Crop Improvement and Plant Propagation

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Questions and Answers

What is the primary method used in separation propagation?

Separating a clump into portions with root systems (correct)

Using seeds to propagate plants

Cutting plant parts into sections aimed at generating new plants

Rooting branches placed in water

Which of the following specialized organs is NOT mentioned as a method of propagation?

Pollen (correct)

Corm

Bulb

Offset

Which type of cutting is specifically useful for plants with thick and heavy leaves?

Root cutting

Herbaceous cutting

Stem cutting

Leaf cutting (correct)

What defines hardwood cuttings in plant propagation?

Leafless branches from the previous growing season Signup and view all the answers

What condition must be met for stem cuttings to develop adventitious roots?

They need to be placed in a warm, humid environment Signup and view all the answers

Which of the following best describes the process of division in plant propagation?

Separating a clump into several portions, each with a root system Signup and view all the answers

What distinguishes semi-hardwood cuttings from hardwood cuttings?

They are taken from partially mature wood Signup and view all the answers

Which plant species would typically be propagated through root cuttings?

Apple Signup and view all the answers

What is a characteristic of softwood cuttings?

They should be made with leaves intact. Signup and view all the answers

What effect does using a root-promoting chemical have on herbaceous stem cuttings?

Reduces the time needed for rooting. Signup and view all the answers

What is the primary purpose of layering in plant propagation?

To form adventitious roots while attached to the parent plant. Signup and view all the answers

Which of the following is NOT a type of graftage mentioned?

Topcross Signup and view all the answers

What is an example of primary introduction in crop improvement?

Releasing an introduced variety without alteration. Signup and view all the answers

What process leads to the production of homozygous individuals in crop improvement?

Inbreeding related individuals. Signup and view all the answers

Which of the following mating systems involves a cross between a single parent and its hybrid offspring?

Backcross Signup and view all the answers

What characterizes the creation of new variability in crops?

Introducing new genetic material and manipulating traits. Signup and view all the answers

What is euploidy?

A change in chromosome number involving one or more complete genomes. Signup and view all the answers

Which term describes an allopolyploid that has two copies of each genome?

Amphidiploid Signup and view all the answers

What is individuals' selection based on natural survival and reproductive abilities known as?

Natural selection Signup and view all the answers

Which mode of selection reduces variability in a population?

Stabilizing selection Signup and view all the answers

What do quantitative traits represent?

Continuous traits that are highly influenced by the environment. Signup and view all the answers

Which of the following describes aneuploidy?

Change in chromosome number involving one or a few chromosomes. Signup and view all the answers

What is the characteristic of diversifying selection?

It leads to formation of distinct subpopulations or polymorphism. Signup and view all the answers

In the context of selection, what does GxE represent?

The interaction between genotype and environment. Signup and view all the answers

What is the primary characteristic of breeder seeds?

They are the starting point for all subsequent classes of seeds. Signup and view all the answers

What percentage of purity is required for foundation seeds?

98% Signup and view all the answers

Which class of seeds is produced from breeder or foundation seeds and can carry a green tag?

Registered seeds Signup and view all the answers

What is the main function of certified seeds?

To be sold commercially for crop production. Signup and view all the answers

What does cryopreservation refer to in germplasm storage?

Freeze-preservation of seeds. Signup and view all the answers

How did domestication affect modern corn compared to its progenitor, Teosinte?

Modern corn retains seeds more effectively on the ear. Signup and view all the answers

Which term refers to varieties not yet approved by the National Seed Industry Council?

Good seeds Signup and view all the answers

Which of the following best describes biotechnology?

The use of living organisms or their components to create useful products. Signup and view all the answers

What is mid-parent heterosis based on?

Comparison with the average performance of the two parents Signup and view all the answers

What does the general combining ability (GCA) primarily identify?

Additive genetic effects Signup and view all the answers

Which hypothesis suggests that heterosis results from the accumulation of favorable dominant genes?

Dominance hypothesis Signup and view all the answers

Which mechanism promotes cross-pollination with male and female flowers on separate plants?

Dioecy Signup and view all the answers

What type of heterosis has practical importance for breeders?

Standard heterosis Signup and view all the answers

Which of the following statements regarding inbreeding depression is true?

It leads to a loss in vigor. Signup and view all the answers

What is included in the calculation of phenotypic variance?

Genotypic variance, environmental variance, and GxE variance Signup and view all the answers

Which type of gene action results in the heterozygote's value being equal to the dominant homozygote?

Complete dominance Signup and view all the answers

What defines specific combining ability (SCA)?

Deviation from performance based on GCA Signup and view all the answers

How is environmental variance estimated?

By measuring variation in a genotypically uniform population in a specific location Signup and view all the answers

In which mechanism do flowers not open at all, ensuring self-pollination?

Cleistogamy Signup and view all the answers

What does narrow-sense heritability estimate?

The ratio of genetic variance to phenotypic variance Signup and view all the answers

Selection differential refers to what?

The difference between the mean of selected genotypes and the overall population mean Signup and view all the answers

Which form of dominance occurs when the heterozygote has a value outside the range of the two homozygotes?

Over dominance Signup and view all the answers

What is the main purpose of measuring GxE interaction?

To compute variances of genotypes grown in environmentally diverse locations Signup and view all the answers

Which factor is NOT part of calculating gain from selection?

Presence of genetic drift Signup and view all the answers

Study Notes

Crop Improvement and Seed Selection

Crop improvement is synonymous with plant breeding
Plant breeding involves hybridization and selection
The ultimate goal of crop improvement is increased yield to meet growing population demands
Mendelian principles are fundamental to crop improvement
Gene expression is a critical aspect of crop improvement
New hybrid varieties of crops have been developed in various groups (cereals, legumes, vegetables, fruits, fiber)
Hybrid varieties often display improved characteristics such as higher protein content in kernels.

Plant Propagation

Plant propagation is the process of creating new plants through sexual or asexual means
Sexual propagation involves the union of pollen and egg
Asexual propagation involves using plant parts to regenerate a new plant
Methods of propagation include separation/division, cuttings, layering, and grafting

Seed Germination

Seed germination is a series of events initiating metabolic activity and seedling growth from a quiescent seed.
Factors influencing successful germination include viability of the embryo, water availability, oxygen availability, and optimum temperature
Two types of germination are epigeal (cotyledons above ground) and hypogeal (cotyledons below ground)
Seed dormancy is a physiological condition preventing germination despite favorable conditions. This can be due to physical or chemical factors

General Methods of Crop Improvement

Creation of new variations is crucial to crop improvement
Techniques for creating variation include domestication, germplasm collection, introducing new varieties, and mutations
Methods for selection include mass selection, pureline selection, pedigree selection, and recurrent selection

Conservation of Germplasm

Germplasm refers to the genetic material of a species
Centers of biodiversity are important for collecting germplasm
Techniques for storing germplasm include seed storage in cold environments, maintaining living plants in fields, or through in vitro culture.

Plant Breeding Using Biotechnology

Biotechnology techniques enhance crop improvement via methods such as micropropagation, embryo culture, anther culture, and protoplast fusion.
Recombinant DNA technology can introduce desirable genes into crops, leading to transgenic varieties

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Description

This quiz covers the essential topics of crop improvement, seed selection, and plant propagation techniques. It includes fundamental principles such as Mendelian genetics and methods of sexual and asexual reproduction. Test your knowledge on hybrid varieties and seed germination processes.