1. Plant Growth Environment

2. Climate & plant growth Climate – average weather of an area –Air, Moisture, Temperature, Light

3. Regional climate vs. microclimate

4. Air Humidity Wind Air pollution Elevation (temperature)

5. Air and elevation

6. Moisture and plant growth Amount Distribution patterns Access (location) Bodies of water and climate Moisture stress –Deficiency, excess

7. Temperature and plant growth Cold hardiness determines range

8. Temperature & plant growth Plant heat zones influence plant growth

9. Growth responses to temperature Vernalization –Period of low temperature induces flowering (e.g. “forcing” bulbs) Thermoperiodism –Sugar/starch content varies with temperature (cooler temps promote starch conversion to sugars); –some plants grow better if night temperatures are cooler than day temperatures

10. Temperature and germination

11. Stratification –Period of cold required to induce germination –Required by many types of perennials, woody species –Specific temp. and length of stratification varies by species

12. Temperature stress Low temperature stress (p. 643, 645, 655) –Chilling –Freezing –Sunscald –Premature bolting –Cold water stress

13. Preventing low temp. stress Timing of planting Zone rating of species Protective measures (p. 604-605) –Covers –Mounding mulch, soil –Hardening (cold frame)

14. Heat stress (p. 643, 650) Sunscald –Plant relocation

15. Light Intensity Quality Daylength

17. Light Quality

18. Photoperiodism Growth responses to daylength –Flowering, germination, dormancy Mediated by pigment molecule phytochrome

19. Phytochrome and flowering

20. Manipulation of photoperiod Poinsettia industry Chrysanthemums Why won’t my Christmas cactus bloom?

21. Photoperiodic houseplants

22. Phytochrome and stem growth Etiolation occurs in low light or dark…why?

24. Biotic environmental factors Insects Microorganisms

25. Soil (p. 610-622) Mineral particles Organic matter Water Air Living organisms

26. Soils Soil profile –horizons

27. Soil – mineral particles Sand, silt, clay

28. Soil texture triangle

29. Organic matter Humus <20% humus = mineral soil >20% humus = organic soil –Provides nutrients, aeration –Increases water holding capacity Leaf humus

30. Living organisms in soil Microorganisms –Bacteria, fungi, algae, protozoa, actinomycetes Insects –Earthworms, beetles, nematodes, ants Weed seeds

31. How are soil organisms important to plants? Aerate soil Become humus Influence soil pH Can make soil uninhabitable Can compete with cultivated plants (weeds)

32. Plant nutrition 13 essential mineral nutrients –N,P,K,S,Ca,Mg,Fe,Cl,Mn,B,Zn,Cu,Mo 3 essential non-mineral nutrients –C,H,O –What makes these nutrients essential?

34. Nutrient deficiencies iron zinc potassium magnesium phosphorus

35. Chlorophyll contains Mg

36. Amino acids contain N

37. DNA contains N, P

38. Stomata function requires K

40. Mineral nutrients exist as ions How do plants acquire mineral ions that are bound to clay particles?

41. Roots produce hydrogen ions as byproducts of respiration CO 2 + H 2 O  H 2 CO 3  HCO 3 - + H +

42. Soil pH and mineral nutrition Different types of plants have different soil pH requirements

43. Cation exchange lowers soil pH Raising soil pH with lime* (mushroom compost contains lime) Ca(OH) 2 + 2H +  Ca 2+ + 2H 2 O *Never lime with manure! (ammonia produced)

44. Fertilizers Fertilizer analysis –(N-P-K) –“Complete” fertilizers (trace elements/micronutrients) Analysis varies depending on growth objectives

46. Fertilizer application Broadcast Ringing plants Banding

47. Soil analysis County Ag. Extension office (link)link Home test kits

48. Soil cultivation Weed control Soil sterilization (pest/disease control) Digging and forking (p. 613-614) –Aeration, soil crusting, compaction Soil additives –Inorganic, organic

50. Home composting

51. Volume of additive required depends on NPK analysis