03. PLANTS AND ENVIRONMENT FACTORS_03.ppt

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