03. plants and environment factors_03.ppt
TRANSCRIPT
its about ..
An understanding of the ways individual plants and their physiology are
impacted by different factors of the environment is an essential component
in the design and management of cropping system
The ecological study of individual plant response to the diverse factors of
environment (autecology or physiological ecology) is a foundation of
agroecological understanding
1. Photosynthesis2. Carbon Partitioning3. Transpiration
“Plants convert solar energy into chemical energy stored in the chemical bonds of sugar
molecules”
this process is IMPORTANT for plant growth and survival
Remember what plants need…
Photosynthesis light reactions
light H2O
Calvin cycle CO2
sun ground
air
•Fotosintesis
•Proses dimana organisme yang memiliki kloroplas mengubah energi cahaya matahari menjadi energi kimia •Melibatkan 2 lintasan metabolik
•Reaksi terang: mengubah energi matahari menjadi energi seluler
•Siklus Calvin: reduksi CO2 menjadi CH2O
Simple equation :
6CO2 + 12H20 + light energy C6H12O6 + 6O2 + 6H2O
Light energy
ECOSYSTEM
CO2 + H2O
Photosynthesisin chloroplasts
Cellular respirationin mitochondria
Organicmolecules + O2
ATP
powers most cellular work
Heatenergy
Energi mengalir ke dalam suatu ekosistem sebagai cahaya matahari dan meninggalkannya dalam bentuk panas
Types of PhotosynthesisTypes of Photosynthesis
• C3 photosynthesis– Most plants
• C4 photosynthesis– A variety of plants, especially our
summer annuals and many of our grasses
• CAM photosynthesis– Cacti, agaves, bromeliads, and others
C3 plantsC3 plants The first stable compound formed in dark
reactions (Calvin cycle) is 3-carbon compound
A problem with C3, photosynthesis is always accompanied by photorespiration which consumes and releases CO2 in the presence of light
it wastes carbon fixed by photosynthesis - up to 50% of carbon fixed in photosynthesis may be used in photorespiration
C4 plants C4 plants A better way to capture CO2
• 1st step before Calvin cycle, fix carbon with enzymePEP carboxylase store as 4C compound
• adaptation to hot, dry climates have to close stomates a lot different leaf anatomy
• sugar cane, corn, other grasses…
corn
sugar cane
Photorespiration is nearly absent in C4 plants - so greatly increases their efficiency - this is because a high CO2: low O2 concentration limits photorespiration
Thus net photosynthetic rates are higher for C4 plants (corn, sorghum, sugarcane) than in C3 relatives (wheat, rice, rye, oats)
CAM CAM (Crassulacean Acid Metabolism) (Crassulacean Acid Metabolism) plantsplants
separate carbon fixation from Calvin cycle by time close stomates during day
open stomates during night at night, open stomates & fix
carbon in “storage” compounds organic acids: malic acid, isocitric acid
in day, close stomates & release CO2 from “storage” compounds to Calvin cycle increases concentration of CO2 in cells
succulents, pineapple, cactuses, agaves, bromeliads
CAM plantsCAM plants
how plant distributes the carbon compounds derived from
photosynthesis and allocates them to different physiological processes and
plant parts
Transpiration
the continual flow of water from the soil, into the roots, up the stem to the leaves, and out of the leaves through
the stomata
Water moving between soil and plants flows down a water potential gradient
A Plant’s Place in the Environment- Each species occupies a particular place in the ecosystem, known as the
habitat- within its habitat, the species carries out
a particular ecological role or function,
known as the ecological niche of that
species
Responses to Factors of the EnvironmentSetiap fase perkembangan tanaman melibatkan respon perubahan secara fisiologis. Sebagian besar respon tanaman berkaitan langsung dengan kondisi lingkungan
- Triggered Responses- Dependent Responses- Independent Responses
Triggered Responsesrespon tanaman yang dipacu oleh adanya eksternal stimulus tertentu
Dependent Responses respon tanaman yang tergantung pada keberadaan kondisi lingkungan eksternal tertentu secara terus menerus
Independent Responses respon tanaman yang ditentukan oleh kondisi fisiologis tanaman; mis: tanaman jagung akan berbunga karena fase tertentu dari pertumbuhan dan perkembangan sudah tercapai.
Limits and TolerancesEach environmental factor has both minimum and maximum levels, tolerance limits, beyond which a particular species cannot survive
1. Buat tulisan lengkap tentang tipe fotosintesis
2. Buat tulisan tentang kebutuhan unsur hara yang dibutuhkan tanaman