Horticulture Exam 3

Describe the changes in plants that occur during the summer.

A period of maturity, ripening, and storing energy

What is the cause of winter burn?

low soil moisture, freezing temperatures, blowing wind, and frozen soil

What does the term cold hardiness or cold tolerance mean?

The coldest minimum temperatures that a fully dormant plant can withstand

What are the weather conditions associated with radiation frost?

air is cool and calm and clear skies

By what methods can radiation frost be prevented?

thin coat of water to protect the plant, smokers, wind machines, and propane burners

Black Frost

moisture content of air is low, no obvious frost but plants are still injured, blackening of the plant tissues

Hoar Frost

moisture from humid air and temperature drops once ice crystals are formed on plant surface. occurs commonly in the mornings

What are the possible effects of frost heaving of the soil on plant growth?

may break off some of the plant's roots, it also exposes the plant's crown and remaining roots to cold temperatures and drying winds.

What plant problems can be associated with excess rain or rain “out of season”?

promotes disease, stunting, decay on leaves, wilting, death of the entire plant

What is the beneficial effect of a snow layer on plants?

provides a lot of water and protects plants from cold temps

Describe what happens to a plant adapted to partial shade if it is grown in full sun?

it will reduce the plants blooming and cause it to produce weak shoots, leading to an unattractive plant

How do changes in elevation affect temperature?

higher elevation, cooler average temperatures

Explain what is meant by air drainage, and how does it relate to plant growth?

cool air, which is heavier than warm air, will flow down a slope and collect at the bottom. Plants growing higher in the slope are less likely to be damaged by cold than those at the bottom.

How does the presence of large bodies of water affect the temperature of nearby land?

large bodies of water give off heat in winter, therefore milder winters. Water absorbs heat in summer, cooling off the land.

What is a microclimate?

small areas that have slightly different climate characteristics than the surrounding land.

What is the basis for divisions in the Department of Agriculture’s zone map of North America?

minimum winter temperatures for the area's zone

What is the purpose of the American Horticultural Society Heat- Zone Map?

will tell you where a plant with thrive

Name one strategy that plants can use to adapt to cold conditions

Dropping their leaves to reduce surface area that is exposed which saves water.

Name one strategy that plants can use to adapt to dry conditions

Waxy layers, hairs, xerophyte traits, roots adapt, water absorption, slow transpiration

xerophytes

dessert plants

Name one strategy that plants can use to adapt to low light levels

thinner and larger leaves to catch more sunlight

What is Frost tender?

unable to tolerate frost and liable to die. 28 degrees liquid contents inside cell will freeze

What is frost hardy?

can survive 10-5 degrees or even in the negatives

What is chilling injury?

common in house plants, less than 50 degrees will injure

What is chilling requirement?

have to have cold temps to flower

What is humidity?

the amount of water the air contains relative to amount it is capable of holding at a specific temperature; the higher the temp, the greater amount of water the air can hold

What are the advantages of vegetative reproduction in plants?

Plants are uniform, Quick est, Only means of propagation in some species, Seed-borne diseases avoided 

What are the disadvantages of vegetative reproduction in plants?

Plants are uniform; equally vulnerable, Systemic viral infection can spread to all plants, Planting materials are bulky, Storage of asexual material is cumbersome and usually short term, Plants are all genetically identical so they are all subject to the same hazards, Mechanized propagation in some cases is not practical 

What are the advantages of sexual reproduction in plants?

widespread in nature, efficient and economical, best when large numbers of plants are needed, seeds are the best way to store plants

What are the disadvantages of sexual reproduction in plants?

longer time to mature, minor variation in genotype

What are the advantages of direct seeding?

convenient, readily adaptable to to mechanization, easy to plant, lack of bulk, saves time and labor cost

What are the advantages of indirect seeding?

good establishment, early maturity, shortened field growing period

By which part should you pick up a seedling to transplant it? Why?

grab by the leaves, not the stem to prevent damage

Which roots more rapidly, softwood or hardwood cuttings?

Softwood

what time of the year are hardwood cuttings taken?

fall or early spring

If you had a tall, nearly leafless houseplant that was not attractive anymore, what two types of cuttings could you take to propagate more plants from it?

Crown division, root cuttings

How are bulbs propagated?

the bulbs produce a bulbet which then falls off and starts growing a new plant

What is the purpose of budding and grafting?

uniting two genetically different plants so that they can heal and function as a single plan

How would you propagate a plant that has suckers?

produce roots of their own, when taken off and put below ground, they will produce a tree

How would you propagate a plant that has offshoots?

same as suckers, but they grow above ground and fall off naturally

What are the advantages of tissue culture over other propagation techniques?

rapid reproduction of numerous plants, produce pathogen-free plants, explants can be stored frozen, year round production, save space

What are the disadvantages of tissue culture over other propagation techniques?

high cost, rigorous quality control, specialized training

Outline the basic steps that would be followed in tissue culture.

establishment and stabilization, growth hormones are added, shoot multiplication, root formation, acclimation, regenerated plants are trasnferred from test tube

Why is genetic engineering sometimes used in preference to plant breeding?

manufacture otherwise hard-to-obtain plant products, combat genetically caused diseases, improve the tolerance of plants to adverse environmental conditions, and attain other similar commendable goals

List several reasons why horticultural crops are genetically engineered.

imparting disease and pest resistance, imparting resistance to herbicides, extending length of time crop remain fresh for consumer, alternating color

What are the different vegetative propagation methods?

grafting, cutting, layering, tuber, bulb or stolon formation, suckering and tissue culture.

What is propagation?

to multiply/increase in number

What is pollination?

transfer of pollen from the anther to the stigma

What is fertilization?

the union of gametes, sperm and egg

What is self pollination?

when pollen from one plant lands on the pistil of a flower on the same plant

What is cross pollination?

when the pollen from one plant is used to fertilze another plant

What is a clone?

an individual or a group of individuals that develops asexually from cells or tissues of a single parent individual

What is rootstock?

bottom part of a graft that is in contact with the soil and not allwoed to produce side shoots

What is a scion?

plant part that is the top part of graft and grows to become the desired shoot

What is genetic engineering?

the incorporation of genes from one species to another unrelated species

What do we call the plant part that is the top of a graft and grows to become the desired shoot?

Scion

What type of vegetative propagation involves serpsrating one plant into two or more pieces each containing a portion of the roots and crown?

Crown Division

To successfully root a cutting, you need to _____

Reduce transpiration, keep root area warm and remove flowers and buds

Plants higher on the side of a slope are less likely to be damaged by the cold than those at the bottom?

True

Which season is most commonly associated with a period of maturity in plants?

Summer