increase of superior varieties
iv)    Continuing supply of quality material and their maintenance.

The basic aim of seed legislation and its subsequent enforcement is to regulate the quality of seeds sold to farmers. So long as Agriculture remains tradition and static, there is little justification for regulating seed quality. However with technological advancement and the systematic application of science to Agriculture, it becomes compulsory to regulate the quality of seeds through seed legislation and its subsequent enforcement to ensure that seed buyers are not made to run undue risks.

TYPES OF SEED LEGISLATION

Seed legislation can be broadly divided into two groups.

1.    Sanctioning legislation

2.    Control legislation

Sanctioning Legislation

Which authorizes, establishes or otherwise legally sanctions such activities as formation/establishment of advisory bodies, seed certification agencies, seed testing Labouratories, foundation and certified seed programmes, recognition of seed certification agencies of foreign countries, appellate authority etc.

INTRODUCTION

High crop productivity depends on quality of seed as without good quality seed even if we apply manure, Plant protection measure and other cultural practices it is not possible to produce good quality seed. So the basic seed used for sowing must be healthy and good in quality. It is different from commercial production as it need proper care, good quality basic seed, timely cultural operations, thinning, roguing, timely application of pesticides and fertilizers and maintenance of seed quality through inspections. 
Seed production requires technical skill to achieve all the above advantages for which the best approaches Compact Area Approach or Seed Village Concept.
It is selection of compact area by organizing the seed farmers in the selected area. The selected area must be fertile and suitable for reproduction of good quality seed such areas can be organized for self and cross pollinated crops (Groundnut, Paddy, Pulses, Sorghum) especially for the varietal seed production. But the variety should be one another for whole of the selected area.

Advantages of Seed Village Concepts

1. Isolation and Roguing

For maintenance of genetic purity of the crop it requires isolation and proper rouging. This can be achieved in the compact area programme, as it will be the mutual benefit to the farmers who are concentrating growing on single variety on compact area.

Since the dawn of civilization, the human species had an intimate association with fruits, roots, nuts and other vegetables that sustained them through the ages. This mutualism continued and flourished through domestication and organized culture of horticultural crops. Pretty long before, homestead gardening had been evolved in different parts of the globe independently to become a part of tradition in almost every society. Plant domestication by all likelihoods started around the human settlements. The obvious reasons for this were man’s need, better supply of water and organic household wastes and protection against destruction or grazing by animals, that’s why the prospective horticultural enterprise of homestead gardens all over the world is still the most enduring and sustainable form of family food production system and very important micro-units for conservation of plant genetic resources. The traditional and indigenous endeavour of the tribal people for conservation of land races also noteworthy contribution from one generation to the next. Though cereals are staples for most of the world population, there has been sustained emphasis on horticultural crops, particularly vegetables, all over the world during last few decades. The possible reasons are:

The basic feature of the Pre-British India was a village, which was economically a water-tight compartment fulfilling the three basic functions of economy, i.e., production, distribution and consumption, within the village community without outside world dependence, except the salt and kerosene. Every village was a self-sufficient unit with dependence on agriculture carried out by community people of different castes having the occupational specialization with interdependence, viz. jajmani system and alike.

Developments in the means of communications and the opening of Suez Canal in 1869 introduced fundamental and far-reaching changes in the social system and economic life of Indians by transforming self-sufficient village economy to new modes and means based on competition, market and price mechanism. This change was deliberated by Britishers for meeting the requirement of raw material and the diversification to tea, jute and indigo took place. Cotton also got importance but agriculture did not find place for vegetables. Famines were very common and crop production depended on monsoon rains to the large extent. Britishers developed cotton, jute and mineral trade for their vested interests.

Britishers emphasized the development of railways for better mobility of their troops, commercial crop produce and minerals but the Report of Famine Commission 1901 bitterly criticized the Government for the step-motherly treatment given to irrigation facilities as compared to railways. The irrigation policy of the Government in 19th century was determined purely from concerns for adequate returns on investment and profit was of Rs. 81 lakhs after paying 4% interest on amount invested on irrigation development in 1896-97. Irrigation Commission was established and a sum of Rs. 42 crore was spent on irrigation by 1911. By 1930, about 30 million acres were brought under canal irrigation, which was far larger than the irrigated area in any other country of the world. Even in the USA, the area under canal irrigation was two-third that of India. Vegetables cultivation did not find place in Indian agriculture and also in diet of villagers. Their cultivation remained restricted to the periphery of the urban centres for meeting the demand of upper class elites only.

Agriculture is a generic term used to include various types of farming systems, single to multiple crops under various agro-climatic conditions thereby covering crop husbandry, animal husbandry, vegetable growing, floriculture, horticulture, fishery, poultry, goat rearing, piggery, rabbit rearing, sericulture, forestry, vermi-composting, etc. Indian agriculture is a symbiosis of various production systems, a way of life or a tradition, which for the centuries have shaped the thoughts, the outlook, the culture, and the social and economic force of rural life. It is well known for its multi-functionalities of providing employment, cultural heritage, livelihood, social security, family bondage, nutritional and food security. Although agriculture is the main stay of the Indian economy and supports nearly two-third of the work force, yet this is not a highly rewarding enterprise for a large majority of farmers who hold small and marginal size holding. At the same time, the size of the land holding is on a gradual decline, while contribution of farmwomen is on an increase as men go elsewhere in search of better jobs. This sector holds and will continue to be central to all strategies of socio-economic development of the country. A farmer is a multi-purpose entrepreneur (Rajavanshi, 2007).

The importance of vegetables in human nutrition is now well known all over the world. Vegetables are rich and comparatively cheaper source of minerals and vitamins. Their consumption in sufficient quantities provides taste and palatability, increases appetite and provides fair amount of fibre. Besides, they provide many specific chemical substances, which are essential for growth, reproduction and for the maintenance of good health and also beneficial in protecting against some degenerative diseases (Prior and Cao, 2000; David, 2005; Elison and Levin, 2006).

Apart from their nutritive value, vegetables probably do more than any other groups of food to add colour, texture and flavour to our daily diet. Majority of the population in India is vegetarian, and thus, vegetables form an essential item of food for both the rich and the poor people. National Nutrition Monitoring Bureau (1997) surveys indicated that the daily intake of most foodstuffs in Indian households, except for cereals and millets, is much below the recommended dietary allowances (RDA). The diets provided negligible amount of protective foods. It was found that consumption of green leafy vegetables (< 10 g) and other vegetables (70-80 g) per day, which are rich source of micronutrients, are woefully inadequate. However, as per the RDA, an adult man should consume 200 g roots and tubers, 100 g green leafy vegetables and 100 g other vegetables (Table 1) in a day. In addition, fresh fruits (100 g) as available in different seasons should be consumed regularly for the prevention of chronic diseases (NIN, 1998).

Olericulture, a Latin word, is used to designate the science, culture and management of vegetable crops. In India, about more than fifty vegetable crops are grown in different parts, depending on their climatic requirement. A number of vegetables have similarity in their method of cultivation, which makes the package of practices followed by the farmers for their cultivation very complicated and brings about a lot of repetition. Whichever the method is adopted for the classification of vegetables can systematize the preparation and presentation of the material to some extent and can avoid the unnecessary duplication of some of the principles and methods of vegetable cultivation. In different vegetables, different plant parts are used as food in different forms and they belong to different botanical families with varying cultural and climatic requirements but common insect-pests and diseases along with their common control measures.

Various methods may be used to classify all the vegetable crops into different categories but no single method of classification would be useful to serve the purpose for different groups of scientists like taxonomists, botanists, physiologists, horticulturists, agronomists, and breeders. Under field conditions, the classification based on cultural practices has been proved the best adaptable and very useful for the growers. Vegetable crops can be classified in the following ways for the convenience of different groups of scientist and growers:

Olericulture, a Latin word, is used to designate the science, culture and management of vegetable crops. In India, about more than fifty vegetable crops are grown in different parts, depending on their climatic requirement. A number of vegetables have similarity in their method of cultivation, which makes the package of practices followed by the farmers for their cultivation very complicated and brings about a lot of repetition. Whichever the method is adopted for the classification of vegetables can systematize the preparation and presentation of the material to some extent and can avoid the unnecessary duplication of some of the principles and methods of vegetable cultivation. In different vegetables, different plant parts are used as food in different forms and they belong to different botanical families with varying cultural and climatic requirements but common insect-pests and diseases along with their common control measures.

Various methods may be used to classify all the vegetable crops into different categories but no single method of classification would be useful to serve the purpose for different groups of scientists like taxonomists, botanists, physiologists, horticulturists, agronomists, and breeders. Under field conditions, the classification based on cultural practices has been proved the best adaptable and very useful for the growers. Vegetable crops can be classified in the following ways for the convenience of different groups of scientist and growers:

In view of fast development of industrial sector and rapid urbanization, the vegetable gardening of various types has great scope for providing food and nutritional security, promoting health, solving employment problem and raising the economic status of an individual and the country as a whole. In many of the developing countries, protein-energy malnutrition is the most important health problem, which has long-term ailing consequences. Iron and vitamin A deficiencies are also potent contributors towards morbidity, mortality, underweight and stunted growth of individuals. Vegetables from homestead gardens can combat these dreaded social nuisances. In many cases, indigenous vegetables, gathered or grown wild, are more nutritious than foreign high value exotic species (Drescher, 1998). Various types of vegetable farming are being practiced the world over depending on the area available and objectives for the disposal of the produce. Based on the mode of disposal, the vegetable gardening can be categorized into two types:

The importance of fruits and vegetables in human nutrition is well known. Vegetables are a rich and comparatively cheaper source of minerals and vitamins. Besides, their consumption in sufficient quantities provides taste and palatability, increases appetite and provides a fair amount of fibers. These are currently reckoned as an important adjunct for the maintenance of good health and beneficial in protecting against some degenerative diseases, thus, they form a vital part of human diet. Besides, vegetables now a day are being considered as an asset for providing a good source of income to the growers.

Vegetables originated in different parts of the world, some came from tropical or subtropical countries and others from temperate zones, some from humid areas and others from climates that are more arid. Most of the countries in the world are gifted with varied agro-climatic environments for growing an array of vegetable crops to combat the present imbalanced diet of a vast population of the world, particularly in the developing countries. Production of vegetables in developed countries is much higher, for instance in Japan, nearly 40% of the diet of the people is vegetables. To meet out the full dietary needs of the common man, to eliminate malnutrition, deficiency of minerals and vitamins and also to relieve the stress for increased production of cereals, there is a greater need for growing vegetables on larger scale. As such, for increased production of nearly 247 known vegetable crops, a sound knowledge of the various aspects of vegetable production technology, environmental stresses and constraints, techniques of raising, pre- and post-harvest technology, marketing and seed production techniques is of utmost importance. Breeding and selection of new cultivars have allowed for a greater adaptability to less favourable growing conditions than was possible in the past but the inherent agroclimatic requirements of a specific kind of vegetable have not changed materially. Time or season of planting of a particular vegetable crop is determined by its environmental requirement. Knowledge of specific agroclimatic conditions required for a particular crop could enable the grower to select the best season of planting in any particular area (Singh et al., 1991).

Seed is the basic input of agriculture, and its importance has now well recognized in the food supply chain since the warranty for production could be succeeded only based on the availability of seed. Seed becomes the quality seed, on possession of specific characters, viz. germination, vigour, purity and health status, hence, seed production becomes the specified scientific technology with the foreseeing of quality and storability in addition to productivity. From time immemorial, seeds are being imposed with some management techniques for improvement in seed quality and thereby the productivity. These seed management techniques are known as seed treatments. Generally, seed treatment is the application of biological, chemical agents and physical techniques to the seed in order to obtain the benefit of plant protection, production and invigouration. Basically, seed treatments are intended to improve the quality of seeds since nothing can substitute poor quality seed, no matter how lavishly other inputs are spent on the crop established from such seeds. Even for a resource poor farmer, high quality seed would be a great advantage because it ensures the best utility of all inputs in addition to the augmentation of yield increase by 15 to 20%.

In general, seed treatment could broadly be classified into physical and physiological treatment. Physical treatment is external seed treatment, while physiological is impregnation of needy substances into the seed through various seed management techniques. Some of the germination augmenting physiological seed treatments are seed fortification, seed hardening, seed priming, dry permeation and pre-germination. In addition, some of the seeds are imposed with special treatments such as dormancy breaking treatment such as soaking in water, mechanical scarification, acid scarification, bio-scarification, scorching, warm stratification, cold stratification and electrical seed treatment. The common physical seed treatments are seed pelleting, seed coating/film coating and seed colouring. Seeds are also imposed with some other physical treatments that can act on the physiology of the seed such as irradiation, magnetic and electrical seed treatment. In addition, irrespective of seed, seeds are given with protective treatment when they are taken for storage, which are commonly termed as pesticide seed treatment. Seeds are also given with corrective treatment at their initiation reduction with seed quality characters during storage, which are termed as mid storage correction.

Nursery management is indeed a very important operation in successful growing of vegetables especially those, which are raised through seedlings in properly managed nursery beds. Raising nursery from seed provides an easy and convenient way to nourish tender young seedlings in a well-managed small and compact area. The nursery area can be conveniently protected from natural hazards, seed borne diseases and insect-pests and can be well managed economically. Some of the vegetable seeds are very costly, for which it is necessary to raise nursery in the most-optimum conditions. In areas where land holdings are small (in hills), nursery raising helps in making economical use of land for about one month and provides enough time to mature for previous crop, harvesting, threshing and land preparation for next crop. Most of the vegetable crops like cabbage, cauliflower, tomato, eggplant, sweet pepper, hot pepper, onion, celery, parsley, lettuce, etc. can successfully be raised through seed by growing them in the nursery and then transplanting in the field.

“A vegetable nursery is a place or an establishment for raising or handling young vegetable seedlings until they are ready for more permanent planting.”

Nursery can be maintained either for personal or commercial purpose, and each has its own advantages and disadvantages. Seedlings raised for own planting will be true to type, sound and healthy. On the other hand, seedlings purchased from outside may not be true to type, vigorous and healthy and may not arrive at destination in due course of time.

After attaining green revolution, nutritional security is of utmost importance in the current agricultural scenario. Vegetables play a key role in providing nutritional security in the country. They are important and readily available source of mineral nutrients and vitamins and play a vital role in the financial economy of the majority of small and marginal farmers. Further, these roles are becoming more transparent in the light of agriculture diversification as the vegetables have many agro-economic advantages and can fit into varying cropping systems under diversified conditions. After China, India is a leading vegetable producer but the productivity of vegetables per unit area is very low compared to other developed countries. Poor crop stand establishment is one of the factors responsible for low productivity. Yield and productivity can be improved by using advanced technology on the field preparation, optimum sowing conditions, correct nursery practices and planting methods.

Almost all the vegetable crops are propagated by seed, except a few. Crops are raised either by direct seeding in the field or by transplanting seedlings raised in nurseries. Direct seeding is the placement of seeds at desired depth into the final location where soil environment is ideal for optimum germination and crop stand establishment. On the other side, transplanting refers to removal of actively growing seedlings from one place to another with the purpose of having them continue their growth in the new location until harvest.

The vegetable crops like peas, beans, cowpea, okra, beet leaf, spinach, fenugreek, coriander, carrot, radish, turnip, beetroot, etc. are sown directly in the field, while tomato, eggplant, hot pepper, sweet pepper, onion, leek, sweet potato, cabbage, cauliflower, broccoli, Brussels sprout, kohlrabi, kale, lettuce, celery, parsley, rhubarb, squashes, etc. are first sown in the nursery beds where seedlings are raised and then transplanted in the main field. Both direct seeding and transplanting are practiced in most of the cucurbits like gourds, cucumber, melons and pumpkin.

The directly sown vegetable crops do not respond to transplanting because their embryonic roots do not produce lateral fibrous roots after uprooting unlike transplanted crops where numerous fibrous roots are generated, thus, making the plant to absorb more nutrients.

Soil fertility and crop production can be maintained only by efficient and judicious management of nutrients addition to the soil from external sources. Of the two sources most widely used all over the world, one is organic in nature- the organic manures, simply called manures, and the other comprises the synthetic or naturally occurring chemical fertilizers, simply called fertilizers. A brief account of manures is described hereunder:

The word manure came from Middle English manuren meaning to cultivate land, and initially, from French word manoeuvre meaning hand work alluding to the work which involved manuring land. The term manure originally meant that which was worked by hand (Fr. manoeuvre), but gradually, came to apply to any process by which the soil peroperties could be improved. Prominent among such processes was that of directly applying manure to the land, manure in this sense being what is now called farmyard manure or dung, the excreta of farm animals mixed with straw or other litter. Ronald Fisher seems to have used the word manure systematically for what we would call fertilizer today.

Uses of Manure

Manure has been used for centuries as a fertilizer for farming since it is rich in nitrogen and other nutrients, which facilitate growth of the plants. Liquid manure from pig or hog operations is usually knifed (injected) directly into the soil to reduce the unpleasant odours. Manure prepared from hogs and cattle is spread on fields using a manure spreader. Due to the relatively lower level of proteins in grasses, which herbivores eat, cattle manure has a milder smell than the dung of carnivores, e.g., elephant dung is practically odourless. However, due to the quantity of manure applied to fields, odour can be a problem in some agricultural regions. Poultry droppings are harmful to plants when fresh but after a period of composting are valuable fertilizers.

The dried manure of animals has been used as fuel throughout history. Dried manure (usually known as dung) of cow was and still is an important fuel source in countries such as India, while camel dung may be used in treeless regions such as deserts.

Many materials can be applied to the soil as source of plant nutrients but the term fertilizer is often used to refer to relatively soluble nutrient sources with a high analysis or concentration. Commercially available fertilizers supply essential elements in a variety of chemical forms but many are relatively simple inorganic salts. Advantages of commercial fertilizers are their high water solubility, immediate availability to the plants, high concentration and low price per unit of nutrient, and the uniformity and accuracy with which specific amounts of available nutrients can be applied. Since they are relatively homogeneous compounds of fixed and known composition, it is fairly easy to calculate precise application rates and attain relatively consistent performance. This is in contrast to organic nutrient sources, which are a much greater challenge to manage because of their variable composition, variable nutrient availability and patterns of nutrient release that are greatly affected by temperature, moisture and other conditions that alter biological activity.

The solubility of commercial fertilizers can sometimes be a problem since soluble nutrients may move out of farm fields when applied in excess or large rains occur soon after fertilizer application. Soluble nutrients can be lost by leaching on well-drained soils and through tile outlets or in runoff on poorly drained soils. Denitrification can cause large losses of nitrate-N from water-saturated soils in wet springs.

Increasing soil cation exchange capacity by increasing organic matter reduces the movement and loss of some nutrients, although not nitrate-N (an anion). Management practices that synchronize nutrient availability with crop demand and uptake also minimize losses. Both application timing and the amount of fertilizer applied are important. Splitting fertilizer application into several small applications rather than a single large one is especially important to limit nitrogen leaching on well-drained sandy soils. Split nitrogen applications can also reduce nitrogen losses in runoff or from denitrification on poorly drained soils. Excess nutrient applications can be eliminated or at least significantly reduced by soil testing on a regular basis, setting realistic yield goals and fertilizing accordingly, accounting for all nutrient sources such as legumes, manure and other amendments and using plant analysis as a monitoring tool for the fertilizer program.

Increasing food need, decreasing land availability and concurrently attenuating synthetic nutrients supply envisage the use of alternate supplementary inputs for the cultivation of crops. India is among the few nations where systematic farming started thousands of years ago. It was not only the source of income but was also a way of life. Agricultural activities and the techniques adapted to suit local needs and conditions. Different farming systems were followed by the farmers in different areas according to their needs and weather conditions. The produce was usually shared with other communities of the society involved in other professions. Almost all the nutrients removed by the crops were recycled to the soil directly or indirectly (Yadav and Mowade, 2005). In economic terms, the system followed by the then farming community was highly cost effective since all the inputs needed were locally available and practically no expenditure was incurred except labour. The traditional agriculture was though less productive but self-sufficient. With the advent of modern scientific discoveries, agriculture also changed its face, and with the introduction of high yielding varieties, synthetic fertilizers and effective plant protection measures through chemicals, Indian agriculture made rapid strides in the shape of Green Revolution. As an upshot of Green Revolution, the grain production increased two and a half folds in about three decades with a marginal increase in net-area under cultivation.

India is a major exporter of vegetables with 10th position in the world. In the past, the Dexport of Indian vegetables was restricted to potatoes and fresh onions, however, now, the Government of India finds great opportunities for expanding exports of several vegetables including lettuce, fresh peppers, tomatoes, squashes, gherkins, etc. Under World Trade Organization (WTO) regime, the development of stronger seed industry and improved production technology will give India a competitive edge in global market. New opportunities and challenges are emerging every day in the dynamic and global vegetable-based industries. However, such opportunities can be harnessed only if assured quality, in terms of organic farming and reduced pesticide residues, is maintained (Shanmugasundaram, 2004).