Horticulture Exam Review Flashcards
Exam Study Guide: Ornamental Horticulture Review
This guide summarizes key concepts and terms for your upcoming ornamental horticulture exam, categorizing them into what needs to be memorized and what requires understanding and application.
Exam Preparation Guidelines
Memorization: Essential for fill-in-the-blank, matching, and true/false questions.
Understanding and Application: Necessary for scenario-based, short answer, and multiple-choice questions where you apply concepts.
The exam will directly reflect lecture and lab content.
Ensure adequate rest prior to the exam.
Upcoming field trip to Plant Farm for practical exposure (details to follow).
Unit 1: Introduction to Ornamental Horticulture
Vocabulary to Memorize (Core Terms for Matching, Fill-in-the-Blank, True/False)
Five Sectors of Ornamental Horticulture: Floriculture, Nursery Production, Landscaping, Interior Scaping, Turfgrass.
Floriculture: The cultivation of flowering and ornamental plants, including potted flowers and cut flowers.
Nursery Production: The large-scale growing of trees, shrubs, and perennials, primarily for resale.
Phytosanitary Certificate: An official document required for shipping plants across state or international borders, certifying the plant is free of pests and diseases.
Pot-bound / Circling Roots: A condition in container plants where roots fill the pot and begin to grow in a circular pattern, which can harm the plant long-term.
Concepts to Understand & Apply (Good for Multiple Choice & Short Answer)
Container Grown Method:
Description: A major method used for approximately 80\% of nursery crops.
Pros: Offers flexibility, enables year-round production, and facilitates easy shipping.
Cons: Can lead to "pot-bound" or "circling roots," which are considered a "silent plant killer" due to long-term harm.
In-ground Method:
Description: The classic method, particularly for larger plants.
Cons: Implies a rigid harvest schedule, especially for very large plants.
Pot-in-Pot Method:
Description: A hybrid system where a production pot sits inside a permanent in-ground socket pot.
Benefits: Combines the advantages of both container-grown and in-ground methods, such as guaranteeing year-round harvest capabilities.
Greenhouse Production
Vocabulary to Memorize (Essential Terms for Matching, Fill-in-the-Blank, True/False)
Photoperiodism: The physiological flowering response of a plant to the length of uninterrupted darkness it receives.
Daily Light Integral (DLI): The total quantity of photosynthetically active light (PAR) a plant receives over a 12-hour period.
DIF: The mathematical difference between the day temperature and the night temperature. The formula is: \text{DIF} = \text{Day Temperature} - \text{Night Temperature}.
Flagging / Wilting: A condition where a plant's leaves begin to droop; it's a key indicator for the perfect timing to water the plant.
Fertigation: A technology involving the application of water-soluble fertilizers directly through the irrigation system.
Concepts to Understand & Apply (Good for Multiple Choice & Short Answer)
Controlling Light to Regulate Flowering:
The primary control mechanism is the length of unbroken darkness.
Forcing Flowering in Short-Day Plants (e.g., Mums, Poinsettias): Create long nights using blackout covers.
Forcing Flowering in Long-Day Plants: Create short nights by interrupting darkness with supplemental lighting (light-interrupting lighting).
Controlling Temperature to Control Plant Height (DIF):
Negative DIF (\text{Day Temp} < \text{Night Temp}): The goal is to create a compact plant by utilizing the environment as a tool.
Effect: Colder days and warmer nights result in shorter internodes, leading to a more compact plant.
Benefit: This method can help reduce the need for chemical plant growth regulators.
Managing Plant Watering (The Golden Rule):
Water thoroughly, but only when the plant is displaying flagging or wilting symptoms.
Important Note: Flagging can indicate both under-watering and over-watering. Over-watering can lead to root death.
Monitoring Substrate pH and EC (Electrical Conductivity) to Prevent Problems:
pH: A measure of the acidity or basicity of the substrate. Critical for controlling nutrient availability, as overly high pH can lead to nutrient lockout, even if nutrients are present.
EC (Electrical Conductivity): A measure of dissolved salts in the soil solution. This is the best indicator of the fertilizer level in the substrate (higher salt content means higher EC).
Leachate: The water sample that drains from the bottom of a container after irrigation.
PourThru Method: A non-destructive technology used to collect leachate samples for testing their EC and pH values.
Why Monitor pH and EC? Visual diagnosis (e.g., nutrient deficiencies) is often too late. Monitoring provides a real-time snapshot of the root zone environment, allowing for proactive problem prevention.
Interpreting Data and Corrective Actions:
High EC Value: Indicates high salt levels, which can damage roots. Your daily fertilization plan likely results in EC above the optimal range.
Correction: Flush the substrate with a substantial amount of clean water to wash out excess fertilizer salts and decrease the EC value.
Low EC Value: Indicates that the plant is nutrient deficient ("hungry").
Correction: Increase the fertilization rate or frequency.
Ideal pH Range for Container Plants: From 5.8 to 6.2. If measurements fall outside this range, it could be due to nutrient lockout or human error in measurement.
Fertilizer Math (Converting Oxide to Elemental Nutrients):
Numbers on fertilizer packaging typically represent nutrient oxides, not the actual elemental forms absorbed by plants.
Converting Phosphorus (P) from Phosphate (P(2)O(5)): Multiply the P(2)O(5) value by 0.44 to get elemental P.
Converting Potassium (K) from Potash (K(2)O): Multiply the K(2)O value by 0.83 to get elemental K.
Integrated Pest Management (IPM)
Pests & Diseases to Memorize (Symptoms & Identification for Matching)
Aphids: Characterized by honeydew production and subsequent black sooty mold on the leaf surface.
Whiteflies: Appear as a "cloudy" or "fluffy" disturbance when the plant is agitated.
Thrips: Cause silver stippling or streaking on plant surfaces.
Spider Mites: Indicated by the presence of fine webbing on the plant.
Armored Scale, Mealybugs, and other Scale Insects: Typically appear as bump-like shapes, often with pink legs or other distinctive forms on plant surfaces.
Bagworms: Common on junipers, characterized by visible sacks attached to branches.
Red Headed Flea Beetle: A notable pest in Alabama nursery production.
Fire Ants: Subject to specific quarantine policies.
Key Diseases: Powdery Mildew, Root Rot.
Concepts to Understand & Apply (Good for Multiple Choice & Short Answer)
What is IPM?
Definition: A comprehensive strategy that integrates cultural, biological, and chemical tactics to maintain pest populations below economically damaging levels in an environmentally friendly manner. It does not aim for complete eradication.
IPM Tactics (Hierarchical Approach):
Cultural Methods: Preventative measures that modify the growing environment.
Examples: Proper spacing to enhance airflow, selecting genetically resistant cultivars, and thorough sanitation (cleaning tools and growing areas).
Physical Methods: Direct removal or modification.
Examples: Removing or trimming contaminated plant parts or twigs.
Biological Agents: Utilizing natural enemies to control pests, often effective in early stages of infestation.
Examples: Introducing beneficial insects like lady beetles, lacewings, or predatory mites.
Chemical Methods: Pesticide application, used as a last resort when infestation is severe and other methods are insufficient.
Important Consideration: Rotate IRAC (Insecticide Resistance Action Committee) codes when applying pesticides to delay the development of pest resistance.
Application Example: Suggesting the use of a disease-resistant plant is applying a cultural method. Introducing lady beetles to control aphids is a biological method.
Tissue Culture and Propagation
Key Concepts to Memorize
Asexual Propagation: A method of creating a new plant from a part of a parent plant (e.g., cutting, division, tissue culture) to produce genetically identical clones.
Heterozygosity: The genetic characteristic of most unique ornamental plants that prevents them from growing true-to-type from seeds. This is why asexual propagation is crucial for maintaining desired traits and genetic consistency.
Totipotency: The fundamental scientific basis for tissue culture; it is the unique ability of a single plant cell to regenerate into an entire, complete organism.
Golden Rule of Tissue Culture: Aseptic Technique: The necessity of performing all tissue culture procedures in a completely sterile and contamination-free environment. This requires specific tools and methods to achieve.
Explant: The small piece of parent plant tissue that is used to initiate an in vitro (in glass/test tube) culture.
Hardening Off (Acclimatization): A crucial process (typically Stage 4/5 in tissue culture) where regenerated plants are gradually adapted to external, non-sterile, and lower-humidity conditions, preparing them for survival in the real world.
Concepts to Understand & Apply
Phytohormone Ratio (Cytokinin vs. Auxin) in Tissue Culture:
High Cytokinin : Low Auxin Ratio: Promotes the development of new shoots from the tissue.
High Auxin : Low Cytokinin Ratio: Promotes the development of roots from the tissue.
Balanced Ratio (Species-Dependent): Induces the formation of a callus (an undifferentiated mass of plant cells), which can then be differentiated into shoots or roots based on subsequent hormonal adjustments.
Five-Stage Tissue Culture Procedure:
Stage 0: Stock Plant Selection: Choose a stock plant that is healthy, strong, juvenile (if possible), disease-free, and genetically valuable.
Stage 1: Initiation: Sanitize the chosen plant material using agents like ethanol or bleach to ensure explants are contamination-free before culturing in jars.
Stage 2: Multiplication: Apply cytokinin in appropriate ratios to encourage the explant to sprout multiple shoots, leading to an increase in plant material.
Stage 3: Rooting: Use auxin, often in specific concentrations, to induce root formation on the regenerated shoots.
Stage 4/5: Acclimatization (Hardening Off): Gradually decrease the humidity (e.g., by slowly opening a humidity dome) to allow the plant to strengthen and adapt to ambient conditions outside the sterile culture environment.
Principle of Air Layering:
What Tissue to Remove & Why: During air layering, the phloem tissue (part of the bark) is intentionally removed. This interruption causes sugars and auxins to accumulate in the plant parts above the cut area, which stimulates and induces root formation at that specific point on the twig.
Physical and Chemical Characteristics of Substrate (Extra Credit Topic)
Important Concepts to Memorize (for Multiple Choice Extra Credit)
Soilless Substrate Properties: These engineered substrates fundamentally differ from field soil. They are designed to possess:
Low density.
High porosity (for air and water).
High drainage capabilities.
They are primarily composed of organic components.
Grower's Management of Pores: Growers must effectively manage the pore spaces within the substrate, as these critical areas are where plant roots access essential air and water.
Relationship Between Particle Size and Pore Size: There is a straightforward relationship between the particles constituting the substrate and the resulting pore spaces, which influences overall substrate characteristics (details discussed in lecture slides, though not explicitly detailed here).
Final Exam Tips
The exam content will be a direct reflection of both the lectures and laboratory sessions.
Thorough memorization of definitions and understanding of highlighted concepts from the slides will significantly improve your performance.
Prioritize getting sufficient sleep before the exam.