eChapters

Animal Fibers                   The animal materials like wool, hair, fur, mohair and silk used for weaving, knitting or felting into a fabric are                                                      generally termed as animal fibers. Animals used for the purpose are sheep, goat, llama, alpaca, camel, vicuna                                                and silk worm.

India is one of the chief carpet wool producing and exporting countries of the world. A large quantity of carpet wool is exported to the developed countries. Wool production in Indian subcontinent is mainly dependant on distinct type of sheep producing wool in a particular geographical area. For example small and course wool is produced by Bikaneri breed in North Western India, course wool by Deccani breed and hair type breed by Mandya breed in Peninsular India and fine wool is produced in Himalayan region. In general, tropical breeds of sheep are mainly producing course wool which is highly suitable for carpet manufacture. Most of the Indian sheep breeds are producing low fleece yield. The annual total yield of greasy wool is in the range of 1-1.5 Kg. Overall great quantity of wool is produced in southern hemisphere but consumption is in northern hemisphere.

Wool is a thick and wavy animal fiber makes fibrinous protective covering of sheep. There are 170 different types of proteins are found in wool but the major and foremost protein is keratin. It is insoluble in nature and forms most of the part of wool. True wool fiber is basically modified hair that is not shed like the hair of most farm animals and medulla is absent in true wool. Wool contains excessively scaly surface but hair surface is mostly smooth, less elastic. The matured keratinized fiber extruding above the skin is considered dead tissue. Wool fiber is basically originated from follicle situated in dermis or middle layer of skin. Wool fiber is elastic, hygroscopic, retains warmness, durable, non inflammable and transmits ultra-violet light.

Wool is a fibre basically composed of amino acids and have excellent absorbency, moisture regain capacity, tend to warm the human body if used in form of cloths and others, good in elasticity and resiliency but poor in resistance to alkali but acid tolerance is good. To get better utilization of wool, they may be classified into various categories based on their origin, fleece quality, fineness of wool fibres etc.

Shearing is an operation of clipping the wool from sheep body. It is essential to get the wool from animals as well as to provide comfort to the sheep and enhance the economic status of sheep farm. The time of shearing is twice in a year preferably once at beginning of summer (march-April) and second at the start of winter (September – October). However, for veterinary reasons and other requirements of animals, shearing can be performed any time.

Wool is a natural fiber and considered as renewable, sustainable and environmental friendly. It is capable to keep the body warm and can be utilized as casual bears and also in formal bears and provide comfort to the human body in both of the active and passive situations. So to maintain a standard quality of wool for fabric development it is utmost important to test the wool fiber for certain qualities. Testing of wool fiber is also important to retain the unique physical and chemical properties of wool which makes this fiber versatile. Fiber quality is in real sense is a set of characteristics and defects in the fleece; both inherited and acquired, which influence its end use. The term quality testing includes a process of critical examination of material to draw the information’s related to qualitative or quantitative aspects of wool fibers. There are number of standard test procedures are in prevalence but most commonly followed test procedures for wool are American Society for Testing Materials (ASTM), British standards, Indian Standard Institution (ISI) or International Wool Textile Organization (IWTO) etc.

Veterinary public health deals with the contributions of veterinary medicine to public health. It is concerned, in the first instance, with the control and elimination of zoonoses and also with the following areas of activity:
    ·    Food hygiene (production, processing and distribution of foods of animal origin)
    ·    Environmental contamination and degradation by animal wastes and animal products
    ·    Comparative medicine (eg. Studies in animals on naturally appearing cancer, cardiovascular disease, metabolic and other disorders encountered in humans)
    ·    Laboratory animal medicine
    ·    Education and training in VPH and communication with the public
    ·    Reproduction biology
    ·    Aspects of mental and societal health
    ·    Emergency veterinary functions in natural disasters and other catastrophes.

Life forms are composed of one of two basic cell types : Eukaryotic or Prokaryotic. Generally, eukaryotic cells are larger and more complex than the prokaryotic cells and possess a membrane-enclosed nucleus; eukaryotic means ‘true nucleus’ (eu=true; karyon = nucleus). All plants, animals, fungi, protozoa and algae are composed of eukaryotic cells. Only the microorganisms classes as bacteria and the archaea are prokaryotic cells. Prokaryotic cells have no nuclear membrane and therefore lack a true nucleus. The latin prefix pro means ‘early’ and in this instance suggests the somewhat primitive nuclear structure found in bacterial cells. Eukaryotic microorganism are sometimes simply referred to as eukaryotes, and the prokaryotic microbes as prokaryotes.

The term growth as applied to higher organisms such as animals commonly is concerned with increase in protoplasmic mass and does apply to reproduction or to increase in number. In microbiology the term refers to increase in the number of organisms. Bacteria increase in number by a process of simple binary fission. Each cell increase in size and redivide into two similar cells. Each of the divide cells may in turn divide to become two cells. Each division produces what is termed as new generation of cells, theoretically there are 2,4,8,16,32,64,128,256 cells in the 2,3,4,5,6,7,8,& 9th generation, this is known as logarithmic growth – the population doubles with each successive generation. Under favourable conditions, bacteria produce generation within 15min. Under unfavourable conditions 24 hours of more may be needed for each generation. Generation time for E.coli is 17 to 20 minutes.

The sources of contamination of milk on the farm can broadly be categorized as

    a)    Interior of the Udder
    b)    Exterior of the Udder.
The interior reflects the health of the animal, while the exterior depends on the farm condition, equipment, persons, water etc.

a) Interior of the Udder
The animal by itself is one of the most significant contributors of microorganism in milk. The bacteria in the udder usually enter from the teat opening and get distributed internally by their own growth and physical movement. In the normal healthy udder, the types encountered in milk are most predominantly Micrococci, followed by Streptococci, Corynebacterium and others. Most of the bacteria are excreted in fore milk.

The Concept of ‘Clean Milk’ Production

Although milk is nature’s most ideal and perfect single food both for the newborn and the mature human beings, the possibility of it being a source of biological and chemical hazards cannot be excluded. In view of the immense dietary importance of milk, the need for production of safe, clean and wholesome milk is emphasized. The term ‘clean milk’ does not mean milk in which all visible dirt is absent or milk from which it has been removed; rather it does denote raw milk from healthy animals, that has been produced and handled under hygienic conditions; that contains only small number of harmless bacteria and that possesses a good keeping quality without being treated by heat. In other words, the unhygienic production of milk may lead to inferior keeping quality as a result of rapid microbial multiplication under favourable storage conditions apart from serving as a potential health hazard. These microorganisms cause the milk to sour quickly, putrefy and develop undesirable flavours, colour defects, ropiness and bitterness. On the other hand, the pathogenic microorganisms, which may gain entry through various sources, may cause many diseases to the consumers.

In India, the collection, transport and distribution of raw milk involves a number of agencies and persons at rural and urban level – village producers, milk collectors, halwais (Sweet-makers), milk vendors, dairies, producer-retailers and wholesale or retail markets.

1. Collection

Usually, the milk collectors approach the small village producers to collect milk and the same is sold directly or indirectly (through agents) to a dairy (milk procurement centres) or halwais or city milk vendors or consumers. The producer – retailers themselves, in some cases, supply the milk to the above said parties. The production of milk in small, scattered holdings in village causes problems during its collection. It involves visits to many villages, some of which are not easily accessible for the purpose.

Starters are selected strains of micro-organisms deliberately added to milk during conversion into cheese, dahi, yoghurt and other fermented dairy products to bring about specific changes in the appearance, body, texture and flavour characteristics of the desired final products.

Functions of Starters

The primary function of almost all starter culture is to develop acid in the product. The secondary effects of acid production include coagulation, expulsion of moisture, texture formation and initiation of flavour production. In addition to these, the starters also help in imparting pleasant acid taste, conferring protection against potential pathogens and providing a longer shelf life to the product. These bacteria convert 1% of lactose in milk approximately to lactic acid with very little by-products such as acetic acid, ethanol, CO2 and normally with no substances causing taints and hence leading to a clean and wholesome milk souring.

Milk fermentation is process by which a change is produced in milk through the activity of microorganism. As milk leaves the udder it serves as a medium for the growth of many species and accordingly undergoes a series of changes, the processes producing these changes constitute the milk fermentation.

Fermentation of organic compounds, especially in the lack of oxygen leads to the rapid break-down of ‘biopolymers’ to produce ‘anaerobic food chains’.

Bacteriophage is the term applied to bacterial viruses. Bacteriophage having the ability to lyse certain sensitive living cells. Phages are small particles, which can only be seen in the electron microscope after the application of suitable staining techniques. All phages have a head and most have a tail. The head may be isometric or prelate with a hexagonal outline.

There are two types of phages virulent and temperate which enter a different relationship with the host, the lytic and lysogenic cycles respectively.

The significance of milk in human nutrition is now well established as it is considered as the best, ideal and complete food for all age groups. However, in spite of being so, milk can also serve as a potential vehicle for transmission of some diseases under certain circumstances. Moreover, by virtue of possessing almost all the essential nutritional factors, milk can also serve as an excellent culture and protective medium for certain microorganisms, which may include potential pathogens capable of causing serious health problems to the consumers. In this way, milk may serve not only as a vehicle of transmission of disease causing organisms, but it can also allow these pathogens to grow, multiply and produce certain toxic metabolites, thereby making itself an extremely vulnerable commodity from public health point of view.

According to International Dairy Federation(IDF),1980, Mastitis also called as ‘mammitis’ is defined as an inflammation of the udder, almost always of microbial origin and is the outcome of a local or a general infection. The common symptoms are related to inflammation, viz., swollen, hot, red, and painful udders. Mastitis can be classified based on symptoms or on the causative organism.

A) Forms of mastitis based on symptoms

    1.    Acute or clinical
    2.    Sub-acute or subclinical
    3.    Chronic.

Tuberculosis

Tuberculosis has been recognized as one of the most important infectious diseases in the world because of its high global impact and its chronic debilitating character, particularly in the poor section of society. Milk-borne tuberculosis is directly or indirectly related to the consumption of raw milk from infected dairy herds.

Normally raw milk contains different levels of inhibitory substances, which restrict the normal development of bacteria and some times may even kill them. The degree of inhibitory activity varies considerably in milks of different species, viz, cow, buffalo, human. Maximum activity present in human milk, variations occur in the milks of individual animals and some times even at different milking or from different quarters of the udder of the same animal.
There are two groups of antimicrobial substances present in milk:
    1.    Inherent or naturally occurring substances in milk. 
    2.    Non- inherent compounds secreted into milk from other sources.

Dairy equipment and utensils with which milk and milk products come into contact are the main sources of contamination in the products. By the use of effective equipment cleaning and sterilization methods on routine basis, milk of high bacteriological quality can be consistently produced. In composite milk plant, a variety of equipment and utensils are used. The use of stainless steel for the fabrication of dairy utensils and equipment provide highly polished and hard smooth surface that can be cleaned readily, apart from showing resistance to corrosive action of detergents and bactericidal solutions. Utmost care is taken to avoid dents and scratches, which could be the possible focal points of subsequent contamination. To overcome all these problems aluminium and stainless steel vessels and equipment present an ideal situation.

Introduction

Numerous characteristics of food determine its acceptability to consumers and to regulatory officials. Before accepting a food for consumption, it must be attractively presented, must have desirable odour and flavour characteristics and other qualities and must be free from potential pathogens or their toxic products. The ultimate nutritive qualities, flavour and appearance have been preserved and no harmful organisms or substances are present to affect the consumer adversely. If the quality of the product is good, its keeping quality is also likely to be substantial. Conversely, there are more chances of spoilage of an inferior quality food product during storage.

India

Milk legislation and regulations are designed to prevent fraud and adulteration. But they now cover many factors that affect sanitation and public health. Milk generally is classified into grades according to the care with which it is produced.

The shift from vegetative to reproductive phase in plants is the result of multiple gene cascades in response to photoperiodic and temperature dependent pathways, gibberellic acid pathway, vernalization pathway and autonomous pathway. The environmental cues are initially detected in the leaves and the mRNA of the flowering signal integrator FT gene, moving to the shoot apical meristem, acts as a long-distance signal for floral meristem identity. At SAM, FT-FD protein complex, based on signals from above said pathways in association with the signals from age-dependent and miRNA pathways, leads to the activation of master regulator gene of flowering AP1. The activation of genes involved in ABCDE model of floral organ differentiation, based on the directions of various cadastral genes lead to the development of floral organs. Thus, the sequential action of floral meristem identity genes, floral organ developmental genes, floral meristem size and organ number genes, floral organ pattern genes and cadastral genes leads to the flower development. This chapter sums up the gene interactions happening in leaf and SAM, leading to the development of a complete flower.

Endophytic Microorganisms

Endophytes (‘endo’, inside; ‘phyte’, plant) include microorganisms that thrive inside the plant tissues without any obvious adverse effects on the host, and they include mainly bacteria and fungi (Hallmann et al., 1997; Bacon et al., 2002; Hardoim, 2015). Endophytic microorganisms share an intimate association with the host adding essential and functional capabilities. Therefore, plant may be considered as a superorganism composed of an amalgam of both selected symbiont microbiota and host cells (Hardoim, 2015) with the new concept of holobiome, i.e., plant together with the associated microorganisms collectively governing the plant activities (Hardoim et al., 2015; Vandenkoornhuys et al., 2015).

The scientific community working in the field of crop protection is experiencing an increasing academic and industrial interest in the discovery and development of new bio-insecticides as environmentally friendly pest control tools to be integrated, in combination or rotation, with chemicals in pest management programmes. In this context, Entomopathogenic nematodes (EPNs) as a bio-control agent have proven successful and are now commercially mass produced in six of the seven continents to treat pest problem in agriculture, horticulture and forest crops. They actively search for the host, including those in cryptic habitat stages of insect pests in soil environment. They can be considered as good candidates for integrated pest management in ustainable agriculture due to plants and mammals which are not adversely affected and have ease of mass production. We present a general overview on the current state of knowledge of EPN and their mutualistically associated bacteria and their utilization as biological control agent against insect pests in world and India are briefly presented in this chapter.

“Standards are to Industry as Culture is to Society” said Shri C. Rajagopalachari, the first Governor General of India. Shri C. Rajagopalachari was inaugurating a conference on Standardization and Quality Control in February 1948. The great statesman has beautifully summed up the importance of standardization.

The basic principles on which procedures and practices are based had their origin in the United Kingdom, where the first national standardization movement started as early as 1901. Thereafter, procedures have been continuously developed, modified and improved till considerable similarity is achieved.

Every research in agriculture aims at developing a promising new technology or refines an age old technology that can help addressing the improvement in crop yield. This is a worldwide scenario to meet up with the food needs of the growing population and reducing agricultural land resources. Many traditions in the world are associated with vast knowledge of cultivating the food crops, vegetables, fruits etc using selected methods that are modified based on the needs, climatic conditions and the resources available in the place of settlements. Soil based agriculture is the most popular method of growing plants since soil is considered as the main source of nutrients and water required for the healthy growth of crops. Generally it includes 3 major steps, ploughing, sowing and harvesting.

Labour is one of the biggest input costs for vegetable growers. Vegetable farming is labor intensive and time consuming. Frequently, it is associated with low yield and poor quality production. The constraints are high labor requirements for land clearing, ploughing, bed forming, mulch laying, seeding, transplanting, harvesting and transporting. Mechanization is interjection of improved tools, implements, machines and other equipments between man and materials (soil, water, environment, seed, fertilizer, pesticides, growth regulators, irrigation water, agricultural produce and by-products such as fruits, vegetables, and seeds, etc.)

The vegetables and fruits are largely consumed fresh and day by day, their market demand is increasing due to nutritious quality. However, market supply is not sufficient to meet public demand throughout the year as production is inadequate because crop production has not increased substantially in recent years due to climatic changes. Another important reason for low production is the economic losses incurred due to damages of insect pests and plant diseases.

Since ancient times, reduction in pest and disease incidence is sought by spraying of pesticides including conventional preparations such as tobacco decoction, Bordeaux mixture, neem leaf extract etc. During the green revolution years, the synthetic pesticides were greatly recommended for pest and disease control and thereby increasing crop yields many-fold. Having experienced the spectacular improvement in both yield and quality of marketable produce, farmers were solely dependent on synthetics and ultimately abandoned other control measures.

Pesticides are an undeniable part of modern life, used to protect everything from flower gardens to agricultural crops from specific pests. Pesticides have contributed significantly to improving quality of life and safeguarding the environment. Some 20 to 40 percent of the world’s potential crop production is already lost annually because of the effects of weeds, pests and diseases (according to the FAO reports) (www.CropLifeAmerica.mht). In addition to increasing crop yields, crop protection products used in stored products can also prolong the viable life of products, prevent huge post-harvest losses from pests and diseases and protect food safety for eating.

Soybean, a source of 40 per cent good quality protein, 20 per cent oil and other nutrients has great potential in meeting nutritional requirements and extending health benefits through soy based food products to Indian population. Soy foods are nutritious, economical and good for health. Regular food use of about 10 per cent processed soybean flour with cereal flours or 25-30 g properly processed soybean per day in a diet entitles the consumer to derive maximum nutritional and health benefits at a relatively low-price. Soy food products like fullfatsoyflour, soy-based bakery products and dairy analogs (soy milk, soy paneer (tofu), curd (dahi), soyshrikhand, soy amrakhand), being the products of acceptable type to Indian population, have good scope. Different organizations have given input in R&D work on soybean processing. SPU Centre at ICAR-CIAE, Bhopal has been involved in development of number of soybased food products, technology and equipment for preparation of those. To make available the properly processed soy food products to our population, the centre is actively engaged in capacity building of upcoming entrepreneurs and entreprise development for soybean processing for food uses. Around 500 cottage scale soy food enterprises have been established in different states of the country.

Centuries before Greece and Rome were discovered, sailing ships carried Indian spices, perfumes and textiles to Mesopotamia, Arabia and Egypt. It was the lure of these that brought many seafarers to the shores of India. Emperors, kings, senators and the aristocracy transformed spices into the mostly highly prized commodities of ancient trade routes The story of Indian Spices is more than 7000 years old. By the 1400s, when navigational equipment had improved to the point that long-haul sailing became possible, European rulers set out to change the balance of world trade by funding spice-hunting missions of their own. Christopher Columbus who, in searching for a quick route to India, reached the Americas. Vasco de Gama was the first to surround Africa, and with a crew led by Ferdinand Magellan, fully circumnavigated the globe.

Spices play important roles in daily life and India is a rich repository of spices. Various biotechnological approaches like micropropagation, somaclonal variation, in vitro conservation, synseed technology, protoplast fusion, production of flavor and coloring components, and development of novel transgenics have great significance in conservation, utilization and increasing the production and productivity of spices. Protocols for micropropagation and production of disease free planting materials are available for many spices. Efficient plant regeneration protocols are also available for exploiting somaclonal variation ,where the available natural variability is relatively low. Technologies for isolation and culture of protoplasts were reported in a few spices. Development of transgenics for disease resistance is gaining momentum. Synseed and Micro-rhizome technology are also available for many spices for safe propagation, conservation, movement, and exchange of germplasm. In vitro and cryo preservation technologies for conservation of spices germplasm are available for many spices.

Mango (Mangifera indica L.) is one of the most important tropical fruits of the world and is commonly known as the ‘King of fruits’ for its high quality fruits which are very popular among the Indians (Sharma et al., 2008). It is the oldest and extensively cultivated fruit crop in India having high socio-economic significance. India is the home of more than 1000 mango varieties, which originated in the Indo-Burma region (Mukherjee, 1958). India is the largest producer of mango, grown in about 2.3 million hectares with an annual production of 15.02 million tones. However, its productivity is only 6.5 tones per ha against 30 tones per ha in Israel (Bijay Jumar, 2010). Improvement of productivity in mango continues to be the foremost issue in mango production (Sauco, 1993). Of late, all the mango importing countries are considering the India as a source of quality mangoes due to its varietal wealth and availability. Hence, it is imperative to improve the productivity and quality of Indian mangoes to meet the global need (Balamohan et al., 2014).

The word Cymbidium has been derived from a Greek word ‘Kumbos’ meaning ‘hole or cavity’ referring to the structure of the base of the lip. The genus consists of 44 known evergreen species in the family Orchidaceae, subfamily Vandoideae, tribe Cymbidieae and sub-tribe Cryptopodiinae. It is distributed from northwestern India to China, Japan, south through the Malay Archipelago to the north and east Australia. (DuPuy and Cribb, 1988). Cymbidiums have been for over hundred years one of the most famous orchids in commerce.

The orchids are commercially important group of flowering plants and their flowers are affluent in uniqueness in their shape, size and colour, exquisitely attractive, remain fresh condition for long period of time in comparison to other flowers. Orchidaceae is the second largest family among floriculture; about 25000 to 35000 species of orchids have been reported over the world (Rampal and Nagrare, 2006). India accounts for nearly 7 per cent of world’s orchids genetic diversity contributed 1300 species under 184 genera (Arora, 1983; Rampal and Nagrare, 2006) and 1150 species belonging to 164 genera (Satish Kumar, 1994) of which about 800 species are found in the North Eastern region of the country (Nagaraju et al., 2006) and many more are discovered year after year because of the prevailing congenial climatic conditions, diverse terrain and altitudinal variations, which provide suitable habitat for orchids.

Methylene-cyclo-propyl-glycine (MCPG), is a cyclopropyl derivative, grouped into the amino acids that have been isolated from the higher plants (Fowden, 1960). MCPG was identified to be closely related to two other cyclopropyl derivatives (Fig. 1), 1-aminocyclopropane – 1 – carboxylic acid from Vacciniumvitis-idaea and perry pears (Vahatalo and Viertanen, 1957; Burroughs, 1957) and â- methylenecyclopropyl alanine (MCPA or Hypoglycin A) from Blighia sapida (Hassall and Rayle, 1955; Anderson et al., 1958; Ellington, Hassall and Plimmer, 1958).

Mango (Mangifera indica L), the king of fruits, is cultivated throughout a wide range of frost-free climates (Litz 1998). It is commercially the most important fruit crop of India, accounting for more than 54% of the total mango production worldwide. The fruit of mango (Mangifera indica L.) is exceptional for its juicy, succulent, thick fruit pulp and nutrient abundance in terms of wide range of amino acids, sugars, organic acids, minerals including Ca, P, Fe, and K and vitamins. Out of several diseases which attack mango crop, mango malformation disease is a serious threat to its cultivation since it causes gross deformation of the vegetative and floral tissues (Ploetz et al., 2002; Kumar et al., 2011). Floral malformation is a major problem in mango, rendering mango cultivation unproductive in northern India and other regions of the world (Pandey et al., 1977; Ram, 1991).

Tomato (Solanum lycopersicum L.) is one of the most important vegetable crops cultivated in the world. It is used as raw in salads and also used as cooked vegetable in the preparation of curries. Processed items such as tomato puree, ketchup, pickle, chutney, whole peeled tomatoes and tomato powder are also consumed considerably. It is a rich source of Vitamins A & C. Lycopene and other flavonoids in tomato serve as good source of antioxidants. Tomato occupies 5 million hectares with a productivity of 34t/ha. in the world. In India it is cultivated in an area of 0.88 million hectares with productivity of 21 t/ha.

Visit to a seed processing unit and attending the following questionnaire to know firsthand information on operations of shop floor

1.1 Problem
    1.    Compare the seed quality at different physiological maturity stages
    2.    Compare the seed recovery in acid and fermentation method

1.2 Materials
    ·    Tomato fruits – 4 batches
    ·    Plastic bucket/ Beaker
    ·    Water

Seed processing is specialized activity and also a tool to improve seed quality further to an acceptable standard. Seed quality parameters like germination, vigour or genetic purity can be improved using processing. Say a seed lot having a minimum standard of 90% germination, but the competition in the market offering seed quality 92 or 95 % then to meet the market demand we can process the seed lots using re-milling or re-conditioning techniques. Also sometimes simple techniques like liquid density separation which uses specific density of the seed to separate good seed from inferior quality can be considered.

The physical properties of seeds are a basic activity for designing processing equipments and precision planters. Since these characters vary with crop or variety, one needs to have the data handy to be used on shop floor. This data also helps to quantify processing efficiency, presence of dormancy and suitability for seed treatments for all existing and new crops or varieties.

Methods in Seed Blending

For good seed blending there are three methods and details of which given as below:

Mechanical damage is inflicted on seeds during harvesting, threshing drying, processing and handling. Injury may occur from any kind of physical abuse. Threshing abuse probably is most serious but, seed conditioning and handling also contribute to seed injury. High temperatures during drying or drying too quick or excessively can cause injury. Susceptibility to mechanical injury increases as the moisture content of the seed decreases. Effect of all individual impacts received by the seed appears to be cumulative in total seed damage. Cereals are largely immune to mechanical injury presumably because of the protective outer structures, the palea and lemma. Large sized legumes are more suscepitable. Small seeds tend to escape injury during harvest and seeds that are spherical tend to suffer less damage than elongated or irregularly shaped ones.

The processing operations are carried out based on the principle of physical differences found in a seed lot.

9.1 Magnetic seed separator

These machines use a magnetic force to separate damaged seeds or other particles from the good seeds. This is used to solve special problems in seed lots that can not be taken out with our other basic seed cleaning equipment. Most of the time it is used for vegetable and field seeds that have problems in seed damage (fish mouth in cucumber or melon seeds / cracked radish or cabbage seeds), insect damage (beetle holes in cotton seeds) or contamination with soil or plant parts (white plant parts in onion seed) etc.

Seed size is an important parameter of seed vigor as it in influences the performance of seed in soil. Seed bulk at harvest contains a wide range of seed sizes but these may not all be of equal value for sowing. Farmers have always realized the necessary of using uniform seeds for good viability to obtain high emergence and growth. This will also help in getting optimum plant population and higher yields.
 
The influence of seed size on seedling vigor and crop productivity has already been proven since the days Hannaford who was considered as father of seed processing. To achieve uniformity in seed size this optimum sieve/screen size is very critical for optimum seed recovery and economical seed yield. Though the screen sizes are standardized for different crops but vary with different varieties. The shop floor should continuously explore and fine tune screen sizes for different varieties.

This practical in continuation of the practical no.10 explore the effects of screen sizes on different varieties. The screen sizes vary not with crops but with varieties also. To know the effect of screen sizes among the varieties we need to take the top and middle screens as standard or as recommended. These methods can be applied to any crop and to different varieties.

The use of seed processing equipments helps in improving the seed quality by inducing uniformity of physical properties of seeds. This help in achieving optimum plant population and desired economic yield. In certain crops like soya bean, standard seed processing may not give desired seed quality because of sensitivity towards moisture. As general practice seed need to be dried to its safe moisture content of 9 before processing. But in case of soya bean lower seed moisture may result higher mechanical damage after standard seed processing. Drier seed are more vulnerable for mechanical damage. In this practical w try to explore the importance of moisture in seed processing and also need of alternative processing equipments like spiral graders to minimize mechanical damage.