29/09/2011. Remember what plants need. its about.. this process is IMPORTANT for plant growth and survival. Photosynthesis

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1 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 sun H 2 O ground Calvin cycle air CO 2 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 CO 2 menjadi CH 2 O 1

2 Simple equation : 6CO H light energy C 6 H 12 O 6 + 6O 2 + 6H 2 O Light energy ECOSYSTEM Photosynthesis in chloroplasts Organic CO 2+ H 2O molecules + O 2 Cellular respiration in mitochondria 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 CO 2 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 CO 2 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 2

3 Photorespiration is nearly absent in C4 plants - so greatly increases their efficiency - this is because a high CO 2 : low O 2 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 CO 2 from storage compounds to Calvin cycle increases concentration of CO 2 in cells succulents, pineapple, cactuses, agaves, bromeliads CAM plants how plant distributes the carbon compounds derived from photosynthesis and allocates them to different physiological processes and plant parts Transpiration 3

4 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. 4

5 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 5