eChapters

INTRODUCTION

The purpose of writing this chapter is to develop a comprehensive understanding of the role of functions of water in plant growth and development. Water is essential to life on earth as the living organisms contain 80-90 per cent water. A typical crop or grassland will transpire approximately 500 ml of water per 10 g of dry matter produced. Water has a tremendous effect on the environment near the earth, which on regional basis we call ‘climate’. Ecological importance of water is due to its physiological importance because water affects the plant growth through physiological processes. All metabolic activities in the plant cell or tissue depend on water status of the plant. For example, in a maturing seed, respiration rate is highest as it moves towards maturation stage, water content decreases and hence rate of respiration slow down. At the harvesting stage, when the water content is 10-20%, the respiration rates become negligible. Now in a stored seed if the water content will be high it will result into higher respiration, thus release energy, which will increase the temperature and will finally destroy the seed.

INTRODUCTION

Among plant nutrients, our soils are particularly low in nitrogen and therefore, require is high doses of nitrogenous fertilizers for getting optimum productivity. Added to this is the problem of poor efficiency of nitrogeneous fertilizers which under normal conditions is only 40 – 50 %, still less for rice ranging from 25 – 35 %, and the residual effect for the succeeding crops is never more than 10 %. The rest of the applied nitrogen is lost either through volatilization, leaching or denitrification (Kashyap, 1978). The high cost of nitrogenous fertilizers and their poor utilization efficiency very much add to the high cost of cultivation. Hence, the need of the hour is to decrease our dependence on chemical fertilizers and increase the efficiency of the fertilizer thus used. The increase in nitrogen efficiency in crop plants can be achieved by reducing denitrification with the use of nitrification inhibitors, reducing the soil compaction, improving drainage conditions, use of soil improving crops, and adopting carefully the irrigation procedures (Carlson, 1980). No doubt exploration of this possibility is a big task, nevertheless, the understanding of physiology and biochemistry of nitrogen nutrition at molecular level is obligatory and is likely to add insight to achieve the hard task goal.

INTRODUCTION

The metabolism of carbohydrates is vital for plant growth and development, and to the yield of major plant products such as starch and sucrose. Starch, sucrose and fructose are the three important carbohydrates which are utilized in most of the higher plants. The majority of sucrose that is synthesized in higher plants during photosynthesis is exported to non-photosynthetic cells (ap Rees, 1992). Starch serves as an important storage for carbohydrate residues. The degradation (breakdown) of starch ensures retaining of important life processes in plants when there is carbon shortage, for instance, during night period in leaves or in resting organs such as potato tubers.

Phospholipids are the most abundant lipids of biological membranes. They serve primarily as structural components of membranes and are never stored in large amounts. As the name of phospholipid implies, this group of lipids contains phosphorus in the form of phosphoric acid groups. The major phospholipids found in membranes are the phosphoglycerides (phosphatides) (Fig.1). Which have two fatty acid molecules esterified

INTRODUCTION

Iron in the terrain’s crust is more oxidized now than it was when life evolved. It has been hypothesized that dissolved ferrous iron could have been a convenient oxygen acceptor and that deposition of oxidized iron in sediments must have taken place before oxygen could have entered the atmosphere in significant quantities. Obviously, during early evolution on this planet, the essential elements are present only in reduced form. Today a number of elements are present only in a highly oxidized form and considerable energy must be expanded to reduce them to a form similar to that on early earth which plants can utilize.

Iron represents essential elements which are usually available in oxidized form but must be reduced, often using metabolic energy, before they can be utilized. For the first time, Gris (1844) observed yellowing of grapevine leaves in absence of iron in the nutrient solution in which these plants were growing. Later, iron was reported to be essential for diverse group of plants. Due to a great variation in iron requirement by different plant species, it is difficult to decide whether iron is a macro or micronutrient.

Introduction

Salinity is a significant environmental stress for crop plants it account for about 70% of the losses in the crop yield. It adversely affects seed germination, seedling growth and different metabolic activities in plants (Begum et al. 1997). It reduces DNA, RNA and protein synthesis and differentially influences the activities of the hydrolytic enzymes (Kumar et al. 1996).

Plants are classified as glycophytes or halophytes according to their capacity to grow on high salt medium. Most crop plants are glycophytes and cannot tolerate salt stress. High salt concentration decreases the osmotic potential of soil solution creating a water stress in plants. Secondly they cause severe ion toxicity since Na+ is not readily sequestered into vacuoles as in halophytes.

The widespread nature of saline soils compounded by the geographical distribution of man’s population and agricultural practices are largely succeeded in increasing salinization in arid and semi-arid lands. Most of the crops are sensitive to even low concentration of NaCl.

Introduction

Chickpea, the world’s third most important food legume, is currently grown on about 10 m ha worldwide, with 95% cultivation in the developing countries. India is the largest producer of chickpea in the world. Chickpea is grown under rainfed conditions in winter in India subjecting it to abiotic stresses. Consequently it experiences water deficit stress at one or the other growth stage(s) which affects the crop productivity.  Among the abiotic stresses to which chickpea is subjected to drought stands to be the number one problem in major chickpea growing regions because the crop is grown on residual moisture and the crop is eventually exposed to terminal drought (Johansen et al., 1994). A distinctive variation exists between the plant in sensitivity to water stress. Chickpea is considered relatively more tolerant, possibly because of its deeper root system is and its smaller leaves and canopy. Several adaptive mechanisms are evoked by plants in response to water stress (Chaves et al., 2003). These traits enable chickpea to ensure its survival in different environmental conditions.

Introduction

It is an established fact that water in terms of direct deficit (drought) as well as water surfeits (flooding and water logging) and poor irrigation water quality (salinity)- are major constraints on the use of solar energy for food, feed and fiber production in almost all the agricultural regions of the world. The various biophysical, physiological, genetic, agronomic and ecological aspects of plant water relations have been thoroughly reviewed in recent years with the objective aimed at water availability as a constraint on crop production. This review will attempt a limited synthesis of these aspects, drawing mainly from research on drought resistance in grain crops, rice in particular, and emphasizing the progress- theoretical and practical- that could result from collaboration between physiologists, geneticists and plant breeders. A central theme will be research and development aimed at fitting crop plants to fluctuating drought prone environments. It is noteworthy that shortage of water restricts crop productivity all over the world-not just in those areas classified as arid or semiarid, but in any area in which the evaporative demand exceeds rainfall during the growing season. As such, the interaction between genotype and environment in situations has an important bearing affecting the physiology and also biochemistry at cellular level vis-à-vis the crop phenology. Cultivars with better ability to access soil water and improved water use efficiency could increase yields in an economic and environmentally sustainable way.

Introduction

The study of abiotic stresses in plants has advanced significantly in recent years. However, the majority of experiments testing the response of plants to changes in environmental conditions have focused on a single stress treatment applied to plants under controlled conditions. In contrast, in the field, a number of different stresses can occur simultaneously. These may include conditions such as high irradiance, low water availability, extreme temperature, or high salinity and may alter plant metabolism in a novel manner that may be different from that caused by each of the different stresses applied individually. The response of plants to abiotic stresses in the field may therefore be very different from that tested in the laboratory (Cushman and Bohnert, 2000).

Introduction

The phytohormone abascisic acid (ABA) was discovered in connection to studies related to shedding of fruits and leaves, also called abscission, and the dormancy of buds. It was first identified and characterized by Frederick Addicott and his associates in 1963 while studying the compounds responsible for the abscission of cotton fruits. Inhibition of growth and maintenance of the dormancy of buds are the most important visible effects of ABA. The concentration of ABA does not remain constant as its concentration decreases in the buds significantly after sprouting and rises during seed and fruit production. Its concentration in dormant seeds is very high and considered as an efficient inhibitor of germination. The role ABA plays during the abscission of fruits and leaves is not clearly understood as its effect is very clear in case of fruit abscission where as it is not very clear on the abscission of leaves. However, the regulatory effect of ABA on the water balance is established in plants. It also induces stomatal closure to inhibit further loss of water. Being a growth inhibitor, ABA also reverses the effect of growth-stimulating hormones like auxin, gibberellins and cytokinin in different tissues of a plant. One of the main goals of phytohormonal ecology is to study the interactions between biotic and abiotic stress at hierarchical levels of biological organization.

Introduction

There are a number of chemicals in the environment, some natural other man-made, some toxic other non-toxic. These are toxic chemicals, whether natural or man-made, which has created problems for the environment and biota on the earth. Of these toxic chemicals, heavy metals are extremely hazardous. Metals are present naturally in the earth’s crust at various levels. However, increasingly widespread heavy metal pollution resulting from anthropogenic activities has caused serious environmental problems and is posing threat to both wild life and human population (Nriagu and Pacyna, 1988). Natural sources include weathering of mineral and metal ions from rocks, displacement of certain contaminants from groundwater or subsurface layers of soil, atmospheric deposition from volcanic activity, and transport of dust. The anthropogenic sources include deposition of industrial effluents, application of sewage sludge, deposition of air-borne industrial wastes, military operations, mining, landfill operations, use of agricultural chemicals, gas exhausts and energy and fuel production (McIntyre, 2003).

Introduction

The term ‘lectin’ was coined by William C. Boyd in 1954 for their property of selectivity (Latin ‘legere’, to pick up or choose). In 1888 H. Stillmark of Russia gave the first description of what we now know as lectin. While investigating the toxic effects on blood of extracts of the castor bean (Ricinus communis), Stillmark observed that the red blood cells were being agglutinated by a protein and gave it the name ‘ricin’. Shortly afterward ‘arbin’ was extracted from Arbus precatorius. Because they were first isolated from plants, lectins came to be known as phytohaemaglutinin. Now it has become clear that lectins are present not only in plants but also in some bacteria, vertebrates and invertebrates. However, lectins are most widely distributed in plants, reported in almost 1000 plant species.

Plant lectins are a very heterogeneous group of proteins; as far as their occurrence within the plant kingdom and distribution over tissues are concerned. They show high degree of heterogeneity with respect to biochemical and physiological roles, because of their widely different carbohydrate binding specificities (Etzler 1986; Rüdiger 1988; Goldstein and Hayes, 1978). Besides the fact that they all exhibit carbohydrate binding activity, most of the plant lectins behave as typical storage proteins (Peumans and Van Damme, 1995 b).

Introduction

Phenolic compounds have been shown to be of importance in regulation of plant growth, development and metabolism, therefore now they are not considered as passive by products of any catabolic or anabolic processes. Salicylic acid is one of them and it is a naturally occurring phenolic which has received much attention due to its association with economically important plant responses to disease and other stresses (Raskin, 1992; Borsani et al., 2001; Clarke et al., 2004). Centuries before medical scientists had identified numerous therapeutic effects of salicylates. Leaves and barks of willow tree were used by women as a pain reliever during child birth in 4th century B.C. It also cured aches and fevers. Due to a number of curative properties of willow bark, in 1828 Jahann Buchner, a scientist from Munich had isolated a small amount of silicin - a salicylic alcohol glucoside, the major salicylate in willow bark. In 1838, Rafaela Piria had given the name salicylic acid (SA), from the Latin salix, a willow tree. Further during 19th century SA and other salicylates, mainly methyl esters and glucosides easily convert to SA, isolated from a number of plants. Salicylic acid has an aromatic ring which bears a hydroxyl group or its functional derivative (Fig. 1).

Introduction

The respiratory electron transport pathway of plant mitochondria comprises the cytochrome (Cyt) pathway and alternative pathway (McDonald et al., 2002). Both the cyt and the alternative respiratory pathways start at protein complex I when NADH is being oxidized. One H+ (proton) is transported by the complex I to inner membrane space, whereas two electrons are transported within the inner membrane by the ubiquinone, which at its reduced state (Qr) transfers these electrons either to complex III or to the Alternative oxidase (AOX). Ubiquinone is the point in which reactions can proceed in different ways, and it is called the branch point. Cyt respiratory pathway is present in all living organisms. It proceeds while complex III pulls out a proton from the mitochondrial matrix to the inter membrane space. The electrons are received by cytochrome c which spreads up to the outer side of the inner membrane towards protein complex IV, which then pulls out another proton similar to complexes I and III, and transports the electrons back to inner domain of the mitochondria. As a result, oxygen is consumed with a proton and the two electrons to produce water (Fig 1).

Introduction

Seed, the basic input of crop production technology, is exposed to various stress factors right from its formation to the completion of its germination. Even after germination, the stressed seeds may fail to emerge into a healthy plant and thus, the subsequent seed formation is also affected both quantitatively and qualitatively.

The stress factors may be abiotic, biotic or mesobiotic. Environmental factors such as climatic parameters, nutritional deficiencies, soil factors and conditions of storage are the examples of abiotic stress factors. Insects, fungi, bacteria, nematodes and other plant parasites constitute biotic stress factors whereas viruses, viroids and virusoids and similar agencies are the examples of mesobiotics factors that bring about stress over the seed. Apart from these conspicuous causes of stress, there are certain other factors also, which may affect the influence of stress over the total performance of the seed. For example, the crop improvement efforts bring about changes in seeds quality that can have considerable effects on the vulnerability of the seed to invasion by various biotic factors.

Introduction

The life cycle of a plant passes through biotic and abiotic stresses and plants are being attacked at different stages of growth by a number of disease causing organisms. These organism including bacteria, fungi, viruses, and nematodes attacks plants. These pathogens caused large crop losses and probably since the beginning of agriculture have contributed to human hunger and malnutrition. The control of plant diseases is thus of fundamental importance and is a major objective of plant breeding and pathology programme and agriculture chemical industry. Plants resists pathogens attack both with preformed defenses such as antimicrobial secondary compounds and by inducing defense responses (Hammond and Jones, 2000, Heath, 2000). Inducible defenses can be activated upon recognition of general elicitor such as bacterial flagellin and even host cell fragments released by pathogens damage (Gomez and Boller, 2000, Hammond and Jones, 2000). However, plants also involved sophisticated recognition systems to detect proteins produced during infection by specific races of pathogens (Martin et al., 2003).

Introduction

Plants are responsive to the applied Non-scheduled caste, which constitute most of the vital macromolecules and metabolites related to its vegetative and reproductive cycle. The applied fertilizer N enhances crop productivity per unit area, as agricultural soil deficient in N worldwide. The fertilizer application is thus considered essential to meet the requirement of the burgeoning population, particularly in the developing countries (Abrol et al., 1999; Chanda and Sati, 2005). The farmers practicize heavy dressing of N-fertilizers in crop fields for high productivity, which has resulted into world including Indian sub-continent and China have resulted into the excessive use of N-fertilizers intending to maximize crop yield. Decrease in the organic fertilizer input and depletion of micronutrients in intensive cultivation zones have caused a decline or stagnation in the crop productivity, which  has been attempted with a further loading of soluble chemical fertilizers (Maleshwar, 2003; Kumar and Yadav, 2003; Anonymous, 2004; Chanda and Sati, 2005; Abdin et al., 2006).

The mites belong to the Class - ‘Arachnida’, Order - ‘Acarina’. Most of the phytopathogenic mites are classified under the two Families - Tetranychidae and Eriophyidae.

The mites belonging to the Family - Tetranychidae are generally known as Tetranychids. They are very minute, and less than 100 microns in size. The body is non-segmented and the head, thorax and abdomen are  not distinct, but rather fused together. The life cycle of a tetranychid mite consists of an egg stage, three nymphal stages viz., protonymph, deutonymph and tritonymph and an adult stage. In the protonymphal stage, which is also called the larval stage, the mites have only 3 pairs of legs. In all the other nymphal stages and the adult stage they have 4 pairs of legs. The mites are roundish or oval in shape, with biting and chewing, as well as piercing and sucking type of mouthparts (Fig.190).

All control measures are directed to bring down the nematode population low enough to raise the crop successfully and profitably. The choice of control measures to be taken depends upon the nematode species to be tackled and the crops involved.

1. Cultural methods 
The objective of these methods is to adopt suitable land management practices, so as to bring down the nematode population in the field to a low level, which may not cause economic injury to the crop or to keep the field free from parasitic nematodes by adopting suitable preventive measures. Besides causing direct damage to the crops, several nematode species are known to transmit many fungal, bacterial and viral pathogens, which aggravate the extent of damage caused to the crops. Many of these pathogens gain access to the host plants only through mechanical injury caused by the nematodes. By controlling the nematode parasites, the incidence of diseases caused by such phytopathogens can also be avoided to a large extent. Cultural methods, though may not give spectacular results within a short span of time of a single season or year, as in the case of chemical control measures, if followed over a number of years is sure to give encouraging results. Cultural methods include crop rotation, fallowing, ploughing, flooding, trap cropping, use of organic amendments, selection of seeds and seed materials, use of resistant and tolerant varieties etc.

‘Nematodes’, otherwise known as ‘eel worms’, ‘thread worms’, ‘round worms’, and ‘nemas’ are unsegmented, smooth-bodied, mostly minute, worm-like metazoan organisms. They are classified under the Phylum - Nematoda. The term ‘Nematode’ has been derived from the two Greek words ‘Nema’ = thread and ‘Eidos’ = form, which means thread-like organisms. At present, the nematodes, which are exclusively parasitic on man and livestock are studied under ‘Helminthology’ or ‘Parasitology’, while the plant parasitic or phytonematodes, as well as free-living nematodes are studied under ‘Nematology’, a branch of biological science that exclusively deals with nematodes. Cobb coined the term Nematology in about 1920.

Nematodes are ubiquitous and are found every where life can sustain. They can survive in any type of environment and are found from the arctics to the tropics and from the oceans to the top of hills. Though basically aquatic, nematodes have adopted terrestrial habits. They are mostly found in the soil around the rhizosphere of roots of plants. They constitute 80 - 90 per cent of all multicellular organisms and the number of nematodes may vary from 1.8 - 120.0 million per sq. m. of soil according to Kevan (1965). At present the number of established species is about 15,000, but there may be several thousands more.

For effective and economic control of pests, besides selection of appropriate plant protection chemicals, application of the chemicals at the most vulnerable growth stage of the pests and use of chemicals at the correct dosages, selection of proper plant protection appliances to carry out the operation is also of vital importance so as to ensure uniform application of the chemicals.
 
Plant protection chemicals are mostly used as sprays and dusts using sprayers and dusters respectively. However, in most of the cases spraying is preferred to dusting. Different types of sprayers and dusters are being used for these operations and in both, there are manually operated as well as power operated equipments and in sprayers there are both hydraulic and pneumatic types of sprayers.

The nature of the pesticide formulations to be used and the purpose for which they are used also determine the type of equipment to be used. Dusters are used for dusting insecticidal dust formulations; sprayers are used for spraying insecticidal liquid formulations; granular applicators are used to apply granular formulations; fumigators are used to apply fumigants to fumigate godowns, warehouses, rat holes etc.; soil injectors are used to inject pesticides at a particular depth of soil under pressure; flame throwers are used to throw flames at specified targets.

The chemicals, which can destroy pests or prevent their occurrence by their chemical action, are known as ‘pesticides’. Pesticides include ‘insecticides’, ‘acaricides’, ‘nematicides’, ‘rodenticides’, ‘molluscicides’ etc., which are used to destroy insect pests, mites, nematodes, rodents, slugs and snails respectively.

Pesticides have been used even before the time when man never knew how to read or write. Even before 200 BC, several substances were known to control pests. Sulfur, arsenic poisons, fluorine poisons, as well as some plant extracts and oils were used to control pests. However, these substances could destroy only a few specific pests.

Advances in the invention of pesticides

The invention of many of the present day pesticides started only after 1867. Paris green, a synthetic chemical was the first pesticide used to control the Colorado beetles of potato.  Up to  1939,  only  a few inorganic  chemical compounds and plant poisons were used as pesticides. Only after the Second World War much advances were made in chemical research. After the invention of DDT in 1939, a revolution had started in the field of pest control.  Following the introduction of DDT,  several other pesticides were identified and introduced for pest control. In 1941, BHC was invented by the British and French scientists. During the same period, organophosphorus pesticides were invented by the German scientists and parathion, malathion, demeton etc. were introduced.

Insect pest control includes all measures adopted to make the life of insects hard and ultimately to destroy them or to prevent their multiplication and spread. Such measures can be taken up before the appearance of the pests or after occurrence of the pests. To achieve this purpose, it is quite necessary to know the factors which favor the occurrence of the pests and acquire enough knowledge about the nature and life cycle of the pests, the vulnerable growth stage at which they can be effectively destroyed and appropriate measures of control. Control measures may be either preventive or direct.
Insect pest control is broadly classified under two different heads viz., natural control and applied control.

I. Natural control
    1.    Climatic conditions. Temperature, rainfall, sunshine etc.
    2.    Physical or topographic factors. Mountains, oceans, rivers, lakes, forests, deserts etc.
    3.    Natural enemies. Parasitoids, predators including insects, birds, mammals, reptiles etc.
    4.    Disease causing organisms or parasites. Entomophagous fungi, bacteria, viruses and other microorganisms.

Collection and preservation of insect specimens is the best way to study their morphology, habitat, distribution, host relationship and many other interesting features. Killing, mounting and arranging the insects in some particular sequence creates much more interest than merely studying museum specimens or looking at pictures. A collection of varied types of insects goes a long way in increasing the knowledge and understanding of the taxonomy of insects.

Not all insects are found in every season and in every place. Their presence mostly depend on the availability of the host, as well as the climatic conditions. Though many insects can be collected in any season, they  are  naturally  abundant  in  moist,  warm  weather,  especially  in the  spring and early summer. To get a good collection, insects have to be collected continuously in all the seasons of the year, from all plants and plant parts, from stored grains and food products. Several types of butterflies, moths, bees, wasps, beetles and flies can be collected from flowers, which they frequent to collect nectar. Many insects can be collected from leaves, stems, fruits, roots and such plant parts. Many insects are found in water and on water plants. Some are found in barks of trees or in decomposing organic matter. These insects have to be collected from different localities where they are found. Most of the insects are diurnal, while some of them are nocturnal. Some are attracted to light. So, a knowledge of the habits of insects is important in making a good collection. Sometimes better specimens may be obtained by collecting the immature stages and rearing them into adults wherever possible. Keeping records of pest collections may help Entomologists to forecast largescale pest occurrence.

Though many of the insect species are injurious to man, his crops and his livestock in different ways, not all the insects are injurious. Some insect species are beneficial to man in many ways.  A  few  are  productive insects and yield materials directly useful to man. Of these, the most important ones are the honeybees, which give honey and bee wax, the silkworms, which give silk and the lac insects, which give lac. Some other insects are useful to man indirectly in many ways.

productive insects

1. Honeybees (Apis species)
Order - Hymenoptera
Family - Apidae

Kinds of honeybees

There are five kinds of honeybees in India. They are :
Apis dorsata - the rock bee
Apis florea - the little bee
Apis indica - the Indian bee
Apis mellifera - the European bee
Melipona iridipennis - the dammer or stingless bee

One of the chief aspects of Entomology is the study of insects from the standpoint of their innumerable relations and activities affecting the interests of man. More than any other living organisms, insects have more intimate and complex relationship with man. It is well known that insects affect human interests both for good and bad. However, their injurious activities are of much greater concern to man than the beneficial aspects of their activities. Several insects are beneficial to man in several ways, both directly and indirectly and there are scores of other insects, which do not interfere with the interests of man in any way.

From the time man stepped into the domain of insects, a stifle has started between the insects and man. To meet his various demands for food, clothing, shelter and various other requirements, man cultivates various crops and raises many domesticated livestock. Unfortunately for man, insects also have started depending on these for their living. When the requirements for man and insects happen to be the same, a race is on for their survival and existence. Insects attack plants and livestock and cause extensive damage and economic loss. So, man considers such injurious insects as his enemy and to safeguard his interests tries to destroy them by various means. However, man’s supremacy and intelligence have not proved a match to the rapid propagation of insects and their various adaptations to withstand any hardship and adverse conditions. In the effort to gain an upper hand, it has not been possible for man to destroy the unwanted insects completely and the struggle is going on as a never-ending ordeal.

The classification of living organisms has passed through several changes and has reached the present stage with the gradual assimilation of more and more knowledge about them. The classification is mainly based on the anatomy, life style, habits, habitats, metamorphosis and such other characteristics. Though the concept of classification of living organisms was perhaps started by Aristotle between 384 - 322 BC, it was the Swedish scientist Carl Linnaeus (1758) who presented the classification, which was acceptable to most of the Taxonomists. He propounded the binomial nomenclature of naming each and every organism of animal and plant origin with a generic and species name. In his classification, he was consistent in using Latin names for all the organisms. He was the originator of a regular system of classification in which he recognized larger and smaller categories, the larger ones comprising of a varying number of smaller ones. Because of his contribution in the field of Taxonomy, he is rightly called the ‘Father of nomenclature’. A.D.Imms later modified the system to some extent in 1961. However, Brauer (1885) laid the foundation of the modern system of classification of insects. He was the first one to emphasize the fundamental division into primitive wingless insects, the ‘Apterygota’ and the winged or secondarily wingless insects, the ‘Pterygota’. The latest code on classification and nomenclature was approved and published by the ‘International Trust for Zoological Nomenclature’, London in 1964.

Protection from natural enemies and adverse environmental and climatic conditions is vital to safeguard insects and to this effect, insects possess a great variety of protective structures and mechanisms without which they cannot survive.

    i)    Food. Each insect species has certain nutritional requirements for the completion of life cycle. If the required food for any particular species gets reduced in a particular locality, that species will gradually disappear from that locality, though other environmental conditions may be favorable. Under normal conditions, there may be sufficient food for the insect to live on and continue its race. In the event of sudden increase in the population of an insect, the density of the population becomes too high to be supported by the food available in the area. Under such conditions, some individuals of the species either migrate to other suitable areas where enough food is available or else starve, if the species has limited power  of  dispersal  as  in  the  case  of  many  coccids.  According  to  the nutritional requirements insects are characterized as ‘omnivorous’ (feeding on different kinds of both plant and animal food), ‘carnivorous’ (feeding on animal food) and ‘herbivorous’ or ‘phytophagous’ (feeding on living plants). Those insects, which feed on many cultivated and wild species of plants, are termed ‘polyphagous’ (e-g) Locusts, grasshoppers, cutworms etc. If the feeding activities of a particular species of insect are confined only to plants of one botanical family, it is termed ‘oligophagous’ (e-g) cabbage butterfly - Pieris brassicae. When only a single species of plants constitute the food of a particular species of insect, it is termed ‘monophagous’ (e-g) Brinjal fruit borer.

Insects generally reproduce by laying eggs or ‘ova’. The initiation of growth inside an egg, which in most cases is preceded by fertilization, leads to a long series of changes, finally attaining the adult stage and in due course to sexual maturity and finally to reproduction of a new generation. This chain of events from the egg stage to death constitutes the ‘life history’ or ‘life cycle’ of an insect.

Eggs are laid singly or in batches of only a few or up to hundreds or  even thousands. Generally eggs are laid under conditions, where food is available for the feeding of the future young ones.  The eggs are generally smooth, elliptical or oval, but some have diverse shapes such as, disc-like, hemispherical, conical, globular, spindle and many other forms. The egg surface may also have a variety of textures. In some aquatic insects, the eggs are covered with a gelatinous secretion, which swells in water forming a jelly-like spawn. In mosquitoes, the lateral sides of the eggs are expanded, which serve as floats. Eggs vary in size, from microscopic to about 3.0 mm. in diameter and 5.0 - 6.0 mm. or even more in length.

The development of an insect is a continuous process, but on the basis of external manifestations, it is divided into definite stages. The stage within the egg is termed ‘embryonic development’, that after hatching ‘post-embryonic development’ and the changes of form during the post-embryonic development constitute ‘metamorphosis’.

Similar to animals of the higher order, insects also possess all important internal systems of organs necessary for the proper performance of the various vital functions. The most important of the systems are the alimentary or  digestive  system,  the  circulatory  system,  the  respiratory system, the reproductive system and the excretory system. The fundamental arrangement of the various organs is more or less similar in all insects and does not exhibit much remarkable variations as seen in the external morphological features. The dorsal blood vessel or heart runs along the median line immediately below the dorsal wall. The digestive system including the alimentary canal and its appendages lie in the middle, below the heart. The nervous chain lies below the alimentary canal and immediately  above  the  ventral  wall.   The  organs  connected  with  the reproductive system are found in the posterior region of the abdominal cavity on both sides of the alimentary canal.  Though these arrangements are characteristic of all Arthropods, including insects, they are quite different in the higher animals (Fig.23)

‘Integument’, the outer layer of insects consists of the ‘basement membrane’, ‘epidermis’ and the ‘cuticle’. One of the most important characteristics of insects is the presence of the rather hard, flexible chitinous exoskeleton or cuticle, which covers the entire body and provides support to the body. The exoskeleton of insects that is akin to the internal skeleton of vertebrates accounts for their size and shape. Movement is made possible by the division of the cuticle into separate plates or sclerites.  Primarily these  sclerites  are confined to segments and the sclerite of one segment is connected to the sclerite of the adjoining segment by means of an articulate called ‘suture’, a region in which the cuticle is very thin and flexible. The cuticle of each segment is divided into four primary sclerites viz., a dorsal tergum, two lateral pleura and a ventral sternum. The dermal glands present in the epidermal layer secrete the entire cuticle of the insect.

Like that of the body, the cuticular skeleton of the appendages is divided into tube-like segments connected to one another by articular membranes, thus creating a joint at each junction. Such joints enable the segments of the appendages, as well as those of the body to move freely.

In addition to the exoskeleton, an endoskeleton is also developed. This may be an infolding of the procuticle that produces inner projections or ‘apodemes’ equal to bones in vertebrates on which the muscles are inserted.

Insects came into existence in this world some 250 - 500 million years ago, while man appeared in this planet only about a million years ago and intruded into the domain of insects. From this time onwards, a rapport had started between the insects and man. Man considered insects obnoxious and not worth consideration in the early days. However, the real impact of insects on the activities of man became manifested to a greater extent only during the past few thousands of years. Gradually man began to understand the nature of insects and started looking at insects, both as his adversaries and as his beneficiaries. He started exploiting the useful insects for his own benefit and tried to destroy those, which are harmful to him.
 
There are numerous references in the ‘Ancient Epics’ and ‘Puranas’ such as, ‘Ramayana’, ‘Mahabharata’ etc. to show man’s acquaintance with insects even from very early days. Several references to insects are found in the ‘Holy Bible’ also. Ancient people of India were quite aware of insects, which provide honey, lac and silk. They were familiar with honeybees and gathering of honey and bee wax from hives. Honey was used in most of the religious rituals. Honey and bee wax were used in many Ayurvedic medicines against various diseases. The story of the lac palace constructed by the Cauravas to destroy the Pandavas by setting the wax palace on fire at night as narrated in Mahabharata is quite well known. The ancient Indians knew how to manufacture silk from silk thread produced by silkworms. Records show that an Indian king had sent some silken stuff to a Persian ruler even as early as in 3870 BC. References to insects such as, flies, beetles, bees, wasps, moths, ants etc. are found in old Sanskrit literature. The Ancient people also used some Mercury, Arsenic and Sulfur compounds for the control of some of the harmful insects. Numerous references to insects are found in the ‘Holy Bible’ also. King Solomon, the wise (971 BC), who ruled Israel had told his people to learn from the ways of ants, which are so active and orderly (‘Proverbs’, Chapter 6). He had mentioned as to how the ants gather and store food at the time of harvest, when food is available in plenty to be used in summer when food is scarce (‘Proverbs’, Chapter 30).

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Ananthanarayan, R. and Paniker, C.K.J. 2005. Textbook of Microbiology (VII Ed.) Orient Longman Pvt Ltd, Chennai-600 002. pp 1-657.
Asthana, R.K., Srivastava, A., Singh, A.P., Deepali, Singh, S.P., Nath, G., Srivastava, R. and Srivastava, B.S. 2006. Identification of an antimicrobial entity from the cyanobacterium Fischerella sp. isolated from bark of Azadirachta indica (Neem) tree. Journal of Applied Phycology. 18, Number-1, 33-39.
Ayehunie, S., Belay, A., Baba, T.W., and Ruprecht, R.M. 1998. Inhibition of HIV-1 replication by an aqueous extract of Spirulina platensis (Arthrospira platensis). J. Acquir. Immune. Defic. Syndr. Hum. Retrovirol. 18, 7-12.

The objective of the present investigation was to evaluate the antibacterial properties of cyanobacterial species viz., Anabaena variabilis, Anabaena fertilissima, Nostoc muscorum, Nostoc punctiforme, Nostoc linckia, Nostoc commune, Spirulina platensis., Westiellopsis prolifica and Hapalosiphon sp. against some pathogenic species including Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pnumoniae and Salmonella typhi. The following are the major findings of the study.

    •    Extracts prepared in methanol were found more active as compared to ethyl acetate, hexane and dichloromethane.
 
    •    Antibacterial activity of extracts varied with the test organisms. Maximum antibacterial activity was shown against Staphylococcus aureus followed by Escherichia coli, Pseudomonas aeruginosa and Salmonella typhi. Klebsiella pneumoniae was found to be least susceptible against all tested cyanobacterial extracts.

    •    Antibacterial activity was observed against both Gram-positive and a spectrum of Gram-negative bacteria by almost all the cyanobacterial species examined in the present study except Westiellopsis prolifica where activity was observed only against S. aureus, a Gram-positive bacterium.

Present work was aimed to determine the antibacterial activity and minimum inhibitory concentration (MIC) of active crude extracts of selected cyanobacterial species. Nine cyanobacterial strains viz. Anabaena variabilis, A. fertilissima, Nostoc muscorum, N. punctiforme, N. linckia, N. commune, Spirulina platensis, Westiellopsis prolifica and Hapalosiphon sp. belonging to family; Nostocaceae, Oscillatoriaceae and Stigonemataceae were selected from the herbarium of Indian Agricultural Research Institute, New Delhi, and maintained in BG-11 growth medium throughout the study in the laboratory.

In the present investigation, nine cyanobacterial species viz. Anabaena variabilis, Anabaena fertilissima, Nostoc muscorum, Nostoc punctiforme, Nostoc linckia, Nostoc commune, Spirulina platensis, Westiellopsis prolifica and Hapalosiphon sp. were tested for their activity pattern against some selected bacterial species.
 
Each cyanobacterial species was initially subjected to determine the early stationary phase of their life-cycle, which is believed to be the most appropriate period for the production of secondary metabolites by an organism. The growth curve for each cyanobacterial species was prepared by culturing them in BG-11 growth medium. Optical densities (OD) recorded at 650 nm were plotted against number of incubation days for each cyanobacterium. After 23-25 days of incubation period, each culture was harvested to obtain the biomass and spent medium, which were then subjected to process of extraction by using various solvents viz., Hexane, ethyl acetate, dichloromethane and methanol. The extracts and spent medium thus obtained were then investigated for antibacterial activity against five pathogenic bacteria including Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pnumoniae and Salmonella typhi.

Nine cyanobacterial strains viz., Anabaena variabilis, A. fertilissima, Nostoc muscorum, N. punctiforme, N. linckia, N. commune, Spirulina platensis, Westiellopsis prolifica and Hapalosiphon sp. were cultured in the laboratory. The growth curve for each culture was studied by growing them in Erlenmeyer flask using BG-11 growth medium. They were examined to determine the early stationary phases of their life-cycle, which are believed to be the most appropriate period for the production of secondary metabolites by an organism. After 23-25 days of incubation period, each culture was harvested and spent medium was collected by filtration of the biomass. Hexane, ethyl acetate, dichloromethane and methanol were used as the solvents for obtaining the extracts from biomass and spent medium of each culture which were then investigated against five pathogenic bacteria viz., Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Salmonella typhi. Antibacterial activity of different cyanobacterial sp. has been shown in various tables.

Culture Media and Reagents

The media used throughout the study were procured from Hi- Media Laboratories, Mumbai, India and the chemicals used were procured locally. Composition of each medium is as follows:

Cyanobacterial species

Cyanobacterial species viz., Anabaena variabilis, Anabaena fertilissima, Nostoc muscorum, N. punctiforme, N. linckia, N. commune, Spirulina platensis, Westiellopsis prolifica and Hapalosiphon sp. were obtained from National Center for Conservation and Utilization of Blue-green Algae, Indian Agricultural Research Institute, New Delhi. Cultures were maintained in BG-11 growth medium throughout the study in the laboratory.

Cyanobacteria have been identified as one of the most promising groups of organisms from which novel and biochemically active natural products are isolated. Cyanobacteria such as Microcystis, Anabaena, Nostoc and Oscillatoria produce a great variety of secondary metabolites. The only group comparable to cyanobacteria is actinomycetes, which has yielded a tremendous number of secondary metabolites. The rate of discovery from traditional microbial drug producer like actinomycetes, which is in the focus of pharmaceutical research for decades, is decreasing and it is the time to turn to cyanobacteria and exploit their potential. Recently, there has been an increasing interest in cyanobacteria as a potential source of new drugs (Glombitza and Koch, 1989; Schwartz et al., 1990). This is of paramount importance to fight increasingly resistant pathogens and newly emergent diseases (Hayashi et al., 1994).

Cyanobacteria are photosynthetic microorganisms that have flourished on earth for more than 3 billion years with some genera showing only minor morphological changes since that time (Hagmann and Juttner, 1996). The medicinal and nutrient qualities of cyanobacteria were first appreciated as early as 1500 BC, when Nostoc species were used to treat gout, fistula and several forms of cancer (Pietra, 1990; Bladon, 2002; Liu and Chen, 2003).

Some cyanobacteria (Blue-green algae) like Nostoc are known to work as one of the two coponenents (photosynthetic partner or phycoboint) of lichens. The second partner of lichen is a lichen fungus or mycobiont. The lichens have not been described as a therapeutic agent in Charak Samhita, the monumental work on materia medica prepared by great Acharya Charak and his group in India more than three thousand years ago. However, these have been used in folklore medicine in many countries of the world and have been regarded to bear antibacterial properties (Katiyar and Katiyar, 2009). They are found in tundra even, the treeless plain of the arctic regions of Russia, Siberia, marshy in summer and frozen hard in winter. It is common to see gunny bags full of lichens for sale in the Masala market near Kesa House, Express Canal Road, at Kanpur. They also comprise a part of meat masala (spices for meat). There are references that Raja (King) Todarmal studied algae in relation to purification of water.

However, the search for antibiotics began in the late 1800s, with the growing acceptance of the germ theory of diseases; a theory which linked bacteria and other microbes to the causation of a variety of ailments. As a result, scientists began to devote time searching for drugs that would kill these disease-causing bacteria.

Abstract

Grains in present context are food grains. The PFA Act includes cereals, millets, and pulses in food grains. At times, seeds of certain oilseeds like soybean are also referred to in the discussion of food grains. Grains have been cultivated for thousands of years. We have Grain Standards as established by the International Organization for Standardization (ISO), which are considered as International Standards. Another source is Codex Alimentarius Commission (Codex) under the aegis of FAO (UN), which operates a Committee to formulate standards that are referred to as Codex Standards. Many countries have a National Standards Institution, which develops National Standards for their main grain crops and other commodities and issues specifications along with methods of testing and analysis. Several countries, which are in developing status, adopt or modify international standards into their national system. The Grain Standards have been evolved and established for a variety of purposes but primarily to grade produce in agricultural marketing largely to facilitate the movement of grain, provide both sellers and buyers with guidelines to support financial transactions, and ensure that the produce will meet up with end-use requirements, or, increasingly to protect the consumers.

Abstract

A survey of various wheat milling units (atta chakki) available around Indian Agricultural Research Institute, New Delhi was conducted to study the performance of these. The mills of various sizes (12", 16", 18", 20", 24" and 30" stone disc diameter) with horsepower ranging between 2 to 20 are in operation. Both horizontal and vertical disc types of mills are in use. The capacity of these units ranges between 10 kg/h to 200 kg/h. The stationary sieve, hand sieve, pedestal/exhaust fan are used for cleaning. The average wheat cleaning cost is Rs. 200 per ton. A small room of 8' x 10', 10' x 10' and 10' x 12' size is used for running the mills and storage of wheat grains. The grinding charges (Rs./q) of wheat, coarse grains (maize, sorghum, millet etc) and spices are 100, 200 and 1000, respectively. Sample of 500 g of wheat and flour were collected from each chakki and were analysed for wheat grain and flour quality. Infested, damaged grains were observed to be in 2-10% range. Sieve analysis of the flour was done and the average particle size, fineness modulus and uniformity index of the flour were calculated. Average particle size, fineness modulus and uniformity index were found in the range 0.1875 to 0.2023 mm, 1.052 to 1.297 and 0:1:9, respectively. Average particle size of the flour obtained from horizontal mills was found to be higher than vertical mills. Temperature of the flour at the outlet was observed in between 45 and 50°C at room temperature of 18.5°C.

Abstract

There is an urgent need to – create market driven linkages rather than do it alone by building new infrastructure. A lot needs to be done to improve infrastructure in terms of reducing the logistics cost, eliminating middlemen influence and eliminating the wastage of basic inputs. There is a need to blend technologies based on principle of dovetailing production for masses with the advantage of mass production, particularly in the area of grain processing, packaging and marketing which would help combine livelihood, security with agricultural competitiveness. Risk in crop production is not new to any age and the farmers have been bearing it since times immemorial. The farmers should be allowed to maximize their grain. High performance continuous and batch dryers remove moisture in a way that is predictable and reliable. The problems associated with moisture content may be harmful to international trade in grain and need to be addressed adequately by the standardization institutions.

Abstracts

About 60-70% of total food grain production is retained and stored by farmers for household consumption, use as seed, feed for cattle and payment of wages to labours etc. in our country. Yet the quality of grains stored is not so good, and hence, preserving the harvested crops without loss or damage has always been a problem of national importance. This study was conducted in Jabalpur district of Madhya Pradesh state. A tribal block namely Kundam was selected for study purpose. The responses of 120 women were recorded in pre-tested structural schedule through interview. Rural women are an important source of information on the use of indigenous practices for grain storage. The data reveals that the majority of respondents are using dry leaves of Neem, dry onion bulb, wheat straw, Nirgudi leaves, roots of bach etc. for storage of grain at household level. In our country, indigenous practices of grain storage have always been and are still followed, because it is supposed that these practices are useful in control of grain loss.

Abstract

Pulses constitute an important component of the diet and are a major source of protein in vegetarian diet. India has largest area under pulse cultivation and produces a variety of pulses. A large portion of this produce gets spoiled due to insect and fungal attack. A variety of insecticides and fungicides are used for the control of pest during storage. There is an increasing trend towards the reduction in the use of pesticides in storage due to strong demand from consumers to choose food with no pesticide residue, development of insect resistance to pesticides and the impact of pesticides’ use on environment. All these have posed a challenge to refine the existing management procedures of storage and commodity to find the optimal solution. Controlled/ Modified Atmosphere storage offers an alternative to the use of pesticides extends storage life and maintains product quality. The Controlled/Modified Atmosphere is created by altering the composition of the atmosphere in terms of CO2, O2, and N2 concentration. High CO2 produce undesirable conditions for insects and microbes and thus control their activity.

Abstract

Maintaining grain in good condition in storage requires careful, routine inspection and good storage practices. An integrated approach of several management tools and practice factors are necessary to manage stored grain to prevent deterioration and wastage: This includes:1) harvesting, handling, and storage equipment; 2) initial condition of the grain; 3) grain moisture content; 4) grain temperature; 5) aeration system management ; 6) insect and mold control; and 7) monitoring grain condition. An effective management program greatly enhances the likelihood of maintaining top quality grain. A well- designed and properly operated storage system with adequate aeration capacity, storing only clean grain at the proper moisture content and temperature, sanitizing the bin before loading, checking the grain condition regularly and correcting problems before they get out of hand are critical management strategies that must be implemented to prevent grain damage and possible serious economic loss.

Abstract

The demand for the food for ever increasing population is always continuous, but the production is limited to specific seasons. Therefore the food grains have to be stored for sometimes. Grain is a living biological material and therefore storage structures should be suitably designed to protect them from the ravages of pests, rodents and micro-organisms. However, the storage losses account for a major portion which can be reduced to considerable extent if proper care is done. The faulty design, poor maintenance and limited knowledge of the farmers concerning storage technology have greatly added to the spoilage of the food grains during storage. Sometimes the foods if not properly stored may be edible but it may lose the essential vitamins and minerals, thus their nutritive value has been lost. There is a major requirement of a good storage structure. Various food grain storage structures (small and large scale) are described.

Abstract

Three-point bend test (three point bend ring-HDP/3PB) for five types (Good day, Butter bite, Marie, Krack Jack and Salted) of commercial biscuit brands (Britannia, Supreme, Parle, Lancer, Priya Gold and Dalmia) was developed using TA-XT2, texture analyzer and probable factors affecting the results were assessed. Maximum force to break the biscuits, number of fracture before break, thickness of biscuits and percent break point penetration were found in the range of 1006.5 to 3456.5g, up to 3, 4.2 to 6.3mm and 5.54 to 22.62%. The rupture of biscuits were observed on the basis of probe penetration into the biscuits and found that maximum resistance for penetration offered by Marie whereas minimum by salted biscuits, which was respectively the hard dough and fermented dough biscuit varieties. The analysis of variance for the results revealed that there is significant difference (P£0.01) in the maximum force of break for the biscuit types and brands individually or in combination. Difference in the thickness of biscuits was also found significant among types and commercial brands. The number of fractures was not consistent among the types as well as biscuit brands before reaching the maximum force of breaking the biscuit.

Abstract
 
Technological advancement, increased urbanization, awareness and interest of consumer for variety products have given a great challenge to the food sector to develop inexpensive foods that are nutritionally superior and acceptable to the intended consumers. Keeping this objective in view, we have made an attempt to develop technology for variety products from wheat and corn and suitability of available varieties judged. With the emerging trends of food market towards fast foods, there are vast prospects for efficient utilization of cereals by exploring varieties products. A steamed bread (a Chinese traditional product) and Tortilla and corn chips (Mexican snacks) were developed. Steamed bread is defined as the product resulting from cooking or steaming fermented dough. Recipe and method for its preparation was standardized. Nutritionally rich steamed bread can be prepared by supplementing 10% level of chickpea and defatted soybean flour. Corn snacks have become a prime target of some consumer advocates and nutritionists who have referred them as a source of ‘empty calories’. But reality is that these snacks provide instant energy, as they are rich storehouse of nutrients. Process and recipe for the preparation of Tortilla and corn chips from Indian maize were standardized. The quality and acceptability of these snacks were worked out and found that these products were highly acceptable. Indian consumers have versatile taste, so these products will be readily accepted in Indian market.