Auxin

auxin

1. University of Salahaddin College of Education Environmental science department Auxin 1 Halala Rahman Qadir 4/27/2017

2. 2 Plant hormones (Phytohormones) Are naturally occurring organic substance that can be transported from the synthetic tissue to a specific target tissue where, at low concentration, exert a profound influence on physiological process. Plant growth regulators Plant growth regulators – include plant hormones ( natural & synthetic ), but also include non-nutrient chemicals not found naturally in plants that when applied to plants, influence their growth and development.

3. 3 Auxins Auxin is a general name for a group of hormones that are involved with growth responses (i.e., elongate cells, stimulate cell division in callus). the term " auxin " is derived from the Greek word "to increase or grow".

4. Discover of auxin This was the first group of plant hormones discovered in 1881 by Charles and Francis Darwin , They reported experiments on the response of growing plants to light associated to phototrophic response. Occurs in very low concentrations. Isolated from human urine, (40mg 33 gals -1 ) In coleoptiles (1g 20,000 tons -1 ) Differential response depending on dose. 4/27/2017 4

5. 5

6. 4/27/2017 6 Site Auxin is made in actively growing tissue which includes young leaves, fruits, and especially the shoot apex. Made in cytosol of cells .

7. 4/27/2017 7 Auxin Actions 1. Cellular Elongation: Auxin can induce and amplify proton pumping. Acidified cell walls have increased elasticity which lead to cell elongation. 2. Cell differentiation Auxin promotes differentiation of vascular tissue (i.e., xylem & phloem). 3. Ethylene production IAA apparently stimulates the production of ethylene.

8. 4/27/2017 8 4. Inhibition of root growth 5. Auxin Promotes the Formation of Lateral and Adventitious Roots. 4-Auxin Promotes Fruit Development & fruit set. 5-Auxin Delays the Onset of Leaf Abscission. 6- Auxin induce secondary growth . 7- Tropic responses Such as gravitropism and phototropism Phototropism :is a growth movement induced by a light stimulus.

9. 4/27/2017 9 Gravitropism

10. Phototropism Movement of plants toward light Why? Maximize amount of sun for photosynthesis to make their food.

11. Application of auxin Application of hormone depend upon of: Type of plant and age of plant. Doses and concentration of axuin . Methods used for application (like foliar , soil application, stem injection, pretreatment seeds with auxin . 4/27/2017 11

12. Pretreatment seeds with auxin The high percentage of germination of sown seeds in the field has a bearing on the output.  Pretreatment of seeds with IAA, has been found to be very effective not only in increased the percentage of germination but also in the total yield of the crop plants.  Suitable concentration and combination have to be determined for each and every crop plants. 4/27/2017 12