eChapters

Wilt

Fusarium oxysporum f. sp. lentis

Economic Importance

• The disease is present in countries such as India, Jordan, Nepal, Pakistan, Syria, Turkey, Russia, France, Hungary, Ukraine, Egypt, Ethiopia, Morocco, Sudan, Tunisia, Canada, Argentina, Chile and Uruguay etc.
• It may cause 5-10% yield losses but sometimes severe damage may result complete crop failure under favorable conditions.

Anthracnose

Colletotrichum lindemuthianum

(Sexual stage: Glomerella lindemuthianum)

Diagnostic Symptoms

• The pathogen can attack all aerial parts at any stage of plan growth.
• Main symptoms are circular, black, sunken spots with dark center and bright red orange margins on leaves and pods.
• In severe infections the affected parts wither off.
• Seedling get destroyed due to infection soon after seed germination.

Anthracnose

Colletotrichum lindemuthianum

(Sexual stage: Glomerella lindemuthianum)

Diagnostic Symptoms

• The pathogen attacks all aerial parts of plants and at any stage of their growth.
• Initial symptoms are circular, black, sunken spots with dark center and bright red orange margins on leaves and pods.
• In severe infections, the affected parts wither off.
• Seedlings get blighted due to infection soon after seed germination.
• The infected pods have discolored seeds.

Powdery Mildew

Erysiphe polygoni

Economic Importance

• Powdery mildew can be a serious disease of peas grown in India.
• It appears in epidemic form in the plains almost every year when the pods are formed in January-February.
• Since the disease occurs more frequently and covers a large host surface, it proves much more destructive than the downy mildew disease of the same crop.
• It is worst in dry weather as against the downy mildew, which flourishes in moist weather.
• Severe infections can reduce yield by 10–20%.
• Severe pod infection can lead to poor seed quality.

Wilt

Fusarium oxysporum f. sp. ciceris

Economic Importance

• Wilt is a serious disease of chickpea in India, Iran, Pakistan, Nepal, Myanmar, Spain, Tunisia, Morocco, Algeria, and Syria.
• Wilt is prevalent in most chickpea growing countries and is a major disease of economic importance in Asian countries.
• It was first reported in India.
• The yield losses encountered was reported to the tune of 60 per cent. However, it causes complete loss in grain yield if the disease occurs in the vegetative and reproductive stage of the crop.
• Seeds harvested from infected plants are lighter and duller than those from healthy plants.

Wilt

Fusarium udum

Economic Importance

• Wilt is widely prevalent throughout the world but more important in India and in eastern Africa.
• Wilt is the worst disease of red gram in India, causing severe damage wherever the crop is grown, especially in Maharashtra, Madhya Pradesh, Uttar Pradesh, Bihar and Tamil Nadu.
• The disease is reported to cause 30-100% loss in grain yield and may cause 100% yield losses in susceptible genotypes.
• The annual losses due to wilt have been estimated at $71 million in India.

Downy Mildew (Green Ear)

Sclerospora graminicola

Economic Importance

• Downy mildew is reported from temperate and tropical regions of the world.
• In India, the disease is a major stumbling block in the full exploitation of yield potential of hybrids.
• Several epidemics have been observed which resulted in substantial grain yield losses (upto 60 percent) in F₁ hybrids under South Indian conditions.
• Usually the losses in grain yield are directly proportional to disease incidence in the field.

Loose Smut/Kernel Smut

Sphacelotheca cruenta

Economic Importance

• Loose smut is distributed in Africa, Europe, Asia and America.
• In India, it occurs in the states of Andhra Pradesh, Maharashtra, Karnataka, Madhya Pradesh and Tamil Nadu.
• It is less common than grain smut.
• The pathogen affects plant growth and development adversely.
• Grain yield losses correlate well with percentage of the disease distribution in fields.

Southern Leaf Blight

Helminthosporium maydis (Syn: H. turcicum)

Economic Importance

• The first epidemics of the Southern corn leaf blight also known as Maydis leaf blight took place in the USA in 1970.
• A highly virulent strain called Race T appeared on maize hybrids with Texas male sterile cytoplasm.
• The disease development was related to the growing of maize with T-cytoplasm on large areas.
• Since 1990 the use of cultivars with T male sterile cytoplasm has been forbidden in selection.
• Presently, the cultivars with M and C types of sterility are used.

Rusts

The following three rusts are known to occur on barley

1. Stem black rust: Puccinia graminis tritici f. sp. tritici
2. Leaf rust: Puccinia striiformis
3. Leaf rust: Puccinia hordei

Of these, the first two are described under wheat and the disease symptoms are identical. These two rusts occur commonly on barley and cause severe damage in certain years.

Loose Smut

Ustilago nuda tritici (Ustilago tritici)

Economic Importance

• Loose smut has been observed and recorded on cultivated wheat from all over the wheat growing regions of the world.
• In India, it is prevalent in areas having cool, humid and semi humid climate during flowering period.
• Loose smut has recently became a more serious problem in the Ladakh region in the Himalayan mountains of India.
• If uncontrolled, loose smut can wipe out entire crops, since it replaces the grain.
• In areas where people depend on their grain crops for survival and don’t have the money or technology resources to control it, the disease can be devastating.
• Not only does it wipe out the crop, growers cannot even try again next year since any seeds they were able to harvest will be infected and will not produce seed the following season.

Fungal Diseases

Blast

Pyricularia oryzae (Sexual stage: Magnaporthe grisea)

Economic Importance

• Rice blast is the most important disease concerning the rice crop in the world.
• It has been found in over 85 countries across the world.
• The disease was first recorded in China in 1637.
• In India, occurrence of this disease was first reported from the Tanjore district of Tamil Nadu in 1918.
• The disease now occurs in almost all principal rice growing areas of India.
• Every year the amount of crops lost to rice blast could feed 60 million people.
• In severe cases losses amounting to 70-80% of grain yield was recorded.

A. Diseases

1. Bacterial Disease: Angular leaf Spot

Occurrence & severity status

Angular leaf spot disease, also known as ‘Black arm disease’ or ‘Bacterial blight’ is a disease of cotton potentially destructive in all cotton-growing areas of the world. The disease became prevalent in the USA during the 1950s (Schnathorst et al., 1960) and in India in the 1970s (Verma, 1986). In the USA, losses of between 34 and 59% were reported (Leyendecker, 1950; Bird, 1959). In India, losses of 5-20% were common in crops (Verma and Singh, 1971). Late and very late sowing of crops resulted in more yield reductions (Meshram and Raj, 1992). In general, losses due to bacterial blight in India are ranged between 1% and 27% depending on the cultivar and crop age (Mishra and Krishna, 2001). In Africa, data on crop losses is available for only a few countries. In Sudan, losses of 20% were common from severe infection (Last, 1960). However, nowadays, due to the wide availability of resistant varieties, its importance has been declined, with certain deviations where proliferation of new races has occurred as in Australia (Anonymous, 1980).

A. Diseases

1. Anthracnose

Occurrence & severity status

Anthracnose of sisal is also called as leaf spot or ring spot disease. The disease is frequently accompanied with sun scorch in Kenya and Tanganyika (Morstatt, 1930). This is considered as a leaf disease of minor importance, occurring on numerous species of Agave as well as the closely related genus Furcraea, including F. macrophylla Baker (wild sisal). The disease is distributed in warm temperate and tropical regions including southern Europe, British Guiana (Bancroft, 1914), the Neotropics, Cyprus (Georghiou and Papadopoulos, 1957), Kenya (Nattrass, 1961) and USA (Parris, 1959). It is also been reported to occur in various countries of Asia, including China (Tai, 1979), Korea (Cho and Shin, 2004), the Philippines (Teodoro, 1937) and Taiwan (Anonymous, 1979). In India, the disease was first reported as leaf spot caused by Colletotrichum agaves Cav. (Butler, 1905). Its occurrence was also reported from Antigua (Bancroft, 1910) and Puerto Rico (Macedo, 1943). Apart from sisal, the disease also occurs on tomato (Lycopersicon esculentum), potato (Solanum tuberosum) and over 35 other hosts, representing 13 families, chiefly in the Cucurbitaceae, Leguminosae and Solanaceae (Chesters and Hornby, 1965). The disease also occurs on onion and strawberry (Mordue, 1967).

A. Diseases

1. Anthracnose

Occurrence & severity status

Anthracnose has a serious impact on yield and fibre quality of flax (Linum usitatissimum) and is well-known in Europe, Asia and America. Flax anthracnose increased in Germany when flax production was expanding in the 1930s (Rost 1938). The anthracnose pathogen is seed- and soilborne, causes damping off of flax seedlings (Rost 1938), and is one of the causal organisms of so-called flax-sick soils (Bolley & Manns 1932). It has been recorded in nearly every country where the crop is grown either for fibre or oil. It is known to occur in Belgium, the British Isles, Canada, Formosa, France, Germany, Holland, Japan, Latvia, Lithuania, New Zealand, Poland, U.S.A. and the U.S.S.R. (including Siberia), in most of which countries its incidence has resulted in appreciable crop losses (Muskett and Colhoun, 1947). The disease is most common in cool and humid flax-growing areas (Nyvall, 1989). The disease is destructive to the crop, especially when the seed source is contaminated by the fungus. It can spread rapidly under favourable conditions causing severe local epidemics and heavy losses in yield and quality of both fiber and seed (Mercer, 1992c; Rashid, 2003b). The losses of 50% in fibre yield in an epidemic year were reported by Muskett and Colhoun (1947). Ondrej (1985) indicated a considerable loss in fibre strength on attack by anthracnose.

A. Diseases

1. Anthracnose

Hemp anthracnose is caused by two different fungi, viz., Colletotrichum coccodes (=C. atramentarium) and Colletotrichum dematium (Saccardo, 1882; Cavara, 1889).

i) Anthracnose (Colletotrichum coccodes)

Occurrence & severity status

The anthracnose disease occurs on many plants, including hemp (Cannabis sativa). The disease causing fungus is well-studied and it is an important pathogen responsible for black dot disease on potato. The fungus is an unspecialized pathogen, infecting a wide range of host families. It is most common in Canada and commonly regarded as a minor pathogen or secondary invader, but the fungus may seriously affect yield where intensive cropping without rotation occurs. It primarily affects the growth rate of plants and diminishes harvest. Moreover, it becomes fatal occasionally. Hoffman (1958, 1959) reported heavy hemp losses in central Europe. Conversely, Gitman (1968b) considered the pathogen was of little importance in the USSR.

A. Diseases

1. Alternaria leaf spot

Occurrence & severity status

In the years 2012 and 2013, black leaf spot disease was observed on ramie plants in Hunan and Hubei Provinces, China (Yu et al., 2016). Yu et al. (2016) claimed that their report was the first report of Alternaria leaf spot of ramie in China.

Symptoms

In the field, the symptoms of this disease included dark green to black big spots on leaves (Fig. 20A), often resulting in upwardly curled leaf margins (Yu et al., 2016).

A. Diseases

1. Anthracnose

Occurrence & severity status

The Anthracnose [Fig. 14 (A-B)], also called as ‘Stem-break’, is one of the most serious diseases of sunnhemp (Crotalaria juncea ) in India. It occurs in all sunnhemp growing areas of India (Mitra 1934; Kempanna et al., 1960; Kundu, 1964; Kumar et al., 2016). Apart from India, its occurrence in several countries of South Tropical Africa, like, Rhodesia (Whiteside,1955), Zimbabwe, and other tropical countries including Trinidad and Tobago (Damm et al., 2009), was also noticed as a major disease (Purseglove, 1974). In many places, the disease is considered as the second most serious disease of sunnhemp, causing wilt and weakening of the stem.

A. Mesta diseases

1. Anthracnose

Occurrence & severity status

Mesta (Hibiscus cannabinus) is very much prone to be attacked by anthracnose disease (Singh, 2014). It is very destructive disease in India (Ghosh, 1983). The disease also occurs in South Korea with overall disease incidence of 20%. (Kwon et al., 2015).

Symptoms

Symptoms on kenaf plants include dark brown spots on the leaves, petioles and stems. New leaves and shoots are most susceptible to infection (Kwon et al., 2015). Initially the terminal bud is attacked, where stipules and young leaves are affected and develop necrotic spots and withers (Singh, 2014). Mature lesions on fully expended leaves are dark brown and often irregular in shape, and not vein delimited. Later, the infected leaves fall off; Flowers and seed capsules are also affected by the disease (Singh, 2010). The stems are affected in patches. On stem the lesions are elongated and black, which later form cavities and in severe cases, stem-dieback or wilt occurs (Singh, 2010; Kwon et al., 2015).

A. Diseases

1. Bacterial leaf blight

Occurrence & severity status

The disease Bacterial leaf blight, also known as ‘Bacterial leaf spot’, occurs on white jute (Corchorus capsularis) and tossa jute (C. olitorius) in seed crops of jute at the ICARCRIJAF research farm, Barrackpore, West Bengal, India (Biswas et al., 2013, 2014), in Formosa (Elliott, 1951) and Sudan (Sabet, 1957). The incidence of the disease varies from 25% (Borker and Yamlembam, 2017).

Symptoms

The disease initially appears on leaves as small brown circular spots of 25mm diameter (in tossa jute) or angular brown spots (in white jute), In most cases, the spots are surrounded by a yellow halo and the angular spots coalesce at later stage show larger blighted areas on lamina (Borker and Yamlembam, 2017). The lesions on the stems are elongated; sometimes the spots girdle the stem. The disease on the capsules produces small sunken brown spots. Defoliation and death of the plants may result in severe infections. In the later stages of disease, brown sunken spots were found on the green capsules (Sabet, 1957; Biswas et al., 2013, 2014).

Looking forward, it is clear that traditional and western medicine have the potential for rich collaboration that benefits both disciplines. There is growing interest in this partnership, as shown by the number of international journals now dedicated to such research, such as Journal of Ethnopharmacology, Complementary Therapies in Medicine, eCAM, Alternative Therapies in Health and Medicine, and the Journal of Alternative and Complementary Medicine. Even the WHO has taken note of the rich possibilities of the future of TM, having put out such documents as ‘WHO General Guidelines for Methodologies on Research and Evaluation of Traditional Medicine’ and ‘WHO Guidelines on Good Agricultural and Collection Practices (GACP) for Medicinal Plants’. Despite this enthusiasm, there are several areas where the international community will need to focus their attention if the goal of integrating botanical medicines for the good of human health is to be reached.

The traditional medicines are actually used in human for number of years and therefore its clinical existence comes as a presumption. However, for bringing more objectivity and also to confirm traditional claims, systematic clinical trials are necessary. In Ayurvedic medicine research, clinical experiences, observations or available data becomes a starting point. In conventional drug research it comes at the last. Thus, the drug discovery based on Ayurveda follows a ‘Reverse Pharmacology’ path546.

Nevertheless, all the critical Pharmacopoeial tests such as dissolution time, microbial, pesticide and heavy metals contamination etc. must be in accordance with global standards. It is important to ensure that all the Ayurvedic medicine manufacture is in accordance with Current Good Manufacturing Procedures for herbal products547,548. There have been concerns about quality standards and safety issues of herbal medicines549. The need for new regulations for botanical medicines has also been frequently stressed and some such regulations are coming in force in different parts of the world550,551.

Very few traditional systems have a fair level of documentations in place. Most of the little traditions, the flow of knowledge is mainly through word of mouth, however, the great traditions such as Ayurveda and Traditional Chinese Medicine do have a good level of documentation. For instance, Ayurveda means science of life in Sanskrit and aims at holistic management of health and disease. It remains one of the most ancient medical systems widely practiced in Indian subcontinent and has a sound philosophical, experiential and experimental basis541. Charak Samhita and Sushrut Samhita (100-500 B.C.) are main Ayurvedic classics, which describe of over 700 botanicals along with their classification, pharmacological and therapeutic properties542,543. A classic diagnostic text Madhav Nidana includes over 5000 signs and symptoms. During the course of evolution and years actual practice, the interpretation of such documents developed different schools of thoughts and resulted in wide variations in understandings. Similar situation also exists in other systems including TCM. These differences often raise issues related to authenticity and correctness of Traditional Knowledge (TK). Thus systematic documentation, interpretations and harmonization of concepts and practices remain a major challenge in most of the systems of TM. Many governments, professional and community organizations have undertaken such documentation and harmonization exercises. Projects like Traditional Medicine Knowledge Digital Library, AyuSoft, Triskandha Kosha and Medicinal Plants Database of FRLHT are attempting systematic documentation of Ayurveda in India544. Other databases such as The NAPRALERT (NAtural PRoducts ALERT) developed by Professor Norman Farnsworth contain bibliographic and factual data on natural products, including information on the pharmacology, biological activity, taxonomic distribution, ethno-medicine and chemistry of plant, microbial, and animal (including marine) extracts. Another project relates to the Global IP, Benefit Sharing and Traditional Medicine Database. It is being developed as a component of the Global Information Hub on Integrated Medicine from the work of the Commonwealth Working Group (CWG) on Traditional and Complementary Health Systems, now directed by the Malaysian Ministry of Health. This Information Hub is planning to create a network of legal centers, scholars and NGOs working together to develop a comprehensive legislative and policy review, information resource and exchange on issues pertaining to IP rights over traditional medical knowledge and the use of medicinal plants545. Other than such efforts, there is limited systematic documentation of TM knowledge and practices.

Genetics forms the basis of human life. All individuals have a physical and physiological self, determined by the interactions of genes and environment. Pharmacogenetics is the connotation used to study how heritability affects an individual’s response to drugs.494 The term ‘Pharmacogenomics’ represents systematic identification of all human genes, their products, interindividual variation and intraindividual variation in expression and function over time. It focuses on candidate genes and may include transcriptome and proteome information that affect drug metabolism, pharmacokinetics, and pharmacodynamics. It helps in predicting the patient’s response to a drug and to design new drugs495. Pharmacogenetics is study of single genes and the effects on drug response while pharmacogenomics is related to overall variation in genome. A gene is considered polymorphic when a mutation appears in more than 1% population, which may be present in the form of single nucleotide polymorphism (SNP), simple sequence length polymorphism (SSLP) and nucleotide addition or deletion. After the Human Genome Project, study in this field is accelerated dramatically. It was found that out of 1.4 million SNPs identified in the human genome, over 60,000 are present in the coding region496. These SNPs lead to miscoding of the various proteins that plays crucial role in the biological processes. If a point mutation is present in the gene coding region for various drug-metabolizing enzymes, drug target and drug transporters, it can lead to many non-therapeutic and unpredictable drug responses. In United States, over two million people suffer from severe adverse drug reactions per year and about 100,000 cases are life threatening497.

In the area of pharmaceutical discovery, screening methods continue to play a major role in drug discovery. The screening process is simply testing molecular entities (compounds/natural products) for activity to advance those that exhibit the desired activity. This process has evolved over time in both the testing methods and in the degree of testing. Originally, the screening was done entirely by dosing animals and studying their responses. Then came test tube experiments and now, testing is conducted either with cell lines or with purified proteins in miniaturized test tubes called microplate wells. Screening by microplate has allowed the degree of testing to increase from a very small selected set of compounds to libraries, which contain thousands of test substances. Technological improvements in many areas of science and information technology have led to the evolution of screening methods from time consuming, animal dosing studies to high throughput screening (HTS) methods that have the potential to generate very large datasets of information in a very short time. Today, developments in bioinformatics have opened up the possibility of virtual (in silico) screens for targets where there is sufficient knowledge of the target or of its ligand. High throughput screening has become a pivotal part of drug discovery for identifying potential lead molecules for specific disease targets. The success of screening is measured by several factors including the throughput and costs of the assays, but ultimately by how many of the HTS hits progress forward through the drug discovery pipeline. Miniaturization of assays by conversion from 96- to 384- to 1536- wells to well-less platforms, such as microarrays and the utilization of automated equipments are methodologies implemented to increase the throughput and reduce the cost of the screen.

The main purpose of herbal drug technology is to convert botanical materials into medicines with a focus on standardization and quality control with proper integration of modern scientific techniques and traditional knowledge. The use of chromatographic techniques and marker compounds to standardize botanical preparations has limitations because of their variable sources and chemical complexity. DNA-based molecular markers have utility in fields like taxonomy, physiology, embryology, genetics etc. DNA based techniques have widely been used for authentication of plant species of medicinal importance. Pharmacognosy mainly addresses the quality related issues using routine botanical and organoleptic parameters of crude drugs, and chemoprofiling assisted characterization with chromatographic and spectroscopic techniques. The new pharmacognosy includes all the aspects of drug development and discovery where the biotechnology driven applications play an important role. Current focus on chemotype-driven fingerprinting and related techniques require integration with genotype-driven molecular techniques so that an optimal characterization of botanical materials is possible. This review provides a brief account of various DNA based technologies that are useful in genotyping and quick identification of botanicals with suitable examples.

Review of Health Claims

Regulators of different countries have different procedures and views to review health claims of traditional medicine, herbal medicines, botanicals, functional foods, nutraceuticals, health products, diatory supplements and such other natural forms of materials intended to use for health promotion. However, if such products carry any therapeutic or health benefit claims then the regulators may provide general guidance and demand for sufficient evidence base in support of such claims. For instance, U. S. Food and Drug Administration, Center for Food Safety and Applied Nutrition (CFSAN) provides general guidance to review of health claims in functional foods and dietary supplements. Ethnopharmacological preparations involving herbal medicine and traditional medicines prepared from natural ingredients also will need similar process. The scientific review process for health claims of such products is comprehensive and mainly focuses on review of individual studies³²⁴

This guidance explains when a botanical drug may be marketed under an over-the-counter (OTC) drug monograph and when FDA approval of a new drug application (NDA) is needed. In addition, this document provides guidance to sponsors on submitting investigational new drug applications (INDs) for botanical drug products, including those botanical products (or botanicals) currently lawfully marketed as foods and dietary supplements in the United States. This guidance also discusses several areas in which, because of the unique nature of botanicals, FDA finds it appropriate to apply regulatory policies that differ from those applied to synthetic, semisynthetic, or otherwise highly purified or chemically modified drugs (including antibiotics). In particular, the guidance states that applicants may submit reduced documentation of preclinical safety and of chemistry, manufacturing, and controls (CMC) to support an IND for initial clinical studies of botanicals that have been legally marketed in the United States as dietary supplements or cosmetics without any known safety concerns.

The development of a new drug begins typically in the chemistry laboratory and is followed by a wide range of biological studies in vitro (cells/tissues) and in vivo (animals), which forecast what the agent would do in humans. The focus of these studies moves from evaluating the safety of a drug for use in humans to looking at its clinical relevance. Pharmacodynamics involves a set of biological studies both in vitro and and in vivo to get a better understanding of the mechanism of action of a drug. Preclinical studies mainly include safety and toxicity to ensure its safety for use in humans. Typically, preclinical in vitro, in vivo, and Phase I testing may not be necessary if preliminary data on safety are available. However, preclinical data or clinical observations are still necessary to justify a rationale for use and safety in initial clinical studies.

Three main screening approaches are generally used in drug development. Simple Screening evaluates substances that have a particular property by one or two tests. There is no need for a series of tests in which the interpretation of results of one test may depend on others. Blind Screening is used for a new plant extract where no adequate pharmacological information is available. Blind screening may give clues for potential activity and worthiness to probe further for pharmacological activities. Programmed screening involves a new plant extract or substance with known pharmacological effects and results in more precise information.

Typically herbal pharmaceutics may include any medicinal or functional food preparations such as phytopharmaceuticals, single or poly herbal formulations, and nutraceuticals made out of botanical materials. This includes two broad categories. First, there are many evidence based formulations and mixures that may or may not be based on traditional knowledge or practices. The second group includes all the traditional or ethnopharmacological preparations. Bringing herbal medications from either group to the market will require a pharmaceutics approach balanced with an understanding of the original context in which the treatment was used.

As an example, Ayurvedic medicines have been used safely for many years on a wide variety of patients. Medications that have not been altered from their original form have de facto gone through a type of safety testing. When a traditional medicine is prepared differently, then it is essential to validate the drug safety to be sure that the effects of the new procedure don’t cause harmful effects. In this same way, the value of animal testing to establish safety and toxicity is not as critical if the botanicals are used in traditional forms. Suitable animal models help in understanding the mechanism of action or pharmacodynamics of medicines. However, it is well known that no good animal models exist for many human diseases, such as asthma, diabetes, and rheumatism. The use of modern technology in making traditional preparations more contemporary and scientific is important but it should not compromise the original basis and principles described in tracditional medicine. The following examples highlight some of the concerns of this approach.

Despite its existence and continued use over many centuries, and its popularity and extensive use during the last decade, traditional medicine has not been officially recognized in most countries. Consequently, education, training and research in this area have not been accorded due attention and support. The quantity and quality of the safety and efficacy data on traditional medicine are far from sufficient to meet the criteria needed to support its use worldwide. The reasons for the lack of research data are due to not only to health care policies, but also to a lack of adequate or accepted research methodology for evaluating traditional medicine235.

The statement from General Guidelines for Methodologies on Research and Evaluation of Traditional Medicines (World Health Organization, 2000) highlights the need for consensuous in addressing the problems related to the quality of botanical drugs, which ultimately is a critical determinant of safety and efficacy of medicine. Further, the distribution and widespread sale of adulterated, misbranded, spurious botanical drug products and marked increase in misleading health claims of these products demands proper regulations on botanical medicine to protect public health236. Considering these two issues development of parameters for quality control standardization and regulatory norms for controlling the growing business of botanicals is a big task. Various regulatory authorities, research organizations and botanical drug manufacturers are constantly contributing to developing guiding principles addressing issues related to quality, safety and efficacy237. In this chapter we have highlighted problems associated with quality control of the botanicals and tried to guide a way towards a globally acceptable quality standard.

Safety is a primary concern regarding traditional and complementary therapies. There are two aspects of safety evaluations. First, to ensure that the right quality of material and apt possesses are used from sourcing to marketing; and second, there is no contamination, adulteration or spiking. Few studies have reported adulteration with steroids in some traditional Chinese dermatological preparations. In an analysis of Chinese herbal creams prescribed for dermatological conditions, Keane et al. found that eight of eleven creams analyzed contained steroids194. Spiking with corticostreoinds has been observed in some market preparations claimed to be useful in the treatment of arthritis and asthma195. Recently, Saper et al. from Harvard Medical School have reported heavy metal content of Ayurvedic herbal preparations and have recommended mandatory toxic heavy metal testing196. There have been few reports of heavy metal toxicity following traditional medicine use197,198. Such studies are important and needed, however they are more related to the quality control failures of the mass manufacturing activities. Often they are wrongly used to limit the use of TM. In reality, such a QC failure should not be considered as a general negative notion to create a bias against TM. We certainly need effective QC and regulation of herbal medicines, without limiting public access to these preparations and ensuring public interest and constituting restrictive trade practice.

Ethnopharmacology and Traditional medines use natural resources as medicines. They have developed the knowledge of this through the generations of traditions and experiences. Therefore the protection of this knowledge and protection of natural resources both remain critical. Bioprospecting involves sustainable, ethical and legal processes to access natural resources and use them judicially so that the business needs do not pose any threat to nature and to people.

One important consideration is assuring the preservation of traditional knowledge, particularly oral knowledge, within communities, for the potential benefit of others. Developing mechanisms to document traditional knowledge, such as national inventories, can be beneficial in identifying cases where conservation or cultivation is needed, based on an understanding of existing natural resources used for medicinal purposes. Decisions about access and ownership of information can also be made (including those relating to intellectual property rights, where appropriate) once methods have been found to collect and preserve traditional knowledge. On the other hand, the livelihood of traditional healers may depend on maintaining the secrecy of their healing methods - one argument for consulting with traditional healers as part of the process of planning and executing the collection, storage and testing of traditional medicines.

Extending some form of intellectual property protection to traditional knowledge, of which traditional medical knowledge is a significant part, is being actively debated in WIPO and other international forums. Existing intellectual property regimes can offer protection for purified compounds (produced by scientists and companies) isolated from a natural medicine. But traditional medicines, whose method of action may not be well understood, and which often consist of mixtures of different active substances, may not meet criteria for patentability. The principal impetus for international debate is a desire to compensate the holders of traditional knowledge appropriately for the use of their knowledge by others, or to prevent so-called “biopiracy” where knowledge or genetic materials are used without the consent of the holder. China and Kenya are examples of countries that have modified their laws in an effort to accommodate traditional medicine. It is not intended that the Commission should enter into this debate, except in so far as aspects of it may be relevant to its terms of reference, in particular stimulating innovation in traditional medicine with the purpose of expanding access to affordable medicines.

Contrary to “Law of Finite Biology” though the number of genetic codes will exhaust soon in an exponential way (presumably leading to solutions to every known genetic anomaly related health problem), the number of NCE (New Chemical Entity), their number being finite⁹⁹ too, will run out of fuel soon too, despite unraveling of genomic decoding. The bleak scenario in the pharmaceutical field is a testimony to the latter surmise. As many a wise scholar has pointed out, the era of single molecule drug seem to drawing curtains. However, unlike what seems common sense, the era of combinational drug therapies of MM paradigm probably will not foot the bill. Just as very high speed serial computing simulates parallel processing but does not make real time parallel processing, mixtures of prima facie complementary medicinal molecules will perhaps not make combinational recipes. The fundamentals of non-linear dynamical complex systems (NLDCS) paradigm demand so. The odds against success with such efforts are close to odds of success of creating life one bit at a time out of mixing C, H and O molecules in a jar would be. The number of genes might be finite, but data on their combinations (and their corresponding effects) and more so on their permutations (one has to only imagine the vastness of those possibilities) would, as of now or in near future, cause an information overload and comprehension failure¹⁰⁰ (limitation of human biological brain apparatus) pitting researchers and industry against a futility barrier. However, TM provides a silver lining to these bleak analyses. Analytical comprehension of TM recipes, regimens or techniques might be unachievable by contemporary science, empirical testing of their efficacy and safety being doable and therefore taken care of, TM can provide an outlet to the drug discovery impasse because the same natural forces that shaped multi-gene interaction into complex and dynamical mode have created some of, if not all, TM solutions.

The R&D thrust in the pharmaceutical sector is focused on development of new drugs, innovative/indigenous processes for known drugs and development of plant based drugs through investigation of leads from the traditional systems of medicine. In addition, many nutraceuticals are being consumed from unregulated markets for their perceived benefits in health care and improvement of quality of life.

Natural pharmaceuticals, nutraceuticals and cosmeceuticals are of great importance as a reservoir of chemical diversity aimed at new drug discovery and can be explored as potential antimicrobial, cardiovascular, immunosuppressive, and anticancer drugs. Around 80% of all such products are of plant origin; their sales exceeded $ 65 billion in 2003. Examples of plant products and derivatives used by the pharmaceutical industry include Paclitaxel, Vincristine, Vinblastine, Artemisinin, Camptothecin, Podophyllotoxin and such.

The nutraceutical marketplace in Europe is estimated to be $ 9 billion, while the US marketplace, estimated to be $10-12 billion in 2003, is expanding at a compounded rate of more than 20% per year. US Congress has fueled the rapid growth of nutraceuticals with the passage of the Dietary Supplement Health and Education Act (DSHEA) in 1994. Globally, there have been efforts to monitor quality and regulate the growing business of herbal drugs and traditional medicine.

Historically, the terms alternative, complementary or traditional medicine (TM) all referred to a genre of health care practices or services that got bound together as a class through the logic of reductio-ad-absurdum, or because of their “absence from the mainframe of” what has come to be known as Modern Medicine (MM). However, since Stephen Fulder¹ , the identities of TM have become more distinct, MM-TM blending more active and, the line separating the two more fuzzy. To date, the World Health Organization offers the most comprehensive definition of TM² .

WHO defines traditional medicine as including diverse health practices, approaches, knowledge and beliefs incorporating plant, animal, and/or mineral based medicines, spiritual therapies, manual techniques and exercises applied singularly or in combination to maintain well-being, as well as to treat, diagnose or prevent illness.

The phraseology MM/TM is syntactically incorrect because it is contended that medicine as such, modern or otherwise, evolves and progresses through traditions. The major difference between the various traditions of health care practices is that MM rode the crest of the high wave of reductionist-scientistic rigor of modernity³ to reach the shore of global acceptability while the others never crossed the threshold of geographical and cultural locality, remaining untested, neither proved nor disproved. Darwinian principle of survival of the fittest also endorses a truism that survival is a proof of fitness. Given this principle, it makes sense that TM as we know of it today may be useful for promoting human health. Moreover, most TM considers human beings and their health in the context of their environment. This criteria, not only defines TM apart from MM but also provides for a reason as to why lately TM is emerging out of long hibernation. Developmentally, MM isolated “human” from its global environmental context as a static, stand-alone, complete, total and delimited system in itself. While this reductionist approach has a very high pay off for the first 90% of human health problems, it fails when dynamic non-linear complex systems elements kick in (I’m not exactly sure that you mean by this phrase). TM covers some parts of those hidden variables and thats the utility to modern mankind.

To fully explore the history of medical and drug development, it would be necessary to go back as early as 13,000 BCE, where drawings on the Lascaux caves in France suggest that humans were using plants for medicinal purposes. Since then, medical traditions have evolved and dissolved across societies all over the globe. Natural products including plants, animals and minerals have been the basis of treatment of human diseases. The last two centuries have seen a focus on scientific medicine, with a focus on drugs whose effects that have been proved by the scientific method. Yet given this setting, many of the major pharmaceutical corporations have renewed their strategies in favor of natural product drug discovery. Numerous drugs have entered the international pharmacopoeia via the study of ethnopharmacology and traditional medicine. At this point in history, it is possible for both traditional and western medicine to benefit from collaboration between the two disciplines. For traditional medicines, newer guidelines of standardization, manufacture and quality control and scientifically rigorous research on the scientific basis for traditional treatments will be required. In return, traditional medical traditions can offer a more holistic approach to drug design and myriad possible targets for scientific analysis. Powerful new technologies such as automated separation techniques, high-throughput screening and combinatorial chemistry are revolutionizing drug discovery. Traditional knowledge can serve as powerful search engine, which will greatly facilitate intentional, focused and safe natural product drug discovery and help to rediscover the drug discovery process. By looking at the historical trends in drug and medical developments, it is possible to understand how current drug development will benefit from this partnership.

‘Fungi’ including ‘mushrooms’ are ‘Thallophytes’, which do not possess chlorophyll and have been classified under the Kingdom - Myceteae. They do not have stems, roots and leaves and they lack a vascular conducting system as in the case of plants. They propagate by means of spores, either asexual or sexual. Though almost all the fungi are microscopic, the mushrooms are among the largest fungi and had attracted the attention Scientists and Naturalists of many countries dating back to centuries. The Greek word ‘mykes’, which means ‘cap’, was given to the mushrooms because of the ‘cap-like’ appearance of the pileus and the Greek word ‘Mycology’ (mykes = mushroom + logos = discourse) denotes the study of mushrooms. What we call mushrooms, are actually the sporocarps produced by several species of fungi, while the mycelium that produces them live in various types of substrata and obtain nourishment from them. Usually, the fleshy, macroscopic fruiting bodies or sporocarps produced by fungi belonging to Basidiomycetes and Ascomycetes are called ‘mushrooms’

The Romans attributed the appearance of mushrooms and truffles to lightning hurled by Jupiter to the earth. Even now in India and several other countries, people believe that mushrooms appear only after lightning and thunder. The Greeks believed mushrooms as ‘Food for the Gods’. The Romans supplemented mushrooms in the food of soldiers for strength and vitality. The much-priced mushrooms were supposed to be the food delicacy of the elite society of the Romans and Greeks in olden days. The Chinese consider mushrooms as a cure for many diseases and they believe that mushrooms increase the longevity. A number of medicines in all forms are prepared from mushrooms by the Chinese.

FRUIT CROPS

Banana (Musa species)

1. Panama disease of banana
Fusarium oxysporum f.sp. cubense

‘Panama disease’, ‘Fusarium wilt’ or ’vascular wilt’ of banana is one of the most serious and destructive diseases of the crop. The disease was first reported from Australia in 1874. Now, it is widely distributed all over the world, including America, Africa, Sri Lanka, Burma, Thailand, Malaysia, Indonesia, Hawai, Fiji, the Philippines, India, Australia and New Zealand. In India, it is prevalent in the states of Assam, Bihar, Karnataka, Kerala, Tamil Nadu, Telungu Desam, Maharashtra and West Bengal.

Symptoms. Usually the symptoms are manifested, when the banana plants are about 5 months old. However, under highly favorable conditions for the pathogen, even 2 - 3 months old plants show wilt symptoms. Initial visible symptoms appear as pale yellow streaks, lengthwise in the petioles of the oldest, lowermost leaves. Two types of symptoms follow this. In the first type, the old leaves turn yellow progressively and finally they break from the petiole and hang down. In the second type, the leaves break from the petiole and hang down, without becoming chlorotic. Gradually, all the leaves collapse and hang down, except the crown, which alone stands upright. The newly formed leaves show yellow blotches and wrinkling of the lamina. Often, the leaf sheaths covering the pseudostem show longitudinal splitting above the ground level. But, sometimes this symptom may not appear. The affected plants may die completely in about 4-6 weeks after the appearance of yellow streaks on the petioles.

The vascular strands show discoloration varying from yellow to dark- brown, which is the characteristic internal symptom of the disease. The discoloration usually appears first in the outer leaf sheaths and extends to the vascular strands of the pseudostem. Vascular discoloration is more pronounced in the corms, but is not common in the roots. When the rhizome of an infected plant is cut transversely, the discoloration of the vascular bundles is distinctly seen as numerous, pin-point like dots all over the cut surface. The roots of affected plants become black and rotten. The suckers growing from the diseased corms are systemically affected and they wilt and die very soon (Fig. 71).

The causal organism. The mycelium of the fungus is hyaline, septate, much branched and mostly intracellular. Few hyphae may also be present in the intercellular spaces. The hyphae are largely confined to the vascular bundles, often filling the cavity of the vessels. The fungus produces three types of spores viz., macroconidia, microconidia and chlamydospores. The sporodochia bearing conidiophores and conidia emerge through the stomata on the petioles and leaves. The conidiophores are vertically branched. Macroconidia are borne at the apical ends of the main and lateral branches and are formed in succession one after another. They are thin-walled, hyaline, pedicellate, sickle-shaped, with both ends somewhat pointed, 2 - 5 septate, mostly 3-septate and measure 22.0 - 36.0 x 4.0 - 5.0µ in size. Microconidia are produced from the branches of conidiophores or from the tips of hyphae in very large numbers. They are single-celled or two-celled, thin-walled, hyaline, ovate or elongated and measure 5.0 - 7.0 x 2.5 - 3.0µ in size. Terminal or intercalary chlamydospores are formed from the hyphae, as well as from the conidial cells. They are oval or spherical, thick-walled and usually occur in pairs. They measure 7.0 - 13.0 x 7.0 - 8.0µ in size (Fig. 71).

The fungus is a facultative parasite. It can invade the host mainly through wounds in the corms or roots. After entry, the fungus develops extensively in the vascular tissue of the corm and then proceeds systemically to the leaf sheaths and pseudostem through the vascular system. The fungus colonizes the vascular bundles and produces masses of mycelium, which bear conidia and chlamydospores, filling the cavity of the vessels. The plugging of vascular elements by the fungus obstructs the translocation of water and nutrients to the aboveground parts of the plant leading to wilting and death of affected plants.

Mode of survival, spread and epidemiology. The fungus is soil-borne in nature. It can survive saprophytically in the diseased corms and other plant parts for prolonged periods and cause fresh infection. The chlamydospores can also remain in a viable state in the soil and diseased plant parts for a long time. The disease can be easily spread through spores present in the infected banana trash and soil, which may be carried in surface flooded water. Suckers used for planting from diseased areas to other places spread the disease easily. Contact of the roots of healthy plants with the roots of diseased plants carrying the spores also leads to fresh infection. The entry of the pathogen is mostly through wounds in the roots or corms, especially deep wounds up to the xylem vessels, caused incidentally during cultural operations or by soil-inhabiting pests, particularly nematodes.

Light textured, sandy loam soils, with acid reaction and low soil moisture of 25 % favor the occurrence and development of the disease. Ratooning of infected banana plants increases the disease incidence to a great extent and leads to continuous accumulation of soil inoculum.

CEREALS

Rice (Oryza sativa)

1. Rice blast
Pyricularia oryzae

‘Rice blast’ occurs in more than 80 countries across the world. The disease is more prevalent in Thailand, Japan, America, Guyana, Philippines and India. It is particularly serious in places, where rice is irrigated or receives heavy rainfall and where high levels of nitrogenous fertilizers are applied. Rice blast was first reported in China in 1637, in Japan in 1704 and in India in 1913. In India, it is found in all rice growing states, particularly in Telungu Desam, Karnataka, Maharashtra, Uttar Pradesh. Assam, Tripura, West Bengal, Bihar, Orissa, Himachal Pradesh, Punjab, Madhya Pradesh, Gujarat, Kerala, Tamil Nadu and Pondicherry and causes considerable damage to rice crop. In Tamil Nadu, the disease occurs in all rice growing districts and attains epidemic proportions in some seasons. Several rice blast epidemics have occurred in different parts of the world, causing yield losses ranging from 50 to 90 %. In Tamil Nadu, a serious epidemic of the disease occurred in 1919 in the Thanjavur Delta.

Symptoms. The disease, though chiefly a foliage disease, attacks other parts of rice plants, such as leaf sheath, rachis, joints of the culms and even the glumes. On the leaves, the initial symptoms appear as small bluish or grayish specks, which remain circular in older leaves. On young leaves, they enlarge and become eye-shaped, diamond-shaped or spindle-shaped spots, extending over several centimeters in length and about 1.0 cm. in width. The central portion of the lesion appears pale green or grayish green and water-soaked in the beginning. In older spots, the center becomes white to gray with a dark-brown margin surrounded by a yellow hallow. The lesions may coalesce, cover large area of the leaves and eventually the entire leaves are killed. The shape, size and color of the spots vary depending upon the variety, growth stage of the plants and environmental conditions. Similar spots may be formed on the leaf sheath also. During severe incidence, large areas of the leaves dry and die and the entire crop presents a burnt appearance. Hence the disease is known as ‘blast disease’. Leaf blast is more severe during the seedling and maximum tillering stages. In the nursery, the seedlings show numerous spots on the leaves, which wither and die. In case of severe infection, large number of seedlings may die. Blast also affects the leaf collar, which results in the death of the entire leaf.

The disease attacks the stem-nodes at the heading stage leading to production of ‘white panicles’ or the stem may break at the infected node. Rarely the internodes are affected. Further, at heading the fungus also attacks the panicle neck, which is girdled and becomes shining black and shrivelled. This is the most destructive phase of the disease and is known as ‘neck blast’, ‘neck rot’ or ‘panicle blast’. If infection of the panicle neck occurs early, the grains become chaffy and the panicle remains erect. If panicle neck infection occurs late, the grains become partially filled and because of the weight of the grains, the panicle breaks at the neck- node and droops. Sometimes, only parts of the panicle and joints of the culms and some glumes are infected and develop brown to black spots (Fig. 1).

Under conditions highly favorable for the pathogen, even the varieties resistant to the fungus under normal conditions are also attacked and small, round or short elliptical spots develop. However, the spots normally do not enlarge as typical blast spots.

7.1 Economics and Valuation of ghgs emissions

Since the late 20^th century, it has been largely accepted that cause of high concentration of GHGs in atmosphere is induced by human activities. Greenhouse gas emissions and related climate change has opened up debate on overall economic losses and ways to reduce these loses. Moreover, apart from curbing monetary losses; the global political leaders as well as reputed economists are looking towards making money by saving the emissions. Recently, the researchers have started to emphasize on the actual value added to the ecosystem by curbing emissions, discrete of the economic benefits. This section will discuss the economics and ecosystem services related to the management of GHG emissions.

Origin

The initiative to curb the emissions started in 1992 with the United Nations Framework Convention on Climate Change (UNFCCC) at the Earth Summit in Rio de Janeiro. The Convention took place from 3 to 14 June, 1992. The UNFCCC is an international environmental treaty designed to “stabilize greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system”. The UNFCCC had non-binding limits on greenhouse gas emissions for individual countries and the framework was only meant for formulating precise international treaties (called “Protocols” or “Agreements”). It contained no execution mechanisms, however, it considered some negotiations and suggestions to formulate the action plans and regulation guidelines under UNFCCC to fulfill the objective of reduction of GHG emissions to the desired level.

What is mitigation of GHGs emission? We must be clear about the answer of this fundamental question. In simple term, the mitigation of GHGs emission is the way or means by which the emission of those gases could be reduced. As we know from the previous chapters of this book that the GHGs emission could be occurred from natural as well as anthropogenic activities. Natural activities included volcanic eruptions, ocean current fluctuations, continental drifts which are responsible for emission of huge amount of CO₂ and other GHGs. The reduction of emissions from those natural activities is beyond our capabilities. However, the human induced emissions of GHGs emission could be reduced. We studied in previous chapters that fossil fuel burning, industrial and energy sector pollution, deforestation, land use change and agricultural could contribute to GHGs emission considerably. Mitigation techniques are different for each of those sectors that governed by lot of interrelated factors. In actual sense, the mitigation of GHGs emission should includes all the measures that can curtail the anthropogenic emission from all sectors. But that is out of the scope of this book. In this book, we specifically address the mitigation principles, options and efficiency of different techniques/ practices in agriculture only.

In that aspect, the mitigation of greenhouse gases emissions in agriculture is defined as “the means and ways by which emissions of GHGs could be reduced from agriculture”. The ways and means actually referred to the techniques and practices and their amalgamation in agricultural sector both in production, processing and consumption aspects. So, mitigation is not only a techniques or combination of techniques it is actually an integrated approach for reducing greenhouse gases emission from agricultural systems. Primarily, there are two complementary approaches for mitigation of GHGs emissions from agriculture. Those two approaches are (i) supply-side and (ii) demand- side options or pathways. The supply-side approaches includes scientific land- use-changes, improvement of crop management, better livestock management practices, enhancing carbon storage in biota, soil carbon sequestration, significant substitution of fossil fuel by bio-fuels and use of renewable energy in agriculture. On the other hand, demand side approaches, taken in to account of shifting in the dietary pattern from non-vegetarian to vegetarian, curtail down the food loss and waste, and reducing the supply-chains (Figure 6.1). We can see, most of the approaches in supply-side are technology driven, while, approaches in demand-side are socio-economical and or policy driven. In this chapter we would thoroughly discuss the principles of mitigation, options of mitigation, mitigation cum adaptation approaches to reduce GHGs emission and climate change and few strategies to cope up with the vagaries of climate change.

5.1 Impact of climate change on agriculture

Climate change has both positive and negatively impact on agriculture, food security and land degradation. Climate change could exacerbate the land degradation processes by increases in rainfall intensity, drought frequency and severity, dry spells, f looding, heat stress, sea-level rise and permafrost thaw. The 1/4^th of ice-free land area in the world is prone to human-induced anthropogenic degradation (Certini and Scalenghe, 2011; Hooke et al., 2012). Soil erosion rate is 20-100 times faster than that of soil formation in agricultural field. The erosion rate is least is zero-tillage (non-disturbed field) and maximum at conventional intensive tillage practices. Climate change further exacerbates the land degradation. The permafrost areas, dry-lands, low-lying coastal regions, river deltas are more vulnerable. The occurrence of drought in dry-land was increased by around 1% per year during 1961-2013 periods. On an average 380-620 million people globally experienced desertification who lived in dry-land areas (1980s and 2000s) in South and East Asia, North Africa, Middle East, Sahara region, and Arabian peninsula. Moreover, people who are already living in degraded/ desertified regions are more negatively affected by climate change.

Specifically, the land surface air temperature has increased about twice as much as the global average temperature since the pre-industrial era. The land-surface air temperature has increased relatively higher than the world’s average surface (land and ocean) temperature since the pre-industrial era (1850-1900). The average land-surface air temperature has enhanced by 1.53°C (1.38-1.68°C), whereas, world’s surface (including land and ocean) air temperature has enhanced by 0.87°C (0.75-0.99°C). Subsequently, global warming triggered the frequency, intensity and duration of heat waves and related damage. The direct and indirect impacts of climate change on global agriculture is summarised below for an overall idea about the importance of the issues.

The measurement of greenhouse gases (GHGs) has been started during middle of the last century. Initially, CO₂ and water vapour were measured with other common meteorological variables like temperature, sunshine hours, rainfall, humidity etc., for monitoring the weather condition and pollution. The absolute or relative concentrations of gasses in atmosphere are used to measure basically for monitoring purpose. However, limited studies were dealt with actual gaseous exchanges of fluxes. The concern about gaseous flux measurement and GHGs-exchanges started after 1900s when people got concerned about anthropogenic pollution, environmental sustainability and climate change issues. The GHGs-exchanges in earth-atmosphere systems primarily occur due to change in meteorological variables, soil responses and physiological activities of crops. If we are interested for environmental data inventories, then absolute GHGs concentrations of atmosphere at a specific time is required. However, presently researchers, students, environmentalists, climate scientists are primarily interested for quantitative data on GHGs fluxes and or GHGs-exchanges. They want to know what and how much quantity of a particular GHG is emitting from unit area at unit time.

Flux refers to the amount of any gas emitted per unit area per unit time. The dimension of that is M A^-11 T^-1. (Where, M= Mass/ Quantity; A= Area; T= Time). The SI unit of flux is g m²s^-1. Therefore, flux is a vector. It has magnitude as well as direction. As for example positive flux of CO₂ from earth surface means, CO₂ is moving out from earth surface to atmosphere. If it moves in opposite direction then the flux would be negative. In that case CO₂ gas may be absorbed by the soil surface from adjacent atmosphere. Similarly, GHGs fluxes of earth surface are either positive or negative. Generally, positive GHGs flux refers to emission of GHGs from earth to atmosphere and vice versa.

3.1 Chemistry of greenhouse gases (ghgs)

Greenhouse gases (GHGs) are atmospheric-gases that have capabilities to absorb and radiate-back the infrared (IR) radiation in the earth-atmosphere system (Figure 3.1). In this process the atmospheric-gases absorb and radiate- back IR radiation in lower atmosphere effectively emitting and absorbing heat energy heat energy. They maintain the heat budget of earth-atmosphere and keep our plant warm. If we typically see the chemistry of those gases, the key point is that they should have dipole moments. This is the property which makes them capable to absorb and radiate-back the range of IR radiation. In a molecule when valence-electrons are not equally shared in a bond between the two atoms, a slight positive charge is developed above one atom and a negative charge on the other atom. That charge difference of the different atoms in a molecule generates the dipole moment. For instance, in water vapour (H₂O- vapour), an unequal sharing of electrons and or separation of charge causes dipole moment. In H₂O, the centre has a positive charge at the hydrogen atoms and negative charges are located on the oxygen atom. The magnitude of dipole- charges, vibration and stretching of O-H bond generates certain frequency of the oscillating dipole moment that actually regulates the absorption capacity of IR radiation by H₂O vapour.

Climate change is caused by both natural as well as anthropogenic causes and it has been changing since the inception of earth-atmosphere (Figure 2.1). In a broader sense, anthropogenic activities (human activities) also must be considered as natural one in longer time scale as human and their activities are also a part of natural-ecosystem-functions. Among the natural phenomena, volcanic eruptions and continental drifts significantly affect the earth’s precipitation and temperature. A huge volume of CO₂ is released due to volcanic eruption at a little span of time-period which heated up the earth-atmosphere. Climate variability is primarily governed by rise in sea temperature, movement of warm water from the Western Pacific towards Peru, and El Nino which occurs at an intervals of 3-7 years. Climate variability also influenced the alteration in temperature and precipitation world wide. And persistent climate variability cause long term climate change. Therefore, basically three drivers that causes climate change are, the alteration in the energy of sun received by earth-atmosphere (natural causes), variations of ref lectivity of earth-surface- atmosphere system (natural as well as anthropogenic causes) and fluctuations in the greenhouse effect (natural as well as anthropogenic causes).

1.1 Weather

Firstly, what is weather? Simply, the conditions in the atmosphere above the earth is called weather. It refers to the conditions such as wind, rain and temperature, prevailing at a particular location during periods of hours or days. We often ask “what’s the weather like today”? Any individual can answer to this question as it requires only a short term experience or say exposure to the atmosphere. The TV news forecasters predict weather each day and inform about the temperature, cloudiness, humidity, or possibility of storm in the next few days. Weather is localised, say, it’s a hot and cloudy weather in one part of the country and dry and windy on the other part.

1.1.1 What are the factors that influence weather?

Before we try to understand the factors that influence weather, we must understand what the components that describe a weather conditions are? Is it the rains, or the air temperature or both? The answer to this question is not so easy, and it’s a bit complicated. There are many components that constitute weather. Weather components include rain, cloud cover, sunshine, winds, hail, snow, sleet, storms, thunderstorms, heat waves and many more. These components are sometimes referred as weather parameters or climate elements. Each of these components define weather patterns of a particular area. These components determine the status of local atmospheric conditions. Again, as a basic definition, weather is the state of the atmosphere and majority of weather phenomena occur in the lowest layer of the atmosphere, called as the troposphere. Does it mean that ground conditions such as the topography, water bodies and vegetation of a particular area has nothing to do with it? No, it is not so. The state of the atmosphere is subjected to various processes taking place not only in the atmosphere but also in the ocean, the sea-ice, the vegetation, etc. Weather parameters or the components of weather form a sequence of events, and the influences are far reaching and they do not remain solely in the atmosphere. For example, terrestrial radiation impacts the air temperature, air pressure and humidity. The terrestrial location also influences the cloud formation. The clouds may or may not turn into precipitation depending on the outcome (cloud or rain), which is by and large governed by troposphere. Likewise, a lack of precipitation affects not only weather conditions, but also soil moisture conditions that may result in lowering of water levels (ground water table) in soil. Wind speed and direction are governed by the atmospheric pressure and air temperature. So, all these parameters or components are interrelated and the weather conditions are the outcome of their interactions. Therefore, we can say that, the three main components of weather are temperature, precipitation and solar radiation. These components are influenced by different factors.

19.1. Remedies to Combat Unemployment in Nigeria

(a) Rural development

One way of stemming the rural-urban drift, and thus control the resulting unemployment in our urban centers, it for the government to develop the rural areas. Not only should amenities be provided, but jobs should be created in the rural areas to stem the exodus. Fortunately, the Babangida administration seemed to have realized this with the huge amount allocation for the development of rural areas in the 1986 and 1987 budgets.

(b) Population control

Government must intensity the effort to control population growth Nigeria already has a huge population and with an estimated growth rate of about 3 percent annually, this can only compound the unemployment in the face of inadequate resources. It is therefore advocated that the government should renew the family planning campaign to check the population growth.

18.1. Basic for Government Intervention in the Economy

One of the most powerful arguments to justify government intervention in the economy in the economy is the so-called concept of market failure. In a typical free enterprise system where demand and supply forces operate, the efficiency which results only relates to economic welfare. The social cost implications of economic activities tend to be ignored. Governments therefore intervene in the economy with the social welfare objective in mind. One popular way by which governments have intervened in the economy is through ownership of particular industries or outright nationalization of some private enterprises. The advantages usually claimed for such an action are as follows:

17.1. The Nigerian Unemployment Milieu: Control Measures taken by the Government

At this juncture, the little efforts that have been made by the government to control unemployment to an extent shall be examined. Records from the Central Bank of Nigeria (1987), show the following efforts made by the government:

1. Youths Empowerment/ employment and skills programme. This was done in terms of provided minor jobs or ‘white-colar’ jobs.

2. Agricultural programmes such as the ‘Operation Feed the Nation’ by the Obasanjo Military Administration.

3. Provision of small scale industries and graduates employment.

4. Special public works (which were temporary). Some of these efforts are still in place while others are forgotten. For example, on the pages of the Businessday Newspaper, on August 4th (pg 13), 12th (pg 49), 21st and 27th, 2009 were the following headings revealed: