Plant Breeding Concepts Quiz

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Questions and Answers

Which of the following is a consequence of the introduction of high-yielding varieties in plant breeding?

Genetic erosion of landraces (correct)

Improved resistance to pests and diseases

Increased genetic diversity

Enhanced yield plateau

What is a potential drawback of breeding for intensive resistance to a particular disease in crops?

It can make the crop more susceptible to other diseases. (correct)

It can increase the cost of production.

It can reduce the need for pesticides.

It can lead to a decrease in crop yield.

The Vilmorin principle is primarily concerned with?

Identifying and isolating superior plant lines (correct)

Maintaining genetic diversity in crops

Developing hybrid vigor in crops

Preventing genetic erosion of landraces

What is the main concept behind Johannsen's 'pure line theory'?

All individuals within a pure line are genetically identical. (B) Signup and view all the answers

Which of the following early plant breeders was instrumental in demonstrating the concept of hybrid vigor in F1 generation?

Joseph Koelreuter (C) Signup and view all the answers

Who made significant contributions to plant breeding by practicing individual plant selection in wheat and oats?

Patrick Shireff (A) Signup and view all the answers

The first artificial hybrid, popularly known as 'Fairchild mule', was produced by crossing which two plants?

Carnation and Sweet William (C) Signup and view all the answers

Which of the following is NOT a consequence of narrow genetic base in crops?

Enhanced resilience to environmental stress (A) Signup and view all the answers

Which of the following is NOT a characteristic of primary centers of diversity?

More crossing over (B) Signup and view all the answers

According to Harlan's theory, which of the following factors likely influenced the domestication of plants?

Dominance of certain vegetation types (D) Signup and view all the answers

What is the primary purpose of a gene bank?

To preserve genetic diversity of plant species (B) Signup and view all the answers

What is the significance of 'parallel series of variation' according to Vavilov's Law of Homologous Series of Variation?

Similar variations occur in related species due to common ancestry (A) Signup and view all the answers

What is the defining characteristic of a microcenter?

Extensive genetic diversity in a small area (C) Signup and view all the answers

Which of the following is NOT a benefit of preserving plant genetic resources?

Expansion of agricultural land for monoculture farming (B) Signup and view all the answers

What is the relationship between plant genetic resources and crop improvement?

Plant genetic resources provide the foundation for developing improved crop varieties (C) Signup and view all the answers

Which of the following best describes 'gene erosion'?

Loss of genetic diversity in plants due to human activities (A) Signup and view all the answers

What defines the base collection of germplasm?

Includes maximum number of accessions available in a crop (D) Signup and view all the answers

Which statement accurately describes the secondary gene pool (GP2)?

Partial fertility occurs when crossing with GP1 plants (A) Signup and view all the answers

What is the primary characteristic of working collections in germplasm storage?

Frequently utilized by breeders for crop improvement (C) Signup and view all the answers

Which of the following is true about modern cultivars?

They possess a high yield potential and uniformity (D) Signup and view all the answers

Which type of collection is often conserved for medium-term storage?

Active collection (C) Signup and view all the answers

What is a characteristic of land races?

Evolved under sub-resistance agriculture with high diversity (C) Signup and view all the answers

What describes the tertiary gene pool (GP3) in breeding?

Leads to sterile hybrids with difficulty in crossing (B) Signup and view all the answers

Which of the following statements accurately describes obsolete cultivars?

Represent improved varieties replaced by newer generations (A) Signup and view all the answers

What is the primary result of allogamy in plant species?

Heterozygosity (A) Signup and view all the answers

Which mechanism involves flowers with both male and female reproductive parts on the same plant?

Monoecy (C) Signup and view all the answers

What type of dichogamy occurs when the pistil matures before the anthers?

Protogyny (C) Signup and view all the answers

Which mechanism prevents self-pollination through physical barriers around the anther?

Herkogamy (A) Signup and view all the answers

What type of self incompatibility is characterized by the inability of pollen to fertilize the same flower?

Sporophytic (A) Signup and view all the answers

Which type of male sterility arises due to genetic factors?

Genetic (D) Signup and view all the answers

What does heterostyly refer to in plant reproduction?

Different lengths of styles and filaments (A) Signup and view all the answers

Which of the following is NOT a mechanism that promotes cross-pollination?

Inbreeding (A) Signup and view all the answers

What is parthenogenesis?

Development of embryo without fertilization (D) Signup and view all the answers

What does apogamy refer to?

Origin of embryo from synergids or antipodal cells (C) Signup and view all the answers

What is the main characteristic of apospory?

Formation of embryos from diploid ovule cells outside the embryosac (B) Signup and view all the answers

Which of the following describes autogamy?

Pollen transfer from anthers to stigma of the same flower (B) Signup and view all the answers

Which mechanism, essential for self-pollination, involves male and female organs being present in the same flower?

Bisexuality (A) Signup and view all the answers

What is cleistogamy?

Pollination occurring in unopened flower buds (A) Signup and view all the answers

What does homogamy ensure in the context of pollination?

Simultaneous maturation of anthers and stigma (A) Signup and view all the answers

How does the position of anthers facilitate self-pollination in some species?

Stigmas are surrounded by anthers (A) Signup and view all the answers

What is the purpose of using Chemical Hybridizing Agents (CHAs)?

To improve the efficiency of hybrid seed production (C) Signup and view all the answers

Which agent was used by Moore in 1950 for inducing male sterility in maize?

Maleic hydrazide (MH) (A) Signup and view all the answers

What is one of the limitations of using Chemical Hybridizing Agents?

Production of all selfed seeds from female parents (D) Signup and view all the answers

Which of the following CHAs is used in wheat, specifically under the name RH0007?

RH0007 (Hybrex) (D) Signup and view all the answers

What common problem may arise from the use of certain Chemical Hybridizing Agents?

Low female fertility and adverse growth effects (B) Signup and view all the answers

Which of the following statements correctly describes an advantage of using CHAs?

F2s produced are fully fertile for commercial cultivation (D) Signup and view all the answers

What role does Ethephon (Ethrel) play in hybrid seed production?

It reduces vegetative growth while inducing male sterility (B) Signup and view all the answers

Which of the following describes a property of Sodium methylarsenate in hybrid seed production?

It has been popular for rice hybrid production (C) Signup and view all the answers

Study Notes

Plant Breeding Principles and Methods

Plant breeding is a science and an art of improving plants' genetic makeup for economic use.
Plant breeding has been practiced for thousands of years and is considered a current phase of crop evolution.
International development institutions believe plant breeding is essential for food security through higher yields, pest and disease resistance, drought resistance, and regional adaptation.
Plant breeding is divided into three main areas: plant genetic resources (germplasm), breeding techniques, and seed production techniques.

Germplasm

Germplasm is the total variability found in plant species, including cultivated and wild relatives.
It encompasses collection, conservation, evaluation, documentation, and utilization of crop plants.

Breeding Techniques

General breeding methods include introduction, selection, and hybridization (inter varietal).
Special breeding techniques include mutation breeding, polyploidy, wide hybridization, and other specific techniques like tissue culture and genetic engineering for crop improvement.

Seed Production Techniques

Seed production techniques primarily involve seed production principles and methods.

Objectives of Plant Breeding

Increased yield through efficient genotypes.
Improved quality (e.g., milling, cooking quality, aroma, grain colour, gluten content, protein content; reducing toxic substances).
Resistance to biotic and abiotic stresses (e.g., pests, diseases, drought, soil factors, edaphic).
Improved agronomic characteristics (e.g., plant height, branching).

Centres of Origin

Vavilov, a prominent botanist, proposed the concept of centres of origin in which crop plants evolved from wild species.
These areas of diversity are critical for new crop development and offer significant genetic diversity for breeding and improvement.

History of Plant Breeding in India

Organized agricultural research in India started in 1871.
The Indian Council of Agricultural Research (ICAR) was established in 1929.
Many crop-specific commodity committees were established (e.g., cotton, jute, sugarcane).
Important research activities have been carried out by ICAR and affiliated institutes.
Agricultural universities were established across India in the early 20th century, leading to progress in agricultural research.

Activities in Plant Breeding

Creation of variations: The first step of developing new crop varieties involve creation of variations. Methods includes domestication, germplasm collection, plant introduction, hybridization, mutation, polyploidy, and genetic engineering.
Selection: Plants with desired traits and characteristics are identified and selections are done. This process of selection is carried out based on phenotype.
Evaluation: Traits are evaluated in several conditions or locations by comparing them to established variety.
Multiplication: The seed of the selected cultivar, if a new variety is ready for release is produced on larger scale.
Distribution: The appropriate seed multiplication agencies sell certified seeds to the farmers.

Modes of Reproduction and Pollination

Sexual Reproduction: Involves the fusion of male and female gametes.
Asexual Reproduction: Multiplication of plants without sexual fusion.
Pollination: Transfer of pollen to female stigma. This includes: Autogamy (self-pollination), and Allogamy (cross-pollination).

Methods of Breeding Self-Pollinated Crops

Pure line selection
Mass selection.
Single seed descent method.

Methods of Breeding Cross-Pollinated Crops

Recurrent selection
Backcrossing
Top cross
Hybridisation

Polyploidy Breeding

Euploidy: involves whole sets of chromosomes.
Aneuploidy: a numerical change in a chromosome.
Polyploidy results in changes in the genetic makeup of the organism leading to variations or creating new varieties.
Common methods of polyploidy breeding include Colchicine treatment and in vitro culture.

Wide Hybridization

Wide hybridization is the crossing of plants from different species or genera.
It is a significant method of transferring desirable genes from wild relatives to cultivated crops.
Techniques such as: direct hybridization, chromosome doubling, use of pollen mixtures etc.

Molecular Markers

Molecular markers assist in identifying, characterizing, and mapping genes in plants.
Examples include RFLP, RAPD, STS, AFLP.

Genetic Theories

Dominance Hypothesis: Heterosis is due to masking of deleterious recessive traits in heterozygotes.
Overdominance Hypothesis: Superiority of heterozygotes is due to the production of novel products or gene interaction that provides better performance.

Heterosis Breeding

Heterosis breeding focuses on creating hybrids with improved traits compared to their parental inbred lines.
Methods include: top cross, single cross, three-way cross and double cross.

Mutation Breeding

Mutation breeding introduces changes in the genetic material to generate variation for desirable traits.
Chemical mutagens and physical mutagens can be used in the mutation process.

In Vitro Selection

In vitro selection involves selecting desired varieties in a controlled environment, outside the plant.
Applicable to plants in which asexual reproduction is the primary method of reproduction, like potato, sugarcane, etc.

Characteristics of Pure Lines & Mass Selection

Purelines: Uniformly similar genotypes.
Mass Selection: Selection of superior plants from a mixed population with similar phenotypes.

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Description

Test your knowledge on key concepts in plant breeding, including high-yielding varieties, hybrid vigor, and pure line theory. This quiz covers historical contributions and significant theories in the field of agriculture, specifically plant genetics and breeding practices.