Horticulture Final

Geophtyes

Plants that can survive as specialized underground storage organs

Geophytes are typically

herbaceous perinneals that store energy in bulbs, tubers, or rhizomes.

Geophytes reproduce

sexually and asexually/ clonal

Clonal Reproduction

utilizes the specialized storage organ (Geophytes)

Geophytes Classes

Bublbs, corms, tubers, tuberous roots, rhizomes, and pseudobulbs

Geophyte primary function

Storage of food, nutrients, and water; survival during adverse environmental conditions

Geophyte characteristics

Herbaceous perennials, shoots die down at the end of the growing season dormant, fleshy organs bear buds for new shoots

Geophyte adaptions

1) withstand adverse growing conditions

2) never physiologically dormant

3) Act as bio processors sensing and responding to the environment

4) Adaptations are for survival during warm- cold cycles (temperature zones) or wet dry (tropical and subtropical)

Geophyte Roots

Fibrous and contractile

Fibrous Roots

Formed as adventious roots, absorb water and nutrients, function for one growing season

Contractile Roots

Pull the bulb/corm to the proper soil depth by shrinking and expandingto ensure optimal moisture and temperature.

Droppers

Modified stems used by certain geophytes where a new bulb forms at the end of a stolon, helping move it to the proper depth

Types of Geophyte Droppers

tulips, trout lilies,seedling bulbs

Bulbs

specialized underground organ consisting of a short, usually vertical stem axis (basal plate) bearing at its apex a growing point or a flower primordium enclosed by thick, scale like leaves

Bulb Basal Plate

short, vertical stem axis

Bulb scales

Outer scales are fleshy and contain reserve food material: inner scales are more leaf like with less storage functions

Bulb Central Structure

Vegetative meristem or unexpanding flowering shoot

Bulb hardness

Hardy, semi-hardy, or tender

Bulb Structure

Tunicate (laminate) or Scaly (non-turnicate)

Tunicate Bulbs

Dry, membranous outer scales called a “tunic” which protects from drying and mechanical injury. Fleshy inner scales provide food storage, scales are in continuous, concentric layers

Tunicate Bulb examples

Onion, garlic, daffodil, tulip, many amaryllidaceae, hyacinth with papery cover

Non tunicate Bulbs

Have no tunic, scales are separated and attached to the basal plate, easily damaged and must be handled more carefully, must be kept continuously moist as they are injured by drying

Non-tunicate bulbs

Lily, Fritillaria

Bulb plant type

mostly produced by Monocotyledonous plants; sorrel is one dicot genus that produces bulbs

Bulb reproductive phase

Forms flower primordia, shoot emerges, blooms, produces seed

Bulb vegetative phase

new leaves emerge, new offsets form, the old bulb may decay (tulips) or remain (daffodil)

Bulb Storage Conditions

Stores in cool, dry 40 to 50 Degrees F with good circulation to prevent premature sprouting.

How to store Bulbs

1) allows bulbs to dry first to remove excess moisture

2) avoid extreme temperature flunctuations or high humidity

3) Use containers that allow circulation

4) Regularly check for root rot or dehydration

Bublet

a miniature bulb that forms in teh axil of a bulb scale and provides a method of vegatative propagation

How do most bulbs naturally multiply

by bulblets that form as offsets from the basal plate

Propagation methods for bulbs

1. Normal offsets

2. underground stem bulblets

3. aerial stem bulbets

4. Scaling for non tunicate

5. Twin scaling for tunicate

6. Scoring and scooping wounding the basal plate

7. Bulb cuttings

8. Leaf cuttings

   1. Tissue Culture

Describe Twin scaling propagation for bulbs

Cutting the bubs into sections each containing two scale sections and a portion of the basal plate, new bulbets form between the pair of scales.

Describe scoring and scooping propagation fo rbulbs

Methods that wound the basal plate to promote adventous bulbet formation, scooping removes tissue while scoring cuts through it. Used for plants like hyacinth and pineapple lily

Corm

The swollen base of a stem axis enclosed by a dry scale like tunic. Solid stem structure with distinct nodes and internodes, The tunic protects against injury and water loss

Corm examples

Gladiola and Crocus

How does the growth pattern of corms differ from bulbs?

Bulbs may retain old bulbs. Corms are stem tissue with only distinct nodes and internodes and are solid with no scales. Bulbs have leaves, stem, and flower tissue, indistinct nodes/internodes,and scales

Cormel

Miniature corms that develop between the old and the new corms

Propagation methods for corm

1. sexual/ seeds

2. new corms

3. cormels

4. corm division (large corms cut with each section containing a bud)

5. tissue culture

Tuber

a swollen modified stem with nodes and internodes. It functions as both storage structure and an organ of vegetative reproduction.

How are tubers propagated

usually by division where the tubers are cut into sections, usually with two buds per piece (known as seed potato). Some plants also produce aerial tubers (tubericles) in leaf axils

Tubercles

aerial tubers produced in the axils of the leaves, which can be removed, stored, and planted for propagation. Uncommon method used by plants like begonia, evansiana and cinnamon vine

Tuberous root

Thickened and underground structures for food storage that are modified roots

Tuberous Roots propagated

dividing the crown so that each section bears a shoot bud. THe fleshy root of a few species can also produce advetious shoots called slips

What are slips to Tuberous roots

advetious shoots that can be produced by the fleshy roots of some species, from which adventious roots develop, these slips are removed and transplanted

rhizome

a modified stem structure that grows horizontally at or just below the ground surface. Distinguished from a stolen by also functioning as storage. They also have nodes and internodes with lateral shoot buds

Propagation for Rhizomes

by division , where the rhizomes is cut into piece containing at least one bud. A section with roots and a terminal bud is sometimes called a pip or crown

Pseudobulb

a specialized storage structure produced by many orchid species consisting of an enlarged, fleshy section of the stem made up of one to several nodes. Also called a false bulb

Propagation for Pseudobulb

offshoots, division (during dormany requiring 4-5 bulbs) back bulbs (leafless psuedo bulbs), and green bulbs (psuedobulbs with leaves)

Tissue Culture

method for propagating various geophytes , including crinum lily, gladiolus, potatoes, and orchids. Allows for rapid multiplication and production of disease free stock.

Micropropagation

asexual propagation method where plants are manipulated on a cellular level to duplicate themselves rapidly. Propagating plants using a small piece of tissue under aseptic conditions

Explant in tissue culture

ANy part of a plant taken out and grown vitro, under aseptic conditions in special nutrient media

Totipotency in Tissue Culture

the capacity of plants to generate a whole from an explant

Advantages of micropropagation

1. Clones

2. grow larg numbers rapidly

3. produce plants when traditional methods are difficult

4. vast quantities from one plant

5. produce pest free plants

   1. aid conservation of rare plants

Disadvantages of micropropagation

1. requires expensive facilities,

2. trained personnel,

3. specialized techniques,

4. high labor costs,

5. requires high volume distribution or storage

6. pathogen/ insect contamination cause high losses

Stages of micropropagation

0. Selection of Cultivar of STock plant

1. Initiation or Esyablishment

2. Multiplication

3. Roooting

4. Acclimatization

Purpose of Stage 4 in micropropagation

the gradual exposure of rooted plantlet to different environmental conditions before they can resume growth outdoors or in the greenhouse

Plant Disease

Caused by infectious agents (biotic or abiotic), can be transmatted from one plant to another

Plant disorder

Caused by non-infectious agents (nonliving) cannot be transmitted from one plant to to another

Symtoms of plant disease

visual effects produced by pathgens or pests. Signs are the physical evidence of the pathogens and pests

3 components of disease triangle

Susceptible host, virulent pathogen

Principle of Start Clean Stay Clean

It emphasizes preventing the introduction and spread of pathogens33. Requires using clean stock plants, a clean propagation area, clean cutting tools, a clean greenhouse, and not reusing growing media

three main principles of Disease Management

exclusion (prevent introduction), Eradication (Stop pathogen establishment), and protection (management, including barriers and cultural practices)

Examples of plant diease

Oomycetes, fungi, bacteria, viruses, nematodes

Examples of plant disorders

Enviornmental extremes, chemical misuses, nutrient deficiencies or toxicities.