1. Climate and Adaptation of Agricultural Crops

3. Elements of climate most directly affecting plant growth: Temperature Moisture Solar radiation Wind, etc.

4. Elements of climate most directly affecting plant growth: Temperature Moisture Solar radiation Wind, etc.

5. Elements of climate most directly affecting plant growth: Temperature Moisture Solar radiation Wind, etc.

6. Elements of climate most directly affecting plant growth: Temperature Moisture Solar radiation Wind, etc.

7. Wind Damage Hurricane Frances

8. Wind and Agriculture - Infrastructure

9. Wind and Agriculture - Crops

10. Elements of climate most directly affecting plant growth: Temperature Moisture Solar radiation Wind, etc.

11. Adaptations of plants to climatic (physical) factors determine: Geographic distribution Growing season Limits are set by extremes such as killing frost vs high temperature. Within a geographic location, plants may exhibit dormancy at certain times (out of season). Dormant stages may require environmental cue (higher temp., more moisture) to continue development.

12. Dormancy and Easter Lilies

13. Agricultural climate types recognized by Carroll et al. (1990): Wet tropical (about 5N-5S, 11 months w. rainfall >15 cm) Wet-dry tropical (about 5-25N&S – distinct wet and dry seasons Cool tropical (> 1000 m elevation) Moist midlatitude (25-55N&S, e.g. - eastern North America) Dry midlatitude (25-55N&S, e.g. - central North America) Mediterranean (some continental coasts 30-40N&S, wet winter and dry summer Arid

14. Agricultural climate types recognized by Carroll et al. (1990): Wet tropical Wet-dry tropical – seasonal moisture Cool tropical Moist midlatitude – seasonal temperature Dry midlatitude – seasonal temperature Mediterranean Arid

15. Agricultural climate types recognized by Carroll et al. (1990): Wet tropical (about 5N-5S, 11 months w. rainfall >15 cm) Wet-dry tropical (about 5-25N&S – distinct wet and dry seasons Cool tropical (> 1000 m elevation) Moist midlatitude (25-55N&S, e.g. - eastern North America) Dry midlatitude (25-55N&S, e.g. - central North America) Mediterranean (some continental coasts 30-40N&S, wet winter and dry summer Arid

16. Gainesville, FL Weather Summary

17. Subtropical – some seasonal fluctuation in both moisture and temperature

18. Temperature and Plant Growth(similar pattern for most physical factors)

19. Temperature and Plant Growth(similar pattern for most physical factors)

20. Temperature and other Physical Factors Optimum range for plant growth Below minimum – can’t grow Above maximum – can’t grow

21. Applications of Temperature Adaptation and Preferences Determines distribution and growing season Competition with weeds depends on relative adaptation of weed vs. crop plant

22. Heat Units Over the adapted range, vegetative growth of plants increases with temperature So crop cycle can be longer at low temperatures Often convenient to measure life cycle in terms of heat units

23. Heat Units Heat Unit = days or hours of accumulated temperature above some threshold (but below max. limits) Measured in degree-days or degree hours Lower temperature is called the threshold or base temperature

24. Heat Unit (Degree Day) Calculation

25. Max, Min, Mean, and Base Temperatures

26. Mean Temperature can be Estimated from Daily Max and Min Readings

27. Example for Heat Unit (Degree Day) Calculation

28. Degree Days – Sample Calculations

29. Degree Days – Sample Calculations

30. DD calculations are good approximations, for more detail can go to hourly temperatures, etc.

31. Heat Units and Degree Days Good approximations for plant growth, insect growth, etc. Opposite effect – some plants, such as some temperate fruits, may require a certain amount of chilling days or chilling hours below a certain temperature before they can set fruit.

32. Plant Growth

33. Effects of Light on Plants Photoperiod (hours of day and night) Light intensity (affects photosynthesis)

34. Flowering Response to Photoperiod (can end vegetative growth) Short day plants – flower only when day length is less than some critical value (spring, fall) Long day plants – flower only when day length exceeds some critical value Day neutral Flowering accelerated by shorter or longer nights; similar response to short or long day, but not complete (most plants)

35. Flowering Response to Photoperiod Determinate plants – vegetative growth stops at flowering Indeterminate plants – vegetative growth continues after first flowering, may have multiple cycles of flowers and fruit

36. Determinate vs Indeterminate Characteristics in Cowpea

37. Soybean = short day plant, highly determinate

38. Soybean Maturity Groups

39. Soybean and day length

40. Light Intensity – Different photosynthetic pathways allow adaptation to different light intensities C3 – Most plants, adapted to various light levels, can reach max growth under cooler conditions, lower light intensity. C4 – Many grasses – adapted to high sunlight, more efficient in photosynthesis and use of water CAM – some cactus, pineapple – adapted to water-deficient habitats, deserts.

41. C3 vs C4 Plants

42. References Text: climate, pp. 76-83; light, C3/C4, pp. 20-22; heat units, photoperiod, pp. 103-107. Carroll, R.C., J.H. Vandermeer, and P. Rosset. 1990. Agroecology. McGraw-Hill, New York, Ch. 2. Scott, W.O., and S.R. Aldrich. 1970. Modern Soybean Production. S & A Publications, Champaign, IL. Thomas, B.P. et al. 1985. Soil Survey of Alachua County, Florida. USDA Soil Conservation Service, Washington. Tivy, J. 1992. Agricultural Ecology. Longman Scientific and Technical, Essex, UK. Ch. 3, pp. 21-28.