Cannabis Botany - Exam II

What is the main purpose of applying ethylene inhibitors like silver nitrate and STS to female cannabis plants?

To induce the formation of male flowers

What is the purpose of placing explants in a vessel with 10% commercial bleach and 0.01% Tween 20 during the tissue culture process?

To sterilize and reduce contamination

Which system has been used successfully to replenish culture medium for in vitro “micro” mother plants?

Temporary immersion rocker system

Which statement about somatic mutations in micropropagated cannabis is supported by current studies?

Molecular marker analysis may miss some genomic mutations.

Which plant hormone was highlighted for its role in refining in vitro mass propagation protocols for Cannabis sativa L.?

Meta-topolin

Auxin

A class of plant growth regulators, such as indole-3-butyric acid (IBA), which encourages root initiation and formation during propagation.

Why do producers induce genetically female cannabis plants to form flowers during feminized seed production?

To produce seeds that are all genetically female

De Novo Regeneration

The process by which new plants are formed from non-meristematic tissues (e.g., leaves, roots) through callus formation and subsequent shoot development. 

Isolation Distance

the minimum spatial separation required between plant populations to prevent cross-pollination and maintain genetic purity.

Propagation

The process of growing new plants from a variety of sources: seeds, cuttings, tissue culture, or other plant parts.

Feminized Seed

Seed produced to give rise predominantly or exclusively to female plants by manipulating female plants to produce male flowers.

Callus

A mass of undifferentiated plant cells that can be induced to regenerate into whole plants via de novo regeneration.

Vegetative Propagation

A form of asexual plant reproduction where new plants are grown from cuttings or other vegetative parts, maintaining genetic consistency with the parent plant.

What is a major environmental concern when using a silver-based compounds like STS in plant pollination?

Potential toxicity to aquatic life

THC (tetrahydrocannabinol)

The principal psychoactive cannabinoid found in cannabis plants.

What is the primary purpose of the modified nodal cuttings and shoot tis protocol mentioned in the text?

Rapid regeneration of Cannabis sativa L.

Which of the following steps is essential during the acclimization stage of plant micropropagation?

Gradually decreasing humidity and increasing light

Somaclonal Variation

Genetic variation that arises in plants regenerated from tissue culture, often undesirable for clonal uniformity.

Apical Cuttings

Cuttings taken from the tip of a plant, commonly used for vegetative propagation.

Hermaphroditism

A condition in which an individual cannabis plant develops both male and female reproductive organs. 

Landrace

A locally adapted, genetically diverse cannabis population, often open-pollinated and maintained by traditional cultivation.

Plant Growth Regulators (PGRs)

Chemicals that influence plant growth and development, including auxins, cytokinins, giberellins, and ethylene inhibitors. 

Cytokinin

plant hormones that promote cell division and are curcial for cannabis growth; leads to more vigorous shoots, leaves, and lateral branches.

Gibberellins

a group of plant hormones that can induce male flowers on female plants

Ethylene Inhibitors

ethylene inhibitors induce male flowers on female plants to produce feminized seeds; female plants are richer in THC and CBD.

What process do producers use to induce female cannabis plants to produce male flowers for feminized seed production?

Treating female plans with chemical or stressors 

Why do cannabis mother plants often show a decline in health and cannabinoid content over time?

They accumulate genetic mutations or epigenetic changes 

What is one consideration that must be made before adopting the modified micropropagation method descried in the text?

It increases labor costs and contamination risk

What storage conditions are reccomended for 0.1 M stock solutions of silver nitrate and sodium thiosulfate?

Stored in the dark at low temperatures

What is the main benefit of using a higher concentration (3mM) of STS in hemp plants, according to the study?

It is more reliable in inducing male flower production across genotypes

Which of the following statements about ethylene inhibitors in cannabis cultivation is true?

They inhibit the action of ethylene, leading to hermaphroditic flowers.

Why is it recommended to transfer explants into pre-sterilized vessels containing distilled, deionized, or reverse osmosis (RO) water after the bleaching step in tissue culture?

To rinse off residual chemicals and reduce toxicity

What is a potential drawback of self-pollinating female plants to produce feminized seeds?

Inbreeding depression

Which cultivation issue arises due to variation in maturation dates among cannabis plants in large-scale operations?

Need for selective harvesting

What is a key difference between seed-based propagation of hemp and drug/medicinal cannabis according to the text?

Hemp seed is heavily regulated and must meet strict guidelines, while drug/medicinal cannabis seed is mostly unregulated. 

What is a key reason for pre-soaking growing media before rooting plant cuttings?

To ensure adequate moisture and provide weak nutrients

Why might suboptimal stock plants sometimes be used in micropropagation, even though ideal plants are preferred?

Because micropropagation can rescue plants affected by stress, disease, or insects

What is a sign of nitrogen deficiency in plants?

Lower leaves becoming yellow first

What is the primary reason optimal nitrogen (N) levels are required in soilless cannabis production?

To achieve both yield and quality goals

What do the percentages listed on a fertilizer label, such as 20-8-20, represent?

The percentage by weight of nitrogen, phosphorus (as P205), and potassium (as K2O) in the fertilizer

What is one unique feature of aquaponics compared to other soilless systems?

Plants and fish are grown together in the same system

Integrated Rootzone Management (IRM)

A holistic approach to managing the rootzone environment by considering and optimizing factors such as water, nutrients, oxygen, and temperature to maximize plant health and yield. 

Rootzone

The environment where plant roots reside, influenced by factors such as water content, temperature, and oxygen availability, and critical for plant health and function.

What does a pH value of 7 in water indicate?

The solution is neutral

What does ‘bulk density’ refer to soilless media?

The dry weight of the medium divided by its volume

What is important to consider when making nutrient solutions for plants?

The chemical form of nutrients and the target concentration

Which of the following gases is commonly purged from the rootzone along with CO2 to prevent harmful levels?

Ethylene

Electrical Conductivity (EC)

A measure of the total dissolved salts (ions) in water or nutrient solution, used to assess the suitability of water for plant irrigation.

Fertigation

The process of supplying plants with both water and nutrients simultaneously, typically through an irrigation system.

What is one visible symptom in plants that are deficient in zinc (Zn)?

Youngest leaves show interveinal chlorosis

Hydroponics

A technique of growing plants in liquid nutrient solutions without the use of solid soil as a growing medium. though the term is sometimes used more broadly for soilless systems. 

Alkalinity

A measure of the acid-neutralizing capacity of a solution, often represented as the equivalent concentration of CaCO3, affecting the pH and buffering capacity of water. 

Soilless Cultivation Sytems (SCS)

Plant cultivation systems that do not use natural soil or use growing media where the majority of the constituents are not natural soil, such as peat-based, coir-based media, hydroponics, aquaponics, and rockwool

What determines the physical properties required of a growing medium in cannabis cultivation?

The size and shape of pots, bags, or slabs

pH

a scale from 0 to 14 expressing the acidity or basicity of solution. It is critical for nutrient availability and plant health, with most plants preferring a rootzone pH of 5.5-6.5

Drip Irrigation

A method of delivering water or nutrient solution directly to the plant rootzone using emitters at controlled flow rates, known for its efficiency but prone to emitter blockage.

Total Dissolved Solids (TDS)

The total concentration of dissolved substances in water, typically expressed in mg?L, and used to assess water quality for irrigation.

Which of the following is a primary function of calcium (Ca) in Cannabis sativa plants?

Supports cell wall and membrane stability

What is a benefit of using larger containers with the same growing medium for cannabis cultivation?

They need to be watered less frequently

Why are wetting agents added to peat-based growing media?

To help peat moss reabsorb water after drying

What is one unique feature of aquaponics compared to other soilless systems?

Plants and fish are grown together in the same system

Which of the following can occur when plants receive too much nitrogen?

Leaves become dark green and plants may become overgrown

Why is soilless media often preferred over soil for indoor cannabis production?

Soilless media can be consistently prepared crop after crop

What is often required if source water for cannabis production does not meet quality guidelines?

Water treatment

Why is CEC important in a growing medium?

It measures the ability to retain nutrients like K+

What physiological stress do cannabis transplants exhibit when left in the dark and watered excessively?

Waterlogging stress

Why is it important to create a composite sample from representative plants when collecting leaf samples for nutrient analysis?

It ensures the sample reflects the overall field conditions

Why has wood fiber been recently incorporated into peat-based growing media for cannabis cultivation?

To improve aeration and water conduction

What factor can influence both the intensity and spectrum of light experienced by individual leaves within a dense plant canopy?

Vegetated shade from upper leaves

What is a disadvantage of using CMH (ceramic metal halide) lighting in horticulture?

Higher luminaire costs and need for more fixtures

What is CO2 compensation point in plant physiology?

The concentration where photosynthesis and respiration rates are equal

Which factor influences the economic feasibility of CO2 supplementation in controlled environment cannabis cultivation?

Air exchange rate of the growth room or greenhouse

Why is it challenging to obtain reliable studies on cannabis growth response to CO2 concentration?

Because high-tech instrumentation and sophisticated controls are required, which are rare.

Short-day Plants

Plants that flower when the uninterrupted dark period is long enough, commonly including many cannabis genotypes.

Long-day Plants

Plants that flower when the dark period is kept short, requiring shorter or interrupted dark periods. 

Light-Emitting Diode (LED)

A solid-state lighting technology using semiconductors to emit light, increasingly used in horticultural lighting for high efficiency and spectrum control.

Day-neutral Plants

Plants that flower regardless of the photoperiod, such as autoflowering cannabis genotypes.

Photosynthetically Active Radiation (PAR)

The range of light wavelengths (400-700 nm) that plants can use for photosynthesis.

Day Light Integral (DLI)

The total amount of PAR received by a plant in a day, measured in mol·m2·d1

Spectroradiometer

An instrument that measures absolute light intensity and spectrum across very narrow wavelength intervals, used for detailed analysis of light in horticultural environments. 

Quantum Sensor

A device that measures the number of PAR photons in the 400-700 nm range, used for evaluating light sensitivity in crop production.

Photoperiod

The duration of light and darkness in a 24-hour period, affecting plant flowering and growth cycles.

Photosynthetic Photon Flux Density (PPFD)

A measure of the number of PAR photons striking a square meter per second, commonly expressed as ¼mol·m2·s1

According to recent studies, how has the efficacy of legacy horticultural lighting technologies changed over time?

It had remained relatively stagnant

Which type of plant only flowers when the uninterrupted dark period is increased to a certain length?

Short-day plants

What characteristic of LEDs allows them to emit relatively narrow wavebands of radiation in horticultural lighting?

The chemical makeup of the semiconductor material

What metric can be used to manage planting density and de-leafing practices in cannabis cultivation?

Average light intensity at the bottom of the canopy

What operational challenge may limit the adoption of inner-canopy lighting in commercial cannabis production?

Complexity of installing light fixtures

Inbreeding Depression

reduced fitness or biological well-being of offspring resulting from the mating of closely related individuals

Metal Halide (MH)

Blue-rich, “cool” light; best for vegetative growth and leafy greens

High-Pressure Sodium (HPS)

Red-orange, “warm” light; best for flowering and fruiting

Ceramic Metal Halide (CMH)

Full, balanced spectrum, similar to natural sunlight; good for all plant growth, from seedlings to flowering.