eChapters

We must know our family, its members and their relationships. Let us first look at basic relationships which often figure in the questions. If you are conversant with the given items in the table below, half of your battle is already won. It is not required to mug-up these names, but instead make a clear picture in your mind as you go through each one of them. This will go a long way in retaining the details of these given shortcut tricks for solving Blood relations problems for logical and analytical reasoning. Read the following thoroughly before moving on

Introduction

Almost every test of reasoning contains questions on coding. In such questions, generally one word and its code are given, and the students are required to find the code for the other word. The student is required to apply the same logic, as was applied in the given words.

Let’s discuss some of the commonly asked questions based on coding : Some of the major types of coding logics are

What is that the grower wants to achieve while he nourishes the crop with costly fertilizer inputs? He would like to get maximum output (yield and quality) of the produce; and for the maximization of out-put the fertilizer input should be utilized by the crop to its maximum potential. Thus it is not higher fertilizer dose that decides the highest yield; but the highest efficiency in crop’s use of those fertilizers. The efficiency, yield/unit fertilizer can be enhanced by the following factors;

a) Plant roots absorbing (in-take) total quanta of applied fertilizer and minimizing the loss of applied nutrients by not having spare quantities lying around the soil profile. This is possible only if the quantum of application matches with the quantum of need.

b) Plants utilizing the absorbed nutrients for metabolic activities concurrent to absorption. This is possible only if the fertilizers are applied in times of need of the plants and not before or after. This compels the grower to know the physiological need of the nutrient during each developmental stages; which nutrient required when.

Here the grower must have a powerful tool or method to provide nutrients to the plants strictly following the above two factors. Fertigation offers an opportunity to practice nutrient inputs based on the above two factors: the grower is able to correctly decide the dose, type and time of providing the correct nutrient at precise quantity and at the required stage of plant/ crop development.

Thus the purpose of Agriculture, to maximize yield and quality of crops and minimize the costs of production while maintaining sustainability can be put into practice by fertigation. Two most important prerequisites to achieve all of these are the optimal and balanced supply of water and nutrients. Tuning of plant nutrient supply with the uptake and utilization rates by crops is essentially an art and is made doable by fertigation technology.

Only a very brief mention of various basic aspects of plant nutrition is given here. Associates wanting to know more details should refer to any one of the standard Plant Nutrition publication (PRINCIPLES OF PLANT NUTRITION by K. Mengel and E.A. Kirkby).

Increased production of food and cash crops is the need of our times; as land and irrigation water are limited and beyond any means of expansion. Crop yields per unit input should increase. Crop yield under natural production systems is limited by the availability of nutrients in the soil. Unless the supply of nutrients can be enhanced yields cannot be high.

Although the application of fertilizer to even fairly fertile soils can give a great increase in crop yield, soil fertility is not simply a matter of nutrient content. It is dependent on a number of complex of issues:

Soil depth

The volume of soil from which the crop draws its nutrition varies according to the rooting depth of the crop. However hard or rocky layers can restrict natural root development; this is particularly the case with micro irrigation systems.

Soil structure

Particle size and soil aggregate size and distribution, effect the size and distribution of pores and therefore the availability of air and water to the roots.

Organic Fertilizers and Manures

Farmers have been using organic waste as fertilizers for a very long time. As previously mentioned, the application of O.M. to a soil can have number of beneficial effects on soil structure, C.E.C. and microbial activity. However, organic manures mainly originate from the waste products of animal and plant production and although rich in carbon compounds, they are usually relatively poor in available plant nutrients.

The nutrient content of organic manures varies widely depending on their source and moisture content. Farm yard manure (F.Y.M.) is one of the most common organic fertilizers used. Others are concentrated animal manures, and crop residues such as straw.

There is a lot of confusion and lack of understanding when it comes to scheduling of fertigation. Even crop specialists prepare a fertigation dosage by dividing the total fertilizer quantity by the number of days of crop growth. This is highly erroneous. A scientifically prepared fertigation plan allows coordination of nutrient supply with changing demands of the growing crops which changes with the physiological shifts in the crop. Fertigation planner requires following information to prepare this schedule- which, when and how much plan:

The crop growing environment, both soil/media and aerial are controlled in green house. Therefore, the movement of water (liquid and vapour) and minerals (nutrient ions) follow a different pattern altogether. This factor should be considered while preparing the fertigation program. This becomes all the more different if soil-less rooting media is used.

Table 7.1: Differences in Nutrient uptake in open field and Protected (GH) conditions.

Fig 8.1: A scheme for fertigation program working with automation

In modern farming with fertigation machines (NutriCare) and automated drip irrigation systems, fertigation set up schemes like the above are put into practice. This scheme will stream line the installation, operation and monitoring of the entire process. An informed grower would be able to control crop performance more precisely and achieve his objectives.

The term agriculture is derived from the Latin words ager or agri meaning soils and cultura means cultivation. Agriculture is the art, science and business of crop production. It encompasses all aspects of crop production, livestock farming, fishery and forestry. Agriculture is the conversion of solar energy into the chemical energy. Crop production is the conversion of environmental inputs like solar energy, carbon dioxide, water and nutrients in soil to economic products in the form of human or animal food or industrial raw materials.

Agriculture is a science, an art and business of crop production

Agriculture is a science of farming. Scientific principles are employed to find ways of making it as efficient as possible. Through scientific principles plants and animals are transformed genetically and most favorable environment is provided to harvest higher yields of good quality with least expense of energy. The scientific principles of various branches viz. soil science, genetics and plant breeding, entomology, plant pathology, microbiology, agricultural engineering etc. were employed in agriculture. Agriculture like any other science is a body of truths synthesized and systematized and arranged in such a way as to show the operation of general laws and principles.

Agriculture is an art which embraces knowledge of the way to perform the operation of a farm in a skillful manner. The physical and mental skills are involved in agriculture. The skills may be acquired through years of experience viz. ploughing, stacking hay bundles, handling animals, sowing seeds, transplanting, driving a tractor etc. Mental skills are those involved in decision making for example when to plough the land, selection of appropriate crops, seed selection etc.

Agriculture is a business which is no longer a way of living or subsistence agriculture, where production is intended to meet the home requirements. Agriculture is intended to earn more income. Land, labour, capital are judiciously used. Like in any industry the farming industry should forecast the demand, tailor the production with demand to earn more profits. It involves processing, value addition, transportation, packing and storage in scientific way. Knowledge of employee and employer relationship or human resource management, export and imports, taxation, customs, tariffs and trade are required. All these aspects demand business knowledge in addition to the production and managerial skills. Traditional agriculture is no longer relevant for success in agriculture. Commercial agriculture or corporate farming, agribusiness development corporations demand entrepreneurs in agriculture rather than technologists alone.

Crop growth is influenced by internal factors and external factors. Internal factors are controlled by the genes and hereditary. External factors are climate, edaphic, biotic, physiographic and anthropic.

Genetic Factors

Genetic factors are controlled by the genes. Plant height, yield, size and color of the grains or fruit etc. The productivity and quality of the crop can be improved by breeding through conventional methods or by biotechnological approaches.

Environmental factors Climate

Precipitation occurs in the form of rainfall, snow, hail and fog.

Fog: Consists of water droplets so small that their fall velocity is negligible. Fog particles contact vegetation and may adhere, coalesce with other droplets and eventually form a drop which is large enough to fall to ground.

Field Crops: Refers to the crops grown on a vast scale. They are classified in the following ways

1. According to the place of origin

2. Botanical classification

3. Commercial classification

4. Economic classification

5. Seasonal classification

6. Classification according to ontogeny

7. Agronomic classification

8. Classification based on leaf morphology

9. Classification based on serving special purpose

The word soil is derived from the Latin word ‘Solum’ means soil. In general the top 15-20 cm cultivated layer is referred as soil. It is a loose and unconsolidated outer layer of the earth crust that is crumbly and powdery in nature. Soil below the plough layer is called subsoil.

Soil is formed by weathering of rocks. Weathering may be physical or chemical or both. Factors of soil formation are parent material, climate, living things-plants, animals and microorganisms, topography and time. Soil formation is a function of parent material (P), climate (C), topography (T_o), life (L) and time (T) which is represented by f(P C To L T).

Soil fertility is the ability of the soil to supply all the essential nutrients in optimum amount in balanced proportion in a form readily available to plants under conditions favourable for plant growth and should be free from toxic substances.

Soil productivity: Soil productivity is defined as the capability of soil for producing a specified crop or sequence of crops under defined set of management practices. It is measured in terms of outputs or harvests in relation to the inputs of production factors for specific kinds of soils under a physically defined system of management according to USDA (1957).

Tillage is the physical manipulation of the soil with tools and implements which, results in good tilth for better germination and subsequent growth of crops.

Tilth is the physical condition of the soil resulting from tillage. Soil is said to be in good tilth when it is mellow, friable and adequately aerated. Tilth is dynamic. Mechanical forces may change the roughness of the soil surface, the total porosity and bulk density of the tilled layer and the aggregate or clod size. Heavy rainfall and high velocity wind or water destroys the tilth. The action of wetting and drying, freezing and thawing regenerates desirable tilth. The roughness of the soil surface is an index of the amount of water that can be stored in soil depressions and may also be related to the resistance of the soil surface to sealing. Roughness may be related to rate of evaporation, transfer of heat and air between the soil and atmosphere.

A seed consists of a plant embryo, stored food material surrounded by a seed coat. Seeds of cereals and grasses consist of embryo or germ, endosperm and the pericarp.

Seeds of legumes contain no endosperm, the bulk of the seed being made up of the two cotyledons. The cotyledons constitute the food storage portion.

The embryo of the grass seed is made of epicotyl, hypocotyl and scutellum- the single cotyledon of monocots, the epicotyl gives rise to the shoot and the hypocotyl produces the roots.

Criterion for essentiality of plant nutrients

Arnon’s (1954) criteria for essentiality of elements for plant growth:

1. The plant must be unable to grow normally or complete its life cycle in the absence of the element,

2. The element is specific and cannot be replaced by another and,

3. The element plays a direct role in metabolism.

Manures are the plant and animal wastes that are used as source of plant nutrients. They release nutrients upon their decomposition.

Bulky organic manures contain small percentage of nutrients and they are applied in large quantities. e.g,. farmyard manure, compost, green manures.

Knowledge of fertilizer dose, selection of fertilizer sources, time and method of application is essential for achieving efficient use of fertilizers and profitable yield.

A. Fertilizer Dose

Fertilizer dose for crops is determined based on the field experimentation. It varies with the crops and varieties, initial fertility of the soil, soil properties, cropping system, climate, season, rainfed or irrigated crop, expected yield etc. Fertilizer dose for rainfedcrops (Kg/ha)

Plant growth is defined as the progressive development which is irreversible. It is expressed in terms of dry weight plants, height of plants, girth or diameter of the stem or tree trunks, spread of the tree canopy, number of branches or tillers. Plant growth is a function or various factors which may be expressed as G = f (x, x₂, x₃ x_n ).Some factors may be controlled while some cannot be controlled. The following are the factors which influence the plant growth.

An ideotype is a crop plant having desirable morphological and physiological characteristics or both for cultivation in a specific agroclimate situation. An ideotype is constructed by the breeder on the basis of indepth study of morphological and physiological characters including their interrelationships, and intuition of the breeder based on his experience.

Adaptation is any feature of an organism which has survival value under the existing condition of its habitat. The basic of successful crop production is the selection of an adapted plant species and varieties. Plants may have morphological adaptation or physiological adaptation or both for the existing environment.

Adaptation to soil moisture

Hydrophytes: More number of stomata on the upper surface of the leaf, aerenchyma tissue in the roots of rice plants, stem is hollow/straw, internodes are longer in floating and submerged rice,

Mesophytes: Stomata are normal. Present both on upper and lower leaf surface, medium root growth.

Cropping system is the cropping patterns used on a farm and their interaction with farm resources, other farm enterprises, available technology and environment (Physical, biological and socioeconomic) which determine their makeup (Krantz et al., 1975). Cropping system is subsystem of the farming system.

The cropping system aims at increasing the benefits derived by crop production from available physical resources (land, climate, water resources etc.) that are not readily changed through optimization of input levels for a given crop or cropping pattern. The objective of any cropping system is to increase the efficiency of utilization of resources. The efficiency in measured by the quantity of product obtained per unit resource in a unit time in cropping system.

The problematic areas for crop production may be soils affected with acidity, high concentration of salts, water logged soils or soils in steep sloppy areas. These soils have limitations or ill effects for crop growth and productivity.

Removal of entire plants or the economic parts after maturity from the field is called harvesting. Portion that is left behind on the field is known as stubble. The economic product may be grain, seed, leaf, root or entire plant.

Time of Harvesting

If the crop is harvested early, the produce contains high moisture and more immature grains. The yields will be low due to unfilled grains. It is very difficult to store the produce as shriveled grains with high moisture are highly prone to infestation by pest. The quality of the grain as well as germination percentage is also reduced. Late harvest results in shattering of grains, germination even before harvesting in rainy season and breakage during processing. Hence harvesting during correct time is very important.

Plants may be harvested at physiological maturity or harvest maturity. Plants are said to be in physiological maturity when the translocation of the photosynthates ceases to the economic part.

Weeds are the plants growing where and when they are not desired. They compete with crops for soil moisture, nutrients, solar radiation and space, and thus reduce crop yields. Weeds also act as alternate hosts that harbour insect pests and diseases and other microorganisms. Some weeds release poisonous substances into the soil which may be harmful to crop plants, human and livestock. Weeds reduce the quality of marketable produce and render harvesting difficult, leading to increased expenditure on labours, equipment and chemicals for their removal.

Classification of weeds

A. Based on life cycle

Annuals-Complete their life cycle in a year or in a single growing season. Based on the season they may be summer annuals and winter annuals.
Summer annual e.g, Echinochloa crusgalli

ESSENTIAL ELEMENTS FOR PLANT GROWTH

Arnon (1954) set three criteria to state an element is essential to plants. They are:

1. The plant must be unable to grow normally or complete its life cycle in the absence of the element,
2. The element is specific and cannot be replaced by another and,
3. The element plays a direct role in metabolism.

Accordingly there are 16 elements essential for plant growth. They are carbon, hydrogen and oxygen called primary nutrients, calcium, magnesium and sulphur called secondary nutrients; iron, zinc, manganese, copper, boron, chlorine and molybdenum are known as micronutrients.

Concept of nutrient availability: The ions in the soil solution are available to plant provided they can reach an active root or it can reach them. The concentration of ions in the soil solution at any given moment is however; usually low, except immediately after the application of water soluble fertilizers.

Most of the nutrients are taken up by the plant in the form of cations which are positively charged. Available cations either in the soil solution or held against leaching by negatively charged clay or humus particles are easily taken up by the plants. Other plant nutrients notably phosphorus, boron and molybdenum are taken up by the plant as anions which are negatively charged. The concentration of anions in the soil solution is usually low because they become converted to new less soluble forms e.g., soluble phosphate ions forms less soluble iron or aluminium phosphates. Minerals upon weathering and organic matter upon mineralization release nutrient ions.

Physical factors

However, much readily available nutrients a soil may contain various physical features of the soil make it impossible for the plant roots to absorb it. It then becomes positionally unavailable. These features include hard pans, undesirable soil structures, presence of hard clods, dry soil horizons and water logged situation.

Low soil cation exchange capacity leads to less retention of calcium, magnesium, potassium, copper and zinc.

Plants are the generators or the primary source of organic matter while animals are the transformers- secondary source of organic matter. In agriculture, plants add 10–30 percent of organic matter through their roots stubbles and leaf fall and exudations. The excreta of livestock, the organic wastes of urban and rural residential areas include the garbage and sewage and sludge. The by products of agro based industries viz. bagasse, vinasse, pressmud from sugar industries, the coir dust from the coir industries, dust of cotton from ginning industries, the fruit and food processing industries wastes.

Greek scientist Theophrastus (300 BC) advocated legume rotation. As early as 1750 AD it was known that plants require Nitre. Louis Pasteure in 1860 AD stated the possibility of atmospheric nitrogen fixation by microorganisms. Hellriegel and Willfarth (1886) strengthened the views of Louis Pasteure by his observations on the irratic behaviour of legumes to nitrate nutrition. Beizerink (1890) isolated the organism involved in nitrogen fixation. The systematic field experiments conducted at Rothemstead experimental station showed that the plants respond to inorganic nitrogen.

ROLES OF NITROGEN IN CROPS

Plants contain 1-5 per cent nitrogen by weight. It is a structural component of chlorophyll, aminoacids and proteins. Plant proteins contain 16 per cent nitrogen (6.25 × %N = protein). Plants are dependent on protein for their propagation. Cereals possess a threshold protein level below which grain will not form.

Liebig (1840) on the basis of soil and plant analysis deduced the phosphorus requirement of plants. J.B. Lawes conducted series of field experiments to improve the fertilizer value of common sources of phosphorus such as bone meal, apatite, rock phosphate. Lawes (1843) produced super phosphate by treating apatite mineral containing phosphorus with sulphuric acid. He also stated that the phosphorus present in bones of higher animals can be made available by treating with sulphuric acid.

Phosphorus is the second most deficient nutrient in the world. Annual application of phosphorus fertilizers to crops is 36 million tons of which

1.32 m tones are consumed in India. Most of the arable soils in tropical and subtropical regions are deficient in phoshphorus, but the response of crops to phosphorus is uncertain. Phosphorus concentration in plants ranges from 0.1 to 0.4 per cent.

Glauber J. R. (1604–1670) in Netherlands first proposed that the salt peter (KNO₃) was the principle of vegetation. He obtained large increases in crop yield by addition of salt peter.

Mineral soils contain 0.04–3.0% K. Total potassium content of soils range from 3000 to 100000 kg per ha in the upper 0.2 m of soil profile. Of this total potassium approximately 98 percent is bound in mineral form whereas 2% in soil solution and exchangeable phases.

ROLE OF POTASSIUM

It is Involved in activating the enzymes (as many as 80) responsible for carbon dioxide reduction and required for synthesis of adenosine triphosphate. Hence deficiency of potassium reduces crop growth and yields.

CALCIUM

Calcium is important in imparting structure and permeability to cell membrane. Deficiency produces general breakdown of membrane structure. Calcium enhances the uptake of NO₃ ^– N and interrelated with NO₃ ^– metabolism. It regulates cation uptake, required for cell elongation and cell division. Deficiency causes failure of terminal buds and apical tips of roots to develop. Blossom end rot of tomato, bitter pit of apples are due to calcium deficiency. Calcium is beneficial in imparting good soil structure.

It is immobile in plant. Very little translocation of calcium in the phloem is observed. Hence there is poor supply of calcium to fruits and storage organs. Downward translocation of calcium is also limited. Hence roots fail to enter the low calcium soils.

ZINC (Zn)

Chandler et al., (1932) deduced the requirement of zinc by plants while working solution for little leaf or “rosette” on peach. Zinc plays significant role in assimilation of NO₃ and for synthesis of tryptophan. Involved in biosynthesis of indole acetic acid which is responsible for f lowering and fruiting, it is an activator of several enzymes (triphosphate dehydrogenase and tryptophan synthetase), involved in photosynthesis and nitrogen metabolism.

Deficiency results in poor growth of the terminal bud. Decrease in stem length resulting in resetting and whorling of leaves. Zinc deficiency disorder in rice is called khaira. Common when zinc availability is < 0.7 ppm. White bud in maize and malformation of fruits, reduction in water uptake. Interveinal chlorosis often with necrosis and pigmentation and reduced leaf size in broad leaved crops known as little leaf and malformation of leaves.

The crops which are known to respond for zinc application are maize, rice, soyabean, castor, onion, barley, wheat, potato, sorghum and cotton

Farmyard Manure is the manure prepared by using the mixture of dung and urine soaked litter by microorganisms.

Good farmyard manure is one

Green manure is defined as fresh organic matter/undecomposed plant material/ real organic matter, natural plant food added to the soil for the purpose of supplying plant nutrients.

CLASSIFICATION OF GREEN MANURES

Nonlegumes: Rape seed, buck wheat, niger, rye, oats and maize

Legumes:

Grain legumes: cowpea, mungbean, pigeon pea, soybean, khesari (Lathyrus sativus)

Dual purpose legumes: cluster bean (Cyamopsis tetragonoloba). pillipesara, Sesbania speciosa.

Non grain legumes: sunnhemp, dhaincha, pillipesera (Phaseolus trilobus), stylosanthes and desmodium.

Biofertilizers act as complementary and supplementary sources of plant nutrients. Biofertilizers help in increasing the biologically fixed atmospheric nitrogen and enhancing phosphorus availability to the crops. Among the biofertilizers for increasing nitrogen supply, nitrogen fixing bacteria (Rhizobium, Azotobacter and Azospirillum), blue green algae (BGA) and Azolla are important. The availability of phosphorus is improved by phosphorus solublizing microorganisms (PSM) and mycorrhizae (VAM).

Rhizobium is of vital importance to various pulses and some of the oilseeds and fodder legumes as 80–90 per cent of their nitrogen requirement is met through biological nitrogen fixation (BNF). Rhizobium fixes atmospheric nitrogen ranging from 50–60 kg per ha in groundnut, 100–300 kg per ha in alfalfa. In pulses it is estimated at 50–110 kg/per ha. Field studies indicated a yield increase of 14–53 per cent due to Rhizobium inoculation. Nitrogen left over the demand of legumes in combination with the nitrogen present in roots of the legumes will enhance the soil fertility. Consequently the nutrient needs of the subsequent crop from applications will be reduced.

Integrated plant nutrition system conceptualized by food and agriculture organization is the maintenance or adjustment of soil fertility and of plant nutrient supply to an optimum level for sustaining the desired productivity through optimization of benefits from all possible sources of plant nutrients viz. organic manures, fertilizers, crop residues, compost or nitrogen fixing crops etc. in an integrated manner.

SOIL MANAGEMENT PRACTICES

Good soil management is the basic for deriving greater benefits from the fertilizers used in crop production. Some of the good soil management practices are

Good tilth is the first feature of good soil management. It means a suitable physical condition of the soil and implies in addition a satisfactory regulation of soil moisture and air.

The maintenance of soil organic matter which encourages granulation is an important consideration of good tilth.

Tillage operations and timings should be adjusted as to cause the minimum destruction of soil aggregates. Good tilth minimizes erosion hazards.

The choice and sequence of adaptable crops or crop rotation are other very important considerations. These are related to climate, particularly rainfall and its pattern of distribution and the characteristics of the soil profile, including drainage and extent and duration of available soil moisture. A proper sequence of crop varieties greatly influences soil conditions. It is more realistic to evolve cropping patterns and land management practices according to land capability. Cropping patterns chosen and management practices adopted should aim at soil and moisture conservation for efficient nutrient and moisture utilization.

Salt affected soils occupy 962.2 m ha globally which accounts for 33% of the arable land. In India 8.373 m ha is affected with salts. Of which 2.359 m ha are alkali soils, 3.829 m ha are saline soils and 2.185 m ha coastal saline soils. Reclamation of these soils provides additional area for food grains production and employment.

R software is a programming language used for statistical analysis, graphical representation and reporting, and is currently developed by the R Development Core Team. R software is available freely under the GNU General Public License, and the binary versions are provided for the Windows, Linux and Mac operating systems. To develop R, effort from all over the world is made in a collaborative manner.

What is GNU?

GNU stands for GNU’s Not Unix. It is a Unix like computer operating system, but different from Unix. GNU consists of GNU packages which are program specific and released by GNU project. Free software means that the users of the software have freedom to run and use the software and also can copy, change, improve and distribute the software freely.

Development of R

R software was initially written by Robert Gentleman and Ross Ihaka also known as “R & R” of the statistics department of the University of Auckland, New Zealand. R appeared first in 1993. Since then various contribution to R has been made by a large group of talented individuals by sending code and bug reports. A core group, known as the “R Core Team” modify the R source code archive since 1997. Thus R is a collaborative project with many contributors.

This chapter deals with the objects used in R which contains the data in various formats. The data types used in R has also been mentioned in this chapter. The chapter also includes the functions used in R as the codes for accomplishing several jobs related to data analysis.

Unlike C language and Java, the variables in R are not declared as some data type. The variables are assigned with R object and the data type of R object becomes the data type of the variable. The commonly used R objects in R are vectors, lists, matrices, arrays, factors and data frames. The vector object is the simplest one and other R-objects are built upon the vectors. The different data types of these vectors are logical, numeric, integer, complex, character and raw. The objects in R are stored by the name of a variable and the data type of the object is determined by its content. To know the data type of a variable the class() function is used. The various data types are described as below:

R packages include functions, codes and sample data. The functions used in R are contained in packages. A package in R contains several functions which are related to some particular type of job. A package conatins at least one function and there is no maximum limit to the no. of functions in a package. The set of packages in R which are set by default in the software is called base package. It contains a lot of commonly used functions. The packages in R are stored under a directory called “library” in the R environment. The packages get installed by default while installing R in the computer. Also more packages can be added later on after installation, when required for some specific purposes. The base packages are available by default when we start using R. But the other packages which are already installed while installing R have to be loaded while using R. These packages can be viewed in the package window by clicking on package. To install the package we have to click on install menu in the package window and then write the name of the package.

The packages can also be installed by using the function install.packages(“abc”) where abc is the name of the package to be installed.

Once a package is installed, it remains in the hard disk of the PC/laptop. But the package will have to be called for use in the current R session. The package once installed can be loaded for use in the current R session by checking the box near the name of the package displayed after clicking on the install menu in the Files/ Plots/Packages/Help window. The package can also be loaded by using library() function. The command will be library(“abc”) where abc is the name of the package. The loaded package remains in the memory for the current R session. Once we quit the R session, the installed package has to loaded again if needed.

In R there is facility of reshaping the data. Reshaping of data includes joining of two or more vectors to create a data frame. Also two or more data frames can be merged. Appropriate functions are available for these jobs. While merging the data frames, we can join columns or rows.

Illustration of joining two vectors by using cbind() function.

The most important use of R programming lies in importing of data files which serves as input for the analysis work. After the analysis is over by using R codes, operators and functions, the output result must also be exported in form of files. The files are imported in form of csv files (comma separated variable), text files or excel files.

Before going to the actual content of the chapter we have to have an idea about csv files. CSV stands for Comma Separated value. It is used to store tabular data, such as a spreadsheet or database. CSV is delimited text file in which the values are separated by commas. CSV files occupy much less space than excel files and also gets imported in a program at a much faster rate than Excel files. CSV Files also does not manipulate data and stores as it is.

Let us consider that an excel file named as ‘plant’ which stores three variables, named as ph, pd and yield is created inside the folder named as ‘My Data’ which is placed in the desktop. Thus the path of the file is “C:\\Desktop\\My Data\\plant”

To import excel file the package will be readxl and the command will be library(readxl)

Matrix is a rectangular array of numbers arranged in rows and columns. The order of a matrix is written as r x c, where r is the no. of rows and c is the no. of columns. The numbers included in a matrix are called elements of the matrix. The name of the matrix is denoted by an uppercase English alphabet.

Frequency Distribution is the arrangement of various values of a variable in order of magnitude either individually or in groups alongwith their corresponding frequencies or class frequencies. Frequency distribution is necessary for data condensation and revealing pattern within the data. Frequency distribution can be (i) Ungrouped Frequency Distribution (ii) Grouped frequency distribution.

In case ofungrouped frequency distribution, the individual values ofthe variable are arranged in ascending order alongwith their frequencies. Frequency is the number of times a particular observation is repeated.

In case of grouped frequency distribution, the values of variable are grouped into classes alongwith their corresponding class frequencies. Class frequency of a class is the number of observations lying within the upper class limit (maximum value) and lower class limit (minimum value) of the class.

Let us first illustrate the preparation of ungrouped frequency distribution. Consider 50 petridishes each containing 6 no.s of seeds for germination. Let the variable x_i denote the no. of seeds germinated in a petridish.

Diagrams and graphs are the effective and attractive ways of presenting data. Widely used diagrams for data presentation are pi chart and bar diagrams. Bar diagrams are also of various types; (i) Simple bar diagram (ii) Component or sub-divided bar diagram (iii) Multiple bar diagram (iv) Percentage bar diagram. The widely used graphical presentation are histograms, frequency polygon and frequency curve.

There are numerous libraries to create charts and graphs in R programming language.

Pie-chart- A pie-chart is a representation of values of variable as sectors of a circle with different colours/shadings. The colours/shadings used for different sectors are indexed at the side of the graph. pie() function is used to create pie chrt in R.

Let us create an exel file names as ‘exp_sports’ which contains the expenditure made (in Rs.) under various sports in a sports club. The name of the sports are cricket, hockey, tennis and football. The names of sports are placed under the column head ‘sports’. The corresponding expenditure (in Rs.) are 7200, 3600, 1800, 1800 and they are placed under the column head ‘expenditure’.

The basic syntax for creating a pie-chart using the R is.

The branch of statistics which describes the data is called descriptive statistics. After collection, the data are presented in form of tables, diagrams or graphs. This facilitates the further analysis of data. The most basic form of data analysis is descriptive analysis of data collected and presented for the study. The descriptive statistics summarises the data and helps to find the representative value of the entire data set and the variation of the other values in the data set around the representative value. The descriptive statistics includes the measures of central tendency or averages, measures of dispersion or scatteredness, measures of skewness and the measures of kurtosis. Before going to discuss the R codes for various measures of descriptive analysis, we would first discuss in brief about these measure. This will help in better understanding of the R codes.

Measures of central tendency or averages: They are the representative values of the data series. They give an idea about the concentration of the values in the central part of the distribution of the data. There are five types of averages. They are 1. Arithmetic Mean (A.M.) 2. Geometric mean (G.M.) 3. Harmonic Mean (H.M.) 4. Median 5. Mode.