Seed Science and Pathology Practice Flashcards

Vocabulary flashcards covering key concepts, pathogen classifications, testing methods, mycotoxins, disease management principles, and international trade regulations in seed science.

Abiotic Factors (Seed Health)

Non-living factors that adversely affect seed health, including mechanical injury (such as broken seeds) and chemical injury (such as high dosage of chemicals damaging the embryo).

Biotic Factors (Seed Health)

Living organisms that affect seed health, including viruses, bacteria, fungi, nematodes, phytoplasma, and protozoa.

Mesobiotic

A term describing organisms, such as viruses, that exhibit living characteristics when inside living host tissues and non-living characteristics when outside living tissues.

Fungi

Small, generally microscopic, eukaryotic, usually filamentous, branched, spore-bearing organisms that lack chlorophyll.

Bacteria

Single-celled prokaryotic microorganisms whose genetic material (DNA) is not membrane-bound and is not organized into a true nucleus.

Nematodes

Microscopic, un-segmented, worm-like, and bilaterally symmetrical animals that feature a mouth part with a spear (stylet) and a digestive system, but lack respiratory and circulatory systems.

Amphids

Sensory organs situated in the head region of a nematode.

Phasmids

Sensory organs located in the tail region of a nematode.

Plant Parasitic Nematode Anatomy

Anatomy of a typical female plant parasitic nematode, illustrating internal and external structures such as the stylet, oesophagus, ovary, intestine, vulva, and anus.

Low-Constant Temperature Oven Method

An ISTA-prescribed oven drying method utilized for determining moisture content in oily seeds, such as groundnut.

High-Constant Temperature Oven Method

An ISTA-prescribed oven drying method utilized for determining moisture content in non-oily seeds, including sorghum, millets, chickpea, and pigeonpea.

Top of Paper (TP) Method

A seed germination testing technique used for millets where seeds are spread evenly on the surface of moistened paper inside petri dishes.

Between Paper (BP) Method

A seed germination testing technique (rolled towel method) used for sorghum, chickpea, pigeonpea, and groundnut where seeds are placed between layers of paper towels.

Topographical Tetrazolium Test

A backup viability test applied to firm seeds that fail to germinate, utilizing a buffered $1\%$ 2,3,5-triphenyl tetrazolium chloride solution to stain viable tissues bright red.

Lactophenol

A clearing solution prepared from $200\,\text{ml}$ phenol, $200\,\text{ml}$ lactic acid, $400\,\text{ml}$ glycerine, and $200\,\text{ml}$ water, used to immerse seeds for 1–2 hours prior to evaluating tetrazolium staining patterns.

Seed Vigor

The sum total of all properties in seed which upon sowing result in rapid and uniform production of healthy seedlings under a wide range of environments, including both favorable and stress conditions.

Germination Index

A measure of seed vigor calculated using the formula $\Sigma(t \times n)/\Sigma n$, where $n$ is the number of germinated seeds and $t$ is the number of hours from the start of the germination test.

Blotter Test

A seed health testing method where seeds are spaced on 3 layers of blotter paper moistened with sterile water and incubated under near ultraviolet light in alternating 12-hour light/darkness cycles for 7 days at $20 \pm 2^\circ\text{C}$.

Agar Plate Method

A common identification method for seed-borne fungi, involving placement of surface-disinfected seeds onto Potato Dextrose Agar (PDA) medium that was autoclaved at $121^\circ\text{C}$ for 15–20 minutes under $15\,\text{lb}$ pressure.

Mycotoxins

Primary or secondary toxic metabolites produced by certain species of seed-borne fungal pathogens.

Aflatoxins

Mycotoxins produced primarily by fungi of the genus Aspergillus (e.g., A. flavus, A. parasiticus), among which Aflatoxin B1 is recognized as the most potent natural carcinogen known.

Fumonisins

Mycotoxins produced mainly by Fusarium species (such as moniliforme, nygamai, and proliferatum) that commonly attack maize and have been linked to esophageal cancer in humans.

Ochratoxins

Mycotoxins produced by Aspergillus ochraceus, A. carbonarium, certain strains of A. niger, and Penicillium species, which primarily target and damage the kidney.

Trichothecenes

A family of fungal metabolites produced by genera such as Fusarium, Myrothecium, Phomopsis, and Trichoderma, which act as extreme inhibitors of eukaryotic protein synthesis.

Zearalenone

A secondary metabolite produced by Fusarium graminearum that interferes with hormonal functions and causes hyperestrogenism in swine.

Disease Triangle

A core plant pathology model illustrating that plant disease development requires the interaction of a susceptible Host, a virulent Pathogen, and a conducive Environment.

Exclusion (Plant Disease Management)

The principle of preventing the entrance and establishment of a pathogen into an un-infested area, field, region, or country.

Avoidance (Plant Disease Management)

The principle of avoiding environmental conditions favorable to disease development when the pathogen is already present.

Eradication (Plant Disease Management)

The principle involving complete elimination or partial reduction of pathogen inoculum at its source.

Protection (Plant Disease Management)

The principle of making the pathogen inoculum ineffective at the site of possible infection through chemical applications or physical barriers.

Host Resistance

The principle of reducing the effectiveness of a pathogen within a host using genetically based physical or biochemical factors.

Therapy (Plant Disease Management)

The principle focused on curing or inhibiting an existing infection inside a diseased plant, such as through heat treatment or systemic fungicides.

PPRSD

The Plant Protection and Regulation Services Directorate of MOFA in Ghana (headquartered at Pokuase near Accra), which enforces plant quarantine laws under Act 307 of 1965.

SPS Agreement

The Sanitary and Phytosanitary Agreement under the WTO that empowers member nations to apply necessary measures to protect human, animal, and plant life without creating disguised trade barriers.

The Three Sisters (International Regulatory Bodies)

The three international standard-setting bodies under the SPS Agreement: Codex Alimentarius Commission (CAC) for food safety, World Organisation for Animal Health (IOE) for animal health, and International Plant Protection Convention (IPPC) for plant health.

HACCP

Hazard Analysis and Critical Control Point; a preventive food security technology management system that uses scientific risk assessment to identify key control points and prevent hazards across the food chain.