Horticulture psc 1800 usu exam 4

Which of the following is NOT a general characteristic of a hormone?

responses to hormones and their interaction are completely understood

Auxins

Hormones involved in plant-cell elongation, shoot and bud growth, and rooting. The tip

Gibberellins

A class of related plant hormones that stimulate growth in the stem and leaves, trigger the germination of seeds and breaking of bud dormancy, and stimulate fruit development. Comes from a fungus

Cytokinins

Stimulates cell division and growth of lateral buds. Causes dormant seeds to sprout. Produced at meristems

Gibberellins

A class of related plant hormones that stimulate growth in the stem and leaves, trigger the germination of seeds and breaking of bud dormancy, and stimulate fruit development. Comes from fungus

Brassinosteroids

Comes from canola pollen. Essential for stem elongation. Helps plants resist environment stress

Ethylene

The only gaseous plant hormone. Among its many effects are response to mechanical stress, programmed cell death, leaf abscission, and fruit ripening.

Absicisic Acid (ABA)

Promotes root growth from respond to drought (closing of stomates) promotes seed and bud dormancy

Jasmonates

Wounding increases plant growth. Aid in plaint resistance to pathogens and insects

A product called Sucker Punch is advertised to help prevent dormant buds from breaking. This product is supposed to prevent suckers and water sprouts. What is most likely the active hormone ingredient?

Auxins

The changes induced in a plant by pinching or disbudding are mediated by which hormone?

Auxins

We can apply chemicals that will literally shrink a plant.

False

How do growth retardants work?

they keep the internodes from elongating as much

Seedless grapes, red delicious apples and celery that you buy in the grocery store most likely have been treated with _____________________ to help them elongate more.

Gibberellic acid

Ethephon is a chemical used to loosen cherries and citrus fruits that are used for processing to aid in harvest. It's active hormone is ______________.

Ethylene

Plant phenotype is an interaction of the genotype and the environment. Changes in a plant's phenotype due to environmental triggers are hormone-driven.

True

Hormones are

Active in low concentration

Signals a change in the plant

Received at certain locations

Effective at only certain times

Too much causes problems

Dormancy

ABA promotes dormancy

Gibberellins breaks dormancy

Auxins maintain apical dominance

Growth retardation

Block Gibberellins

Very common

Compact plants more desirable

Vegetative growth prone

Gibberellins used to elongate grape clusters

Elongation of celery and rhubarb

Flowering

Sometimes desirable sometimes not

Florigens promote flowering

Antiflorigens inhibit flowering

Not well understood

Sex expression

Can create more make or female

Can increase yield

Fruiting

No pollination is no fruit setting

Ovary expands rapidly with pollination

Auxins can prevent flowering

Development is driven by hormones

Fruit growth

GA3 is used to increase size of seedless grapes

Auxins and normal development

Abscission and harvest

Ethephon is used to loosen fruits to aid harvest (cherries, citrus for processing, olives)

Plant phenotype

is an interaction of the genotype and environment (changes are hormone-driven)