ENVIRONMENT FACTORS

1. SUN LIGHT ENVIRONMENT FACTORS

2. Contents Solar Radiation The Atmosphere as Filter and Reflector The Ecological Significance of Light on Earth Characteristics of Visible Light Exposure Determinant of Variations in the Light Environment Other Forms of Response to Light Managing The Light Environment in Agroecosystem

3. SOLAR RADIATION What is Light ? • Energy in the form of Electromagnetic Radiation (EMR) that produces a visual sensation • Light is that part of the radiant energy which is visible to the eye. • The chief radiation or energy source for the earth is the sun • Light is one of the most important factors determining the growth of plants and the development of vegetation.

4. Figure 1. The electromagnetic spectrum

5. wavelength and energy is inversely related • the higher the wavelength the lower the energy E = h x v v= E/h

6. THE ATMOSPHERE AS FILTER AND REFLECTOR

7. Cahayamatahari yang pertama kali sampaipadalapisanluaratmosfirterdiridari : • ± 10 % sinar ultraviolet (UV); • 50 % cahayatampak (Visible light) • 40 % sinar infra merah (IR) • Σenergimatahari yang sampaidipermukaanbumi (Rs) secaraumumditentukanolehtransparansiatmosfer (q) danbesarnyatetapansurya (solar constant = Io), Rs = q x Io Rs = jumlahenergimatahari yang sampaidipermukaanbumi q = trasnparansiatmosferdan Io = solar constant, yaituΣenergimatahari yang sampai padapermukaanterluaratmosfersecarategaklurus.

8. Apabilatransparansiatmosfersemakintinggi, menunjukkanatmosferbersihΣenergi yang diterimaolehbumisemakintinggi. • Apabiladiatmosferbanyakterkandunguap air (awan) / gas-gas polutan (ex : CO, NO2, SO2, CH4) danpartikulat(ex: debudanasap) nilaiq semakinrendah • Apabilaatmosfercerah, yaitubilakandunganawandan gas-gas rumahkacasedikit, berartinilaiq nyatinggi, Σ radiasimatahari yang sampaipermukaanbumisemakintinggi

9. Radiasimataharidipermukaanbumi Di atmosfer, radiasi matahari mengalami pengurangan melalui : • Absorbsi • Refleksi • Re-radiasi • Di permukaan bumi, radiasi matahari mengalami: • Refleksi, • Absorbsi • Re-radiasi • konveksi, • konduksi dan untuk evaporasi

10. Figure 2. The fate of light upon reaching the earth

11. THE ECOLOGICAL SIGNIFICANCE OF LIGHT ON EARTH • Ultraviolet Light • Photo synthetically Active Radiation (PAR) • Infrared Light

12. A. Ultraviolet Light (UV)

13. Ozone and Ultraviolet Radiation • UV “light” has a high energy level and can damage exposed cells and tissues. • Ozone in upper atmosphere absorbs strongly in ultraviolet portion of electromagnetic spectrum. • Chlorofluorocarbons (formerly used as propellants and refrigerants) react with and chemically destroy ozone: • ozone “holes” appeared in the atmosphere concern over this phenomenon led to strict controls on CFCs and other substances depleting ozone

18. B. Photosynthetically Active Radiation (PAR) Figure 3. Visible light (PAR) spectrum

19. Photosynthetically Active Radiation (PAR) • The photoreceptors in chlorophyll are most absorptive of violet-blue and orange-red light • Since chlorophyll cannot absorb green light very well, most of it is reflected back, making plants appear green

20. Figure 4. Absorbance of chlorophyll in relation to the wavelength of light

21. Plants Respond to Light Figure 5. The Absorption Spectra of Plants • Various substances (pigments) in plants have different absorption spectra: • chlorophyll in plants absorbs red orange and violet light, reflects green and yellow • water absorbs strongly in red and IR, scatters violet and blue, leaving green at depth

22. C. Infrared Light (IR) • Infrared light energy with a wavelength from 800 nm to 3000 nm, • IR has an important role in influencing the hormones involved in germination, plant’s responses to changes to day length and other plant processes.

23. CHARACTERISTICS OF VISIBLE LIGHT EXPOSURE • Quantity (Intensity) • photosynthesis • Quality (Wavelength - Color) • photomorphogenesis • Duration • photoperiodism

24. Light Intensity • The total energy content of all the light in the PAR range that reaches a leaf surface • Energy units: Calories cm-2, Joule second-1, Lux or Watt. m-2 • Intensity provides energy for photosynthesis The rate of photosynthesis is affected by the availability of water, CO2 and sunlight.

25. PENGARUH INTENSITAS TERHADAP SIFAT FISIOLOGIS TANAMAN • Lajufotosintesis • Lajutranspirasi • Pertumbuhanbatang (memanjangdanmenujukearahdatangnyasinar) • Perkecambahanbenih • Pembungaan

26. Figure 6. The relationship between solar radiation and photosynthetic rate

27. KELOMPOK TANAMAN BERDASARKAN KEBUTUHAN DAN ADAPTASI RADIASI MATAHARI 1. Sciophytes/shade species/shade loving tanaman yang tumbuhbaikpadatempat yang ternaungdenganintensitasradiasi mataharirendah. (kopi (30-50%,Coklat (25 %) 2. Heliophytes/sun species/sun loving tanaman yang tumbuhbaikpadaintensitas radiasimataharipenuh.(padi,jagung,tebu,ubi kayudsb.)

28. Light Quality KUALITAS RADIASI MATAHARI • Proporsipanjanggelombang yang diterimapadasuatutempatdanwaktutertentu • Menggambarkanspektrumcahaya yang dipancarkanolehmatahari yang terdiridariberbagaigelombang

29. Figure 7. The electromagnetic spectrum

30. Light quality controls Photo-morphogenesis (plant development and form) • Mediated by phytochrome (protein pigment) • red light absorbing form (Pr) • FR light absorbing form (Pfr) • Forms are photoinconvertible, depending on the which type of light is absorbed

31. Fitokhrommerupakansenyawa (pigmen) yang menentukanresponsifatmorfogenetiktanaman (inisiasibunga,perkecambahanbenih,perpanjanganruas (internode) batangdanpembentukanpigmen) Fitokhromberupasenyawatetrapirolseperti: klorofilterdiridarikhromoforedan protein. Khromoforesangatpekathdkualiasradiasi danbersifatreversible (dapatberubahubah) tergantungpadapanjanggelombangradiasiyang mengenaifitokfhrometsb.

33. FAKTOR FAKTOR YANG BERPENGARUH DISTRIBUSI SPEKTRUM (PANJANG GELOMBANG) • Sudut datang matahari atau jarak antara matahari dan bumi - dataran rendah …….. Sinar merah - dataran tinggi………... Ultra violet 2. Letak daun pada tajuk

34. Peranan kualitas cahaya matahari dlm kehidupan Tanaman

35. Photoreversibilitydarifitokhrom merah inframerah Benih lettuce ----- bunga Xanthium Figure 8. Responpanjanggelombangpadaperkecambahanbenihdanpembungaanpada

36. Tabel 3. Persentase perkecambahan benih Lettuce sebagai akibat dari pemberian radiasi dengan panjang gelombang silih berganti

37. Photoperiodism(Duration of the Light Period) • ialah : lamanyasiangharidihitungmulaimatahariterbithinggaterbenam • berpengaruhpada: 1. inisiasibunga 2. produksi 3. pembentukanumbi 4. dormansibenih 5. pertumbuhantanaman (pembentukananakan percabangandanpertumbuhanmemanjang)

38. Berdasarkan respon tumbuhan pada variasi panjang hari, maka dikenal : • Tumbuhan Hari Panjang (Long day plant) : kelompok tumbuhan yg akanmemasukifasegeneratifnya (membentuk organ reproduktif) hanyajikatumbuhantsbmenerimapenyinaran yang panjang (> 14 jam), contoh : spinasi, beberapajenis radish dansawi. • TumbuhanHariPendek (Short day plant) : kelompoktumbuhanygakanmemasukifasegeneratif (membentuk organ reproduktif) hanyajikatumbuhantersebutmenerimapenyinaran yang pendek (< 10 jam) contoh : labusiam, kecipirdanbayam. • TumbuhanHariNetral (Neutral day plant) : kelompoktumbuhanygfaseperkembangannyatidakdipengaruhioleh lama penyinaran. Kelompoktumbuhaninitetapakanmemasukifasegeneratifbaikjikamenerimaygpanjang/ pendek contoh : tomat, blewah, kacang-kacangandll.

39. We can control light and influence blooming or vegetative growth by: • Shortening day with black cloth: covering the growing plant with an opaque cover to exclude light. • Lengthening day with artificial light: adding light in the evening hours.

40. DETERMINANT OF VARIATIONS IN THE LIGHT ENVIRONMENT • Seasonality • Latitude • Altitude • Topography • Air Quality • Vegetation Canopy Structure

41. OTHER FORMS OF RESPONSE TO LIGHT • Germination • Growth and Development - Establishment - Plant Growth - Phototropism - Photoperiod • Production of the Harvestable Portion of the Plant

42. Phototropism: the tendency for plants to “lean” in the direction of the greatest light intensity.

43. Phototropisms • Phototropic responses involve bending of growing stems toward light sources. • Individual leaves may also display phototrophic responses. • auxin most likely involved

44. Plant Physiology Under Low Light Intensity 1. Longer internodes, increased stem elongation 2. Leaves have larger surface area 3. Thinner leaves and stems 4. Thinner cuticle 5. One layer of palisade cells

45. MANAGING THE LIGHT ENVIRONMENT IN AGROECOSYSTEM

46. Ditinjaudariaspekenergi, fotosintensismrpproses yang tidakeffisien(1-2 % energimatahari yang jatuhdiubahmenjadienergikimiadalambentukkarbohidrat(hasilpanen). Contoh: Rata rataintensitasradiasidi Malang 400 kal/cm2/hari. 1 gram karbohidratmengandung4000 Kal makahasilpanenyang diperolehseharusnya : ton karbohidrat/ ha/tahun Kenyataandilapanghasilterbaiktidaklebihdari 50 ton karbohidrat ( bahankering total tanaman = biji +batang + daun + akar ) per hektar per tahun

47. Effisiensi : 50/3650 x 100 % = 1,5 % Artinya : dari 100 % energimatahari yang jatuhhanya 1,5 % yang dapatdiuubahtanamanmenjadienergikimia

49. Suatuprosesproduksipertanian (agronomi) ditinjaudariaspekenergimataharibertujuanuntukmeningkatkaneffisiensikonversienergimatahariataumengurangihilangnyaenergimatahariselamaprosesproduksiharusmengetahuikemanahilangnyaenergimataharitersebut.

50. Energimatahari yang telahtertangkaptidakseluruhnyadapatdiserap (diabsorpsi) olehtanaman. • 65 % diserap (diabsorbsi), • 20 % dipantulkan (refleksi) • 15 % diteruskan (ditransmisi) Refleksidipengaruhioleh : • kekasarantajuk, • sudutdaun, • ILD (IndeksLuasDaun) • warnadaun • sudutdatangradiasimatahari.