Horticulture Exam 2

Commercial Seed Production

The process of growing, harvesting, and processing seeds on a large scale for sale to farmers, gardeners, and other agricultural producers.

What does commercial seed production ensure?

High-quality, genetically pure, and viable seeds.

Genetic purity

Ensures that seeds are true to type and possess the desired characteristics of the parent plants.

What are methods of genetic purity?

Maintain isolation distances to prevent cross-pollination.

Utilize roguing to remove off-type or diseased plants.

Isolation Distance

Physical separation of seed fields to prevent cross-pollination between different varieties or species.

Roguing

The process of removing off-type or diseased plants from the seed field. Helps maintain genetic purity and ensures that only desirable traits are passed on to the seed.

Threshing

The process of removing seeds from the plant and breaking up plant materials (stems and leaves) into what is called chaff.

Dry Fruits

Corn, wheat, and most grain crops. Most are harvested by machine.

Dehiscent fruit

Includes okra, pansy, petunia, beans, peas, soybeans. (split open) readily at maturity and release dry seeds.

Fleshy Fruits

Includes tomatoes, peppers, watermelons, cucumbers, squash, pumpkins.

How are fleshy fruit seeds extracted

fruits are crushed and placed in a vat or tank.

How are fleshy fruits fermented.

crushed fruit allowed to ferment for about 3 days at 70+ F (stirring).

Seed Certification

A formal process where seeds are inspected and certified by authorized agencies to meet specific quality standards.

Federal Seed Act 1939

Seeds free of contaminating material, seeds with genetic identity and purity, seeds with germination uniformity.

Plant Variety Protection Act (PVPA)

Legal property rights protection to breeders of new plant varieties. Exclusive rights to sell, reproduce, import, export, and use for cultivars and hybrids. 1970, amended in 1994.

Biodiversity

Preserve genetic diversity and heirloom varieties (old, heritage varieties)

Food Sovereignty

Empower communities to control their food sources and support self-sufficiency.

Economic Benefits

Reduce costs for gardeners and farmers.

Techniques for Seed Saving

Mature embryos before seeds disperse extracted from their fruit and separated from chaff, insect parts, soil foreign material.

Can seeds be saved wet or dry?

Yes

John Coykendall

Seed saver, Storyteller, Master Gardener at Blackberry Farms (TN), Saving the history and heritage of heirloom seeds and their stories, Washington Parish, LA.

Memory Banking

Preserving seeds and the cultural heritage and stories associated with them.

Importance of seed collection

Biodiversity preservation, food security, and agriculture, conservation of rare and endangered species

Types of seeds collected

Orthodox seeds, Recalcitrant seeds and intermediate seeds.

Orthodox seed collection

Can be dried and stored for long-term rice, wheat, beans

Recalcitrant seed collection

Do not survive drying or freezing, require short-term storage or cryopreservation. Mango, avacado, coconut

Intermediate seed collection

Partially desiccation-tolerant, coffee, citrus

Judean Date Palm

In 2005, a team of scientists sprouted a preserved 2000-year-old seed, the oldest seed to germinate with human assistance.

Seed collection methods

Wild collection, agricultural collection

Cleaning

removal of debris and non-viable seeds.

Cleaning methods

manual cleaning, sieving and screening, winnowing, disinfestation, hot water treatment, biological and chemical treatments

Processing seeds

Drying, sorting, grading

Storage conditions

Tempurature, humidity control, light exposure, gases

Storage methods

Short-term (1-5 years), Medium-term (5-20 years) and long-term ( 20+ years)

Pests

Insects, weevils, grain borers, nematodes, rodents, mice, rats, squirrels

Factors affecting seed viability

Moisture content, temperature fluctuations, pest and fungal contaminations, seed age

Seed viability test

Germination test, Tetrazolium test, float test

Future trends in seed preservation

Cryopreservation, genetic modification, digital seed tracking systems

Light is essential for what?

photosynthesis

Photosynthesis

The process by which plants convert light energy into chemical energy.

What does blue light promote

vegetative growth and root development

What does red light promote

supports flowing and fruiting

Light quantity (intensity)

The number of photons (light particles) capable of performing photosynthesis.

Plant usable light

400nm - 700nm

Light Emitting Diodes (LED)

Best for energy efficiency, spectrum control, and low heat emission, making them versatile for all stages of propagation.

Fluorescent

Affordable and low heat, ideal for seedlings and supplemental lighting, emits cool white or warm white light.

High-Intensity Discharge (HID)

Intense light output; requires carful management of heat and energy consumption. Heat may be beneficial in cold environments.

Air circulation

Prevents fungal diseases by reducing humidity around plant surfaces and promoting gas exchange.

Oxygen Levels

Essential for root respiration and overall plant metabolism.

Carbon Dioxide levels

Higher CO2 concentrations can enhance photosynthesis and growth rates.

Humidity Control

Maintaining optimal humidity levels (40-60%) prevents stress and supports healthy growth.

Natural Ventilation

Utilizes windows, vents, and fans to promote air movement without mechanical systems.

Mechanical ventilation

Exhaust fans, intake fans, and HVAC systems

Optimal temperature for seed germination

most seeds 65-75 degree F

Optimal temperature for root development

60-70 degrees F

Temperature control methods

Heating mats, Greenhouses, Thermostats and sensors.

Role of Wate

Nutrient transport, cell turgor, biochemical reactions (photosynthesis and other metabolic processes), water quality (pH-balanced water)

Cell turgor

Maintains cell structure and supports growth by keeping cells turgid.

Irrigation Methods

Mist systems, drip irrigation, ebb and flow bench irrigation, overhead watering

Types of propagation media

Soil, perlite and vermiculite, peat and sphagnum moss, coconut coir.

Perlite and vermiculite

Inorganic media that improve drainage and aeration.

What must work together synergistically to create optimal conditions.

Light, air, temp, water and media

Vegetative propagation

Process of reproducing plants without the use of seeds, resulting in offspring that are genetically identical to the parent plant. Asexual propagation = clonal propagation

Why propagate asexually

Uniformity, faster maturity, some plants don’t produce seeds, avoid seed borne disease, disease resistance, save cost, preservation of declining species

Cuttings

vegetative propagation method involves taking a piece of the parent plant (stem, leaf, root) and encouraging it to develop roots and shoots to form a new plant. Common for ornamental plants and some fruits.

Grafting

Vegetative propagation method of joining two plant parts together so they grow as one. The scion (upper part) is attached to the rootstock (lower part).

Rootstock in grafting

Provides the root system. Adapted to native soil and disease resistance.

Scion in grafting

Selected for desirable traits, fruit quality/flavor, early maturing fruit, unique flower characteristics.

Budding

Vegetative propagation method, a type of grafting where a single bud from the scion is inserted into the rootstock. Bud will grow into a new stem, multiple buds can be grafted onto 1 rootstock.

Layering

Vegetative Propagation method, involes inducing roots to form on a stem while it is still attached to the parent plant. Once roots have developed, the stem can be cut and planted as a new plant.

Division

Vegetative propagation method, process of splitting a plant into multiple parts, each capable of growing into a new plant. Commonly used for perennials

Specialized Structures

Plant parts that are naturally adapted for asexual reproduction. Includes bulbs, corms, tubers and rhizomes.

Bulbs

Underground storage organs, such as tulips and onions.

Corms

Swollen stem bases, like those in gladiolus and crocus.

Tubers

Enlarged structure, such as potatoes, that store nutrients.

Rhizomes

Horizontal underground stems, like those in irises and ginger.

Cloning

Process of vegetatively propagating a clone.

Clones

The vegetative progeny of a single genotype such as an individual seedling, a mutant branch, a single plant of a clonal population, or recombinant DNA segment.

Propagule

Any plant part used as the starting point of a propagation process.

Progeny

The offspring produced by a parent plant.

Mitosis

Primary cell division process, ensuring that each new cell is genetically identical to the parent cell.

Totipotency

A concept that each living plant cell has the potential to reproduce an entire organism since it possesses all necessary genetic information in its genes. Fundamental to clonal plant propagation.

Chimeras

An individual organism with genetically different tissues in one plant due to spontaneous mutations. Ex, ddifferent colors on the same leaf

Phenotype effects

Difference in leaf color, flower shape, ir other physical traits.

Parenchyma cells

Living cells with thin walls, have large vacuoles and ability to divide, crucial for healing and regeneration, found throughout plant.

Callus

A mass of unorganized parenchyma cells that forms at wound sites, leads to healing, can develop in any plant tissue or organ under right conditions.

Totipotent

Callus cells

Collenchyma cells

Living cells with irregularly thickened walls made of cellulose and pectin. Provide mechanical support and flexibility to growing plants, and supports young stems and leaves. Provide structural support to developing callus and as cells age they accumulate hardening substances and thicken.

Sclerenchyma cells

Dead at maturity and have thick, lignified walls. Proved rigidity and strength to plant tissues, fuction in reinforcement, elastic and resilient. Abundant in plants the yield fiber.

What is the most common way of cutting?

Stem Cutting

Three types of cuttings

Stem, leaf and root

Hardwood cuttings

Dormant wood collected in winter

Softwood cuttings

Late spring and early summer, new growth that occurs from the hardwood and bends but does not snap.

Semi-hardwood cuttings

Late summer and early autumn, as softwood matures

Characteristic of hardwood cuttings

Slow but reliable rooting, highly resilient, taken from fully mature dormant woody stems, long shelf life, easiest to use, grapes, figs and many tress. Length of 4” to 30”, includes at least 2 nodes.

Hw do you know if hardwood is ready to be used for cuttings

Wood is firm and does not bend, leaves can be removes without tearing bark, leaves have abscised, avoid flower buds

Characteristics of semi-hardwood cuttings

Partially matured wood, more resilient than softwood, shoots are durable but may snap under direct force, used in shrubs and broadleaf evergreens, leaves present. 3” to 6” in length, more perishable than hardwood.

Characteristics of softwood cuttings

Young, flexible, root quickly but highly sensitive to desiccation. Require high humidity and auxin treatment for success.

Herbaceous cuttings

From succulent nonwoody plants, high humidity is essential, auxin not needed, and 3” to 5” in length.

Polarity

Cuttings will produce shoots on the distal end (nearest the bud) and roots on the proximal end (nearest the main stem or root system). Cuttings must be oriented properly when planted or it will not root.