Horticulture Exam 2

Why is propagation by seeds the major means of reproduction in agriculture?

Seedas are easy to use and are relatively inexpensive

What are 4 classes of seed production that must occur prior to commercial seed distribution?

Breeder seed

Foundation seed

Registered seed

Certified seed

Breeder seeds

selects for plant that has good ripening and coloring, given to agriculture experiment stations to produce a foundation seed

Foundation seed

given to a certified grower to become a registered seed

4 factors that should be considered for the production of seed planting?

Location

Harvesting and collecting of seeds

Cleaning seeds

Storing of seeds

How can you experimentally determine percentage seed germination?

90 seeds germinate out of 100 seeds 90% germination rate

Describe direct seeding

planting seeds directly into the soil

5 factors that determine success of direct seeding

site selection

seedbed preparation

planting date

planting depth and spacing

moisture

What is indirect seeding?

planting seeds indoors and transporting them outdoors later

What are important factors that should be considered when selecting a germination media?

Proper drainage and aeration

Good nutrient and water-holding capacity

Favorable pH

Provides essential nutrients

Free of insects, weeds and disease organisms

What is damping off and what are 2 ways to control it?

fungal disease which causes stems to rot at the soil line

proper sanitation practices, avoid warm wet conditions, fungicides that will work

What are the 5 major categories of seed dormancy?

Physical

Mechanical

Chemical

Morphological

Physiological

Physical Dormancy

Scarification-breaking the seed coat (microorganisms, freezing and thawing, fire, goes through digestive tract of animal)

Mechanical Dormancy

water can get into the seed coat, but seed coat is too hard for seedling to break out (crack the seed coat, naturally freezing and thawing)

Chemical Dormancy

when the seed coat has inhibitors (safety mechanism)— surgically remove the seed coat or place in water and shake

Morphological Dormancy

undeveloped embryo can speed the phase by using gibberellin (over come the undeveloped embryo)

Physiological Dormancy

when the seeds are in deep dormancy

Stratification-placing seeds in a moist medium at cooling temperatures so germination can occur

Vernelizaiton- putting it in a cooler temperature is to induce flowering

What are 3 reasons to initiate germination prior to planting?

shorten the time to seedling emergence

improve stand uniformity

overcome potentially adverse conditions in the seedbed (improper moisture in soil)

what are 4 methods used to initiate germination prior to planting?

Soaking

Osmotic Priming

Infusion

Gibberellic Acid

What is the most important benefit of asexual propagation?

plants produced by this method are genetically identical

Methods of asexual propagation

Apomixis

Cuttings

Grafting

Budding

Layering

Separation

Division

Tissue Culture

Apoximis

seeds are produced without fertilization

Grafting

process connecting 2 plant parts or 2 plants together in such a way that they will unite and grow as 1 plant

Budding

the scion is reduced to a single bud with a small portion of bark or wood attached

Layering

method of asexual propagation in which roots are formed on the stem white still attached to the parent plant

Seperation

natural structures are removed from the parent plant and planted to grow on their own

Divison

parts of the plant are cut into sections that will grow into new plants

Tissue Culture

a method of growing pieces of plants called explants on artificial medium under sterile conditions

growth of tissues or cells separate from the organism

7 methods of applying rooting agents

Spray and drip down

Total immerse

Basal long soak

Quick dip

Gel dip

Auxin Talcum powder

4 benefits of auxin (HINT)

higher percentage of cuttings will root

root initiation is quicker

number and quality of roots is better

uniformity among the length is better

3 factors determining if cuttings will produce roots

Time of the year

Stage of growth

Type of wood

Stem cuttings

utilizes portion of the stem containing a terminal bud and axillary bud (soft wood, semi hard wood)

Leaf cuttings

leaf blade or leaf blade with a petiole typically used when plant materials are scarce, and you need a large amount (snake plant)

Leaf bud cuttings

Consists of a leaf, petiole, stem, axially bud

Don't plant it too deep--plant with rot

Root cuttings

labor intensive and not genetically identical

what are 4 factors that should be considered to ensure optimal rooting of cuttings

Environmental conditions and physiological status of parent plant

Timing and collection of cuttings

Preparation of cuttings

Root-inducing environment

Fertilization

Important factors for successful graft union

Scion and understock must be compatible

Diameter of the understock must be equal to or larger

than the scion

Scion and understock cambiums must match

Must be done during the proper time of the year

Cover cut surfaces with a water repellent material to

prevent desiccation

Skilled workers should be used

4 major uses of grafting

Maintain clones that cannot be propagated by other asexual methods

Gain benefits of certain rootstocks; for example, a variety of disease resistant and dwarfing rootstocks are currently used

Speed up time to maturity to promote earlier fruit production

Repair damaged parts of trees

What time of year should budding be done and why?

Spring and fall-bark is more slippery

5 types of layering

Simple layering

Serpentine layering

Trench layering

Mound layering

Air layering

5 commonly used methods of tissue culture

Callus culture

Cell suspension culture

Embryo culture

Meristem culture

Anther culture

7 major roles of media

provide the plant with nutrients

anchor the plant

provide good drainage and aeration

provide good nutrient water holding capacity

ensure there are no natural toxins, diseases, insects, weeds

be producible and available

not decompose and must wet easily

4 commonly used kinds of media

Soil

Soilless Medium

Mixtures

Hydroponics

Soil

organic component (comes from plants and animals) inorganic component (sand, silt, clay)

In order to use soil it has to be steem pastureized, kills the non beneficial organisms--fluff up the soil makes it more airated

Disadvantages-hard to get a reproducable type, heavy, more expensive

Types of Soilless medium (HINT)

Peat and Peat Moss-nutrient and water holding capacity

Bark and other woods-same benefit as peat and peat moss, water holding capacity

Sand and Perlite-aeration and drainage

Mixtures

combinations of peat/ peat moss, sand, soil, perlite

Hydroponics

Hydroponics-a method of growing plants in sand, gravel, or liquid, with added nutrients but without soil. (only used for high value crops, lettuce, tomatoes)

Advantages-nutrient is completely controlled yield per unit is greater, don't have to deal with weeds and disease organisms

Disadvantages-only high value crops and is expensive, algae may grow

6 advantages of using soilless media

Lowered environmental impact

Reduction in water consumption

Improved health and nutritional value

Lowered chemical, pesticides, and GMO produce

Ability to scale the agricultural operation to any size

Maximizing of space constraints through vertical growing techniques

3 disadvantages to using soilless media

Environmental impacts

More expensive

Dries out

Substrate system

plants roots are surrounded be either inert or organic materials that provide support for the plant

Something to hold the plant up

Bag culture: get a garbage, put bark chips, apply nutrient

solutions=hydroponic

Bare root system

no physical support for the roots

Aeroponic-roots hanging, with jets that produce nutrient solutions

3 types of parent material to produce soil

Igneous rock (very hard to break down)

Sedimentary rock (sand stone easy to break down)

Metamorphic rock (very difficult to break down)

2 major reasons for aerating soil nutrient soil? (HINT)

Add/ Maintain oxygen

Prevents build up of carbon dioxide

2 principle criteria by which an element can be judged essential to any plant

element is essential if the plant cannot complete the life-cycle

forms part of any molecule or constituent of the plant that itself is essential to the plant

How many essential elements do most plants require for normal plant growth and development?

16

Where do plants get carbon, hydrogen, and oxygen

Carbon-Co2

Hydrogen/ Oxygen-H2O

Primary Macronutrients (HINT)

Nitrogen

Phosphorus

Potassium

Secondary Macronutrients (HINT)

Calcium

Magnesium

Sulfur

Micronutrients

Boron

Iron

Molybdenum

Manganese

Zinc

Copper

Chlorine

2 ways nitrogen can be taken up by the plant

Nitrate NO3-/ Ammonium

What plant constituents have nitrogen as part of their structure?

Chlorophyll, amino acids, proteins, and nucleic acids

2 ways to modify soil pH

Increase pH-adding limestone

Lower pH-sulfur compounds (aluminum sulfate/ sulfur)

3 systems used to determine the nutritional status of the plant

Soil Testing

Foliar Analysis

Visual Diagnosis

Soil Testing

tell you what the pH of the soil and what nutrients are available

Foliar Analysis

what was taken up and accumulated by the plant

Visual Diagnosis

should be used as a last resort

What are four fates or things that can happen when fertilizers applied to the soil?

can be used by the plant

lost due to leaching (goes right into ground water)

lost due to runoff

can be tied up soil colloides

3 ways fertilizers can be applied?

Dry (top/ side dressing)

Fertigation (applied through irrigation system)

Gas

What are 5 factors that should be taken into consideration when deciding the frequency and rate of fertilizer application?

plant genetics

environmental factors

edaphic or soil conditions

biotic environment

stage of plant development

Benefits of organic matter in the soil? (HINT)

Increases water and nutrient holding capacity

Provides pore space and enhances aeration

Regulate soil temperature

Release nitrogen and other nutrients as it decays

Increases CEC

Promotoe growth of microorganisms

List 2 main areas of the plant environment and define each

Atmospheric environment- above ground

Edaphic-soil and area where plant roots are located

List 5 abiotic atmospheric conditions that have an effect on plant growth

Wind

Temperature

Moisture

Light

Air

What are the effects of red/yellow light? (HINT)

promotes plant elongation (taller plants)

What are the effects of green/blue light? (HINT)

inhibits plant elongation (shorter plants)

What are the effects of high intensity light?

plants are shorter and darker green

What are the effects of low intensity light?

plants are taller and lighter green

Why does excessive water applied to roots kill plants?

Depletes oxygen levels

Pesticides can get into water

Excessive nutrients

What are benefits and problems associated with wind?

Benefits: can cool the plant, reduce disease problems

Problems: yields are reduced, physical damage to the plant, disperse weed seeds

What are 2 problems caused by impeded water movement into the soil?

Waterlogging and drought

Why is important to aerate the soil?

maintaining the proper balance of O2 and CO2

High levels of CO2 is toxic

Low levels of O2 inhibit root growth

4 factors that affect soil temperature

Type of soil

Air temperature

Wind

Solar Radiation

One way to control soil temperature in the field

Applying light colored plastic or mulch to the soil surface to cool soil, dark colored to warm soil

What are 2 way salt builds up in the soil and causes problems with plant growth?

Irrigation Water

Fertilizers

4 main categories of soil organisms

Microorganisms-bacteria/ fungi

Arthropods- centipedes

Nonarthropods- worms

Vertebrate- chipmunks

Who made the profound statement "ohne wuchstoff, kein, wachstum" which means "without growth substance no growth"

F.W. Went

What is Arteca expertise? (HINT)

Plant growth regulators (chapter 9)

List the 6 classes of plant hormones

Auxins

Gibberellins

Cytokinins

Abscisic

Ethylene

Brassionlide

Provide one commercial use for auxins, gibberellins, cytokinins, and ethylene

Auxins - Fruit thinning

Gibberellins- Development of fruits without seeds

Cytokinins- senescence in plants

Ethylene- plants to ripen

3 researches who were pioneers in auxin research and list their contributions

Darwin-initiation modern plant hormone research

Went-developed the avena curvate bioassay

Kogel- purified heteroauxin from human urine

Not all plant regulators are organic (HINT)

true

What is the only active auxin found in plants?

IAA

8 physiological processes in which AUXINS have a regulatory role

Cellular Elongation

Phototropism

Gravitropism

Apical Dominance

Root Initiation and Cell Elongation

Ethylene Production

Fruit Growth

Sex Expression

Weed Control

Give 2 synthetic auxins and a commercial use for each

Indole-3-butyric acid (IBA) and Naphthalene acetic acid (NAA) promote adventitious root formation

2, 4-dichlorophenoxyacetic acid (2,4-D) Control weeds

Which scientist first crystallized gibberellin A, and what material was used for purification?

Yabuta

Cytokinins were purified from aged herring sperm DNA

Provide 7 physiological processes in which gibberellins have a regulatory role

Stimulates Stem Growth in Intact Plants

Bolting and Flowering

Seed Germination

Dormancy

Sex Expression

Fruit Growth

Parthenocarpy

What is the series of events that take place during germination in barley seeds. starting with where gibberellins are synthesized?

Gibberellins are produced in the embryo

The gibberellins are then transported to the aleurone layer of the cell

Here alpha amylase is produced thereby causing the conversion of starch to sugar in the endosperm. These sugars are used for energy during the germination process

Who was the first scientist to purify a cytokinin, and what material was used for purification?

Miller and Coworkers were the first to report the identification of kinetin. It was purified from aged herring sperm DNA

Who were the first two scientists responsible for the purification of zeatin, and what source was used to purify this compound?

Miller and Letham and Coworkers discovered it-cytokinin

List 6 physiological processes in which cytokinins have a regulatory role

Cell Division

Organ Formation

Senescence

Stomatal Opening

Lateral Bud Break

Sex Expression

Gibberellins are produced in the ___ layer (HINT)

aleurone (may be a diagram)