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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
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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
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 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 Photosynthesisin chloroplasts Organicmolecules CO2 + H2O + O2 Cellular respirationin mitochondria ATP powers most cellular work Heatenergy 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 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…
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
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
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 respontanaman yang dipacuolehadanyaeksternal stimulus tertentu • Dependent Responses respontanaman yang tergantungpadakeberadaankondisilingkunganeksternaltertentusecaraterusmenerus • Independent Responses respontanaman yang ditentukanolehkondisifisiologistanaman; mis: tanamanjagungakanberbungakarenafasetertentudaripertumbuhandanperkembangansudahtercapai.
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 Buat tulisan tentang kebutuhan unsur hara yang dibutuhkan tanaman