eChapters

Introduction

Cycling of plant material is required for any production system for biological activity, humus formation and thereby formation of a dark colored top soil. Incorporation of biomass results in production and proliferation of soil biota. But under annual crops compared to forest, production is much less, the biomass is largely removed, the soil is tilled several times each year. Consequently, less food and moisture are available for earthworms, insects, micro-flora and fauna; and their habitats are repeatedly disturbed or destroyed. Therefore, the primary need of our agricultural activities is to feed soil organisms (bacteria, fungi, earthworms etc.) and to regulate their living conditions while protecting them from chemical and mechanical impacts.

Introduction

Agriculture is the most important sector in India accounting for 13.7 per cent of the country’s GDP and employs more than 60 per cent of the labour force. Our country has recorded the highest food grain production of 257 million tonnes during 2012-13, under favourable weather conditions those prevailed throughout the year. The mission of increasing food grain production, though realized to a commendable extent at present, but under risk due to climatic aberrations and reduced availability of land, water, nutrients along with poor and continuous degradation of the resources to cope up with the demands of increasing population. Although the country had attained self sufficiency in food grain production through intensification of agriculture with high–yielding varieties, fertilizer application and chemical pest control during the green revolution, productivity is still low and is stagnating.

Object: Effect of ethylene on regulation of stomata.

Material required: Plant leaves, ethaphon, ACC, double distilled water, measuring cylinder, beaker and electric balance.

Theory: Ethylene is a plant hormone that regulates many aspects of growth and development. Despite the well-known association between ethylene and stress signalling, its effects on stomatal movements are largely unexplored. Here, genetic and physiological data are provided that position ethylene into the Arabidopsis guard cell signalling network, and demonstrate a functional link between ethylene and hydrogen peroxide (H₂O₂). In wild-type leaves, ethylene induces stomatal closure that is dependent on H₂O₂ production in guard cells, generated by the nicotinamide adenine dinucleotide phosphate hydrogen (NADPH) oxidase AtrbohF. 

Object: Yield estimation of kharif crops.

Material required: Polythene bags, balance, gunny bags or baskets, pans and harvesting equipment like sickle, knife etc.

Theory: Yield is the ultimate objective of cultivating agricultural plants. Different plant parts constitute the economic yield in different crops, like grain in cereals, pulses and oil seeds, vegetative parts or fruits in record yield at the correct maturation stage. Do not allow excessive wilting or drying of the material. Estimate yield in a sufficiently large sample. Materials required only a representative crop to estimate yields. (Do not select plants of any particular type. Do not damage any plant part vegetable crops; bark or out growth in fiber crops (jute, cotton); and the entire plant in fodder crops. The yield per unit area (per M₂ or ha) is the product of yield per plant multiplied by the number of plants per unit area. It is, therefore, essential to know the yield components per plant as well as per unit area.

Object: Growth analysis: Calculation of growth parameters. 

Material required: Primary data collected from individual plants or derived from whole canopies. 

Theory: The growth analysis study provides information on the growth of plants or of a plant community in a precise way with the available’ raw data. The study also provides precise information on the nature of plant and environment interaction in a particular habitat.

Object: To demonstrate the measurement of growth in plants with the help of Arc auxanometer. 

Material required: Potted plant, Arc auxanometer, rope and weight.

Theory: Growth is a permanent change in plants with respect to its size, form, weight and volume.

Object: Determination of the viability of seeds by tetrazolium test. 

Material required: Healthy seeds, tetrazolium solutions, beakers, water and petridishes. 

Theory: Viability of seeds shows their potential towards germination.

Object: Breaking of seed dormancy to facilitate germination.

Material required: Seeds, water, sharp needle, sharp razor, sandpaper, acids, Potassium nitrate and gibberellic acid. 

Definition: Inability of a viable seed to respond the favorable environmental conditions for germination is known as dormancy.

Object: To demonstrate the optimum conditions for seed germination. 

Material required: Beaker, glass slide, bean seeds, thread and water.

Theory: Germination is a process by which the embryo in the seed becomes activated and begins to grow into a new seedling under favorable conditions. Food is stored in the seeds in dry conditions but the developing embryo cannot utilize this dry food. Food can be utilized in liquid form only and seeds can utilize only dissolved oxygen. Excess water stop germination because once all the dissolves oxygen is utilized by the seed, further germination is not possible as the life supporting oxygen is lacking. Suitable temperature is necessary because low temperature retards the embryo activity and high temperature destroys the delicate embryo tissue. Seed usually germinate between 0oC to 50oC temperature and the optimum temperature is lies between 25 to 30oC. During germination rapid cell division takes place. Energy is required for cell division. This energy is obtained from oxidation. The oxygen is required for oxidation is supplied by the air.

Object: To determine respiratory quotient of different types of respiratory substrates.

Object: To demonstrate that oxygen is used up during respiration. 

Material required: A conical flask, some germinating seeds, glass tube having two bends at right angles, mercury, beaker, small tube and caustic potash (KOH).

Theory: Plants at some stage have a capacity to respire more rapidly in presence of oxygen i.e. aerobic respiration. In this process, oxidation of carbohydrate occurs resulting in conversion of carbohydrate into carbon dioxide (CO₂) and water with release of large amount of energy.

Object: To demonstrate anaerobic respiration. 

Material required: Soaked pea or gram seeds, mercury, test tube stand, forceps and KOH pellets. 

Theory: Generally, plants at certain stage have the capacity to respire in absence of oxygen i.e. anaerobic respiration. In this process, oxidation of carbohydrate takes places, ethyl alcohol and CO2 being end products and only a little amount of energy is liberated-

Object: To demonstrate that O₂ is evolved during photosynthesis. 
 

Material required: Hydrilla plant, beaker, test tube, funnel, pond water and pyrogallol. 
 

Theory: Oxygen is a byproduct of photosynthesis, which is evolved in presence of light and chlorophyll during photosynthesis.

Object: To demonstrate that light and carbon dioxide are essential for photosynthesis (Moll’s half leaf experiment). 

Material Required: A potted plant, a wide mouthed bottle, caustic potash, splits of rubber Cork and vaseline etc. 

Object: To demonstrate unequal transpiration by the two leaf surfaces from four leaf method. 

Material required: four leaves of china rose or any dorsiventral leaves, two stands, thread and grease or vaseline. 

Theory: Transpiration is a process in which loss of water occurs in the form of water vapour from the aerial parts of the living plant. 

Method: Take four leaves of equal size from a plant (e.g. China rose). Now apply or smear the vaseline on the four leaves as follows:

Object: To find out the relation between transpiration and absorption. 

Material Required: Wide mouthed glass bottle, with a narrow graduated side tube, split rubber cork, water and a plant with intact root system.

Theory: The loss in weight of plant indicates the amount of water transpired. And fall in water level of the side tube indicates the amount of water absorbed. This shows that amount of water transpired is normally equal to the amount of water absorbed by the plant roots.

Object: To measure the rate of transpiration by using Ganong’s potometer

Material required: Ganong’s potometer, beaker, wax or vaseline, stop watch and twig or a branch of a plant.

Theory: The amount of water absorbed is almost equal to the amount of water transpired. The difference between the two amounts is negligible. 

Method: Potometer consists of wide mouthed tube fitted with a hard cork in which a twig or branch of a plant is inserted. Other end of tube is dipped in beaker. One half of the tube is graduated. The apparatus is filled with water using the reservoir. An air bubble is inserted in the tube as shown in figure.

Object: To measure rate of transpiration of potted plant by gravimetric (Lysimeter) method. 

Material required: Potted plants, Polythene sheet, Platform and electric balance etc.

Method: Select same size and same type well watered potted intact plants. Seal the pots and the root system with a sheet of polythene so that the water loss to the atmosphere occurs only from the shoot system not from the soil (To check evaporation losses). Immediately record the weight of the potted plant and keep them in different environment such as (1) warm environment (2) cool environment (3) Calm environment.

Object: To demonstrate that water is lost from a living plant during transpiration. 

Material Required: A potted healthy plant, a bell jar, a rubber sheet or oil cloth, a glass sheet and grease.

Theory: Transpiration: Loss of water in the form of water vapour from the internal tissues of living plants through aerial parts of the plant is known as transpiration.

Object: Demonstration of leaf anatomy or structure of C₃ and C₄ Plants (demonstration by already prepared slides).

Material required: Already prepared slides of corn and wheat leaves and microscope.

Object: Estimation of stomatal index and stomatal frequency with replica method.

Material required: Leaf sample, blue/red correction fluid, transparent finger nail polish, brush glass slide and microscope.

Principle: The number of stomata per unit area of the leaf is called as Stomatal Frequency. The stomatal index is defined as the percentage number of Stomata as compared to all the epidermal cells in a unit area of leaf i.e.

Object: Measurement of leaf area by graph paper method.

Material required: leaves, graph paper and pencil or pen.

Object: To demonstrate chlorophyll fluorescence.

Material required: Spectrophotometer, fresh green spinach, mortar, pestle, acid washed sand, acetone, funnel, filter paper and test tubes.

Principle: Chlorophyll molecule absorbs light in the blue (450nm) and red (660nm) region and get into excited state and emits an electron. The electron drops back to the ground state within 10-9 seconds and some energy (which is not used in biochemical reaction) are given out as the observed fluorescent far red light.

Procedure and observation: Take some soft green spinach leaves. Grind these with a pestle -mortar in acetone adding a pinch of acid washed sand. Make a fine paste. Filter to get a clear solution in a test tube. Take the test tube in bright sun light.

Object: Measurement of absorption spectrum of chloroplastic pigments.

Material required: Spectrophotometer, plant leaves, ethanol, electric balance, beaker, test tubes and water.

Objective: Estimation of photosynthetic pigment from plant leaves.

Material required: Plant leaves, test tube, test tube stand, spectrophotometer, balance, centrifuge machine, mortar and pestle, acetone and distilled water.

Theory: Photosynthetic pigments, namely, the chlorophylls are present in green leaves and shoots of plants. There are at least five types of chlorophylls in plants. Chl’a’ and ‘b’ occur in higher plants, ferns and mosses. Chl ‘c’,‘d’ and ‘e’ are found only in algae and in certain bacteria. Chlorophylls are extracted from plant leaves. The absorption peaks of chl ‘a’ at 663 nm and ‘b’ at 645 nm are characteristic measures from which amount of chlorophylls can be calculated.

Object: Estimation of water potential of plant tissue by Chardakov’s method.

Material required: Test tubes, sucrose or polyethylene glycol (PEG) 6000, methylene blue and dropper.

Principle: Concentration of the solution in which a plant tissue is immersed changes. If the solution is hypertonic (with lesser yw) the tissue loses water and the solution becomes dilute. If the solution is hypotonic (with higher yW) the tissue absorbs water and the Solution becomes concentrated. If the solution is isotonic (with yw equal to the tissue sap) the tissue neither loses nor absorbs water and the solution concentration does not change. Thus the yw of this solution gives the yw of the tissue.

Object: Methods of measurement of water status and water saturation deficit in plant parts. 

Material required: Leaf samples, leaf borer, water, petridishes, forceps, oven and blotting paper. 

Theory: Plant water status strongly influences plant growth and biomass production through its effects on leaf and root expansion and on photosynthesis. Therefore, measurement of plant water status is an important component of understanding plant processes and maximizing yield under different ecosystems. 

Method: Plant water status can be measured and computed by any one of the following methods

Object: To demonstrate the process of diffusion.

Material required: Beakers, copper sulphate, distilled water and sugar solution.

Object: To demonstrate the phenomenon of endosmosis and exosmosis by using grapes and raisins.

Material required: Grapes, raisins, beaker or petridish, water and sugar solution.

Object: To demonstrate the phenomenon of osmosis using potato osmoscope. 

Material required: A potato tuber, sugar solution, beaker, water, petridish, knife, measuring cylinder, and stand.

Theory: Osmosis is a phenomenon in which water molecules diffuse through the semi permeable membrane from region of its higher concentration to the region of lower concentration.

Object: Preparation of solutions. 

Material required: Volumetric flask, measuring cylinder, beakers, pipettes, balance, distilled water and chemicals. 

Theory: The use of solution is common in experimental procedures of plant physiology. It is very important for a student to be familiar with their preparation. The substance dissolved in a solution is called solute and the medium in which it is dissolved is known as solvent. Solutions of two liquids (e.g. alcohol in water) and solid in liquid (e.g. NaCl in water) are most common. Solutions are thus a homogenous mixture of a solute in a solvent. 

The Global Environmental Issues

 
Expansion of the scale of human activity in recent years has put so much strain on the natural environment of this planet that in some cases nature can no longer recover. The nature’s ability though recovers damage or harmful effects in one part of the world do not stop in the very area and keeps going beyond national borders and become environmental problems on a global scale, but in a limited manner.

Energy, food production and various other natural resources are the limiting factors on this earth. The result of this bitter truth has been published in a book titled ‘The Limits to Growth’ in 1972. If the enormously growing population and the industrial process is not checked, then the earth’s civilization may come to an end within next hundred years.

By considering the space travel, we can very well understand about the Ecosystem. When we go away from the biosphere, it will be appropriate to develop unlimited environment through the energy accumulated from the sunlight in space. For the space travel for some days to moon and back to earth, we need not establish the entire ecological system as greater quantity of O₂ and food stuffs can be stored and CO₂ and other unwanted materials can be fixed for establishing space colonies, we have to build a special space ship with important abiotic components which can be recycled for use again and again. The vital processes of production, consumption and decomposition can be established and balanced through biotic components. In other words we are creating a complete mini human ecological machine. Before we established this system, we should be quite familiar about the space problems and its implications.

HUMAN POPULATION GROWTH

The evolution of man took place about one million years ago in response to changes in the physical environment. We learnt gradually to adapt different modes of life to varying environments and migrated different parts of the world. Human activities have had their impact on the environment, which was depending on the number of people living in  the area and  their level  of economic development. Per capita consumption of food, energy and other resources in developed countries is larger and its impact on the environment is much greater than equal number of persons living in developing countries in Africa or Asia. Therefore, the distribution of population needs to be examined in detail.

Continental drift is the theory that continents move slowly about the earth’s surface, changing their positions relative to one another and to the poles of the earth. It includes the idea that former continents may have broken apart and that the fragments have recombined in different patterns (Fig. 15.1). Some authorities have considered that this happened only once, beginning within the past 200 million years; others believe that it has long been a continuous process, so that all existing continents are mosaics. Those who accept the theory believe that the rates of motion have been only a few inches a year. Earlier, it was considered that the continents moved like ships through a slightly plastic ocean floor. Today some consider that the continents are frozen into the earth’s surface like rafts in ice, and that the motions are the result of growth of the sea floor along certain midocean ridges and reabsorption of the sea floor elsewhere beneath deep ocean trenches and young mountains. The continents are carried passively about embedded in moving plates of the surface. Some authorities  now  agree  that  there  is  a  deformable  layer,  called  the asthenosphere, at depths of from about 50 to 400 kilometers within the earth. It is white hot, and slightly viscous, and many believe that the surface can break into plates which slide over it.

The phenomenon we call tsunami is a series of large waves of extremely long wavelength and period usually generated by a violent, impulsive undersea disturbance or activity near the coast or in the ocean. A tsunami is a very long-wavelength wave of water that is generated by sudden displacement of the seafloor or disruption of any body of standing water.  Tsunami are sometimes called “seismic sea waves”, although, as we will see, they can be generated by mechanisms other than earthquakes.  Tsunami have also been called “tidal waves”, but this term should not be used because they are not in any way related to the tides of the Earth.  Because tsunami occur suddenly, often without warning, they are extremely dangerous to coastal communities.

It is a well known fact that natural disasters strikes countries, both developed and developing, causing enormous destruction and creating human sufferings and producing negative impacts on national economies. Due to diverse geo-climatic conditions prevalent in different parts of the globe, different types of natural disasters like floods, droughts, earthquakes, cyclones, landslides, volcanoes, etc. strikes according to the vulnerability of the area. India is considered as the world’s most disaster prone country. It has witnessed devastating natural disasters in recent past like droughts, floods, cyclones, earthquakes, landslides, etc. 

Pesticides are used to control plant growth (herbicides), insects (insecticides), worms  (vermicides), bacteria (bacteriocides), fungi (fungicides), and other organisms. Almost without exception, pesticides are used to benefit humans by the control of unwanted species of plants (e.g. weeds in a lawn), disease-causing bacteria (e.g., Pneumococcus, the causative agent of pneumonia), disease-carrying insects (e.g. malarial or yellow fever mosquitoes) or in controlling destruction of agricultural products by disease-causing organisms (e.g., corn-borers, the virus of anthurium blight). Although they are by and large mostly beneficial, pesticides used both properly and improperly are also “resources out of place”, that is pollutants, that are subject to normal ecological processes.

For the hundreds of thousands of years that we lived on earth,there were few rapid changes in the atmosphere. It is only in recent times, particularly since the Industrial Revolution, that our activities on earth began to modify our environment in a significant manner.  Industrial pollution has affected the water we drink, the air we breathe, and in general,the biosphere itself.Now noise has joined the bandwagon of pollutants.

Noise certainly comes within the scope of definition of a pollutant that “..... any undesirable change in the physical, chemical or biological characteristics of our air, land and water that may or will harmfully affect human life or that of any other desirable species or industrial process, living conditions or cultural assets, or that may or will waste or deteriorate our raw material resources.”

Soil pollution happens when we destroy the thin layer of healthy and productive soil, which covers the earth’s surface. Most of the world’s food is produced using this resource and if we don’t protect it the world’s farmers will be unable to grow enough food to support the worlds people.
 
Healthy soil depends on bacteria, fungi, and small animals (such as worms) to break down wastes in the soil and release its nutrients which help plants grow. The over use of fertilizers and pesticides can limit the ability of soil organisms to process wastes, which in turn makes the soil less productive or in the worst case scenario useless or even poisonous. 

Water is indispensable for our life. About 2/3 of earth is covered with water. No organism can survive without water. So keeping water free from any pollutant is very important. Water is said to be  “polluted” when it is hanged in its quality and composition directly or indirectly by man’s activity so that it becomes less suitable for drinking, domestic, agricultural or any other purpose. Polluted water transmits a large number of diseases in man. They are cholera, typhoid, dysentery, jaundice and other bacterial or viral diseases.  Water becomes polluted by the presence or addition on inorganic or organic substances or biological agents. Soil erosion, leaching of minerals from rocks, decaying of organic matter are natural sources of water pollution. There has been an alarming increase in the degradation of water quality in the recent past in the large cities and industrial areas.

Water pollution can be studied under the following heads—  (i) medium in which it occurs (surface water, ground water); (ii) habitat (lakes, estuaries and open seas); and (iii) type of pollutants (bacterial, metallic, thermal and radioactive).

The ozone layer is a region in the Earth’s stratosphere where a certain amount of incoming solar radiation is absorbed. Over the last twenty years or so a series of man-made threats to it have been reported and each has been treated  with more gravity than the last. Now a-days such threats feature  regularly on the agendas of international conferences.

Ozone, Positive and Negative : Ozone, or trimolecular oxygen (O3) can be advantageous or exert harmful influence on human health, as well as that of other organisms. It is all depends on whether it is present in the troposphere or stratosphere (Fig. 8.1). In the stratosphere, ozone is a beneficial serving as a shield in screening out most of the damaging portions of ultraviolet radiation which have wavelengths between 290 and 320 nanometers. In the troposphere, ozone is a negative as it appears as a component of smog with a number of deleterious effects, as will be discussed below.

El Nino is the name given to the occasional development of warm ocean surface waters along the coast of Ecuador and Peru. When this warming occurs the usual upwelling of cold, nutrient rich deep ocean water is significantly reduced. El Nino normally occurs around Christmas and lasts usually for a few weeks to a few months. Sometimes an extremely warm event can develop that lasts for much longer time periods. In the 1990s, strong El Ninos developed in 1991 and lasted until 1995, and from fall 1997 to spring 1998.

The ‘greenhouse effect’ earns its name from the rough similarity between the way it works and the way the glass of a greenhouse works. Glass too, is transparent to short-wave radiation but opaque to long-wave radiation, so the greenhouse traps heat.
Carbon dioxide plays a critical role in controlling the Earth’s climate because as an aerosol it absorbs and reflects or scatters incoming radiation on the one hand and absorbs and reradiates outgoing infrared radiation on the other. This latter phenomenon results in what is popularly called the Greenhouse Effect, an analogy to what happens in a greenhouse.

Air is one of the most important constituents of man’s environment. It is calculated that a roan breathes about 22,000 times a day inhaling about 16 kg of air by weight. Air is present everywhere and its entrance from one place to another cannot be checked. Clean and pure air is very essential for the health and survival of man.

Any living organism in its natural habitat is called a wildlife. It may be plant animal or a microbe. The significance of wild life lies in setting up the balance of population in nature by maintaining food chains and food webs. It acts as the gene banks in relation to breeding of plants and animals for introduction of desirable characters such as high yield of economic product and resistance to diseases. The scientists are performing studies to screen and select useful genes in economically important organisms.

Conservation has always been one of the most important applications of ecology.Unfortunately, the term “conservation” suggest “hoarding”, as if the idea were simply to ration static supplies so that there would be some left for the future. In the eye of the general public the “conservationist” is too often presumed to be an antisocial person who is against any kind of “development”. What the real conservationist is  against  is unplanned  development  that breaks  ecological  as  well as human laws. The true aim of conservation, is two fold–
    
(1)     To ensure the  preservation of a  quality  environment that considers esthetic and recreational as well as product needs; and  
    
(2)     To ensure as continuous yield of useful plants, animals and materials by establishing a balanced cycle of harvest and renewal.

“Natural” means an ecosystem not influenced by man and resources means that reserve stock of supply which living things can take from nature for sustenance of life. In reference to man, natural resources can be defined as those natural reserve stocks of supply which man utilizes for his sustenance and welfare. The reservoirs of natural resources are the sun,  the  atmosphere,  the  lithosphere  and the  hydrosphere.  Natural resources include energy, air, water, soil, minerals, plants and animals. The nature of resource depends upon many factors such as scientific and technological development of the society, profession of that particular society, and culture.

We are entering an era when certain environmental conditions will exert a degree of concern which has never been before encountered by man in the course of human history.

The survival of human beings depends on the realisation that they have to live in harmony with the various elements of the environment which are interconnected.
    
(i)     An understanding of the components and processes which takes place in the environment.
    
(ii)     The relationship between different abiotic and biotic components and the assessment of resources with reference to needs of people in a region is essential for their survival.
    
(iii)     A reduction in rate of growth of population in developing countries and a reduction in consumption of resources by developed countries would lead to a balance between population and resources. In this manner, the awareness of the problems faced by environment would enable people to take appropriate decisions. This makes the earth habitable for future generations.

Introduction

Farming and agriculture are respectively defined as the practice of cultivating the land or raising stock and the production of agricultural goods through the growing of plants and the raising of domesticated animals. In the developing countries frantic efforts have been made through research and enlightenment campaigns to encourage farming and thus ensure significant increases in agricultural production in order to feed and sustain the population that is increasing at geometric proportion. At present, the farmers concentrate mainly on crop production which is subjected to a high degree of uncertainty in income and employment to the farmers. In this context, it is imperative to evolve suitable strategy for augmenting the income of a farm.