PLANTS AND ENVIRONMENTAL FACTORS

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

THE PLANT Photosynthesis Carbon Partitioning Transpiration

1. Photosynthesis “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  air  ground

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

powers most cellular work 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 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 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 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…

sugar cane corn

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 (Crassulacean Acid Metabolism) plants 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 plants

2. Carbon Partitioning how plant distributes the carbon compounds derived from photosynthesis and allocates them to different physiological processes and plant parts

THE PLANT Transpiration

3. 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

Water movement between plants and soils

T r a n s p i r a t i o n

The Plant in its Interaction with The Environment 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

The Plant in its Interaction with The Environment 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.

The Plant in its Interaction with The Environment Limits and Tolerances Each environmental factor has both minimum and maximum levels, tolerance limits, beyond which a particular species cannot survive

Tugas Buat tulisan lengkap tentang tipe fotosintesis Batasan cahaya matahari yang dapat dimanfaatkan tanaman untuk fotosintesis Bagaimana adaptasi tanaman terhadap kelebihan dan kekurangan cahaya?