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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. Photosynthesis

2. Carbon Partitioning

3. 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 CO2menjadi CH2O

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Simple equation :

6CO2 + 12H20 + light energy

C6H12O6 + 6O2 + 6H2O

Light energy

ECOSYSTEM

CO2 + H2O

Photosynthesis

in chloroplasts

Cellular respiration

in mitochondria

Organic

molecules+ O2

ATP

powers most cellular work

Heat

energy

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 enzyme

PEP 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

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� 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 ((CrassulaceanCrassulacean Acid Metabolism) 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

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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 Environment

Setiap fase perkembangan tanaman

melibatkan respon perubahan secara fisiologis.

Sebagian besar respon tanaman berkaitan

langsung dengan kondisi lingkungan

- Triggered Responses

- Dependent Responses

- Independent Responses

� Triggered Responses

respon 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.

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�Limits and Tolerances

Each 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