2. Light and Temperature Interaction

3. Fall Leaf Color cool temps - very bright days

4. Orange yellow, reds, purples and browns chlorophyll cells die as temperatures get cooler

5. Yellow carotenoids after chlorophyll dies you see the other pigments that are always present

6. Red-Purple anthocyanins not always present synthesized in cooler temps made from sugar molecules

7. Brown tanins mask or show up more once chlorophyll dies produced in the leaves

8. Leaf Fall need an abscission layer leaf can no longer translocate carbohydrates out of the leaf

9. Bright Days lots of carbohydrates in the leaf anthocyanins get brighter color

10. The Key…… cool, short days

11. Greenhouse Effect short, high energy wave lengths of light from sun enters house absorbed by structures and plants

12. plants re-radiate green light in longer waves long waves do not have as much energy as the short waves

13. longer waves do not have enough energy to escape from the house result is heat

14. this is how the earth is heated long waves cannot escape through the clouds cloudy nights are warmer

15. Light energy - electromagnetic radiation wavelengths - distance from peak to peak measured in nanometers NM

16. Far Red color plants use

17. Infra Red heat energy

18. Visible light light quality - color quantity - intensity, how bright duration - photoperiod

19. Quality blue - 400-510 NM cell elongation photosynthesis - chlorophyll absorbs red and blue light

20. phototropism - plant tends to grow or bend toward a light source

21. Red photosynthesis stimulates branching encourage growth of axillary buds

22. phytochrome - light absorbing pigment seed germination in photoblastic seeds

23. flowering responses photoperiod

24. Far Red

25. Far red promotes stem elongation

26. Yellow - Green does not effect plants

27. Intensity measured in foot candles amount per unit area on plant

28. Plants shade loving too much sun - leaf burn dehydrate kill chlorophyll

29. sun loving low light, pale color new leaves are small lack vigor

30. dont flower properly if at all

31. Light Light Compensation Point - LCP light intensity where rate of photosynthesis = the rate of respiration

32. LCP Lowest intensity you can grow a plat at If a plant is grown below this level, respiration will be greater than photosynthesis

33. plant will die for a plant to grow photosynthesis must be greater than respiration

34. Acclimitization preparing plant for lower light intensity conditions expose to lower light intensity

35. Artificial Lights Incandescent far red, red - elongation low blue 80% of emitted radiation is heat

36. Incandescent 20% visible light 12% utilized by plant

37. Flourescent red, blue 36% heat energy 22% light used by plant spectral flexibility

38. can change the quality of the light by changing the coating on inside of bulbs Cool White - Ca Halophosphate

39. Gro-Lux coated with Mg Fluorogerminate not as long life as cool white, 30X more expensive

40. Metal Halide increase light intensity

41. Low Pressure Sodium yellow glow energy efficient yellow - orange light

42. High Pressure Sodium red, blue light energy efficient

43. Photoperiod length or duration of the light period biological measurement of relative length of light and dark periods

44. effects flowering leaf abscision dormancy - acclimate for winter

45. Effects….. Sex expression runner formation tuber formation bulb formation

46. Short Day Plants flower when day length is shorter the dark period is critical its dark longer than it is light

47. Short Day Plants examples Chrysanthemum Christmas Cactus Poinsettia

48. Long Day Plants flower when days are long and nights are short example: lettuce, radish, petunias

49. Facilitative Long Day flower any period if long day - flowering is enhanced examples - tomato, begonia

50. Day Neutral flower under long or short day lengths example: African Violet

51. Poinsettias use night interrupted lighting turn on artificial lights from 10 p.m. to 2 a.m. splits up the dark period

52. cyclic lighting from 10 p.m. to 2 a.m. lights on for 6 minutes and off for 24 minutes