eChapters

Variation in field crops between years is associated with many factors. This is mainly due to weather, soil and management factors. There is complex reaction of weather variables among themselves as well as with other factors. Therefore, many attempts were made to study the effect of weather variable on crop yield through simulation modeling.

Climate, soil, input and management factors influence the crop yield. Weather is the most important natural input that affects the agricultural production and productivity. The agricultural activities starting from the land preparation to harvest and post-harvest storage are greatly influenced by the weather. The effects of weather on crops may be direct such as those of precipitation, solar radiation, humidity, temperature, etc., or indirect such as those of pest, diseases, weed competition, etc. Thus, the success or failure of a crop is determined by the prevailing weather conditions. Although influence of weather conditions on yield is well established, the quantitative assessment is not always straight forward and simple. The quantitative assessment of the effect of weather on crops is an important application of agrometeorology. The relationship between weather and crop production has been understood through crop weather modelling and study on this aspect through a systematic approach started a century ago. The aim of developing crop weather models is to ensure better utilisation of resources and hence a more environmental friendly and sustainable agriculture.

A model is a schematic representation of the conception of a system or an act of mimicry or a set of equations, which represents the behaviour of a system. Its purpose is usually to aid in explaining, understanding or improving performance of a system. Agricultural models are mathematical equations that represent the reactions occurring within the plant and the interactions between the plant and its environment. However, it is a difficult task to represent any system completely in mathematical terms because of the complexity of the system. Universal models do not exist for the agricultural systems and agricultural models are built for specific purposes and the level of complexity is accordingly adopted. Different models are developed for different subsystems and several models may be built to simulate a particular crop or a particular aspect of the production system. Crop weather models may be defined as a simplified representation of the complex relationships between weather or climate on one hand and crop performance such as growth, yield or yield components, on the other hand by using mathematical and/or statistical techniques

Plant competition is a powerful force for the elimination of some weaker plants. Plants require nutrients, water, light, Oxygen and Carbondioxide for their growth and development. Weeds compete with the crop for growth factors and the competition is maximum at the early growth stages of the crop. But the competiting ability of the weeds becomes practically nil as soon as the crops attain maturity. Weeds need more nutrients and water than the crop plants. The weeds in general grow faster and shade the crop plant if they are not controlled at proper time and afterwards interfere in the growth of crop plant. Weeds have allelopathic effect on crop growth. Some weeds excrete certain chemicals into the soil which inhibit the germination and growth of other plants in their vicinity and the phenomenon is called allelopathy. Allelopathy is defined as the direct or indirect harmful effects of one plant on another plant through the production of chemical compounds that escape in the environment.

1.1 Weather Parameters

The atmosphere is a gaseous component surrounding the earth as an integral part and its interaction with ocean (water bodies), other planets of the solar system and land (Earth) generates one physical product namely weather elements (temperature, pressure, wind, humidity, precipitation, etc.,) and these form the weather and climate of the Earth. The process of generation of weather and climate of the region is purely natural and cannot be modified by the human being. But they can do adaptation to the existing climate and weather for their sustainable life. The weather can be defined as day to day change in the atmosphere in terms of heat and moisture exchange, while the climate is average of long period weather covering larger area or a region.

The particular climate of a region dictates/permits the genesis of a particular bio-organism in that domain and this selected organism’s growth and multiplication are triggered by the prevailing weather of that particular climate. Hence weather parameters of the atmosphere are very important to human being and other organisms of the Earth. The details on weather elements are given in question and answer section of this book (Annexure-I)

ABSTRACT

Echinacea purpurea (L.) Moench. is a medicinal and nutraceutically important herb of American origin, extended its distribution to other parts of the globe in subtropical and temperate environment. This species is known for various biological properties such as antimicrobial, immuno-stimulatory and anti-inflammatory properties due to the presence to several bioactive compounds loaded in the form of phenylpropanoids, flavonoids, terpenoids, lipids, nitrogenous compounds, carbohydrates and others such as ascorbic acid, sitosterol, linoleic acid, cyanidin glycosides and sesquiterpene esters in different quantities. Published data reveals that its major chemical constituents possess anti-anxiety, anti-depression, cytotoxicity, anti-infective and anti-mutagenicity properties. Besides, plants respond to abiotic and climatic signals that are responsible for various adaptive responses at the cellular level and vary with ecosystem in which the species grows. It may behave differently in different ecological climates, thereby, modifying their gene expressions, and this reveals that the plant growth and the adaptability are mainly affected by microclimatic factors. Experimental trials conducted to collect data on growth phenology in relation to crop-weather interaction and investigated result is presented in this research. Studies on chemical evaluation of E. purpurea under two constrasting environment, subtropical and temperate climate, with reference to cichoric acid and chlorogenic acid undertaken for this plant is also presented. Future studies in relation to the application of biotechnological interventions and chemical evaluation at different time scale would be a great contribution to the science for this species as it has the tremendous potentials which may lead to development of various nutraceuticals and value added products in future for human health and medicines.

There are some weeds which prefer to in crop field and some of them have a distinct association with some crops.

Crop: Plants grown in association, sown (or planted) and also harvested by human being, are collectively known as crop.
Crop plants have some economic values and there is an interaction or competition among the plants.

Comparison of different cropping systems with reference to land use and yield advantages is possible through various efficiency indices. The various cropping and farming systems practiced in an area have to be properly evaluated to decide their suitability and relative advantages. The comparisons can be made with reference to many factors viz., yield, monetary, water use efficiency, nutrient use efficiency, total dry matter production, intensity of land use etc., The cropping as well as farming systems research are being perused at national level with major focus for identification of location specific efficient systems since 1990. However, on perusal of research publications we find that the data of cropping systems are interpreted in different ways with major focus only on production and net return on hectare basis. In fact, these two aspects are not the indicator of the efficiency of a particular system. Many advances have been made in recent years to identify the efficient system for a particular location. Some of the methodologies, which are of concern to crop scientists in general and agronomists in particular, are highlighted here for ready reference to the researchers, agronomists and crop planners. Different indicators of system efficiency are as follows (Gangwar et al., 2003).

What is Crop?
Crop refers to plants sown and harvested by man for economic purposes. 
Cropping Seasons: There are three main seasons and two sub seasons.
1. Rainy or Kharif Season – Main characteristics of the Kharif season are 
    ·    It starts from June and spreads to September.
    ·    There is high temperature and high humidity.
    ·    More than 2/3^rd of annual rainfall is received in a year.
    ·    In the beginning, days are longer than nights while days and nights are equal when season ends. 
    ·    Important crops grown are maize, rice, sorghum, Moong, Urd, groundnut, cowpea, soybean etc. 

1.1. Cropping pattern

Yearly sequence and spatial arrangement of crops or crops and fallow on a given area.

1.2. Cropping seasons in India

1.2.1. Kharif season: Southwest monsoon

Crops - Rice, cotton, jute, jowar (sorghum), bajra (pearl millet) and redgram (Pigeon pea).

Terms associated with cropping and farming systems are:

1. Cropping system: is an important component of a farming system. It represents cropping pattern used on a farm and their interaction with farm resources, other farm enterprises and available technology which determine their makeup.
2. Cropping pattern: means the proportion of area under various crops at a point of time in a unit area. It indicates the yearly sequence and spatial arrangement of crops and fallow in an area.
3. Cropping scheme is a plan according to which crops are grown on individual plot of a farm during a given period of time with the object of obtaining maximum return from each crop without impairing soil fertility. Thus a cropping scheme is related to the most profitable use of resources, land, labour, capital, and management.
4. Multiple cropping: Growing two or more crops on the same piece of land in one calendar year is known as multiple cropping. It is intensification of cropping in space and time dimensions. It includes intercropping, mixed cropping and sequence cropping.
5. Quadruple cropping: Growing of four crops in a year in sequence.
6. Competition effect: Competition of intercropped spp. For light, nutrients, water, carbon dioxide, and other growth factors.
7. Complementary effect: Effect of one component on another which enhances growth and productivity.

In agriculture, the ideal management practices were developed for individual crops through regular research and feedback received from the farmers. However, farmers are growing various crops in different seasons based on their adaptability to a particular season.

System is a set of principles or procedures according to which management is done; it is an organized scheme or method. A system is a group of interrelated or interacting elements (crops or livestock) that act according to a set of rules to form a unified whole.

5.1 Introduction

Rainfed agriculture accounts for about 60-95% of farmed land in major areas of the world covering Saharan Africa, Latin America, North Africa and East Asia and South Asia. Agriculture in about 60 percent of 142 m ha of net cultivated area in India is rainfed without access to any source of irrigation. Rainfed agriculture is mostly practiced in arid, semi-arid and sub-humid regions where the rainfall is low in quantity, erratic in distribution and is also characterized by high inter-year variability. Together with poor and degraded soils, this limits the length of growing season as well as the choice of crops that can be grown sustainably. Coarse cereals, pulses, oilseeds and cotton dominate the cropping pattern in the regions where rainfed agriculture is concentrated. More importantly, these rainfed regions provide a livelihood to a majority of the rural poor, and as a result they are often described as concentrations of mass poverty and hotspots for civic strife. The productivity of crops grown in rainfed areas is considerably lower than its potential and much lower than that of irrigated crops. Enhancing the productivity of rainfed crops is therefore important from the viewpoints of growth, equity and sustainability.

Cropping systems are designed to mimic nature and bring diversity into our farming system. The cropping system should provide enough food for the family, fodder for cattle and generate sufficient cash income for domestic and cultivation expenses.

The objective of any cropping system is efficient utilization of all resources viz., land, water and solar radiation, maintaining stability in production and obtaining higher net returns. The efficiency is measured by the quantity of produce obtained per unit resource used in a given time. The objective of traditional agriculture was to increase the production by two means:

a) By increasing area under cultivation.

b) By increasing the productivity per unit area of the crop.

The types of crops and the practices used to grow them and the sequence in which they are grown altogether refers to cropping system. It comprises of all components required for the crop production and their relationships with the environment. Traditionally the cropping systems aim at maximizing the per unit area productivity, which can be done by growing improved high yielding varieties, by adequate and scientific crop management practices and by increasing cropping intensities with the help of different cropping patterns.

In today’s world cropping system should produce more, at the same time the practices should be ecologically and environmentally sustainable. There should be efficient utilization of land and water. It should be designed to conserve soil, soil moisture and improve soil resilience.

A cropping system refers to the type and sequence of crops grown and practices used for growing them. It is based on the available technologies of crop production. Cropping systems have been traditionally structured to maximize crop yields. Now, there is a strong need to design cropping systems, which take into consideration the emerging social, economic and ecological or environmental concerns for each ecosystem. The goal of a cropping system must be to conserve natural resources i.e. soil, water and sustain crop production. Conserving soil and water and maintaining longterm soil productivity depend largely on the management of cropping systems, which influence the magnitude of soil erosion and soil organic matter dynamics. Crop diversification is an important option in sustainable agricultural systems. Management of cropping systems implies management of tillage, crop residue, nutrients, pests, and practices for soil conservation. Difference between dry land and rainfed farming is as follows.

Growing more than one crop in sequence or simultaneously as a mixed crop is an ancient practice. In Indian Vedas, there is a mention about double cropping. In early periods, the objective to adopt sequential cropping practices was to reduce the risk of total crop failure due to uncertain monsoon and to have a variety of produce to meet food requirement of farmer’s family, fodder to animals and to meet his cash requirements. Other benefits of yield increase was due to complementary effects of the component crops in improving the soil fertility, spreading the labour requirement throughout over a period of time and to reduce damage caused by weeds, pests and diseases were only incidental.

Multiple cropping in simple terms refers to the practices that increase production in a unit area of land through two or more growing crops simultaneously. The importance of intensive cropping in sustainable agriculture has been well understood by the agricultural scientists of late and there has been surge of interest in the research community to explore these complex systems in detail and to see what can be learnt from the farmers in our quest to make cropping system more sustainable progress made in the past through intensive research carried by the various agricultural universities, ICAR, research institutes/ coordinated research projects and international research institutes such as IRRI, ICRISAT, IITA and CIMMYT, it has shown that and more efficient utilization of the natural resources is possible by suitably modifying the present cropping systems in the various regions of the world.

The present cropping intensity in India is 136 per cent. There is a great prospect for increasing the cropping intensity both in irrigated and rainfed areas. In many irrigated areas, cropping intensity can be increased to 200-300 per cent. There is good scope to increase cropping intensity to 180-200 per cent with proper policies and technology options in rainfed conditions also.

A system is a set of components that are interrelated and interact among themselves. A system may be natural, social or artificial. Natural systems consist
of all the materials both physical and biological and are independent of human beings. Our role in relation to natural systems is to try to understand these
systems and make use of them as per our needs. 

15.1 INTRODUCTION

Cropping system is defined as a cropping pattern followed on a farm and its interaction with farm resources, other farm enterprises and production technology. In other words, cropping system refers to a combination of crops in time and space. When annual crops are considered, a cropping system usually means the combination of crops within a given year (Willey et al., 1989). This cropping system might provide insurance against crop failure by reducing disease (Fininsa and Yuen, 2002) and insect incidence (Gahukar, 1989) or against unstable market prices by planting two or more crops under intercropping and thus, reducing the risk of unexpected changeable prices. Intercropping in scientific way should be viewed from a theme of competition to one of collaboration with mutually beneficial relation with proper planning to get more return from limited natural resources. Legumes have been the common intercrops in any intercropping system owing to their short duration, N-fixing ability etc. Even though non-leguminous vegetables require longer duration than legumes and are non-N-fixers, they can also be suitable as intercrops because of their high profitability and higher yields.

In general crop is an organism grown or harvested for obtaining yield. Agronomically crop is a plants cultivated for economic purpose.

Classification of Crops

Classification is done to generalize similar crop plants as a class for attaining better understanding of them. Field crops are classified in the following ways.

1. According to range of cultivation
2. According to the place of origin
3. Botanical classification
4. Commercial classification
5. Economic / Agricultural / Agrarian classification
6. Seasonal classification
7. Classification based on ontogeny

The occurrence of periods of water deficit for crop production, referred to as climatic drought, is commonly observed and leads to low water availability for crops. Besides climatic drought, crop water stress may also result from low levels of plant available water in the soil profile due either to the existence of physical barriers to water infiltration (e.g., surface sealing) or to soil chemical or physical limitations to plant root growth and root water uptake. Drought resulting from such factors will be referred to as edaphic drought since it is caused by soil specific conditions rather than by limited rainwater supply, and can occur even under conditions of sufficient and well-distributed rainfall. Finally, even where water is very scarce, particularly in the driest areas, a surprisingly small proportion of the available water is actually transpired by the crop. Non-productive losses include surface runoff, deep drainage, evaporation from the soil surface and deep cracks, and transpiration by weeds. Dry land farming is a system of crop cultivation depending on rainfall as the only source of moisture and the technologies refers to the cropping pattern/ rotation and agronomic practices adjusted and adopted in accordance with the moisture regime. The crops selected should have short duration, deep root system, erect leaves, moderate tillering and photosynthetically efficient.

Rainfed farming has a distinct place in the Indian agriculture, occupying 67 % of cultivated area contributing 44 % of food grains to our national food basket, supporting 40% of human and 65% of livestock population. The system is characterized by resource poor farmers, poor infrastructure and low investment in technology inputs. Even when full irrigation potential of the country is realized, 50% of the net sown area is continued to be rainfed. The important problems encountered in rainfed areas are unfavorable weather, limited choice of crops and varieties, low cropping intensity and unstable productivity. The research work done by the net work of AICRPDA (All India Co-ordinate Research Project for Dryland areas) centres and SAUs (State Agricultutal Universities) indicated that the production in rainfed environment could be enhanced by 200 % compared to the productivity of farmers’ field by adopting improved cropping systems and agro techniques.

Climate change presents a formidable challenge for agriculture, particularly in regions like South Asia and parts of the Pacific. Severe flooding in Bangladesh, droughts in Afghanistan, and rising sea levels in Fiji exemplify how erratic weather patterns disrupt food production. In Pakistan, erratic monsoons damage crop cycles, while in Nepal and Bhutan, glacial melt threatens downstream water availability. Vietnam and Thailand are increasingly vulnerable to salinity intrusion in the Mekong Delta, jeopardizing rice productivity. According to FAO estimates, post- harvest losses in South and Southeast Asia exceed 15% due to inadequate storage and handling (FAO, 2022). Investment in improved storage facilities, resilient farming systems, better transportation infrastructure, and post-harvest technologies is crucial to mitigating such losses. 4.2 Infrastructure Deficits Infrastructure gaps are a major bottleneck for efficient agri-food supply chains. The Regional Logistics Performance Index (LPI) average for South Asia is 2.6, compared to 3.5

Spikeborer : Helicoverpa armigera : Noctuidae

Larvae of this polyphagous moth feed on the spikelets, flowers and developing seeds. The young larvae bite holes into the spikelets and the grown up ones attack the mature spikes

Crossandra belongs to family Acanthaceae. It is also known as Kanakambaram in Tamil or Kanakambara in Kannada and Fire cracker in English because of cracking sound during opening of seed pod. Crossandra is derived from Greek word “krossoi” meaning fringe and “aner” meaning male i.e. fringed anthers. Crossandra is an evergreen shrub and one of the important loose flower used for adornment. The flowers are commonly grown for flower adornment in the form of garlands, venis and gajras. Though it is not fragrant, flowers are very popular because of its attractive bright colour, light weight and good keeping quality. These are used for making garland, either alone or in combination with jasmine flowers. Using crossandra flowers in combination with jasmine is becoming increasingly popular in India, particularly in southern parts, because the jasmine flowers provide colour contrast and the desired fragrance. Crossandra varieties show a remarkable range of colours, varying from orange, pink, red, yellow and double coloured blue-type with white throat.

Crossandra belongs to family Acanthaceae. It is also known as Kanakambaram in Tamil or Kanakambara in Kannada and Fire cracker in English because of cracking sound during opening of seed pod. Crossandra is derived from Greek word “krossoi” meaning fringe and “aner” meaning male i.e. fringed anthers. Crossandra is an evergreen shrub and one of the important loose flower used for adornment. The flowers are commonly grown for flower adornment in the form of garlands, venis and gajras. Though it is not fragrant, flowers are very popular because of its attractive bright colour, light weight and good keeping quality. These are used for making garland, either alone or in combination with jasmine flowers. Using crossandra flowers in combination with jasmine is becoming increasingly popular in India, particularly in southern parts, because the jasmine flowers provide colour contrast and the desired fragrance. Crossandra varieties show a remarkable range of colours, varying from orange, pink, red, yellow and double coloured blue-type with white throat.

ORIGIN AND DISTRIBUTION

Crossandra is native to Indo-malaya region. They are all native to sub-tropoical regions including India, Southeast Asia, Africa, and Madagascar.

Crossandra Salisb is a genus of about 50 species which are shrubs or herbs from Tropical Africa, Madagascar and Arabia, where it is grown as a perennial shrub. Crossandra undulaefolia Salisb. (Syn C. infundibuliformis Nees) is a native of East Indies. However, it is sometimes considered to be native of south India and Ceylon. C. guinensis is native of east Africa while C. nilotica has its origin in east Africa and Mozambigue. C. flava is a native of tropical west Africa.

The crossandra plants are distributed in tropical as well as subtropical regions of the world such as south Asia, South America, South Africa and Madagascar. In India, it is commercially cultivated in southern states of Karnataka, Tamil Nadu and Andhra Pradesh (Singh, 2006).

INTRODUCTION

Crossandra is an important traditional flower crop of south India. It is small evergreen shrub that is quite hardy and has the ability to produce beautiful flowers with a remarkable range of colours almost all the year. This has made it extremely popular in southern states of India where the flowers are widely used in temple offering and for making gajras and venis to use as hair adornments.

Owing to their attractive colours, light weight and good keeping quality, crossandra flowers are ideal for garland making. Even though the flowers lack fragrance, they are widely used in garlands either alone or along with jasmine to produce charming colour contrasts. Steady market demand and assured and regular income have made crossandra a profitable venture for south Indian farmers.

Abstract: Crossandra, traditional flower crop of India, produce beautiful flowers in remarkable range of colours of almost all the year. Flowers are ideal for garland making and hair adornments. Only few species are cultivated across the world. Improvement is focused on drought tolerant ornamental types for landscape/ container use, better keeping quality, heavy yield and vivid range of flower colours, long spikes, earliness and big flower size. Breeders have created mutant cultivars and F₁ hybrids having valuable traits. Lack of fragrance and meager seed set require biotechnological interventions.

Introduction

Crossandra is an important traditional flower crop of South India. The word crossandra is derived from Greek words ‘krossoi’ meaning fringe and ‘aner’ meaning male, thus word crossandra means fringed stamens. It is grown for loose flower production and commonly used in temple offering and for making Gajras and Venis to use as hair adornments. Owing to their attractive colours, light weight and good keeping quality, crossandra flowers are ideal for garland making. Steady market demand and assured and regular income have made crossandra a profitable venture for South Indian farmers.

Genetics

The genus Crossandra belongs to family Acanthaceae. The diploid chromosome number of crossandra is 2n=40. This genus consists of around 50 species of tropical plants with only a few cultivated species such as Crossandra undulaefolia, C. mucronata, C. guineensis and C. sebacaulis. Crossandra undulaefolia is an important species which is grown for commercial value across the world.

Crossandra is an important tropical flowering crop valued for its attractive flowers and continuous production of loose blooms. It has particular importance in southern India, where flowers are widely used for garlands, hair decoration and religious purposes. This chapter covers the crop’s botanical characteristics, origin, distribution, genetics and commercially important varieties. It explains propagation, nursery management, climate and soil requirements, land preparation, planting, irrigation and nutrient management. Important cultural practices and plant growth management are discussed for obtaining regular flowering and good-quality blooms. The chapter also addresses insect pests, diseases, harvesting and postharvest management, including the correct method of flower collection. It provides a comprehensive production package for growers and students.

11.1 Introduction

The crossopterygians, primitive, lobe-finned, bony fishes, represent a very interesting group of fish showing many features of amphibians and other tetrapods. They possess paired fins with a large median lobe, fins covered by scales, a cosmine layer, swim bladder as lungs, nostrils that open into the mouth cavity and autostylic jaw suspension.

11.2 Taxonomic position

Crowdsourcing is a concept that involves obtaining information, ideas, or services from a large group of people, often through an online platform. This approach has become increasingly popular in recent years, particularly with the rise of social media, mobile devices, and other digital technologies. In the context of agriculture, crowdsourcing can be used to collect data on various aspects of farming, such as crop yields, soil conditions, and weather patterns. This data can be used to provide farmers with valuable insights and advice on best practices for farm management. One of the key benefits of crowdsourcing in agriculture is that it allows farmers to share knowledge and expertise with each other. By pooling their collective knowledge and experience, farmers can gain a better understanding of the challenges and opportunities facing their industry, and develop more effective strategies for overcoming them (Fig.7.1).
For example, a crowdsourcing platform might allow farmers to share data on crop yields and soil conditions. This data could then be used to create detailed maps of soil types and conditions, which could be used to provide farmers with advice on optimal planting and harvesting schedules.
Another example of crowdsourcing in agriculture is the use of mobile apps to collect data on weather patterns. By collecting data from a large number of

This cosmopolitan family of about 375 genera and over 4,060 species, occur chiefly in north temperate regions, especially in the Mediterranean region. About 50 genera and over 140 species have so far been reported from India. Some of the larger genera, along with their reported number of species from the world in parenthesis, include Draba (300), Cardamine (160), Lepidium (150), Alyssum (150), Arabis (120), Erysimum (100), Sisymbrium (90), Heliophila (75), Rorippa (70), Iberis (30) and Raphanus (8). Majority of Crucifers produce an abundance of vitamin C. Characteristic pungent odour of its members is because of sulphur compounds.
Selected Indian Genera and Species
• Vegetables: Several common vegetables of daily use belong to this family. Some of them are radish (Raphanus sativus), cauliflower (B. oleracea var. botrytis), Brussel’s sprout (B. oleracea var. gemmifera), sengri (B. sativus var. caudatus), etc.
• Oils: Fatty oil, used for cooking, pickles, bruning, massaging, etc. is obtained from the seeds of several species of this family. Mustard oil is obtained from several species of Brassica such as B. campestris var. sarson and B. campestris var. toria (Indian rape). Oil is also obtained from the seeds of B. juncea var. cuneifolia (Rai), B. alba (white mustard). The oil cake left after the extraction of oil, is a good cattle feed.

Diamond back moth: Plutella xylostella: Plutellidae
 
The adults of this moth are small, greyish brown having pale whitish narrow wings and with inner margins yellow. There are three pale whitish triangular markings on hind margins of each forewing. At rest, when both forewings come together, they form a dorsal median patch of three diamond shaped yellowish white spots that give them their name diamond back moth. Hind wings have a fringe of long hairs.

1. Alternaria leaf spot
Diagnostic Symptoms
• Spots are small, dark coloured.
• They enlarge, soon become circular & 1mm. in diameter.
• Under humid conditions groups of conidiophores will be formed in the spot.
• Spots develop concentric rings.
• Finally the spots coalesce leading to blighting of leaves.
• Pathogen is seed borne and cause shriveling of seeds and poor germination.
• Linear spots also appear on petioles, stems, pods & seeds (Fig.1).

Crust is characterized by the presence of desquamated squamous epithelial cells. The dried exudate consists of necrotic cell debris, leucocytes, RBC’s, plasma proteins and microorganisms. It is classified into serous crust (eosinophilic protein exudates), hemorrhagic crust (RBC’s), cellular crust (degenerative leucocytes mainly neutrophils), serocellular crust (mixture of serum or plasma or leucocytes) and palisadic crust (presence of leucocytic infiltration, pustules and parakeratosis organized in a horizontal manner).

Early passage cell lines are relatively unstable and go through a period of adaptation to culture. However, between 5^th and 35^th generation (human diploid fibroblasts), the culture is fairly consistent although it varies from one cell to another cell. Finite cell lines should be preserved after adaptation but before senescence (getting older). Cells should be preserved to protect cell line instability, availability in case of contamination, incubator failure or accidental loss.

Introduction

The protocol below describes the use of cell freezing methods involving an electric -80°C freezer for the cryopreservation of cell lines. ECACC routinely use a programmable rate-controlled freezer. This is the most reliable and reproducible way to freeze cells but as the cost of such equipment is beyond the majority of research laboratories the methods below are described in detail. If large numbers of cell cultures are regularly being frozen then a programmable rate-controlled freezer is recommended.

Materials

• Freeze medium (commonly 90% FBS, 10% DMSO or glycerol

• 70% (v/v) alcohol in sterile water

• PBS without Ca2+/Mg2+ • 0.05% trypsin/EDTA in HBSS, without Ca2+/Mg2+

• DMSO

Deep freezing or cryopreservation of semen refers to freezing and storage of semen at –79ºC using dry ice and alcohol or at -196ºC using LN2 as refrigerant. Cryopreservation of semen was first attempted by Parkes in 1945. But cryopreservation of semen received a boost by discovery of glycerol a cryoprotectant by Polge in 1949.  Bull semen was first successfully frozen by Stewart in 1951. Cooling rate is a vital factor determining the post thaw survival of the sperm cells. Cell death occurs in rapid freezing due to formation of intracellular and possibly extracellular ice. In contrast slow cooling rates cause cell death due to diffusion of intracellular fluid into the extender, which then become increasingly hypertonic as the extender’s water freezes causing intracellular osmotic damage as the cell dehydrates. Hence, the cooling rate needs to be balanced in a way that it is neither too fast to cause cell death due to cold shock nor too slow to result the same due to osmotic shock. Ultra rapid freezing gives excellent morphological preservation but with poor retention of functions on thawing due to large number of minute crystal formation.

A useful method for quickly preparing tissue slides for microscopic analysis is the frozen section technique. There are numerous clinical and research contexts where the frozen section technique is employed. For quick intraoperative diagnosis in histopathology, frozen sections are frequently utilized, giving our surgical colleagues direction. To ascertain the extent of excision required to remove a skin tumour, the surgeon doing Mohs Micrographic Surgery depends solely on the frozen sections. The frozen section technique is used in many scientific applications to create microscopic slides using a variety of complex morphologic, immunohistochemical, and molecular techniques. There are several uses for frozen sections, including rapid diagnosis, immunohistochemistry, enzyme histochemistry, lipid detection, cancer margin research, and more. Making frozen section slides is a difficult technical procedure that calls for the mastery of advanced technical abilities in addition to knowledge of the pathology, microanatomy, and histology of the tissues under investigation. The outcomes will depend on our capacity to produce a high-quality preparation, whether it is utilized for research or intraoperative consulting. Dr. Louis B. Wilson’s 1905 description served as the basis for the frozen section technique used in medical labs today. At the request of surgeon Dr. William Mayo, one of the founders of the Mayo Clinic, Wilson devised the procedure based on previous studies. A frozen section was also used in earlier reports by Dr. Thomas S. Cullen of Johns Hopkins Hospital in Baltimore, but only after formalin fixation. Dr. William Welch, a pathologist at Hopkins, also tried Cullen’s technique, but there were no negative clinical effects. Wilson is therefore widely acknowledged as having really invented the procedure.

Etiology

Cryptococcosis (KRIP-toe-cock-co-sis) is caused by the fungus, Cryptococcus neoformans (KRIP-toe-cock-kus knee-O-for-mans). It is found worldwide and primarily affects cats and people with weak immune systems.

Cryptosporidiosis is a protozoan disease.

Species

1. C. meleagridis: Infects small intestine.
2. C. baileyi: Infects digestive tract (bursa of Fabricius and cloaca), kidneys and respiratory tract.

Chemically, sugar candies are broadly divided into two groups: crystalline candies and amorphous or non crystallized candies. Crystalline candies are not as hard as crystals of the mineral variety, but derive their name and their texture from their microscopically organized sugar structure, formed through a process of crystallization, which makes them easy to bite or cut into. Fudge, creams, and fondant are examples of crystalline candies. Amorphous candies have a disorganized crystalline structure. They usually have higher sugar concentrations, and the texture may be chewy, hard, or brittle. Hard candies, such as lollipops, caramels, nut brittles and toffees are all examples of amorphous candies, even though some of them are as hard as rocks and resemble crystals in their overall appearance. Crystalline candies are chemically described as having two phases, because the tiny, solid sugar crystals are suspended in a thick liquid solution. These are also called grained candies, because they can have a grainy texture. Amorphous candies are have only one phase, which is either solid or liquid, and do not have a grainy texture, so they may be called ungrained.

Commercially, candies are often divided into three groups, according to the amount of sugar they contain:

3.1 Introduction

Crystallography is the science of crystals. The term crystal is derived from the Greek word “Crystallos” which means “ice”. The term was used for colorless quartz which was believed to be “fossilized” ice. Crystals are bodies bounded by flat surface, arranged on a definite plan which is an expression of the internal arrangement of the atoms. They are formed by consolidation of magma which is also considered as crystallization.

3.2 Terms in Use to Describe a "Crystal"

3.2.1 Faces

Faces are the plane surface in a crystal. The common faces are usually parallel to net planes containing the greatest number of lattice points or ions. Wide spacing between the net planes leads to development of faces in these planes. Faces are two types like and unlike faces.

The Mineral Kingdom presents a dazzling floral-display in the form of natural crystals. This is what makes mineralogy a very fascinating subject both for an amateur as well as an expert. Unless one visits the celebrated Lechuguilla cave in New Mexcio, USA it will be difficult to visualize the breathtaking beauty that crystals present. This, over 160 km cave is lined with gigantic as well as delicate gypsum crystals- as thin as human hair to several centimetres across and 6 m long . Crystals come in all shapes, sizes and colours. Their beauty and regular shape has not only attracted the scientists but made them objects of magical and mythical powers in many cultures of the world.

The study of crystals - including their growth, structure, classification by form and their physical properties forms the subject of crystallography. As of today one can’t think of this subject without x-ray crystallography, however, this being not in your syllabus only an introduction will be presented in the last chapter, while the entire section will be devoted to fundamental aspects of crystal morphology.

The section comprises four chapters. Chapter I describes and introduces the theme, presents a brief historical background of the development of the subject and gives some fundamental definitions. Chapter II presents the morphological elements including symmetry elements( plane, axes and centre of symmetry), parameters, indices, notation of crystal faces and other related aspects which are the basis for dividing crystals of all shapes and sorts into six or seven systems and several sub-types. This chapter will help you understand as to why mineral galena belongs to cubic system, while gypsum is monoclinic, or as to why an octahedron is represented by a symbol (111) but a cube with (100). Chapter III describes the seven systems and their sub-types and ends with an account of twinning- a curious feature quite often encountered among crystals. The section ends with a preliminary idea about stereographic projection and x-ray crystallography.