T e m p e r a t u r e

1. Temperature

2. Temperature • Plant processes influenced: • Photosynthesis • Respiration • Enzyme activity • Transpiration • Stomatal opening • Pollination • Seed germination

3. Temperature • This factor, more than any other, determines what plants can be grown in a particular area

4. Temperature • Temperature affects the maturity rate of garden products

6. Temperature • Temperature can influence some diseases and insect problems • Temperature influences quality of most fruits and vegetables • Most plants will not grow below 40°F or above 96°F

7. Temperature • Cool season crops • Day temperatures 60 - 75°F • Night temperatures 50 - 60°F • Tolerate some frost • Spinach – Radish – Carrots • Cabbage – Beets – Onions • Lettuce – Peas

8. Temperature • Warm season crops • Day temperatures 70 - 85°F • Night temperatures 60 - 70°F • Usually do not tolerate frost • Should not be planted until the ground warms • Corn – Tomatoes • Beans – Vine crops

9. Temperature • Photosynthesis CO2 + H2O C6H12O6 + O2 • Respiration C6H12O6 + O2 CO2 + H2O • Therefore: Photosynthesis leads to an increase in growth and storage Respiration leads to a decrease in storage and reduced growth

10. Temperature • Growth and plant yield = P - R • During the day, both photosynthesis & respiration take place but at night, only respiration takes place • Best to keep temperatures warm during the day and cool at night! • Respiration increases more than photosynthesis at high temperatures

11. photosynthesis Relative rates respiration 40°F96 °F Sugars burned up as fast as made. No net growth Too cold for growth

12. Temperature • Heat units • Growing Degree Unit = Mean temperature - Base temperature • Base = either 40 or 50 depending on crop

13. Heat units (example) * if mean is less than base, enter “0”

14. Temperature • Uses of Heat Units: • Predict time to harvest • Peas • ‘Accord’ takes 1150 GDU • ‘Nugget’ takes 1570 GDU • ‘Alderman’ takes 1700 GDU • Corn • ‘Aztec’ takes 1330 GDU • ‘Butter and Sugar’ takes 1570 GDU

15. Temperature • Uses of Heat Units: (continued) • Predict flowering date • Predict certain pest problems • Determine if a crop will grow in a certain area!

16. Phenology • Phenology • Relating the development of one plant to some aspect of another • Greek for “the science of appearances”

17. Phenology Lilac When in flower, time to plant tomatoes

18. Phenology Forsythia Rose When in flower, time to prune your roses!

19. Winter temperatures • Winter injury often occurs from: • Intercellular ice formation (between cells) • Intracellular ice formation (within cells)

20. Winter temperatures • Factors that influence hardiness: • Kind of plant (ex: apple vs. peach) • Temperature during autumn • Soil moisture • Light • Nutrition

21. Hardiness curve (degree of hardiness attained) High Hardiness attained Low A S O N D J F M A M J J Months

22. Winter temperatures • Minimum temperature and when it occurs • Rate of freezing • Length of time frozen • Number of times frozen • Amount of snow cover • Wind

23. Winter temperatures • Symptoms of winter injury • Dead flower buds • Dieback of shoots • Brown needles • Bark splits (common on Norway maple) • Sunscald • Root injury/low vigor • Frost heaving

24. Winter damage catfacing

25. Winter damage Bark split Fungi

26. Winter injury • Winter injury is often associated with a particular set of conditions: • Plants grow too late in the fall (Japanese maple)

27. Winter injury • Extreme cold too early in fall or winter • Drying winds • Mid-winter warm period followed by severe cold • Lack of snow cover

28. Winter damage Snow line