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Chapter 3 Plant growth & Development. Growth Factors Chemical Energy  Photosynthesis  Respiration  Net Photosynthesis Temperature  Zone of tolerance.

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Presentation on theme: "Chapter 3 Plant growth & Development. Growth Factors Chemical Energy  Photosynthesis  Respiration  Net Photosynthesis Temperature  Zone of tolerance."— Presentation transcript:

1 Chapter 3 Plant growth & Development

2 Growth Factors Chemical Energy  Photosynthesis  Respiration  Net Photosynthesis Temperature  Zone of tolerance  Optimum temperature Nutrients & water

3 Growth Substances Auxins-  1 st group of plant hormones to be discovered, mid 1930’s  Adventitious root initiation  Weed control (2-4D)  Inhibition of stem sprouting  Tissue culture

4 Gibberellins- Increasing fruit size of seedless grapes Stimulating seed germination * seedling growth Promoting male flowers in cucumbers Overcoming the cold requirement for some plants

5 Cytokinins-  No important agriculture use at this time.  DNA & RNA

6 Ethylene Fruit ripening Flower initiation Changing sex expression (female flowers in cucumbers & pumpkins) Degreening oranges, lemons grapefruit Harvest aids

7 Inhibitors Abscisic Acid Synthetic Used to regulate plant growth

8 Growth inputs & quality Timing Amounts

9 Patterns of plant growth & development Vegetative Phase Reproductive Phase

10 Temperature & Vernalization Some plants need lower temperatures for flower induction Temperature ranges are 32-50 0 F Examples are cereal grains (wheat, barley, rye) Some can be induced to flower by colder temps (spinach, peas, lettuce) Must reach a maturity before vernalization can begin Hormone induced (gibberellins) Look at table 3.1

11 Light & Photoperiod Some plants needs a certain number of hours of day length to flower Short day plants (i.e. poinsettias, strawberries, mums) need long nights uninterrupted to flower Long Day plants (i.e. spinach sugar beets) need short nights Day neutral (i.e. tomatoes)

12 Floral stimulus is transmitted form leaves to meristem Vegetative to flowering Different photoperiods needed to induce Once apex has changed to flower tissue irreversible Flower initiation to anthesis varies.

13 Flowering Response to Photoperiod length of day Long Day Plants greater than13 hours Short Day Plants less than12 hours Day Neutral Plants = no response Look at table 3.2 & 3.3


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