1. Chapter 11
Temperature

2. Temperature Effects on Plants
Growth and productivity can both be affected by unseasonable weather
Unseasonably warm weather can cause some plants to flower too early
Unseasonably cold weather can reduce crop yields

3. Cool-Season and Warm-Season Crops
Cool-season crops
barley, rye, fescue, cabbage, collards, lettuce, turnips, onions
Warm-season crops
cotton, corn, soybeans, grain sorghum, bermudagrass, beans, southern peas, tomatoes, peppers, cantaloupe, squash

4. Temperature and Dormancy
Some plants drop their leaves and appear to be dead but are only resting, or dormant
Even dormant plants can only survive down to a certain temperature and their ability to survive is affected by duration of cold weather, wind, their age and health, and soil moisture

5. Days Needed for Germination at Various Temperatures

6. U.S. Hardiness Zones
Determine types of plants that will grow based on average annual minimum temperatures
11 zones, with Zone 1 being the coldest and Zone 11 the warmest
Generally, colder zones are found at higher latitudes and higher elevations

7. Growing Degree Days (GDD)
Used to estimate growth/development of plants/insects during growing season
Development will only occur if temperature exceeds some minimum base temperature (Tbase)
GDDs are calculated by subtracting Tbase from mean temperature for the day

8. Base Temperatures for GDDs for Crops and Insects

9. GDDs for Corn

10. Vernalization
Promotion of flowering by cold treatment given to plants or embedded seeds
May be reversed by exposure to warm temperatures before required time is up (devernalization)
Plant site for perception of vernalization is areas of active cell division; meristem

11. Frost Classification and Damage

12. Temperature Stress Photosynthesis is slower at lower temperatures
Absorption of minerals and water is determined by temperature
Plants have minimum temperature below which they may be injured or killed
High temperatures cause desiccation and may directly kill cell protoplasm

13. Thermoperiod Refers to daily temperature change
Plants produce maximum growth when exposed to day temperature 10 to 15 degrees higher than night temperature
Plant photosynthesizes (builds up) and respires (breaks down) during the day and slows down respiration at night