plant nutrition(2)

Plant nutrition(2) - Plant nutrition gas exchange and transport Physiology How organisms work A fundamental principle of physiology all organisms

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Plant nutrition, gas exchange, and transport Essential nutrients Macronutrients & micronutrients Nitrogen assimilation Nitrogen fixation, bacterial symbiosis Mycorrhizae fungal symbiosis Uptake of CO 2 Diffusion between leaves and air Water loss and transpiration Fluid transport Xylem and phloem Physiology: How organisms work A fundamental principle of physiology: all organisms must exchange materials and energy with their environments. In the next two lectures we cover the most important of these exchanges for plants. Most plants are photosynthetic autotrophs: -- obtain simple compounds (CO 2 , H 2 0, etc.) from the environment; use light energy to make carbohydrates (carbon fixation; photosynthesis ) CO 2 + H 2 0 (CH 2 O)x + O 2 -- at night, or in non-photosynthetic parts (roots, stem, etc.), the ‘reverse’ process of respiration is used to make ATP: (CH 2 O)x + O 2 CO 2 + H 2 0 Aerobic respiration ADP + P i ATP (+ heat) Plant nutrition, gas exchange, and transport Light energy So to run photosynthesis and respiration, plants need access to water, CO 2 , and O 2 . Essential nutrients for plants In addition to CO 2 , O 2 , and H 2 O, what materials do plants need from the environment? What are the essential elements for plants? More than 50 elements found in plants; not all are essential. Criteria for ‘essentiality’: plant cannot complete its life cycle without the element (deficiency prevents reproduction) the element cannot be replaced by another element Two loosely-defined categories of essential elements (17 total): Macronutrients: required in relatively large quantities Micronutrients: required in relatively small quantities Essential nutrients for plants 9 Macronutrients: mainly structural lipids, carbohydrates, cellulose, etc.: carbon, oxygen, hydrogen -- from CO 2 and water amino acids, nucleotides, hormones, etc.: nitrogen cytoplasmic fluid solutes, etc: magnesium, calcium, potassium ATP, ADP, nucleic acids, other compounds: phosphorus some amino acids: sulfur 8 Micronutrients: often catalytic components or cofactors of enzymes, etc.: chlorine, iron, manganese, boron, zinc, copper, molybdenum, nickel Most often limiting to plant growth: nitrogen phosphorus, potassium
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This note was uploaded on 04/16/2008 for the course BIOL 5b taught by Professor Chappel during the Spring '08 term at UC Riverside.

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Plant nutrition(2) - Plant nutrition gas exchange and transport Physiology How organisms work A fundamental principle of physiology all organisms

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