Land Preparation, Seed Structure, Dispersal, and Germination

Flashcards of key vocabulary and concepts from the lecture notes.

Floriculture

An important branch of horticulture, which deals with cut or loose flowers, ornamental plants, such as foliage plants, trees, shrubs, climbers, palms, bamboo, cacti and succulents, dried flowers, essential oils and landscape gardening.

Sunlight

Most tropical ornamental plants require this, though some may need partial shade.

Sandy Soil

Common in coastal areas, these soils drain well but may require organic matter to improve nutrient retention.

Loamy Soil

Found in many tropical lowland regions, this well-draining soil type is perfect for a wide range of tropical ornamentals.

Clayey Soil

Tends to retain moisture, making it suitable for water-loving plants, but it may need careful management to avoid waterlogging.

Slopes

In hilly tropical regions, use this to manage water flow and prevent soil erosion.

Drainage

Ensure this, especially in low-lying areas, to prevent root rot from heavy tropical rains.

Windbreaks

In coastal or exposed areas, strong winds can damage tropical plants so establish these using hedges or taller trees to protect delicate ornamentals.

Irrigation

While rainfall is abundant in many tropical regions, this is important during dry spells or in controlled environments like greenhouses.

Maintenance

Choose sites that allow for this, such as pruning and pest control. Dense tropical foliage can harbor pests, so accessibility is key for regular upkeep.

Removing Weeds and Debris

It’s essential to clear the site of any of these to prevent competition for nutrients and space. Tropical examples, such as Crabgrass or Nutgrass, can be aggressive, so proper removal methods, including manual clearing or herbicides, may be necessary.

Tilling the Soil

In tropical soils, especially those that are compacted or prone to hardening, this helps break up the soil, improving root penetration and water absorption.

Ensuring Proper Drainage

In tropical environments where rainfall is abundant, proper grading ensures that water does not pool around plant roots, which can lead to root rot.

Adding Organic Matter

Tropical soils often benefit from the addition of this, especially if they are sandy or depleted of nutrients from previous use. Incorporate compost, aged manure, or green manure crops to improve soil structure, water retention, and nutrient content.

Shovels

Used for digging, turning soil, and mixing organic matter into the ground. Essential for smaller ornamental beds or areas with delicate root systems where precision is needed.

Hoes

Effective for breaking up the topsoil and removing weeds.

Rakes

Used for leveling soil, gathering debris, and smoothing the surface before planting.

Ploughs

Often used for larger plots, this helps break up and aerate soil, preparing it for planting.

Rotavators

A powered tool that helps break up soil and mix organic matter, ideal for medium to large garden beds.

Tillers

Useful for smaller areas where hand tilling is labor-intensive or for preparing planting beds for ornamental plants.

Drip Irrigation

Highly efficient for delivering water directly to the root zone of plants, minimizing water loss in hot, tropical climates.

Sprinkler Systems

Suitable for larger areas, ensures even watering, simulating natural rainfall in tropical environments.

Peat

Excellent for water retention, is often used in tropical climates to maintain moisture for delicate ornamentals during propagation.

Perlite

A lightweight volcanic rock that improves aeration and drainage, preventing waterlogging in the tropical humidity.

Sand

Provides excellent drainage, making it a key component in the propagation of plants prone to root rot in tropical, wet conditions.

Vermiculite

A mineral component that helps with both water retention and aeration, ensuring balanced moisture levels in the medium.

Sterilization of the Medium

In tropical climates, soil-borne diseases and pests thrive due to high humidity and warmth so doing this to the propagation medium (via heat or chemicals) is critical to prevent the spread of pathogens.

Importance of Good Water Retention Without Waterlogging

Tropical environments often receive heavy rainfall, so the propagation medium must allow for this to prevent waterlogging and root rot.

pH Balance of the Medium

Different ornamental plants have varying requirements and you can amend the propagation medium with lime to raise pH or sulfur to lower pH, depending on the plant's requirements.

One Cotyledon

Monocot seeds have this, a single seed leaf that stores food for the developing seedling.

Endosperm

Monocots often have this, a large, nutrient-rich area which provides sustenance for the seedling.

Two Cotyledons

Dicot seeds contain two of these, which often absorb nutrients from the endosperm and provide them directly to the seedling.

Embryonic Leaves

The two cotyledons in dicots usually act as the seedling’s these, nourishing the plant until it can photosynthesize on its own.

Seed Coat

The outer protective layer that shields the seed from physical damage and prevents water loss.

Cotyledon

Stores and transfers nutrients during germination.

Endosperm

The tissue that surrounds and nourishes the developing embryo, especially prominent in monocot seeds.

Embryo

The young plant itself, which consists of the radicle (root), plumule (shoot), and hypocotyl (the transition area between root and shoot)

True Seeds

These seeds are the result of sexual reproduction, where fertilized ovules mature into seeds. These seeds carry genetic material from both parent plants, resulting in genetic variation among offspring.

Apomictic Seeds

These seeds form through asexual reproduction, where the seed develops without fertilization, producing offspring that are genetically identical to the parent plant.

Explosive Mechanisms (Self-Dispersal/Autochory)

Some plants have developed mechanisms where their seed pods burst open and fling seeds away from the parent plant, ensuring that they spread over a larger area.

Wind Dispersal (Anemochory)

Lightweight seeds with wings or tufts are carried away by the wind.

Water Dispersal (Hydrochory)

Seeds that are buoyant can float on water to new locations, often across rivers, seas, or lakes.

Animal Dispersal (Zoochory)

Animals play a key role in seed dispersal, either by eating fruits and excreting seeds far from the parent plant or by carrying seeds on their fur or feathers.

Human-Assisted Dispersal (Anthropochory)

Humans often play a major role in dispersing seeds, whether intentionally through agriculture or unintentionally by transporting them on clothes or vehicles.

Gravity Dispersal (Barochory)

In this type of dispersal, seeds simply fall from the parent plant and rely on gravity to reach the soil below. These seeds may germinate close to the parent, often resulting in clusters of plants.

Imbibition – Absorption of Water

The first phase of germination, where the seed absorbs water, causing it to swell and break its seed coat.

Enzyme Activation – Breakdown of Stored Food

Once the seed has absorbed enough water, enzymes within the seed are activated to break down stored food in the cotyledons or endosperm.

Radicle Emergence – Root Grows Downward

The first part of the seedling to emerge from the seed.

Shoot Emergence – Shoot Grows Upward Toward Light

Will eventually develop into the plant’s stem and leaves, emerges after the radicle.

Water – Essential for Activating Metabolic Processes

The key factor that initiates germination. It is absorbed by the seed during the process of imbibition, causing the seed to swell and activate enzymes.

Temperature – Optimal Range for Enzyme Activity

Directly affects the speed of metabolic processes within the seed. Each plant species has a specific optimal range for germination.

Oxygen – Needed for Respiration and Growth

Seeds require this to produce energy through cellular respiration, which powers growth.

Light – Some Seeds Require Light, Others Darkness

Some seeds need this to germinate, while others require darkness. These seeds rely on specific wavelengths of this to trigger or inhibit germination.

Scarification – Breaking the Seed Coat for Water Entry

Involves physically or chemically breaking or weakening the seed coat to allow water and gases to penetrate, initiating the germination process.

Stratification – Chilling Seeds to Break Dormancy

The process of simulating natural winter conditions by chilling seeds for a period to break their dormancy.

Seed Priming – Pre-Soaking Seeds Before Sowing

Involves soaking seeds in water or a nutrient solution for a specific time before planting. This activates the initial stages of germination without allowing the radicle to emerge.

Controlled Environment – Use of Greenhouses or Germination Chambers

Provide optimal conditions for seed germination by regulating factors such as temperature, humidity, and light.