H260 - Lecture Exam #4 - Study Guide

Integrated Pest Management (IPM)

Definition: An approach to pest control that uses a variety of methods to minimize pesticide use and environmental impact.
IPM Triangle: A visual representation of IPM strategies, typically including the following categories:
- Cultural Controls: Practices that reduce pest establishment, reproduction, and survival. Examples:
  - Crop rotation
  - Sanitation (removing infested plant debris)
  - Using resistant varieties
- Chemical Controls: Use of pesticides. Should be used judiciously and as a last resort.
- Mechanical Controls: Physical methods to prevent pests from reaching plants or to remove them. Examples:
  - Traps
  - Barriers
  - Hand-picking insects
- Biological Controls: Using natural enemies of pests to control their populations. Examples:
  - Predatory insects (ladybugs)
  - Parasitic wasps
  - Microbial pesticides (Bacillus thuringiensis)

Plant Tissue Culture (Micropropagation)

Definition: The in vitro (in glass) aseptic culture of cells, tissues, or organs under controlled conditions.
Advantages of Micropropagation:
1. Rapid clonal propagation: Mass production of plants with desirable traits.
2. Disease-free plants: Eliminating pathogens from plant material.
3. Germplasm preservation: Storing and conserving rare or endangered species.
4. Year-round propagation: Producing plants regardless of the season.
Disadvantages of Micropropagation:
1. High cost: Requires specialized equipment and skilled labor.
2. Risk of contamination: Susceptible to microbial contamination.
3. Genetic instability: Potential for somaclonal variation (mutations).
4. Acclimatization issues: Plantlets may need careful acclimatization to survive ex vitro.
Facility Requirements:
1. Preparation Area: For washing glassware, mixing media, and preparing explants.
2. Transfer Area: Aseptic environment for inoculation and subculturing. Includes a laminar flow hood.
3. Growth Room: Controlled environment for incubation. Includes shelving with controlled temperature and light.
Agar Media Components:
- Water: solvent
- Mineral Salts: Macronutrients (N, P, K, Ca, Mg, S) and micronutrients (Fe, Mn, Zn, B, Cu, Mo).
- Carbon Source: Usually sucrose.
- Vitamins: Such as thiamine, niacin, and pyridoxine.
- Plant Growth Regulators (PGRs): Auxins and cytokinins to control growth and development.
- Gelling Agent: Agar to solidify the medium.
Stages of Plant Tissue Culture:
1. Initiation: Selecting and sterilizing the plant material (explant).
2. Multiplication: Inducing shoot formation and proliferation.
3. Rooting: Stimulating root development on shoots.
4. Acclimatization: Gradually adapting plantlets to ex vitro conditions.

Sexual Propagation – Flower Anatomy

Perfect Flower: Has both stamen (male) and pistil (female) parts.
Imperfect Flower: Missing either stamen or pistil.
Monecious: Plant has both male and female flowers on the same plant, i.e. corn.
Dioecious: Plant has either male or female flowers, but not both on the same plant, i.e. holly.
Complete Flower: Has all four floral parts: sepals, petals, stamen, and pistil.
Incomplete Flower: Missing one or more floral parts.
Flower Parts:
- Sepal: Outermost whorl, protects the developing flower.
- Petal: Often colorful, attracts pollinators.
- Stamen: Male reproductive organ.
  - Anther: Pollen-bearing part.
  - Filament: Stalk that supports the anther.
- Pistil: Female reproductive organ.
  - Stigma: Receives pollen.
  - Style: Connects stigma to ovary.
  - Ovary: Contains ovules.
  - Ovules: Develop into seeds after fertilization.
Pollination and Fertilization:
- Pollen grain lands on the stigma.
- Pollen grain germinates and grows a pollen tube down the style to the ovary.
- Three Nuclei in Pollen Grain:
  - Tube Nucleus: Guides the growth of the pollen tube.
  - Generative Nuclei: Divides to form two sperm cells.
- Double Fertilization:
  - One sperm cell fuses with the egg to form the zygote (2n), which develops into the embryo.
  - The other sperm cell fuses with the polar nuclei in the central cell to form the endosperm (3n), which provides nutrients to the developing embryo.

Seed Development and Anatomy

Zygote: The fertilized egg. $Zygote (n) + Sperm (n) = Zygote (2n)$
Histodifferentiation: The process by which cells in the developing embryo differentiate into different tissue types.
Cell Expansion: Cells enlarge and elongate.
Maturation & Drying: Seed loses moisture and becomes dormant.
Seed Parts:
- Embryo: The young plant.
- Endosperm: Food reserve for the embryo.
- Seed Coat (Testa): Protective outer layer.
Other Structures:
- Funiculus: The stalk that attaches the ovule to the ovary wall.
- Hilum: Scar on the seed coat where the funiculus was attached.

Seed Viability and Germination

Viable Seed: A seed capable of germinating.
Tetrazolium (TZ) Test: A chemical test to determine seed viability. TZ turns red in living tissue.
Quiescent Seed: A seed that fails to germinate because the external environmental conditions are not suitable (lack of water, oxygen, proper temperature).
Imbibition: The rapid uptake of water by the dry seed.
Lag Phase: Metabolic activity increases, but there is no visible change.
Radicle Emergence: The first visible sign of germination; the radicle (embryonic root) emerges from the seed coat.
Seed Priming: Pre-soaking seeds in aerated water or solutions of polyethylene glycol (PEG) to promote faster, more uniform germination. Polyethylene glycol (PEG) controls water uptake.
Environmental Factors Affecting Germination:
1. Water: Necessary for imbibition and metabolic activity.
2. Temperature: Optimum temperature range for germination varies by species.
3. Oxygen: Required for respiration.
4. Light: Some seeds require light or darkness to germinate.
Germination Temperatures:
- Minimum: The lowest temperature at which germination can occur.
- Maximum: The highest temperature at which germination can occur.
- Optimum: The temperature at which germination is fastest and most complete.

Seed Germination and Dormancy

Primary Dormancy: Dormancy imposed during seed development.
Secondary Dormancy: Dormancy induced by unfavorable environmental conditions after the seed has matured.
Types of Dormancy:
1. Exogenous Physical Dormancy: Hard seed coat impermeable to water or gases.
  - Scarification: Methods to weaken or break the seed coat.
  - Mechanical Scarification: Using sandpaper, clippers, or a knife to scratch the seed coat.
  - Acid scarification: Soaking seeds in sulfuric acid.
  - Hot Water Scarification: Soaking seeds in hot water.
2. Stratification: Cold, moist chilling to break dormancy in seeds from temperate regions. Seeds are placed in a moist medium and refrigerated for a period of time
3. Water Leaching: Removes chemical inhibitors from the seed coat or embryo. Seeds are soaked in water to rinse away germination inhibitors.

Test on Plant Biology Concepts

Section 1: Multiple Choice Questions

What is Integrated Pest Management (IPM)?
a) Use of only chemical controls
b) An approach combining various strategies to manage pests
c) Complete eradication of all pests
d) Planting seeds without any treatment
What is one advantage of plant tissue culture?
a) Slow growth process
b) Producing disease-free plants
c) Requires no special equipment
d) None of the above
What is a perfect flower?
a) A flower with only stamens
b) A flower with both stamens and pistils
c) A flower with neither anatomical part
d) A flower that lacks petals
In seed germination, which phase indicates the first visible sign of germination?
a) Lag phase
b) Imbibition
c) Radicle emergence
d) Histodifferentiation

Section 2: True/False Questions

True or False: Biological controls in IPM rely on introducing natural enemies of pests.
True or False: Stratification refers to the process of soaking seeds in acid to break dormancy.
True or False: Seeds require light to germinate in all cases.

Section 3: Short Answer Questions

List three cultural controls used in Integrated Pest Management.
Describe the process of double fertilization in flowering plants.
Explain the importance of the endosperm in seed development.