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Centres of Genetic Diversity

Centres of Genetic Diversity Introduction Centres of genetic diversity are geographical regions of the world where maximum genetic variation of plants or animals occurs . These regions contain wild relatives, primitive cultivars, landraces, and domesticated varieties of species. They play a crucial role in evolution, plant breeding, conservation of biodiversity, and food security. The concept of centres of genetic diversity is closely associated with N. I. Vavilov, a Russian geneticist, who studied crop plants extensively and proposed that crop domestication occurred in specific regions showing high variability. Definition A centre of genetic diversity is a region where: A species exhibits maximum genetic variability Both wild and cultivated forms are present Continuous natural selection and adaptation take place Vavilov’s Concept of Centres of Origin Vavilov (1926) proposed that: Cultivated plants originated from definite geographical areas These areas show greatest diversi...

Source of germplasm

Sources of Germplasm Introduction Germplasm refers to the total genetic resources of a crop species, including seeds, plant parts, tissues, pollen, or entire plants that carry hereditary material. It is the basic raw material for plant breeding and crop improvement. The success of any breeding programme depends largely on the availability, diversity, and proper utilization of germplasm. 1. Landraces (Primitive Cultivars ) Landraces are locally adapted traditional varieties developed by farmers through natural and artificial selection over long periods. Characteristics: High genetic variability Adapted to local climate and soil Low yield but stable performance Importance: Source of resistance to pests, diseases, and abiotic stress Example: Traditional rice varieties of Kerala 2. Obsolete Varieties These are varieties once cultivated widely but later replaced by improved varieties. Importance: Possess useful genes lost in modern breeding Provide genetic diversity 3. Modern Cu...

PLANT INTROUCTION: TYPES AND PROCEDURE

PLANT INTROUCTION: TYPES AND PROCEDURE 1. Introduction Plant introduction is the transfer of plant species, varieties, or genotypes from one geographical area to another where they were not previously grown. It is one of the oldest and most important methods of crop improvement and forms the basis of modern agriculture. Many important crops such as wheat, rice, maize, potato, cotton, sugarcane, and tobacco have been introduced from other countries. Definition : Plant introduction is the process of introducing plants or plant genetic material from their native or foreign regions into a new area for cultivation, evaluation, and utilization. 2. Objectives of Plant Introduction To increase crop productivity To introduce high-yielding varieties To obtain disease- and pest-resistant plants To introduce early maturing or drought-tolerant varieties To improve quality traits (oil content, protein, fiber, taste) To broaden the genetic base of crops To replace inferior local varieties To dev...

Concepts of de Candolle and Vavilov

1. Concept of de Candolle (1882) Introduction Alphonse de Candolle, a Swiss botanist, proposed one of the earliest scientific ideas about the geographical origin of cultivated plants in his book “Origin of Cultivated Plants” (1882). Main Concept Cultivated plants originated in regions where their wild ancestors were naturally found. These regions are usually areas of ancient human civilization, where agriculture first developed. Basis of de Candolle’s Concept De Candolle used:(BAHL) Botanical evidence – presence of wild relatives Historical records – ancient literature and scriptures Archaeological findings Linguistic evidence – local names of crops Geographical distribution Key Features Emphasized broad geographical regions rather than precise centers. Believed domestication occurred over a long time. Recognized multiple origins for some crops. Examples Wheat → Near East Maize → Central America Potato → South America Rice → South-East Asia Merits First systematic scientific approach. ...

COLLECTION, CLASSIFICATION AND TABULATION OF DATADIAGRAMMATIC AND GRAPHIC REPRESENTATION OF DATAINTRODUCTION

COLLECTION, CLASSIFICATION AND TABULATION OF DATA DIAGRAMMATIC AND GRAPHIC REPRESENTATION OF DATA INTRODUCTION Statistics deals with the collection, classification, presentation, analysis and interpretation of numerical data. Raw data in its original form is difficult to understand. Therefore, it must be systematically collected, classified, tabulated and presented through diagrams and graphs for better understanding and decision-making. 1. COLLECTION OF DATA Collection of data refers to the process of gathering information for a specific purpose. Objectives of Data Collection To obtain relevant and reliable information To facilitate analysis and interpretation To help in decision-making and planning Types of Data (a) Primary Data Primary data are collected by the investigator for the first time. Methods of collecting primary data: Direct Personal Investigation – Investigator personally collects data Indirect Oral Investigation – Data collected through witnesses Questionnaire Method – ...

Sampling Method and Errors

Introduction In statistics and research, it is often not possible to study the entire population due to limitations of time, cost, and effort. Therefore, a sample is selected from the population to represent the whole. The method used to select this sample is called the sampling method. While sampling makes research practical, it may also lead to errors, known as sampling errors. Sampling Method A sampling method is a procedure or technique used to select a subset (sample) from a population so that it represents the population accurately. Sampling methods are broadly classified into: Probability Sampling Methods Non-Probability Sampling Methods 1. Probability Sampling Methods In probability sampling, every unit of the population has a known and equal chance of selection. These methods are scientific and reliable. a) Simple Random Sampling Each member of the population has an equal chance of being selected. Selection can be done using lottery method or random number tables. Merits:...

••Education Psycology And MCQ

Educational Psychology – Meaning of Educational Psychology Educational Psychology is a branch of psychology that deals with the study of human behavior in educational situations. It applies psychological principles to understand learning, teaching, development, motivation, and individual differences among learners. Definition : According to E.A. Peel: Educational psychology is the science of education. According to Skinner: Educational psychology is the branch of psychology that deals with teaching and learning. N ature of Educational Psychology Educational Psychology has the following characteristics: It is both a science and an art It studies learner behavior It is goal-oriented It uses scientific methods It is dynamic and practical It focuses on individual differences Scope of Educational Psychology The scope is wide and includes: 1. Growth and Development Physical, mental, emotional, social, and moral development Understanding developmental stages of learners 2. Learning Proc...

Measures of dispersion - range, quartile deviation, mean deviation, standard deviation, Coefficient of variation

MEASURES OF DISPERSION (CONCEPTUAL NOTES) 1. Introduction Measures of dispersion show how spread out or scattered the data are. While the mean, median, and mode tell us about the central value, dispersion tells us how far the data are from the center. Two datasets can have the same mean but different spreads, so dispersion helps us understand variability or consistency. Common measures: Range Quartile Deviation (Q.D.) Mean Deviation (M.D.) Standard Deviation (S.D.) Coefficient of Variation (C.V.) 2. Range Definition: The range is the difference between the largest and smallest values in the data. Purpose: Gives a quick idea of how spread out the data is. Advantages: Very simple and easy to calculate. Disadvantages: Uses only two values, ignoring the rest of the data. Very sensitive to extreme values or outliers. 3 . Quartile Deviation (Q.D.) Definition: Quartile deviation measures the spread of the middle 50% of the data. It focuses on the central part of the dataset, ignoring extreme ...

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