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The backwardness and underdevelopment of our rural areas have drawn the attention of not only the planners but also those who are interested in the overall development of the India. The numerous schemes have not appreciably raised the living standard of the rural masses. Adoption of traditional agricultural technologies, lack of knowledge of improved practices, in sanitary conditions, inadequate housing and educational facilities are serious challenges faced by the rural masses. Unless we devote our efforts towards this cause, the chances of improvement of rural areas are remote in the near future.  The youth, who are the citizens of tomorrow have a vital role to play.  Youth reflect the national potentiality and represent the life blood of a nation.  Development of youth determines the future of the community and the country as a whole. As psychologists say, youth possess dynamic energy, creative activity and adventurous spirit and undergo physiological and psychological changes as they grow. In agriculture, due to small holdings, erratic rainfall, unrealistic market and price for the produce and meager income from crops, youth farmers are taking up dairying and sericulture as subsidiary enterprises which provide additional income and gainful employment to them as members of farm families throughout the year.  Young members of farm families play an important role in managing these enterprises. A study was  undertaken to know the role of youth in milk and silk farming.

The coastal zone of Karnataka is marked by highly fragmented agriculture land with more than 70 per cent of the land holders belonging to small and marginal farmer categories. Though the average annual rainfall received in the zone is 4000mm, the kharif season crops suffer from submergence and lodging.  The rabi/summer crops fail due to low soil residual moisture because of high percolation loss and poor water holding capacity of soils. Thus, the returns from the land is very less resulting in migration of youngsters mainly to the Arab countries as well as the neighbouring states in search of a job. In this situation, University of Agricultural Sciences, Bangalore through Extension Education Unit, Mangalore has demonstrated the Integrated Farming Systems (IFS) in Udupi and Dakshina Kannada districts to show that the IFS is profitable, sustainable and can secure the livelihood. The demonstrations were taken up in each farmer’sfield continuously for three consecutive years.

To analyze the impact of these demonstrations, case studies of three IFS demonstrated farmers were done during 2007 with the objective of documenting the farming systems demonstrated and the current farming systems practiced by the farmers; to analyze the income and employment generated and their impact on their socio-economic status. The yearwise documentation of the subsystems of the farming systems practiced by each farmer and the net income, percent increase of income over benchmark year, employment generation, cropping intensity, B:C ratio were analyzed. The results of the case studies are presented below.

Youth, as a concept, has been generally defined all over the world as a group of human beings who have reached the end of puberty but have not yet acquired the full rights and duties of adult life ( Friedman: 1971).  Undeniably, the youth constitute a vast reservoir of energy especially in underdeveloped countries including India. Out of the 120 crores population of India, those in the 15 to 30 age group constitute 50 per cent which means that 60 crore young people, men and women, are available for handling various tasks of development, local, regional and national.  Progress of the country depends on the participation and full involvement of all sections of people especially youth. Youth can make their constructive contribution to national development and through which society can benefit from the idealism and sense of dedication of youth. At the same time, they also benefit from their active participation in developmental activities. Since such participation increases their self esteem, give them a sense of identity and of being needed by society.  The human life passes through various stage such as infancy, childhood, adolescence, youth, adult and old. Out of these stages the youth stage is very crucial and dynamic in the life of an individual as from this stage individual starts assuming responsibilities in the life and learns practically the social rules by coming in contact with world outside the family.  Youth is the time of life marked by growth and development. It is the period between childhood and maturity. United Nation has defined youth as those young people within the age group of 15 to 24 years both inclusive. Youth symbolizes zest, idealism, dynamism, enthusiasm and energy.

The efforts to keep pace with the fast life are causing mental and physical tensions. Diversion and relaxation is needed for the revival of spirit and enthusiasm. Leisure is an unimposed free time, after the practical necessities of life have been attended to. It is the time spent in activities chosen by the individual rewarding for its own sake. Choice of leisure time activities may also depend on the regularity of free time. An activity performed during small amounts of free time may be different than the one planned for a large block of free time. The leisure activities have far reaching influence on the personality development of the youth. If these youngsters are trained to make use of their leisure time for productive purpose, their endless energies could be channelised into fruitful development work.

An investigation was carried out involving 120 rural youth from Kapasi and Mardasgaon villages in Gangakhed taluka of Parbhani district from marathwada region of Maharashtra state, to asses the leisure time utilization by rural youth.  The sample included 70 boys and 50 girls.

Profile of Rural Youth

Education : As regards the education of female youth is concerned, 30 percent of them were educated up to H.S.C. and S.S.C, level where as 20 percent of them were educated up to high school level and 10 percent of them were degree holders and educated up to middle school level.

Youth are the creative force potential and a strength symbol for every community. One of the hallmarks of the positive youth development movement is that it is built on a foundation of scientific research. In addition, youth development programs typically work through existing social organizations rather than focusing on individual counseling. The rural youth work of FAO over the years has made significant contributions to make the lives of young people from rural areas more productive and meaningful by strengthening the organizations which serve them. The needs and challenges of rural young people today are greater than they have ever been in the past. In most developing countries, youth make up well over one-half of the total rural population. Because of their number and potential impact, rural youth must be a major part of any equation dealing with immediate and long-term solutions to solving problems of food security and sustainable development. Rural youth living in rural areas get limited opportunities for educational attainment in village areas. Opportunities for vocational guidance are also limited causing them diverting towards non creative activities and for merely wastage of time. An investigation was undertaken to study the socio-economic characteristics  and leisure time activities of rural youth. The study was conducted in College Development Block comprising Hatkanangle, Radhanagari & Bhudargad Tahsils of Kolhapur district, Maharashtra. From the Tahsil, 10 villages were selected randomly.  From each village, nine rural youths were selected randomly. Thus in all 90 rural youth were finally selected for the study. 

Planning Research and Action Institute, Lucknow (1960) found that lack of initial capital considerably hindered the growth of Animal Husbandry Projects in Youth Clubs. It was also revealed that involvement of non-official agencies and training of youth organizers were very important for strengthening youth clubs.
Singh and Prasad (1963) identified that following deficiencies in the working of youth clubs.
    1.    Inadequate knowledge of youth club work on the part of members as well as on leaders
    2.    Non-availability of literature on youth clubs
    3.    Lack of active leadership‘
    4.    Rift between village youth clubs and village panchayat
    5.    Lack of proper guidance and follow up of youth club programme
Behniwal (1964) revealed the following factors as responsible for the successful working of youth clubs.
    1.    Strength of membership in a club 
    2.    Participation in project work
    3.    Participation in games
    4.    Frequency of meetings
    5.    Attendance in tours, rallies and games
    6.    Actual gains received  
Kumar (1965) found that in the successful clubs the youth had clear conception of the importance and objectives of the youth organization. 

It is now a fait accompli that for enhancement of the economic condition of the farmers, just growing of the variety of crops is not sufficient. Along with the crop husbandry, it is the need of the time that farmers must integrate other enterprises with traditional crop production practices. Integration of various farm enterprises in a farm ensures growth and stability in overall productivity and profitability. It also ensures recycling of residues, optimization of resources, reduction of risk and generation of employment. Various enterprises that could be included in farming system are agronomical crops, vegetables, fruits, flower cultivation, dairy, poultry, fishery, goat keeping, piggery, sericulture, mushroom cultivation, agro forestry, bee keeping, silviculture, agro-based industries and food processing. A judicious mix of enterprises complementary to crops and suited to the given farm situations and farmer’s preference would bring overall prosperity.
 
The Integrated Farming System (IFS)  is a complex inter-related matrix of soil, plant, animals, implements, power, labour, capital and other inputs controlled in part by farm families and influenced by varying degrees of political, economic, institutional and social forces that operate at many levels. Under farming system, the farm is viewed in a holistic manner. Farmers are subjected to many socio-economic, bio-physical, institutional, administrative and technological constraints. Integrated farming system conceptually is a set of elements or components that are inter-related with each other and which are interact among themselves.

In recent years, rainfall pattern is changing and the sustainability of irrigated rice ecosystem is threatened by water crisis. Tanks are often not filling or partially filling due to insufficient rains. In order to safeguard the food security, it is necessary to preserve previous water resources and to utilize the limited water most efficiently. In this regard alternate ways of growing rice using minimum water must be explored. Farmers are adamant to grow paddy crop to meet their domestic needs of food and fodder. In such situation Jalasri method can became one of the alternative for paddy cultivation. The Jalasri method is an appropriate system aimed at reducing the cost of cultivation, saving irrigation water, besides increasing grain yield significantly. Earlier Jalasri method was popular as Madagascar method of paddy cultivation.

The silkworm chawki rearing is a vital stage in rearing as it has major influence on cocoon production.  Temperature, humidity and leaf quality are the three key important factors influencing chawki rearing.  Hence, maintaining these conditions at every step is very important and calls for provision of separate chamber. Any alteration in these factors will influence during later ages of silkworm rearing leading to crop losses.  Taking these factors into consideration the Government of India promoted the establishment Chawki Rearing Centres (CRCs) in private sector also.  These CRCs brush the silkworm eggs at one point under controlled conditions and distribute the worms to the needy farmers.
 
In recent years, bivoltine hybrids are becoming more popular in India and particularly in Karnataka.  This is due to the efforts of the Central Silk Board, Karnataka State Department of Sericulture and Japanese International Co-operation Agency.  These Bivoltines have high cocoon shell ratio (24 to 25%), better quality, fetches high cocoon price, better returns, high rendita (5.1 to 6.1) and raw silk percentage (20 to 22%) with filament length of 11502 to 12200 meters.  The farmers could achieve up to 70kgs cocoon yield per 100 Disease Free Layings (DFLs) and quality silk of 2A to 4A grade. 

1. Success Story of Rural Youth in Dairying
 
M.S. Nataraju, P. Sunil Kumar and R. Shashidhar

There is a proverb in Kannada that “Koti Vidyeginthaloo Meti Vidyee Yee Melu” means - among all the professions for livelihood on this earth agriculture is the best profession for better livelihood.  This proverb suits Sri. Vasudeva Indraje, resident of Yenmoor village in Sulliya Taluk of Dakshina Kannada Dist. in Karnataka State. Sri. Vasudeva Indraje is a role model for today’s youth, who are neglecting agriculture and migrating to cities with an illusion of making a quick buck.  Hailing from an agricultural family his moorings was in agriculture and allied activities.  After passing out from SSLC he did not seek to continue the studies but showed interest in pursuing some small business.  Along with his younger brother he started a cold drink house in Balila and made good profit from it.  When it appeared that the business was seeing a downward trend he came out of the business and invested the money in farming land.

Sri. Vasudev along with his friend visited RUDSETI, Ujire and enquired about the training programmes. After going through his interests Director suggested him to apply for Dairy and Vermicompost training programme.  Later, he was selected and undergone Dairy and Vermicompost training programme in the year 2007.  During his training programme along with the technical inputs regarding the Dairy management he also learnt about different soft skills like how to develop entrepreneurship competencies? How to develop Self Confidence? How to avail Institutional Credit? etc.

In order to portray the conditions of the migrated rural youth in cities, who otherwise would have been practicing agriculture, a few case studies were conducted to know more about the migrated rural youth, their family background, reasons for migrating, satisfaction after migration, type of support given to the family at the villages, assets created at their village and in the cities, types of problems faced, opinion about the environment, and willingness to go back to their villages for continuing farming. The sample included migrated persons engaged in different jobs in Bangalore city as Hotel workers, Construction Workers, Auto Drivers / Taxi drivers, Security Guards, Garment workers and Vegetable/Fruit Vendors. From each category, five respondents were interviewed by using a simple questionnaire. Following are the case studies.

I. Case Studies on Migrated Rural Youth Working as Building Construction Workers

1. Case of Sri Krishnappa : Muttanna, V.L. Madhuprasad and D. Nanjappa

Sri. Krishnappa S/o Saranappa, aged 30 years from Surapur taluk, Yadagiri district had migrated to Bangalore as a construction labourer. He had completed his primary education and got married at an early age. He has two sons and  two daughters.  After marriage, he continued to live in a pucca house along with his parents, one brother and two sisters.  The family has two acres of dry land, and  farming is main occupation. Desire to earn more money by him and non  co-operation among members of his family are the reasons for Sri Krishnappa’s migration.

The pressure of population on land is increasing and the average size of a farm holding is reducing, to below one hectare. Farmers are increasingly getting indebted and the temptation to sell prime land for non farm purposes is growing. If there are other opportunities, about 40 per cent of farmers want to quit farming, says a survey conducted by National Sample Survey Organization. We hear deplorable stories of farmers ending their life not being able to cope with the loss and indebtedness from agriculture.
 
On the closer examination, we find that agricultural land is still a great source of income. But it is the practice of unsustainable methods, improper resource management leading to successive crop failure that makes agriculture non-profitable and risky. As a result, many young farmers are leaving agriculture and migrating to cities. Under these conditions, how are we going to persuade educated youth, including farm graduates, to stay  in villages and take to agriculture as a profession? How can youth earn a decent living in villages and help shape the future of our agriculture? At the same time, we also hear the stories of highly educated persons wanting to move into agriculture as their profession.
 
It is a well known fact that the recession had hit the Information Technology sector and the professionals across the globe in a big way. Some of them were ‘sacked’ and even thrown to streets as ‘loss cutting’ measures by the companies. Many qualified software professionals were forced to find an alternative job. But software professional, Sri. Kondana Chandrashekara Gatty, who was in the Information Technology field for nearly 10 years, did not feel the pinch of recession since he had switched over his carrier field from IT to agriculture. 

During his recent visit, US President Barack Obama pointed out that India is fortunate to have a youthful population with over half the population of 1.2 billion being under the age of 30. Of the 600 million young people, over 60% live in villages. Most are literate. Gandhiji considered the migration of educated youngsters from villages to towns and cities as the most serious form of brain drain adversely affecting rural India’s development. He, therefore, stressed that we should take steps to end the divorce between intellect and labour in rural professions.

The National Commission on Farmers (2004-06) stressed the need for attracting and retaining educated youngsters in farming. The National Policy for Farmers placed before Parliament in November 2007 includes the following goal: “To introduce measures which can help to attract and retain youth in farming and processing of farm products for higher value addition, by making farming intellectually stimulating and economically rewarding”. We are currently deriving very little demographic dividend in agriculture. On the other hand, the pressure of population on land is increasing and the size of the average farm holding is dipping below one hectare. Farmers are getting trapped in debt and, as real estate rates continue to rise, the temptation to sell prime farmland for non-farm purposes is growing. Over 45% of farmers interviewed by the National Sample Survey Organisation want to quit farming.

Abiotic stresses are major constraints for many crop plants in specific areas over the globe which limits the crop production. Dudal (1976) estimated that only 10% of world’s arable land may be categorized as free from stress. The rapid change in environmental conditions likely to override the adaptive potential of plants, this environmental changes mainly originated from anthropogenic activities, which has caused soil and air pollution, plant are exposed to natural climatic or edaphic stresses, such as, high irradiation, heat, chilling, freezing, drought, excess water and waterlogging and nutrient imbalance. Among abiotic stresses drought is the main abiotic factor as it affects 26% of arable area (Table 1.1). Water stress is a single most severe, limitation to the productivity of rice in the rainfed ecosystem (Widawgky and O’Toole, 1990). Mineral toxicity/deficiencies are second in importance. Among mineral toxicity, salinity is wide spread and is estimated to affect 10% of the world land surface (Richards, 1995).

2.1. INTRODUCTION

Salt stress has become an ever increasing threat to food production. It is a major factor limiting the crop productivity in the arid and semi-arid areas of the world (Ashraf, 1994; Foolad and Jones, 1992) and it affects about 10% of the total global land area (Richards, 1995). Increased salinization of arable lands is expected to have devastating global effects, resulting in 30% land losses within the next 25 years and up to 50% by the year 2050 (Wang et al., 2003).

Soluble salts can cause harm to plant, if they are in high concentration in water or soils and it limit crop cultivation world wide. Generally an array of stresses interplay in saline soils and reduces productivity of salt sensitive crops. In India, about 12 mha of land has been affected with salinity and alkalinity (Yadav and Gupta, 1984); an area of nearly 4 mha of land suitable for rice affected with salinity (Paul and Ghosh, 1986). The optimum salt concentration for the growth of halophytes is found to be about 0.5 M NaCl (Flower and Yeo, 1981). Most of the crop plants are salt sensitive glycophytes.

3.1. INTRODUCTION 

Transitory waterlogging occurs extensively in both irrigated and dry land agriculture on clay flats and duplex soils. Most of the humid tropical lowlands, with adequate, rain-fed but poor drainage, have the problems of waterlogging, which is further intensified by low water table and poor root aeration. In submerged condition, only root is exposed to excess water and the injury to the shoot is not a primary effect.

The term ‘waterlogging’ is defined as a condition of the soil where excess water inhibits gas exchange of roots with the atmosphere. Waterlogging is different from ‘flooding’ because the latter results in addition factors of partial or complete submergence of the shoot. The waterlogging replaces a gaseous air by liquid water, leading to the gas stresses. Schematic representation of adverse effects of waterlogging on plant growth and survival has been given in Fig. 3.1.

4.1. INTRODUCTION

Water stress is the single most severe limitation to the productivity of rice in the rainfed ecosystem (Widawsky and O’Toole, 1990). Drought has been defined as the inadequacy of water availability, including precipitation and soil moisture storage capacity, in quantity and distribution during the life cycle of the crop to restrict expression of its full genetic yield potential. Drought is actually a meteorological event which implies the absence of rainfall for a period of time, long enough to cause moisture-depletion in soil and water deficit with a decrease of water potential in plant tissues. Under drought conditions, water stress develops in the plants as the demand exceeds supply of water; this may occur either/or both due to atmospheric or soil conditions, and is reflected in a gradient of water potentials developed between the soil or soil-root interface and leaf, the transpiring organ. Moisture stress is likely to develop to a different rate in different plant organs along with the gradient. Drought like many other environmental stresses has adverse effects on plant growth and yield.

5.1. INTRODUCTION

Temperature is the one of the most important environmental element influencing the plant growth and development limiting the productivity and adaptation of crops, especially when it coincides with critical ranges (Chen et al., 1982; Paulsen, 1994). Nearly all commercial crops in the arid and semi-arid tropics often suffer from heat stress. Every plant has an optimal temperature for its normal growth, deviation from this may cause stress to plants. The adverse effects on plant of temperatures higher than the optimal considered as heat stress. Crops are exposed to periods of heat stress during their life-cycle. The optimum temperature for the most species ranges from 25 to 35 0C. Above this value, a decline in the photosynthesis rate is observed (Berry and Bjorkman, 1980; Pimentel, 1998). Even brief periods of heat-shock between temperature ranges of 45-50 0C induce marked change in plant growth processes.

6.1. INTRODUCTION

Low temperature is one of the major environmental factors that limit the plant growth. Many plants of tropical origin suffer cold damage when exposed to temperature below 20ºC (Graham and Patterson, 1982, Andrews, 1987). Cold temperature in crop plants are compounded by cold snap– a lower than usual drop in temperature that causes the crop to fail. Low temperature in growing season may reduce germination, retard vegetative growth by inducing metabolic imbalances and can delay or prevent productive development. Each plant species has an optimum range of temperature for its normal growth and development. It varies among the genotypes within a species, the specific temperature also depends on the growth stage and development of the particular genotype.

7.1. INTRODUCTION

Abiotic stress is a major limiting factor in crop productivity. Several stresses, such as high temperature, high light intensity, osmotic stress, heavy metals, and several herbicides and toxin lead to over production of reactive oxygen species (ROS), causing extensive cellular damage and inhibition of photosynthesis (Allen, 1997). ROS is produced in both unstressed and stressed cells. Plants have well developed mechanisms against ROS, involving both limiting the formation of ROS as well as instituting its removal. Under unstressed conditions, the formation and removal of O₂ are balance. Introduction of molecular oxygen (O₂) into atmosphere by O₂- evolving photosynthetic organisms, ROS has been the unwelcome companion of anaerobic metabolism. In contrast to O₂, these partially reduced or activated derivatives of oxygen (O₂¹, O2-, H₂O₂, and HO) are highly reactive and toxic and can lead to the oxidative destruction in tissues during stress.

8.1. INTRODUCTION

Aluminium (Al) is not considered as essential nutrient, but at low concentrations it may increase plant growth or induce other desirable effects (Bollard and Butler, 1966; Foy, 1988; Huang et al., 1992a, b; Roy and Mandal, 2005). Al affects about 40-70% of the world arable land, which has the potential for food crops biomass production (Haug and Caldwell, 1985). Acid soils constitute about 3.95 billion hectares globally. About 38% of those are present in Tropical Asia (Datta, 2002). It is believed to cover more than 800 million hectares of forest and tropical Savana ecosystems of tropical America (Jaffe and Rojar, 1994; Prakash 2000). Nearly 75% of Amazon Basin contains acid and infertile soil classified as oxisols and utisols. About 383 million hectares (79%) of the Amazon area, suffers from Al toxicity. Acid soil occurs extensively in the some of the Mediterranean countries and Southern Australia. Low laying acid sulfate of Bay Islands in India chronically suffer from Al-toxicity (Chowdhury et al., 2001).

9.1. INTRODUCTION

Iron (Fe) is important component of a plant’s energy-power house chlorophyll. It also interacts with all the major enzymes and proteins at higher concentration in the soil, and it is toxic to plants. Fe-toxicity creates a range of nutrient disorders and deficiencies of P, K, Ca, Mg, Mn and Zn in plants. These elements were reported to play decisive roles in manifesting toxicity symptoms in rice (Sahu, 1968; Ottow et al., 1983; Yamauchi, 1989; Sahrawat et al., 1996). Excess absorption and translocation of Fe in the rice plants led to toxicity, which has been a major limiting factor in wetland rice. Average yield loss due to Fe-toxicity accounts to 50% and in fact ranges from 10-100% (Brigit et al., 1993).

10.1. CADMIUM
10.1.1. Introduction

Cadmium (Cd) is a strongly phytotoxic heavy metal in an increasing environmental problem worldwide. It is one of the most dangerous metal due to its high mobility and the small concentration at which its effects on the plants being to appear. It is released into the environment by the power stations, heating systems, metal-working industries or urban traffic. It is recognized as an extremely significant pollutant due to its high toxicity and large solubility in water (Pinto et al., 2004). Soil solutions which have a Cd concentration ranging from 0.32 to 1.00 mM can be regarded as polluted to a moderate level (Sanita di Toppi and Garbrielli, 1999).

11.1. BORON TOXICITY
11.1.1. Introduction

Boron (B) is essential micro-nutrient. It is necessary for cell wall formation, membrane integrity, calcium uptake and carbohydrate synthesis and transportation. B affects many functions in plants, which includes flowering, pollen germination, fruiting, cellular activities (division, differentiation, maturation, respiration etc.), water relationships and the movement of hormones. It is not translocated and leached easily from soils.

12.1. INTRODUCTION

Air is polluted when it contains enough unhealthy particles and gases to harm human beings, animals, plants and even objects such as building and statues. Air pollutant may present as solid, liquid or gas form. Industrial revaluation in the 19th and 20th centuries leads faster increase in concentration of air pollutants in the atmosphere. The most important air pollutants that damage the plants’ growth and development, subsequently the economic yields of crop plants are ozone (O₃), nitrous oxides (NO₂ and NO), carbon monoxide (CO), ammonia (NH₄), peroxiacetyl nitrate (PAN), sulphur dioxide (SO₂), hydrogen fluorides (HF), particulate matters (cement dust, magnesium-lime dust, carbon shoot etc.), smoke etc. Burning of hydrocarbons in motor vehicle engines gives rise to CO₂, CO, SO₂, and NO in varying proportions and ethylene (C₂H₄) as well as other hydrocarbons. Industrial plants release SO₂, H₂S, NO₂ and HF into atmosphere. Hydrogen peroxide (H₂O₂) is another potentially injurious molecule, can form by the reaction between O₃ and naturally release volatiles (terpenes) from forest trees.

13.1. INTRODUCTION

Photosynthetically active radiation is a primary energy resource for terrestrial plants, necessary for the plant growth. Plants receives this photosynthetically active radiation from sunlight as a consequence, plants are also exposed to the ultraviolet (UV)-radiation. Seven percent of the electromagnetic radiation emitted by the sun is the UV range (200-400 nm). Though representing only a small portion of the total solar electromagnetic spectrum, UV-B has a disproportionately large photobiological effect. As it passes through the atmosphere, the flux transmitted is greatly reduced, and the composition of the UV-radiation is modified. This UV-radiation is mainly divided into three classes, namely UV-A, UV-B and UV-C. The UV-A region of the spectrum (wavelengths from 320 to 400 nm) are not attenuated by ozone, so their influence will be unaffected by ozone layer reduction. This portion of the UV radiation is less damaging and important for photomorphogenic signal in plant development (Bjorn, 1994). The wavelength of UV-B portion ranges from 280 to 320 nm. This region of UV is very energetic and effectively absorbed by ozone in the stratosphere. Thus, only a very small portion, approximately 4% is transmitted to the earths. Shortwave UV-C radiation (200-280 nm) is highly energetic and strongly absorbed by atmospheric oxygen and ozone. Thus, none of this sterilizing radiation is present in terrestrial sunlight.

14.1. INTRODUCTION

The climate of a place is the average weather that is experiences over a period of time. It is the natural phenomenon that has occurred throughout the history of the earth. Climate change is strongly associated with higher temperature, altered precipitation, and higher levels of atmospheric CO₂ and other greenhouse gases. It is a very slow process; it takes a long time to settle in. Climate change in IPCC (2007) usage refers to any change in climate over time, whether due to natural variability or as a result of human activities. Over the last 150-200 years the changes to our climate are happening more quickly now than they have ever done before in the geological past. Human activities have altered natural climatic processes at a geographically rapid pace by booting atmospheric concentrations of several greenhouse gasses. Following are the changes taken place over years of industrial age (IPCC, 2007):

All living organisms are basically made up of chemical components. The chemistry, composition and energy management of living organisms is what we call biochemistry. It tries to explain life processes at the molecular level. Although different organisms differ outwardly in their life processes, there are striking similarities in executing the different tasks. Genetic code, metabolic pathways, enzymes, coenzymes and even regulatory mechanisms are similar to a large extent in all the living organisms. Living organisms have certain extraordinary properties. They can grow, respond to stimuli and replicate themselves with high fidelity. All these activities are ultimately interpretable in chemical terms. The components that constitute organisms are all inanimate. The lifeless organic molecules with appropriate complexity and properties make a living being.

Biochemistry helps us understand how the inanimate molecules that constitute living organisms interact with each other to maintain life. The basic life processes or the biochemistry remains broadly the same in either the unicellular microorganism or the higher organisms such as the plants or the human beings. Life is nothing but thousands of ordered chemical reactions. In other words, chemistry is the logic of all biological phenomena.

Carbohydrates are the most abundant biomolecules on earth. They occur in nature as glucose, starch and cellulose etc. Each year, photosynthesis converts more than 100 billion metric tonnes of carbon dioxide and water into starch, cellulose and other plant products. Carbohydrates are polyhydroxy aldehydes or ketones and their derivatives. They provide 4k calories energy per gram. They promote utilization of lipids and reduce wastage of proteins. They are readily available in roots, tubers, cereal grains, sugarcane and sugar beet.

Carbohydrates have the general formula C_n( H₂O)n, indicting that they are the hydrates of carbon. Some carbohydrates also contain nitrogen, phosphorous or sulfur. They are characterized by the number of carbon atoms they contain. If n=3, they are trioses, n=4 tetroses, n=5 pentoses, n=6 hexoses and n=7 heptoses. The most common sugars in plants are the hexoses. Two or more simple carbohydrates condense together to form polymer sugars like sucrose, starch and cellulose etc. The basic condensing bond is glycosidic bond.

Lipids are non polar substances of biological origin that are sparingly soluble in water, but soluble in organic solvents like chloroform, hexane, benzene etc. The word lipid comes from the Greek word lipos meaning lard or fat. The lipids present in biological systems are either hydrophobic (non polar) or amphipathic (both polar and non polar). Lipids like fats, oils or glycerophospholipids can be hydrolyzed to get fatty acids and other products. Hydrophobic nature is useful in making lipids as membranes which act as effective barriers to more polar molecules. Steroids are also considered lipids, but cannot be hydrolysed and are components of non-saponifiables in fats. Waxes, which are esters of fatty acids with long chain alcohols are also considered as lipids.

Amino acids are the building blocks of proteins. They occur in all living plant cells as constituents of proteins and as free acids or amides. More than 200 naturally occurring amino acids have been identified in higher plants. Around 20 different amino acids have been observed to be incorporated into proteins. They have two functional groups, an amino group (-NH2) and a carboxylic group(-COOH). Both these groups are attached to the a carbon atom only. Amino acids with this structure are called a amino acids or 2-aminoacids. The unique characteristics of the 20 amino acids are due to the side chain (R), which can be an alkyl, hydroxyl, thiol, amino, sulphide, aromatic, or heterocyclic group.

Amino acids have the general formula, R-CH(NH₂)-COOH. The R represents a side chain. If R=H, the simplest amino acid glycine (NH₂ -CH₂ –COOH) results. Amino acids are alpha (a ) amino carboxylic acids. The carbon atom is tetrahedral in shape. The various groups attached to it are placed in different positions. Since the valence of the carbon atom is four, four groups can be attached to the carbon atom. Based on the groups attached to the carbon atom it may be of two types.

An amine reacts with a carboxylic acid to form an amide. Similarly, the amino group  on one amino acid molecule reacts with the carboxyl group of another amino acid  to form a compound called peptide. A peptide bond is an amide bond that forms when the –COO- group of one amino acid reacts with the -NH₃+ group of another amino acid. The resulting compounds are called peptides. Even after this there is a reactive amino group and a carboxyl group in the peptide. If these groups react further a poly peptide can form and later a polymer called protein can form.

The word protein was first coined in 1838 to emphasize the importance of this class of molecules. The word is derived from the Greek word proteios which means “of the first- rank”. Proteins are polymers/macro molecules made up of several amino acids. When there are more than 50 amino acids in a chain, the polypeptide is normally called a protein. Each protein in the cells of living beings has a unique sequence of amino acids that determines its biological function. The proteins are folded into specific defined structures, which are maintained by a large number of relatively weak bonds. The  three  dimensional structure is well defined and suited to it’s specific function.

Very small changes in the structure can modify the function. Hence, it is important to know the structure of proteins to understand their behavior and function. The biological activity of proteins depends on maintenance of folded conformation. Proteins fold into well defined three dimensional shapes and they are able to recognize their corresponding substrates or antigen molecules and bind them tightly. The protein structure has been classified into four different levels based on the folded conformation of the protein.

Enzymes are organic catalysts produced by living organisms. They make possible biochemical reactions. Hence they are called biocatalysts. They are mostly a specialized class of proteins. However, there are some non-protein enzymes like ribozymes, which are RNAses. Enzymes speed up reactions at ambient temperatures. This is in contrast to chemical reactions like saponification of lipids which take place when lipids are boiled for a few hours with concentrated alkali.  Enzymes, namely, lipases, hydrolyze lipids at body temperatures in minutes. They are superior to chemical catalysts by a factor of 107 to 1014 .  An enzyme may be a simple protein or a complex protein. They are produced by cells and are mostly globular proteins. Each cell contains an estimated 3000 different enzymes.

Nucleic acids were first discovered in 1868 by Friedrich Meischer. Nucleic acids are high molecular weight polymers that are present in our cells. They  store and transfer genetic material from generation to generation. Knowledge of how genes are expressed and how they can be manipulated is becoming increasingly important for understanding   of nearly every aspect of biochemistry. These macromolecules pass on information for cellular growth and reproduction.  All the genetic information in the cells is called the genome. Every time a cell divides, the information is copied and passed on to the new cells.
 
Nucleic acids fall into two main classes according to the type of sugar they contain: the Deoxyribonucleic acids (DNA) and Ribonucleic acids (RNA). Some sections  of  the  DNA  called  genes contain the information to make a protein. RNA translates the genetic information in the DNA to the ribosomes, where the synthesis of proteins takes place.

Plants are responsible for highly useful molecular reactions. All the enzymatic  reactions  that  occur in the cell are  termed  as metabolic reactions.  They  take place within organisms in an orderly and regulated way.  They  are  the  metabolic pathways and the compounds  resulting from the process, namely,  metabolism are called  the metabolites. Metabolism in Greek means change. It is the set of life sustaining chemical transformations within the cells of living organisms. These enzyme-catalyzed reactions allow organisms to grow and reproduce, maintain their structures, and respond to the environments around them.
 
Metabolism is a highly organized,   coordinated and purposeful enzymatic activity inside a cell. Metabolism has four functions: 1. To obtain energy from the environment, 2. To convert molecules into building blocks, 3. To convert the building blocks into proteins, lipids, sugars, nucleic acids and other cell components and 4. To synthesize and degrade organic molecules for specific needs of the cell.

Carbohydrate metabolism in the cell is essentially the metabolism of glucose and other substances related to glucose in their metabolic processes. The chemical reactions involved in carbohydrate metabolism represents complex groups, sequences, and cycles of reactions which integrate at various points with the reactions concerned in the metabolism of lipids and proteins. The major types of chemical processes involved in carbohydrate metabolism may be grouped as follows: a) Anabolism of starch – Photosynthesis, b) Catabolism of starch, c) Catabolism of glucose – 1. Glycolysis and TCA cycle and 2. Oxidative pentose   phosphate pathway.
 
Plant cells “burn “ glucose for energy. Plants also produce sugars through photosynthesis. This is roughly the reverse of the burning process.

The importance of lipids have already been elaborated. They play a major role as source of energy and as components of membranes which have implications in plant growth regulation. The complete metabolism of fat leads to oxidation, the final products being CO₂ and water. The burning of one mole of palmitic acid gives 2340 kcal.  The molecular weight of palmitic acid is 256. This works out to approximately 9 kcal/g of palmitic acid. This energy is twice that derived from either sugars or proteins. Fats and oils are thus better and more efficient forms of storage of energy in living beings.

Plants can synthesize all the 20 amino acids, which include essential and non-essential amino acids. They can be degraded by removal of the amino group and conversion of the remaining skeleton to useful metabolic intermediates which participate in the synthesis of glucose and other ketone bodies.
 
Biosynthesis of amino acids
 
The biosyntheses of amino acids have an important feature. Their carbon skeletons come from intermediates from glycolysis, pentose phosphate pathway and citric acid cycle etc. The biosynthetic pathways depend on the intermediates from which they are derived. The primary amino group normally comes from the transamination of glutamate. Glutamine synthetase is a central control point in nitrogen metabolism, since glutamine is the amino group donor in the formation of many biosynthetic products as well as being a storage form of ammonia. Glutamate is the precursor of proline, ornithine, and arginine. Serine, cysteine, and glycine are derived from 3-phosphoglycerate. Glycine is synthesized from serine by removing CH2OH group. Tyrosine is synthesized from phenylalanine. Asparagine and glutamine are amides that are synthesized from aspartate and glutamate.

Amino acids serve as the building blocks of proteins and as precursors of many other important biomolecules such as hormones, purines, pyrimidines, porphyrins and some vitamins. They also serve as sources of energy when present in excess amounts and when they are used as fuel, amino acids undergo deamination reactions. The remaining carbon skeleton will either convert itself into glucose or undergoes oxidation to CO₂ via TCA cycle.

Central dogma: The Central dogma of molecular biology, which has been formulated as a simple linear progression of information from DNA to RNA to Protein, is summarized in the illustration. The replication process on the left consists of   passing  information from a parent DNA molecule to daughter molecules. The middle  transcription process copies this information to a mRNA molecule.  Finally, this information is used by the chemical machinery of the ribosome to make polypeptides.

Primary metabolism in a plant comprises all metabolic pathways that are essential to the plant’s survival. Primary metabolites, namely, carbohydrates, lipids and proteins are compounds that are directly involved in the growth and development of a plant whereas the secondary metabolites are compounds produced in other metabolic pathways that, although important, are not essential to the functioning of the plant. However, secondary plant metabolites are useful in the long term, often for defense purposes, and give plants characteristics such as color.
 
Secondary plant metabolites are used in signalling and regulation of primary metabolic pathways. Plant hormones, which are secondary metabolites, are often used to regulate the metabolic activity within cells. Secondary plant metabolites help the plant maintain an intricate balance with the environment, often adapting to match the environmental needs. Plant metabolites that color the plant are a good example of this, as the coloring of a plant can attract pollinators and also defend against attack by animals. Terpenes, alkaloids, sterols, pigments, growth regulators, and phenolics are the important secondary plant metabolites.

Phenol is normally a benzene ring containing an –OH group, and hence an aromatic alcohol. The term phenolic refers to similar aromatic compounds with one or more -OH groups. Phenolics constitute one of the most widespread classes of secondary metabolites. Commonly talked about class of compounds like anthocyanins, flavonoids, lignins, tannins, coumarins and chalcones are all phenolic substances. Phenolics are water insoluble substances. However, the water solubility increases with the increase in the number of -OH groups. Phenolics absorb electromagnetic radiation strongly. Many of the phenolics absorb in the visible part of the spectrum (Ex. anthocyanins) and are coloured. Phenolics are produced in plants by 1. Shikimate pathway through phenylalanine (C6.C3)  and 2. Acetate/ malonate pathway.

Plant pigments impart colour to the different components like leaves, flowers, fruits etc. They in turn are responsible for the colour of raw food, we eat. Pigments like chlorophyll, anthocyanins, flavonoids, tannins, xanthones etc. are the different pigments that are present in plants. The primary function of pigments in plants is photosynthesis, which uses the green pigment chlorophyll along with several red and yellow pigments that help to capture as much light energy as possible. Other functions of pigments in plants include attracting insects to flowers to encourage pollination.

Sterols are derivatives of a complex ring system called cyclopentano perhydro phenanthrene. The term sterol means solid alcohol. Sterols, though alcohols, are solids with a M.P. of 100-120^ºC. The 27 carbon atoms impart hydrocarbon character, namely, solubility in non-polar solvents. Free sterols in plants are mono hydroxy  secondary alcohols varying in the constitution of methyl or ethyl group and in double bonds. Cholesterol, ergosterol, bile acids, sex harmones, cortical harmones and D-vitamins are some of the sterol derivatives.
   
The most widely distributed sterols in higher plants are the C₂₉ sterols, stigmasterol, β sitosterol and g sitosterol. Together, they are called steroids. In plants, steroids are present as glycosides. Cholesterol was first isolated from gall stones. The word cholesterol means “solid alcohol from bile”. Bile is a fluid which is formed and stored in the gall bladder. It aids in the digestion of fats in the digestive tract. Sterols form an important group among the steroids. Unsaturated steroids with most of the skeleton of cholestane containing a 3β-hydroxyl group and an aliphatic side chain of 8 or more carbon atoms attached to position 17 form the group of sterols.

Alkaloids are naturally occurring substances of plant origin that are alkaline in reaction. They are optically active, contain nitrogen as part of a heterocyclic ring and have varying degrees of psychological responses in man and animals. They exhibit significant pharmacological activity. Alkaloids are mostly basic in character but also includes some related compounds with neutral and even weakly acidic properties. Presently more than 2000 alkaloids are known.

Nomenclature of alkaloids
Alkaloids are named by adding the suffix ‘ine’ to various distinguishable features such as sources, physiological action in animals, their properties etc. Thus, 1. The name of the genera of the plants containing them Ex. Atropine (Atropa), nicotine (Nicotiana) etc. 2. The names of the species of the plants producing them Ex. Cocaine (Erythroxolon coca). 3. The common name of the organism producing them Ex. Ergotamine (ergot fungus). 4. The specific physiological activity observed in animals Ex. Emetine (emetic – causing vomiting), narcotine (narcotic-alters mind).

Vitamins are essential organic nutrients required by an organism in small quantities. They are essential since they cannot be synthesized in sufficient quantities by an organism, and must be obtained from the diet. The term vitamin does not include other essential nutrients like dietary minerals, essential fatty acids, or essential amino acids which are needed in larger quantities than vitamins. The term vitamin is derived from “vitamine,” coined in 1912 by the Polish biochemist Funk. The name is from vital and amine, meaning amine of life. Thirteen vitamins are generally recognized presently. Vitamins are used in small quantities by an organism to keep it in a healthy condition.

Vitamins are given letters of alphabet (A,B, C, D, etc.) in the order in which they have been discovered. The letters do not bear any relation to their structures or their importance. Vitamins are classified by their biological and chemical activity and not by their structure. Thus, each “vitamin” refers to a number of vitamer compounds that all show the biological activity associated with a particular vitamin. Vitamin A includes the compounds retinal, retinol, and four known carotenoids. Vitamers by definition are convertible to the active form of the vitamin in the body, and are sometimes inter-convertible to one another, as well.

Plant hormones (phytohormones) are chemicals that regulate plant growth and are termed as ‘plant growth substances’. Plant hormones are signal molecules produced within the plant, and are present in extremely low concentrations. Hormones regulate cellular processes in targeted cells. Hormones also determine the formation of flowers, stems, leaves, the shedding of leaves, and the development and ripening of fruit. Every cell is capable of producing hormones in plants. They shape the plant, affecting seed growth, time of flowering, the sex of flowers, senescence of leaves, and fruits. Plant hormones affect gene expression and transcription levels, cellular division, and growth.They direct which tissues grow upward and which grow downwards. Hormones are vital to plant growth. Hence, they are also known as growth factors or growth regulators.

Before the invention of N fertilizer, mineralization of organic N ( present in dead plants and animals or manure) was the main method used to obtain ammonium and nitrate nitrogen. Mineralization is conducted by soil microbes resulting in ammonium ion. Most Nitrogen is absorbed by plants in the form of Nitrate (NO-₃). Ammonium is converted to Nitrate with the help of  soil bacteria. Nitrogen is a very mobile element and is easily lost from the soil. Ammonium (NH₄+) can be converted to Ammonia (NH₃). The gaseous ammonia can be lost to the atmosphere.  Nitrate can be lost through denitrification. Nitrate nitrogen is reduced to nitrous oxide (N₂O), elemental nitrogen (N₂) and nitric oxide (NO). All are volatile. Denitrification occurs under conditions of high water availability and temperatures higher than 10^ºC.

The word cell was coined by Robert Hooke with the help of compound microscope. Cell is the basic unit of life. A plant cell has three distinct components a). Cell wall b). Protoplasm and c). Vacuole. Cell wall  and  vacuole are considered as non-living substances. The protoplasm which is living is  composed of 1. Cytoplasm and 2. Nucleus. The cytoplasm contains several organelles such as mitochondria, chloroplast, ribosomes, endoplasmic reticulum, golgi complex, lysosomes, plastids etc.

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

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