eChapters

There is a very impressive and extensive number of terms and definitions used in plant pathology, many of which you will not come in contact with. With interest, study and practice, terms and names will come to light and become familiar to you. When you start out, don’t worry too much about the terms; but also don’t be afraid of them. The more exposure you have to the subject the more comfortable you will be when dealing with your peers and the public. With these you are going to be exposed to some terms and definitions that will be a good ice breaker and prepares you for the information to follow

Till date, there is no complete agreement on the terms used in cropping system. An attempt was made to standardize the terms and their usage at the symposium on Multiple Cropping held by the American Society of Agronomy, in Knoxville, Tennessee, during August, 1975. Some definitions published in the proceeding (Andrews and Kassam, 1976) which forms the basis for the improvement and additions of definitions made subsequently (Francis, 1989). The terms commonly used in cropping system and their definitions are given in the following paragraphs.

The science that includes classification, nomenclature and identification of plants is called plant taxonomy. Taxa (Sing. Taxon):A general term for taxonomic classification, irrespective of rank.
18.1 Plant Types (habit and habitat)
1. Annual: A plant that completes its entire life cycle, from seed to reproduction to death, in one single year.
2. Biennial: A plant that completes its entire life cycle in two years.
3. Perennial: A plant that grows and reproduces for many years.
4. Monocarpic: plants that flower and set seeds once during its lifetime. They flower only after attaining maturity. They flower gregariously in a single season e.g. Bamboo and Kurinjis.
5. Polycarpic: Plants that flower and set seeds many times during its lifetime.
6. Aquatic: Organisms growing in water.
7. Shrub: A much branched, small, woody perennial plant with several branches from ground level upwards.
8. Tree: A tall, woody, perennial plant with a single trunk which usually bears branches.

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.

Introduction

Antibiotics are the substances produced by one microorganism and are required to inhibit the growth of other microorganisms. Antibiotics are used to combat infectious diseases. The antibiotic sensitivity is very significant due to development of resistance among various microorganisms.

Requirements

1. Swab
2. Nutrient agar
3. Petri plates
4. Bacterial cultures
5. Forceps
6. Antibiotic discs
7. BOD Incubator

Procedure

1. Prepare the bacterial lawn on Nutrient agar plate.

Plants are exposed to various stresses such as temperature, water, oxygen, salts, nutrition etc, during its growth under dry land condition. Various simple tests have been developed by plant scientist for evaluation of different cultivars against these stresses. These tests are simple to perform in the laboratory with fewer instruments that are commonly available in most of the laboratories in developing countries. These tests have significance in plant water relations and cultivars reliably screened for various stresses. The crops upon which these tests have been performed here are used by the proponents of the tests. These tests are not advised to be performed on crops other than those used by the authors. It probably needs standardization for other crops. The following test has been explained for the benefit of the readers.

9.1 Introduction
In the preceeding chapter, we have studied the estimation part of statistical decision (inference) infered about the parameters of the population on the basis of information available in the sample observations drawn from the parent population under study. In the present chapter we discuss the problems related with the tests of statistical hypothesis and its significance about the population parameters under study. For understanding of the subject matter considered in this chapter, very clearly and easily, one must be familier with the statistical terminologies used in the subject matter. Hence we discuss the various notable terminologies with some suitable examples in a simple way for better understanding.

9.1 Introduction

In the preceeding chapter, we have studied the estimation part of statistical decision (inference) infered about the parameters of the population on the basis of information available in the sample observations drawn from the parent population under study. In the present chapter we discuss the problems related with the tests of statistical hypothesis and its significance about the population parameters under study. For understanding of the subject matter considered in this chapter, very clearly and easily, one must be familier with the statistical terminologies used in the subject matter. Hence we discuss the various notable terminologies with some suitable examples in a simple way for better understanding.

4.1 Write True/False

4.1.1 Preliminaries

Q.1    In selection of a test, one should try to keep the probabilities of both types of error small.
Q.2    Under a non-sequential sampling scheme (i.e. fixed sample size n), it is not possible to minimise both the errors at the same time.

Increased ketone bodies level in blood, known as ketonemia and condition is ketosis. The disease respond readily to treatment with glucogenic substances which can be one of the test therapy to differentiate this condition from milk fever and hypomagnesemia. The efficacy of this therapy can be estimates through estimation.

Collection of blood samples

Collection of blood sample is already discussed in exercise no. 4.

Purpose: This test is conducted to determine the boldness and soundness of the seeds. The weight of a given number of seeds of different varieties or kinds will vary. This variation is due to boldness and soundness of the seeds. The seeds will vary according to the soil fertility, variety and other environmental conditions. Higher the weight of a variety per thousand seeds, better is the variety for cultivation.

Materials and equipments: Scale, balance and seeds.

• Spray Angle — The angle subtended at the final orifice by the edges of the spray pattern.
• Variation in discharge rate between first and last observation shall not be more than 5 percent.
• The volumetric efficiency requirement for roller vane type pump shall be minimum 80 percent.
• The volumetric efficiency of piston, plunger type pump shall be minimum 80 percent.
• If the droplet size is reduced from 2 mm to 1 mm, number of droplets produced will increase by 8 times from the same volume.

The objective of correct pesticide application cannot be achieved without good quality Plant Protection Equipment. A sound designed machine shall be proficient as far as pesticide distribution and delivery to the target in minimum time with least wastages is concerned. Hence, the machines should be tested to ascertain that they are:

Introduction

Seeds are regarded as carriers of new technology and serve as basic catalytic input for enhancing the agricultural production. Hence the timely availability of quality seeds of the right variety in adequate quantity decides the strength of an agricultural economy. The intensive crop improvement programmes have resulted in the development of large number of hybrids and high yielding varieties in many important crops. Today, the Indian seed industry is the fifth largest seed market in the world, accounting for 4.4 per cent of global seed market. In terms of global trade, India is almost self-sufficient in flower, fruits and vegetables and field crops seeds (Anonymous, 2015). Economy of crops depends on good crop variety. Farmers choose these verities based on good quality traits and satisfactory yield. Thus, it is always essential to do fidelity check of all plant variety. The genetic purity is one of the most important aspects of quality control. Seed quality includes good germination, purity, seed health and vigour. With the increase in seed industry, there has been a refinement in the techniques used for testing genetic purity or genuineness of seed purity. Methods for testing genetic purity include different morphological, chemical, biochemical and molecular markers. Under PPV & FR Act, DUS (distinctiveness, uniformity, stability) testing procedure is performed with morphological descriptors. However, in agriculture, biotechnology has found applications in checking of true to type of clones and variety identification programs using molecular and chemical markers. Markers that reveal polymorphisms at the protein level are known as biochemical markers, while DNA markers reveal polymorphisms at the DNA level.

Hypothesis testing is the statistical procedure used in order to accept or reject statistical null hypotheses. One of the major purpose for which we formulate the hypothesis is, to test the statistical significance of the relation, difference or variation etc. among given sample/s at a given point of time or at different time points.

Introduction
Some species of rod shaped bacteria e.g. E.coli, Ps. fluorescence, Bacillus subtilis are known to be motile. Bacterial motility is generally associated with the presence of hair-like appendages called “Flagella”. There are several ways for determining the motility of a culture such as the wet mount method, hanging drop method and a culture method (on semisolid medium). Bacterial cells in suspension also exhibit a vibratory or oscillatory movement without changing their relative position. This is termed ’Brownian Movement’ and it should not be confused for true motility of bacteria. In motility the cells change their relative position and move across the microscopic field in different directions.
1. The Wet Mount Technique
This is the simplest and quickest way to determine the motility of bacteria.
Materials
1. Clean glass slide
2. Broth culture of bacteria (E.coli, Ps.fluroscenes)
3. Cover glass
Procedure
1. Place a drop of organisms on clean glass slide and cover with a cover glass.
2. Examine the slide with phase contrast microscope or bright field microscope with reduced light under oil-immersion.

Introduction

Test of pollen viability (extent of pollen viability) is important in pollination experiments to ensure fertility/seed setting. It is also important in monitoring state of pollens during storage in ecological/ taxonomic studies as well as during research on pollen biochemistry, genetics, stigma interactions, and incompatibility studies. Pollen viability refers to the ability of pollen to accomplish post-pollination events to achieve fertilization. Pollen viability test has gained importance particularly in plant breeding and hybrid seed production experiments/ practices. In this chapter, you will be acquainted with the basics of pollen viability test. However, for more professional knowledge on the topic readers are suggested to refer specialized books.

Pollen Viability Test

It is important to know the extent of viability of pollens used in pollination experiment, in finding fertility of a plant of interest, to monitor state of pollen on storage, in ecological/taxonomic studies, as well as in research on biochemistry, genetics, stigma interaction, incompatibility assay, etc. of pollen. Several pollen viability tests have been developed time-to-time. It is recommended to initially use different tests for a given pollen type to find out the most appropriate method that provides reliable result on pollen viability. It is important to note that every procedure requires standardization of protocol according to the sample used. Following different tests are used for assessing pollen viability.

1. In-vitro Pollen Germination Test

It is a simple, speedy, and quantitative test for assessing pollen viability. In this method, a collection/sample of pollen is germinated in vitro and observed under microscope. The percentage of germinating pollens (producing pollen tube) after appropriate treatment and a given period of time is determined. The percentage provides an index of viability of the pollen sample.

True/False

Q.1.    A hypothesis that sets the fundamental objective of scientific study is called the “Research hypothesis”.
Q.2.     A statistical assumption or statement about the unknown parameters of a population is known as Statistical hypothesis.

With increasing industrialization, water sources available for consumption as potable water are being adulterated with industrial, animal and human wastes. As a result water has become a formidable factor in disease transmission. Polluted water usually contains large amount of organic matter which forms nutritional base for growth and multiplication of microorganisms. Usually the water with non-pathogenic organisms, like autotrophs and saprophytic heterotrophs, are not of major concern, but presence of intestinal contaminants of fecal origin are of great concern. These pathogens are responsible for intestinal infection such as bacillary dysentery, typhoid fever, cholera and paratyphoid fever.

The detection of all the intestinal pathogens on a routine basis would be a tedious and difficult task, however, it would be easy to demonstrate the presence of some of the nonpathogenic intestinal organisms like Escherichia coli and Streptococcus faecalis. These are always found in intestine but their detection confirms the contamination of water with fecal material. Such organisms are also called pollution indicator.

The pioneering German microbiologist, Robert Koch, identified a set of four conditions that need to be satisfied to establish that a particular organism is the causative agent of a particular disease. These conditions, known as Koch’s postulates, are:

1. The suspected pathogen must be found associated with the disease in all the diseased plants examined.

2. The organism must be isolated from the diseased tissue and grown in pure culture on nutrient media, with its characteristics described (non obligate parasites) or in a susceptible host plant (obligate parasites), and its appearance and effects recorded