eChapters

1. Introduction

Processed foods have become a way of life in the modern world. Manipulation of chemical and physical properties facilitated by modern food technology and followed by addition of food additives has created a plethora of innovative food products that offer consumers greater convenience, variety, safety, satiety and quality.
Food additives have been in use for centuries for preservation, for providing improved appearance or desired texture and flavour. Preservation of foods started with salting and smoking. The Egyptians used colours and flavours, Romans used saltpeter and in India, turmeric is being used. Similarly additives such as baking powder as a raising agent, thickeners for sauces and gravies and colours- synthetic as well as from natural sources are being used.
Today more than 2500 food additives have been in use mainly due to the spurt in the research activities in food science and technology that are aimed at providing different characteristic functions to foods. Out of these, about 1300 are the flavouring additives.

1. Introduction

Fruits and vegetables in fresh form in general contain very high water content, with the fast rate of metabolic activity, including respiration rate, which may vary with the fruit type. Accordingly, the storage life at room temperature is considerably less, to expect acceptable quality. A range of transformational changes occur in various features of the fruits and vegetables, such as color, flavor, texture, structure, sweetness, sourness, pungency, astringency and so on. Phenolic browning of mushrooms, intensive softening of papaya, coloration and softening of ripe banana, softening of pear and jackfruit , flavor transformations of mango, banana and jackfruit after ripening, their color and texture transformations, are classic examples of post-harvest changes in fresh commodities, over a course of storage period at room temperature. These physical and sensorial perceptions of fresh commodities over a length of storage period are based on the range and multitude of operations of physical, chemical and bio-chemical reactions occurring in various constituents of the fresh fruit or vegetable such as moisture, pigments, vitamins, pectin, cellulose, hemicelluloses, phenolics, lignin, sugars, flavor compounds, amino acids, fatty acids and so on. In order to increase the storage stability, the fresh fruits and vegetables are processed and converted into various products such as juice, RTS beverages, jam, jelly, marmalade, fruit spread, dehydrated, spray dried powder, frozen stored, fruit cereal flakes, canned, candied, fruit bar and so on. Based on the nature of processing, the original form, shape, size, texture and structure are transformed, however with due maintenance in storage acceptability. A number of external factors are applied to achieve this product range such as heat, air velocity, pressure, radiation, chilling, freezing, vacuum impregnation etc. The ultimate quality of the final product is essentially an interaction between and amongst the various chemical constituents so characteristic of each fruit or vegetable under study, and a sum total of positive and negative reactions related to sensorial acceptability of the product. This quality is again a function of the storage period and the conditions of storage. Consumers in modern days are more health conscious to choose between consumption of fresh or processed fruits and vegetables. For trade over distance and time and particularly for geographic regions not producing a particular fruit or vegetable, it is of utmost importance to process the fresh produce. Enzymatic transformations in color, texture and flavor deserve utmost attention to ensure acceptable quality of the processed product, in particular over the course of storage period or until consumed after transportation and marketing. Microbiological quality of the product in final form is a most vital factor of consumers' health and this is dependent on water activity, sugars and protein / amino acid contents. In this regard, additives and preservatives come into picture. Strict regulations are imposed on their use, type and concentration over a storage period, for healthy consumption. Accordingly, this chapter would deal with several examples of processing conditions influencing the quality of the product, that emanates. Processing involving chemical, bio-chemical, engineering, bio-technological and microbiological methods to achieve a product are vivid, varied and different to different species / variety of fruits or vegetables to target different products.

1. Introduction

 Mushrooms have been part of man’s diet for centuries (Rajarathnam and Shashirekha, 2003). Mushrooms grow on wide range of agro-residues, biodegrade and biotransform them into edible fruiting bodies (Rajarathnam and Zakia Bano, 1988a; 1988b; 1990; Zakia Bano and Rajarathnam, 1988; Zakia Bano et al., 1993; Rajarathnam et al., 1998). Their post-harvest life is very ephemeral at room temperature (Rajarathnam et al., 1983) due to delicate flavor (Rajarathnam et al., 1990) and high moisture content, with a range of chemical constituents (Zakia Bano and Rajarathnam, 1986; 1982; 1988; Rajarathnam and Zakia Bano, 1990; Rajarathnam et al., 1983; 1992). Since, they contain large quantities of water and therefore suffer considerable weight loss during transportation and storage, causes serious economic losses, due to reductions in weight and quality (Gray, 1970). When the supply of water, organic substances and minerals are cut off at harvest, the fresh mushroom enters a deterioration or perishable phase. Cap opening and stem elongation are the usual symptoms of senescence constituting visible evidence of deterioration. At room temperature, the shelf-life of mushrooms cannot be for more than 24 h (Rajarathnam et al., 1983). During this period, there are considerable changes in color, texture and taste. In addition, water is continuously being lost as a result of transpiration and respiration. Additional loss occurs from surface cracks and bruises that develop during growth and handling (Salunkhe et al, 1991). Fresh mushrooms are white or light buff, with no dark marks on either the cap or stem. The veil is closed and the gills are not visible. The upper surface of the caps should be strongly convex and stems should be plump rather than elongated. Mushrooms are grown on compost, usually in mushroom houses where the temperature and humidity can be controlled. Eventually after harvest, the mushrooms can never be able to withstand any increase in temperature and decrease in relative humidity. Mushrooms are commercially preferred at the immature stage characterized by closed caps, invisible lamellae, round stipe and light color. Agaricus development is classified into various stages (Table 1). Thus, the concept of physiology of fresh mushrooms being very complicated, bears a great impact on the delicate problem of extending the storage life. The various means and methods studied and adopted by various researchers to aim at extended storage life of fresh produce, underlined by its physical, chemical and biochemical properties and also development of value added products are critically evaluated.

1. Introduction

Bamboo has historically been an integral part of human culture. Bamboo is a mystical plant representing symbol of strength, flexibility, tenacity, endurance and compromise. Throughout Asia, bamboo has for centuries been integral to religions, ceremonies, art, music and daily life. Bamboo provides numerous environmental benefits such as playing a critical role in the balance of oxygen/carbon dioxide in the atmosphere. Bamboo is the fastest growing canopy for the regreening of degraded areas and generates more oxygen than equivalent ultraviolet rays. It is an atmospheric and soil purifier. Its soil conservation properties create an effective watershed, stitching the soil together along fragile river banks, deforested areas, and in places prone to earthquakes and land slides. Its fast growing and high yield nature makes it a highly valued renewable resource. Its low cost and abundance call for its utilization to a full extent. 

1. Introduction

There is intense commercial interest in dehydrated fruit and vegetable products especially mango powder, banana powder, orange powder, papaya cereal flakes to powder, tomato juice powder and other vegetable powders, which are in great demand for soups, biscuit type cookies supplemented with fruit powders (Ana Maria et al. 2009; Sunita and Chauhan 2008), pizza mixes and sauces. Natural fruit and vegetable powders are gaining lot of popularity in recent years as they are very easy to handle after production, require minimum storage space and they are attractive. Tamarind powder is developed from tamarind fruit (Tamarindus indica) (Manjunath et al. 1991) and recently cashew apple and guava residues from fruit juice industry were successfully converted into fruit powders and used at different levels of wheat flour substitution for cookies formulation (Ana Maria et al.2009) and fruit puree like papaya can be mixed with cereal flour to prepare slurry and after gelatinization, the slurry can be useful for preparing drum dried flakes and powder (Sunita and Chauhan 2008). Tropical fruits are exotic in flavor but their juices and purees are seldom available in dehydrated powder (James, 1971). Citrus juice concentrates were produced during world war II in powdered form by using spray, drum, vacuum-puff, and freeze drying (USDA, 1962). The preservation of fruits and vegetables by dehydration offers a unique method, which may be considered as an alternative low cost preservation technique. A shift from fresh to more and more processed foods with significant value addition is bound to occur sooner or later considering the socio-economic changes taking place in the country and the rapid integration of Indian economy with global system. Most popular brands are found in the “ready to consume” food sector.

1. Introduction

Intermediate moisture foods are semi moist foods that have some of their water bound by glycerol, sorbitol, salt or certain organic acids, thus preventing the growth of many microorganisms (Stewart et al. 2001). It is now well recognized that fruits and vegetables are dehydrated to an intermediate moisture level (20-50%) (Stewart et al. 2001; Purvi et al. 2003). As the intermediate moisture products are characterized by a semi moist consistency so these foods have enough moisture content to permit easy chewing but low enough water content to prevent spoilage production of intermediate moisture foods is based on an increased scientific understanding of the chemical reactions involved in traditional food preservation methods (Purvi et al. 2003).
There will be better retention of original flavor and texture compared to fully dried products, with concomitant reduction in bulk, weight and cost of packaging, transportation and storage. Such intermediate moisture foods are more appropriate for developing countries in view of their minimal processing requirements, stability under ambient conditions, safety, convenience, ease of nutrient content adjustment, energy savings and low capital investment. They are also eminently more suited than dehydrated or canned foods for military rations (FAO, 2005).

1. Introduction

Pulpy and juicy fruits like orange, guava, banana, grape, mango, papaya, pears, apples and jackfruit can be converted into fruit products like squashes, juices, cordials and ready-to-serve (RTS) fruit beverages. These RTS fruit beverages are both refreshing and thirst quenching and have become very popular. Liquid fruits are the clarified juices prepared from these pulpy and juicy fruits. There is a demand for liquid fruits in the international market for various applications. The liquid fruits can be used as a natural alternative to synthetic beverages. They can be suitably concentrated or diluted, blended with other juices and also can be carbonated as fruit based soft drinks. Removals of pulpy material from the juices make them easier to preserve by pasteurization and are amenable to carbonation. Pulpy fruits can be successfully processed into liquid fruits (clarified juices) by using pectic enzymes. The emphasis of the fruit juice processing industry has, so far, been mainly on conventional clarification processes like enzymatic and chemical treatments followed by filtration using filter aids; and concentration by vacuum evaporation.

1. Introduction

In this era of genomics, proteomics and metabolomics the challenge in nutritional science is to clarify human nutrient requirements and design nutritional strategies to promote health and functional longevity. Our ancient Indian belief that ‘we are what we ate’ and our future health as individuals may well depend upon what we eat today. Plant-based dietary antioxidants are believed to have an important role in the maintenance of human health because our endogenous antioxidants provide insufficient protection against the constant and unavoidable challenge of reactive oxygen species (ROS). We have various endogenous defense chemicals but they are inadequate to prevent oxidative damage that makes human system prone to various degenerative diseases. Hence, it is necessary for increased intake of dietary nutraceuticals that may help maintain the balance between oxidants and antioxidants, slow age-related changes, and prevent onset of degenerative diseases.

1. Introduction

At present there is an increasing demand for colourants from natural sources. Since there is a possibility of banning of synthetic colours in view of their carcinogenic properties and already a reduction in number of permitted synthetic colours from 13 to 8 numbers in our legislation (PFA, 2005), the demand for natural colours is evident. In Japan and European countries because of the green movement, the demand for synthetic colours has been reduced. Synthetic colours in global market account for 400 million dollars. Despite processing limitations and higher costs, the global market for natural colours is estimated to be more than 939 million dollars (Espszezola, 1998). Color is recognized as a major factor affecting food acceptance. The consumer expects a specific food to possess a well defined colour and rejects any appreciable deviation from the normal. The change in colour during the preparation of food is a useful guide to quality control and is used by many food processors as the criterion for selecting raw materials. The characteristic colour of raw food is due to the natural pigments present in the plant and animal material. These can be enhanced in processed food products through the addition of food colourants. Addition of colour can make up for the colour losses during processing. Some of the major groups of colours are anthocyanins, carotenoids, betalains, chlorophylls, flavones and chalcones. Some of the plant sources of pigments are kokum, roscelle, chilli, marigold, beetroot, grapes and safflower. Sources of natural colours can be plants, animals or microbes. Fruits and vegetables form one of the main plant sources of pigments. Some of the plant materials rich in colours viz., alfalfa, marigold, safflower, strawberry, aronia fruits, grapes, red cherries have been exploited for pigment extraction and the results have shown positive effects. Some of the interesting features of the work carried out by researchers in this area are presented in the following sections.

1. Introduction

Pectin is a polysaccharide present in the middle lamella of plant cell walls. The firmness and structure of the plant tissue are attributed to the presence of pectin in the middle lamella. The insoluble form of pectin is called protopectin and the soluble form is called soluble pectin (Kertez, 1951). Protopectin is abundant in green fruits and contributes to hardness of cell, where as soluble pectin is responsible for viscous nature of juice and pulp. Conversion of protopectin to soluble pectin results in loosening of the bonds between the cells and softening of the fruit tissues. Protopectin is reported to be hydrolyzed to pectin by enzyme action during ripening. Protopectin on restricted hydrolysis yields pectin or pectinic acid. Braconnot (1825) discovered pectin as the gelatinous principle of fruits.

1. Introduction

Food is processed for its preservation, hygienization or value addition. To date, the food preservation technologies such as canning, dehydration, freezing, pasteurization and controlled atmosphere and modified atmosphere packaging have been the main processes employed to preserve foods, with the use of antimicrobials and microwaves also being employed more recently. In future, however, technologies such as exposure to ionizing radiation, high pressure processing, ohmic heating and pulsed electric field processing, could potentially be the new alternatives to the above food preservation technologies.

Irradiation of food involves the exposing of food, either in prepacked form or as such to controlled doses of ionizing radiation being generated either by electrically driven machines such as electron beam accelerators, x-rays or gamma rays produced by radioactive isotopes such as CS-137,CO-60, to achieve certain desirable objectives. The process of exposing a range of food stuffs to specific doses of ionizing radiation is being used to extend the shelf life of food stuffs, to improve their overall safety and quality by eliminating pathogenic bacteria, by reducing number of food spoilage organisms, to reduce the bacterial load on herbs and spices and thereby making them safe to incorporate into food stuffs, to inhibit sprouting in stored tuber and bulb crops such as potatoes, onions and garlic, to disinfest grains, grain products and tropical fruits to prevent damage to the commodity and to meet the quarantine regulations(Arun Sharma, 2004, Farkas, 2006).

1. Introduction

Vegetables and fruits are the next in demand for human consumption after rice and wheat, in all parts of the globe. Fresh fruits & vegetables and their value added products are increasing in popularity day by day almost in all the countries, because of their richness in dietary fibre, minerals & vitamin contents and for their medicinal properties. Maintaining agricultural produce quality and its evaluation are thus naturally important. Decisions concerning maturity and ripeness of fruits and vegetables are based mostly on visual inspections, which are subjective in nature. The quality of fruits and vegetables is mostly decided on the basis of size, shape, colour, gloss, flavour, firmness, texture, taste and freedom from external as well as internal defects. Internal quality factors such as maturity, sugar content, acidity, oil content and internal defects, however, are difficult to evaluate non-destructively. Methods are needed to better predict the internal quality of fruits and vegetables without their destruction. Recently, there has been an increasing interest in non-destructive methods of quality evaluation, and a considerable amount of effort is being made in this direction. But the real problem is how these methods are to be exploited practically on commercial scales and what are the constraints faced in implementing them.

1. Introduction

Fruits and vegetables represent highly perishable items of agriculture, mainly because of their high water content in fresh form. Their production, yield and management under agriculture is dealt essentially under horticulture. They abound in species and varieties in different geographic regions of the world, influenced by the agro-climatic conditions. Some are endemic and confined to certain geographic regions only. Accordingly, they may be tropical, sub-tropical or temperate, depending on their requirements of temperature for growth and yield.

INTRODUCTION

Plants are susceptible to different types of pathogens, which are responsible for production of varied symptoms and causing losses. In the absence of the crops pathogens perpetuates in different manners and survival in the soil is one of the most important amongst these. Because of the constant presence of the pathogen in the soil, these become more destructive. These may reduce the plant growth, results in rotting of different plant parts, reduce yield or may cause the death of the plant. The destructiveness of soil borne pathogen increases because of the ability to survive in the soil as dormant structures for several years. Efficient control of soil borne diseases is thus difficult but can be achieved by employing various disease management practices in an integrated manner (Verma and Varma, 1992; Gupta, 1996, Gupta and Sharma, 1999).

INTRODUCTION

Many economically important diseases are caused by Phytophthora spp. There are as many as 60 described Phytophthora species, most of which are primary invaders of plant tissues with limited saprophytic ability. Some important diseases with respect to symptoms, etiology and management have been described in this chapter as given below.

INTRODUCTION

Soil-borne pathogens cause heavy losses to most agricultural crops. Repeated planting of a crop in the same piece of land results in a high inoculum build-up, which forces the farmers either to change the crop or the land. Thus, the search for new, effective, inexpensive and non-hazardous methods for the control of soil-borne diseases is a continuous one. Over the years, efforts have been made to manage the soil-borne pathogens by employing fumigants, chemical pesticides, biological control agents, different type of soil amendments and also by causing modifications in different cultural practices. But, pathogen control is often hampered by the fact that both the inoculum of the pathogens and the lethal agents applied to the soil are affected by the soil’s physical, chemical and biological environment. Keeping in view the bottlenecks with different methods of management of soil-borne pathogens; harnessing of solar energy i.e. soil solarization is an effective method to control soil-borne pathogens.

INTRODUCTION

The genus Pratylenchus was established in 1936. It has a cosmopolitan distribution prevalent in temperate, sub-tropical and tropical regions. The species of Pratylenchus are popularly known as lesion nematode or meadow nematode. They are migratory endoparasites. Various pulse crops are damaged by them. P. thornei attacks chickpea,  P.zeae on mungbean (Walia and Seshadri, 1986); P. mulchandani on urdbean (Nanad Kumar et al., 1969) and Pratylenchus sp.on lentil (Mishra and Gaur, 1980) and cowpea (Aung and Prot, 1990).
Besides pulses species of Pratylenchus attack a number of other crops also. The infested plants exhibit various types of symptoms and results in heavy yield losses. Investigations have been made on various aspects of host-nematode relationship, distribution, host range, yield losses, biology, life cycle, disease cycle, interaction with other microorganism and management through cultural, physical, chemical, biological methods and host resistance.

INTRODUCTION

Fungi naturally present in soil and rhizosphere of various crops serve as potential biological control agents of various plant pathogens. Species of fungi occurring in the genus Trichoderma have gained significant importance for use as agents for control of several diseases of cultivated crops. The last decade has witnessed a tremendous break-through in the research efforts on biological control of plant diseases in India especially by using species of Trichoderma and Gliocladium. Several economically important plant diseases of a variety of crops were effectively managed by using Trichoderma based biofungicides.

The work on biocontrol of pigeonpea wilt by Bacillus subtilis by Dr. R S Vasudeva and his associates, published as a series of papers in Annals of Applied Biology during 1950 to 1965 can be considered as a starting point for Indian work on biological control of plant pathogens (Mukhopadhyay, 1994).

INTRODUCTION

In arid and semi-arid regions of India, besides weather aberrations, diseases caused by certain soil-borne pathogens are responsible for low productivity of agricultural crops. In addition to losses caused in annual crops, occurrence of these diseases in forestry takes away a major share. Because of the requirement for free water, diseases of aerial plant parts are much less common than those involving roots when plants are grown in dry regions where humidities are low and rains are infrequent and/or of short durations. Under these conditions, pathogens like Macrophomina phaseolina, Ganoderma lucidum, Cylindrocarpon lichenicola, Neocosmospora vasinfectum, Sclrotium rolfii and species of Fusarium (F. oxysporum, F. solani, F. equiseti, etc.) cause root rots and wilts in many commercially valuable and perennial plants.
Certain agro-climatic factors are attributed for the development of few specific diseases caused by soil-borne plant pathogens. Low organic matter, small microbial population coupled with poor moisture retention capacity of soil favour survival and multiplication of soil-borne pathogens (Fig. 12.1).

INTRODUCTION

Burgeoning human population and its elevated living standard have greatly demanded more agricultural production. But unfortunately agricultural crops suffer deadly due to many biotic and abiotic stresses. Of biotic stresses, phytonematodes, the hidden enemies of crops are real threat to successful and profitable cultivation of agricultural crops (Plate. 11.1). These, endoparasitic nematodes, Meloidogyne spp. and Heterodera spp., are mainly dreadful causing wrecking havoc to agricultural scenario. Chemical control of these, tiny parasites created residue, resistance, resurgence, hazardous and pollution problems to the growers as well as soil and atmospheric environment. To overcome these hazards, efforts are being made to go for non-chemicals means of nematodes management strategies in crops. Hence, a research work carried out on management of these endoparasitic nemas particularly Meloidogyne spp. and Heterodera spp., through non-chemical methods is reviewed in subsequent status.

INTRODUCTION

The fine feeder roots of many vascular plants are invaded by specific nonpathogenic fungi forming a distinct morphological unit known as mycorrhiza (In Greek, Mykes mean mushroom or fungus, rhiza mean root). Physiologically mycorrhiza represents a case of symbiosis.

The term mycorrhizae were coined by a German botanist Albert Bernard Frank in 1885 which literally mean “fungus-roots”.  Mycorrhizal fungi form a symbiotic association with agricultural and horticultural crops in addition to certain tropical tree species.
Mycorrhizal fungi are broadly classified in to two groups:
1) Ectomycorrhizae  
2) Endomycorrhizae.

INTRODUCTION

‘Wilting’ is a broad terminology used by Plant Protection Scientists.  Any disturbance or damage to the normal physiology of the plant leads to ‘wilting’ of plants.  Wilting in cotton is attributed to many factors and it is necessary to single out the actual cause for wilting before suggesting any remedial measure (Kannan, 1991).
Wilting in cotton could be due to any one or more factors as indicated below:

INTRODUCTION

In India, temperate fruits are grown successfully at locations above 3000 feet mean sea level in hilly areas of Himachal Pradesh, Jammu and Kashmir, Uttranchal, Sikkim, parts of North Eastern states like Assam, Arunachal Pradesh, Nagaland, Meghalaya etc. Mount Abu hills of Rajsthan and Nilgiris of Tamil Nadu also provide suitable agro-climatic conditions for growing some temperate fruits. Apart from apple; pear, peach, plum, apricot, cherry, almond and walnut are major temperate fruits being grown over 3.38 lakh hectares of area and play pivotal role in the economy of hilly farmers whose land is not otherwise considered suitable for traditional agriculture. They contribute about 11.5 percent of total area under fruits in the country, yet production is only 5 percent of the total. Incidence of many fungal, bacterial and viral diseases in these fruit crops is a major impediment in their successful cultivation and soil borne pathogens are of foremost importance and are responsible for premature death of the trees in the orchards. Amongst these, white root rot, collar rot, seedling blight, crown gall, hairy root are the major constraints which can cause as high as 40 percent damage in certain situations (Sharma and Sharma, 2001). Threat from the replant problem is causing concern due to its negative effect on the establishment of replanted sites due to soil sickness.

INTRODUCTION

Wheat has served as a source of staple food to the mankind since times immemorial. The production of wheat in India got a fillip after green revolution. Wheat production in India has increased by over ten times in the past five decades and India has become the second largest wheat producer in the world. Today, wheat plays an increasingly important role in the management of India’s food economy (Gandhi, et al., 2001). Wheat, primarily the winter cereal of Indo-Gangetic plain, is a major contributor to the agricultural economy of India, occupying nearly 25.9 m ha area with 71.8-mt production (Anon., 2003).

India is also second most populous country with one billion people. Demographers indicate that by 2012 India’s population will reach 1.2 billion. With this ever increasing population, there is also an increase in the demand for food grains. Depending on the rate and nature of economic growth and given the population growth rate about 4 or more per cent, annual rate of growth in the demand for wheat is likely to increase in the near future.

INTRODUCTION

Throughout the history of agriculture, humans have struggled to reduce the adverse effects of plant disease on their crops. Early agriculturalists realized the benefits of cultural practices such as crop rotation and the use of organic soil amendments in promoting plant productivity. It is now well established that many of these effects are achieved by promoting the natural microbiological processes that keep plant disease in check. Cultural practices were mainstays of traditional agricultural systems and still provide the primary approaches for management of many soilborne diseases today. For example, disease suppressive soils, into which pathogen(s) can be introduced without causing the expected levels of disease severity, can result from alterations in cropping patterns or other cultural practices. Recently,

INTRODUCTION

Biological control involves the suppression of pests/organisms with other organisms.  It is an eco-friendly method for management of plant pathogens which can be done exploiting the fungi (Ampelomyces, Trichoderma, Coniothyrium, Candida etc.) or bacteria (Agrobacterium, Bacillus, Pseudomonas and Streptomyces) from rhizosphere,  as well as phylloplane and endophytes (Jayaraman and Verma, 2002). The rhizosphere microfloras are predominantly composed of gram negative pseudomonads.  The fluorescent pseudomonads constitute a large proportion of the rhizosphere microflora presumably due to their nutritional variability being able to use a large number of organic substances (Stolp and Gadkari, 1981). However earlier workers used fluorescent pseudomonads extensively they now prefer Bacillus sp. due to their spore forming ability and heat tolerance which make its formulation easier.

INTRODUCTION
 
The form genus Sclerotium was described by Saccardo (Saccardo, 1913) to include fungi that produce sclerotia and had sterile mycelia. Several fungi were inc1uded in this genus, and all were characterized by production of small, dark brown or black spherical sclerotia that were internally differentiated into a rind, cortex and medulla. Several plant pathogenic fungi with this sclerotial type and with no known sexual or conidial state were placed in the genus Sclerotium. However, as the teleomorphic states were discovered, affinities to the Basidiomycotina (Punja, 1988) or Ascomycotina (Krause and Webster, 1972) were established for some members of the form genus.

INTRODUCTION

All plant species grown on this universe are attacked by insect-pests and diseases, resulting huge yield losses in agriculturally important species. Among diseases, extensive yield losses occurred due to soil borne fungal plant pathogens. Soil borne fungal pathogens infect roots or stem bases, their dispersal and survival stages are primarily confined to the soil. Although many soil pathogens may also produce air or water dispersed spores which results in long distance dispersal. Soil borne fungal diseases are specifically those diseases where the soil borne fungi has the capacity to survive in soil for long periods in the absence of their hosts, or survive in the soil outside of seed or host residues, but infection and symptom expression are confined to the subterranean organs of the plant. Soil borne fungi may be divided into two classes: i) The  soil inhabiting fungus which is characterized by its ability to survive indefinitely as saprophyte (e.g. Rhizoctonia, Sclerotium) and ii) The soil invading or root inhabiting fungus which is characterized by an expanding parasitic phase and a declining saprophytic phase after  the hosts death.

INTRODUCTION

Rhizoctonia solani Kuhn (teleomorph: Thanatephorus cucumeris (Frank) Donk is cosmopolitan in soils. It is a destructive plant pathogen with an almost unlimited host range. The fungus inhabits in soils and causes damping-off of seedlings, root, crown and stem rots, and occasionally foliar blight (Baker, 1970). R. solani is an important symbiont with the saprophytic seedling stage (protocorm) of many orchids (Warcup, 1985). It aggressively colonizes organic matter and is one of the fastest growing fungi. According to available information, the isolates of R. solani possess the following-characteristics (Plate 2.1).

INTRODUCTION

Modern agriculture relies more on monoculture, which is highly energy intensive and has a narrow genetic base. This has disturbed the normal ecosystem and sometime results in disease epidemics. The problem becomes much more serious in case of soil borne pathogens, as soil medium is a highly complex living system and is also the habitat of many micro organisms including the pathogens whose activities are influenced by interaction in it. Many serious plant diseases are associated with soil-borne plant pathogens, which cause root rot, crown rot, damping off, blights, fruit decay and wilts in field and horticultural crops. Soil borne plant pathogens, which are most tricky and challenging ones, cause sustainable economic loss. Many important fungal pathogens reside in the soil and infect roots of crops often causing significant yield losses. Soil-borne diseases result from a reduction in biodiversity of soil organisms.

SUMMARY

Multiplicity of cropping systems has been one of the main features of Indian agriculture and it is attributed to rain-fed agriculture and prevailing socio-economic situations of farming community. It has been estimated that more than 250 double cropping systems are followed throughout the country and based on rationale of spread of crops in each district in the country, 30 important cropping systems have been identified. Cropping systems of a region are decided by and large, by a number of soil and climatic parameters which deter mine overall agro ecological setting for nourishment and appropriateness of a crop or set of crops for cultivation. Much of the Madhya Pradesh area also coincides with the rainfed semi-arid agro-ecological region and sub-regions which are upland, forested with low agricultural productivity and predominately tribal population. It would appear that over the centuries – including in recent history tribals have been inexorably moved off the better lands, into areas which from an agricultural perspective have low productive capacity and little potential for growth. Low agricultural productivity is one of the main causes of persistently high poverty rates in the state and the poor masses not only depends upon the farming system but also chosen different alternatives for their sustanability.

SUMMARY

Organic farming is not new to Indian farming community. Several forms of organic farming are being successfully practiced in diverse climate, particularly in rainfed, tribal, mountains and hill areas of the country. Among all farming systems, organic farming is gaining wide attention among farmers, entrepreneurs, policy makers and agricultural scientists for varied reasons such as it minimizes the dependence on chemical inputs (fertilizers; pesticides; herbicides and other agro-chemicals) thus safeguards/improves quality of resources, and it is labour intensive and provides an opportunity to increase rural employment and achieve long term improvements in the quality of resource base. The popularity of organic farming is gradually increasing and now organic agriculture is practiced in almost all countries of the world, and its share of agricultural land and farms is growing.

SUMMARY

Abiotic stress can be reduced by choosing the most appropriate pulse species and adjusting agronomy (sowing time, plant density, soil management) to ensure sensitive crop stages occur at the most favourable time in the season. For example choosing the optimum sowing time, species and cultivars with appropriate phenology can reduce the effect of frost and drought in pulse crops in dry land environments, which termed stress.

             Most appropriate approach of dealing with stresses caused by extremes in the abiotic environment is to develop cultivars resistant to specific stresses. However, breeding and selection for resistance to these stresses is often considerable difficult because of the unpredictability of climatic conditions. Drought and heat escape through earliness in flowering and maturity is probably the characteristic most widely used by breeders for pulses and other crops to escape drought especially in low rainfall, terminal drought environment. Lack of simple and accurate screening procedures to screen parental genotypes and breeding population for various abiotic stresses is the major bottlenecks in the development of stress tolerant cool season pulse crops.

SUMMARY

In the context of increasing population pressure, diminishing per capita land holding, and employment crisis, livelihood security of Indian rural population has become important concern today. The livelihood of the people is dynamic, diverse and complex in nature. The livelihood comprises the people themselves, the assets they posses, the activities they do and the output they gain from their activities. According to the need, availability of the resources and capacity, people used to select their livelihood strategies like agricultural intensification, livelihood diversification or they migrate to the other places to find alternative livelihoods.

SUMMARY

Fertigation is the injection of concentrated soluble nutrients into irrigation water to enhance crop production. It is used extensively in commercial agriculture and horticulture. In combination with micro-irrigation (drip irrigation), this technique forms an efficient method for precisely applying nutrients close to the crop root zone, especially when a polyethylene mulch is used. Fertigation is used to spoon feed additional nutrients or correct nutrient deficiencies detected in plant tissue analysis and usually practiced with high value crops such as vegetables, turf, fruit trees, and ornamentals. Water supply for fertigation kept separate from domestic water supply to avoid contamination. Fertilizing fruit and vegetable crops requires a delicate balance between yield, quality, and environmental impact. Fertigation increases response to nitrogen (N) and provides greater opportunity to control rates to optimum levels to the root zone. Providing nutrients through the irrigation system enables more flexibility in a fertilizer program. Several types of irrigation systems are available for use in crop production. For any system used, approved backflow control valves and interlock devices are necessary to prevent accidental contamination of the water source due to irrigation system failure or shutdown.

SUMMARY

Plant tissue culture mainly comprises a set of in vitro techniques, methods and strategies that are part of the group of technologies called plant biotechnology. Tissue culture has been exploited not only to create genetic variability from which crop plants can be improved but also to improve the state of health of the planted material and to increase the number of desirable germ plasms available to the plant breeder through a shorter duration in cost effective manner. Tissue-culture protocols are available for most crop species, although continued optimization is still required for many crops, especially cereals and woody plants. Tissue culture techniques, in combination with molecular techniques, have been successfully used to incorporate specific traits through gene transfer. In vitro techniques for the culture of protoplasts, anthers, microspores, ovules and embryos have been used to create new genetic variation in the breeding lines, often via haploid production. Cell culture has also produced somaclonal and gametoclonal variants with crop-improvement potential. The culture of single cells and meristems can be effectively used to eradicate pathogens from planting material and thereby dramatically improve the yield of established cultivars. Large-scale  micropropagation laboratories are providing millions of plants for the commercial ornamental market and the agricultural, clonally-propagated crop market. With selected laboratory material typically taking one or two decades to reach the commercial market through plant breeding, this technology can be expected to have an ever increasing impact on crop improvement as we approach for the need of the hour .

SUMMARY

Vegetables play a pivotal role in food and nutritional security of the ever increasing population of our country. The vegetarian society largely depends on vegetables for the want of their nutritional requirements. Vegetables are exhaustive crop with an exceedingly high turnover of plant nutrients, Thus , nutrient element required for optimum growth and development of vegetables should supplied to soil and plants in right time and in a balanced and integrated mode. Neither the chemical fertilizers are alone nor the organic sources exclusively able to sustain the soil fertility/productivity. The national average productivity of different vegetable crops of our country at present is much below the potential productivity. It may be increased up to 2-3 times more by adoption of appropriate nutrient management practices. The majority of our Indian soils are deficient in about 7-8 macro and micronutrients which leads lower productivity. Integrated nutrient management (IPNM) is one of the recent methods of supplying nutrients to the plants by organic as well as inorganic means together to fulfill the nutrient requirements. Organic manures are the key characteristics including the long term fertility of soil by maintaining organic matter levels, fastening soil biological intervention, nitrogen fixation as well as effective recycling of organic materials including crop residues and live stock wastes and weed. Micro - organisms play an important role in various chemical transformations in soil and thus, influence the availability of major nutrient like N, P, K. and S to the plant.

SUMMARY

To meet the food requirement of spirally growing population we need to produce more crops per unit area of land. Soil is the raw material for land and is the outer covering of earth surface. It is a very important resource and gift of nature for the substrate where plant can grow. Agriculture is the backbone of our country, and agriculture mainly dependent on soil quality. The success management of soil quality depends on the mechanistic approach, how soil responds to agricultural use and practices over times. As soil degradation grows day by day there is a big challenge against agriculture to sustain. Now days the main cause for soil degradation is non-planed use of land resources. This is the time when we think about this big challenge and face it for the future generation which we need to manage the soil quality for self sustainability. Because adaptation of appropriate soil management scientific methodologies and land use planning could replenish the degraded soil properties for sustainable agriculture which is need of the hour.

SUMMARY

The natural drainage systems are severely affected by the development processes and thus increased in waterlogged and salt affected areas. In major and medium irrigation projects due to inadequate designs coupled with poor management practices has raised groundwater table and in turn sizeable command areas are being affected both by water logging and soil salinization, Water logging and salt problem have been experienced in irrigation projects all over the country. Both adversely affect the growth and the yield of the crops. An area with water table within 2 m from the land surface is called as water logged area. It is potential to water logging if water table is between 2-3 m from the land surface. It has been estimated that around 16.71 million hectare land is affected by salt and waterlogging in India. The drainage is the remedy to these problems for sustainable agriculture.

            Drainage is defined as the natural or artificial removal of surplus ground- and surface water and dissolved salt from the land in order to enhance agriculture production. In the case of natural drainage the excess waters flows from the fields to lakes, swamps, streams and rivers. However, in an artificial system surplus ground or surface water is removed by means of sub surface or surface conduits. Improved drainage create a healthier environment for plant growth, It conserve soil and water; and provide drier field conditions for ease in farm operations for the crop production. Agricultural drainage is must to realize the full benefit of irrigation.

SUMMARY

Seed quality comprises the sum of all properties or characteristics, which determine the potential level of the seed or seed lot performance and crop establishment. Once the seed is sown many factors (biotic, abiotic etc.,) influence its survival and potential. Seed priming is one of the short–term and most programmatic approaches followed to improve the quality of seed so as to exhibit maximum possible potential even under adverse conditions. Seed priming is a method that well fit in to the one or more principles of sustainability, as it is practiced as a low-cost, low-risk interventions that increase and stabilize yields to have a large and direct impact on the livelihoods of farmers. Various priming methods viz., hydro priming, halo priming, matrix priming, bio priming are in practice for advancement in seed germination, better crop growth and yield. The adoption of seed priming as a successful technology is widely practiced across the Globe for various benefits at farm level. On-farm seed programme is one such   successful programmes adopted under UK aid across 11 countries towards sustainable agriculture campaign.

SUMMARY

Conventional agriculture has been contributing significantly to several modern day environmental problems like global climate change, soil degradation, water pollution, biodiversity loss etc. directly or indirectly. Organic agriculture has been identified as one of the eco-friendly agriculture techniques and is being promoted worldwide to meet the increasing demand for organic products and conserve the natural eco-systems. It helps mitigating climate change through reduced emission of green house gases (GHGs), greater C sequestration and less use of fossil fuel. Besides, it has been found helpful to reduce export of harmful agro-chemicals to water bodies, biodiversity conservation, restoring soil health etc. Organic agriculture can help to meet the objectives of sustainable and eco-friendly agriculture.

SUMMARY

At present, Indian agriculture faces a severe challenge for the future in view of growing demand for food for meeting the needs of nation’s ever growing population. At the same time, resources are gradually shrinking and the productivity of some resources is already being utilized threatening the sustainability and leading to environmental degradation which necessitates judicious and sustainable management of natural resources, particularly soil and water. Of 142 m ha arable land, nearly 96 m ha (67%) is devoted to rainfed farming, which contributes about 44 % of the total production. Overexploitation of water resources, unequal access to water and adverse impacts on ecosystem services are among the major issues impacting sustainable use of water resources. Crop production in rainfed areas is generally affected by chronic drought, ephemeral drought, and apparent drought. In order to increase production, farmers have two options, either to use extensive systems (horigental) or intensive systems (vertical). There is a meager scope for extensive system in India and the remaining intensive system is the only option for the farmers as well as policy makers. Hence, optimizing soil water management is crucial to enhancing agronomic productivity and meeting the food needs of the growing population with rising standards of living under rainfed area.

SUMMARY

The primary requirement for sustainable agriculture is the maintenance of a satisfactory balance of water, air and salt in the root zone encouraging for plant growth. This balance can be achieved by sufficient drainage. About 22% of the World's irrigated area is affected by waterlogging and salinity. Vertical drainage by pumping can control the increase of ground water table in those areas where the ground water is of good quality. Horizontal sub-surface drainage in which the saline ground water is drained away through pipes and drains, is the other regularly used anti waterlogging methods. In bio-drainage system, the characteristic of the trees to transpire water is used to control the increase of ground water table. It is an alternative drainage method, which would be most economical and environmental congenial. But there are worries and doubts on the long-term sustainability of biodrainage. This chapter describes various aspects of biodrainage.

SUMMARY

Sustainable agricultural development can only be possible, when all agricultural inputs used judicially. Soil management practices, like nutrient management, time schedule of fertilizer application, irrigation management etc. are should be manage in such away that resulted in best remuneration and sustain overall soil health. More over that, soil physical properties like, tilth, aeration and drainage are also play important role in soil productivity, so tillage operation should be carry out at proper  level of soil moisture condition to maintain good soil tilth which result in better soil environment for high crop yield. The most important factor in sustainable soil management for agricultural development is nutrient management and it's only possible through integration. So nutrient management through integrated approaches, like use of chemical fertilizer is decreases by integrating with organic manures, biofertilizer, green manure, neem cake, caster cake etc which resulted in sustainable crop production and good soil health on long-term basis.

SUMMARY

Fly ash, a waste product generated by coal based thermal power plants. The annual production of fly ash in the country has increased from 40 million tones in 1994 to 110 million tones in 2004 and it is expected that by 2012 the annual production of fly would reach the mark of 170 million tones. Owing to its physico-chemical characteristics, it has a vast potential for use in agriculture, forestry and wasteland reclamation. Application of fly ash into soil has been reported to increase the water holding capacity, hydraulic conductivity, porosity and decrease bulk density, modulus of rupture and surface encrustation. The studies conducted by various organizations on fly ash use in different crops have revealed significant increase in the crop yields such as wheat, maize, paddy, soybean, sunflower and vegetables like brinjal, tomato, potato, cabbage. Application of fly ash has been found to increase the level of heavy metals  viz., Co, Pb, Mo, As and Se as well as the activity of radio-nuclides i.e., ⁴⁰K, ²²⁶Ra, ²²⁸Ac  in the soil- plant system; however, the levels of all these heavy metals and radio-nuclides were found to be well below the permissible limits.

SUMMARY

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

SUMMARY

Green manuring is the practice of growing lush plants on the site into which organic matter directly incorporate to the soil while it is still fresh. Green manures, often known as cover crops, are plants which are grown to improve the structure and nutrient content of the soil. They are a cheap alternative to artificial fertilizers and an eco-friendly input for organic farming and can be used to complement animal manures. Growing a green manure is not the same as simply growing a legume crop, such as beans, in a rotation. Green manures are usually dug into the soil when the plants are still young, before they produce any crop and often before they flower. They are grown for their green leafy material which is high in nutrients and protects the soil. It is basically a holistic management system, which promotes and improves the health of the agro-ecosystem related to biodiversity, nutrient biocycles, soil microbial and biochemical activities.

SUMMARY

Agriculture is the largest user of fresh water for irrigation to fulfill the increasing demand of food, feed, fiber, fuel and other need of ever-increasing population. Water availability to agriculture is characterized by declining in share with time, over exploitation, improper mismanagement, deterioration in quality as well as environment. This could be addressed using sustainable management of irrigation water. As per the Brundtland Commission report of United Nations, sustainable development is the development that meets the needs of the present without compromising the ability of future generations to meet their own needs. Sustainable water management aims to improve water productivity, availability and quality over an area.  Improved and efficient irrigation techniques and practices enhance water application efficiencies, and thereby reduction in associated damage to environment, which include water logging, soil salinity, runoff and leaching of nutrients and other chemicals polluting water sources, and over exploitation of ground water. Micro irrigation systems have been characterized to be the most efficient irrigation techniques. These have efficiencies even more than 90%, doubled water productivity with improved quality of produce, reduced runoff and leaching of nutrients and chemicals to water sources. Application of fertilizer through drip irrigation called fertigation could be adopted for efficient use and saving of fertilizer.  Fertilizer savings of 20-60% and 8-41% increase in yields of horticulture and vegetable crops has been realized through fertigation.

Materials Required

Record book

Procedure

    1.    Follow the instructions given by the teacher and the factory representative.
    2.    Listen carefully to the explanations of the factory representative
    3.    Observe the functioning of various equipments
    4.    Ask queries wherever not understood properly.
    5.    Note down the observations in your record book  

Observations

    1.    Name and address of the factory or processing unit
    2.    Size of the Unit (Large, Small, Cottage, Home)
    3.    FPO Licence No.    
    4.    List of products manufactured    
    5.    Height of the processing plant    
    6.    Information regarding raw material store, finished product storage    
    7.    List of equipments installed in the factory
    8.    Water supply system     
    9.    Waste disposal system    
    10.    Hygiene in the surroundings    
    11.    Any other

Materials Required

Sensory scoring card, products, pen/ pencil for coding, plain water.

Procedure

    1.    Assign codes to the samples i.e. a, b, c, …… or 1, 2, 3, ….. etc.
    2.    Keep the coded samples randomly (eg. c, f, a, b, d, e) in a row for evaluation
    3.    Start the evaluation of samples one by one. 
    4.    Evaluator should rank the samples on the basis of intensity of a single sensory attribute according to his / her preference.
    5.    Compute the means on the basis of the evaluation of different evaluators (replications).
    6.    List the samples in increasing or decreasing order of preference.