May 18, 2006

Plant Growth Regulators

Objectives:

1. List the five recognized groups of plant growth regulators.

Auxins, gibberellins, cytokinins, ethylene and abscisic acid.

2. Describe the following effects of auxin on plant growth and development:

Cell enlargement and elongation

Photo and geotropism

Apical dominance

Abscission

Flower initiation and development

Root initiation

Fruit set and growth

Cambial activity

Tuber and bulb formation

Seed germination

3. List the synthetic auxins used for commercial crop production.

4. Explain the commercial importance of auxin in crop production.

5. Where have you noticed growth variation, which might be attributed to auxin in the greenhouse or mesocosms?

6. Describe the following effects of gibberellins on plant growth and development:

Cell division and elongation

Enzyme secretion

7. Explain the following agricultural uses of gibberellin:

Increasing fruit size of seedless grapes

Stimulate seed germination and seedling growth

Promote male flowers in cucumbers

Reducing cold requirement (vernalization) of flowering ornamentals and biennial crop plants.

 

8. Describe the following effects of Cytokinins on plant growth and development:

Cell division the primary function

Cell enlargement

Tissue differentiation

Dormancy

Flowering and fruiting

Retardation of senescence

9. Explain the limited commercial uses of cytokinins:

Auxillary bud growth on roses and chrysanthemums

10. Is lateral bud growth evident on cut chrysanthemums?