Download
plant growth n.
Skip this Video
Loading SlideShow in 5 Seconds..
Plant Growth PowerPoint Presentation
Download Presentation
Plant Growth

Plant Growth

106 Vues Download Presentation
Télécharger la présentation

Plant Growth

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Plant Growth Hormone Function and Tropisms

  2. Primary Meristems Whether they are involved in primary or secondary growth, all plant cells and tissues arise from three primary meristems*: • protoderm •ground meristem •procambium *Meristem: plant tissue that remains embryonic as long as the plant lives, allowing for indeterminate growth

  3. Specialized Tissues in Plants • Plant Growth • Meristems – tissues responsible for growth • Undifferentiated cells • Apical Meristem • Produce growth increased length • Differentiation • Cells will assume roles in the plant • Flower Development • Starts in the meristem

  4. Growth Hormones (Regulation) • Plants produce chemical substances called hormones that inhibit or promote growth. • Common plant hormones are…. • Inhibitors • Cytokinins • Gibberellins • Auxins

  5. Hormones that work with auxins to stimulate cell division. Cytokinins

  6. Gibberellins • Hormones that stimulate cell elongation, premature flowering, and breaking of dormancy.

  7. Hormones that speed plant growth by stimulating cell enlargement. Auxins

  8. Tropisms • A tropism is a growth response involving bending or curving of a plant part toward or away from an external stimulus that determines the direction of movement • Response toward the stimulus is positive, and response away from the stimulus is negative

  9. Phototropism • Phototropism is the growth of stems of plants toward light - it is probably the best known of the plant tropisms - phototropism is caused by elongation of the cells on the shaded part of the plant - so that entire plant bends or curves toward the light • This growth pattern is caused by the hormone auxin- auxin migrates to the shaded part of the plant and stimulates increased cell growth and elongation on the shaded part of the plant

  10. Gravitropism • Gravitropism is a response to gravity - if a seedling is placed on its side, the root will curve to grow downward and the shoot will curve to grow upward • Auxin may play a role in the response of shoots

  11. Gravitropism in plants

  12. Thigmotropism • Thigmotropism is response to touch or contact with a solid object - this is most commonly seen in tendrils, modified leaves or stems depending on the species. • the tendrils wrap around any object they come in contact with and so enable the plant to cling and climb.