Please enable JavaScript.

Coggle requires JavaScript to display documents.

Water Balance of Plants (water movement leaf to atmosphere (final part…

- - - - aka leaf hydraulic resistance
        
        reflects
        
        \( \downarrow\) \( \Psi\) \( \uparrow\) hydraulic resistance
        
        \( \uparrow\) leaf age
        
        growth conditions
        
        light conditions
        
        shade higher resistance
        
        sun lower resistance
        
        xylem
        
        distribution of xylem conduits
        
        vein density
        
        closer spaces veins
        
        2 more items...
        
        size of xylem conduits
        
        number of xylem conduits
        
        hydraulic properties of mesophyll cells
      - ~30% of total liquid-phase resistance
  - - - depend on
        
        diffusional resistance
        
        r
        
        2 components
        
        boundary layer resistance (r\( _b\))
        
        determined by
        
        2 more items...
        
        water vapor diffuse across to reach turbulent air of atmosphere
        
        layer of unstirred air next to leaf surface
        
        stomatal resistance (r\( _s\))
        
        1 more item...
        
        difference in water vapor concentration
        
        \( \Delta\)c\( _w\)\( _v\)
        
        between air spaces & external bulk air
        
        \( \Delta\)c\( _{wv(leaf)}\) - \( \Delta\)c\( _{wv(air)}\)
        
        influenced heavily by temperature
        
        \( \Delta\)c\( _{wv(leaf)}\) difficult assess
        
        great amount of cell surface area
        
        1 more item...
        
        air space volume
        
        4 more items...
        
        \( \Delta\)c\( _{wv(air)}\) measured easily
  - - - cell walls
        
        evaporates into intercellular spaces
        
        through stomata
- - - - consequence of E
      - pulls water through xylem
  - - - Poiseuille's equation
        
        examples
        
        treetops
        
        minimum of 2MPa needed to move water from base to top #
        
        tall trees
        
        Eucalyptus regnans
        
        Sequoia sempervirens
        
        ideal tube compared to living cells
        
        main point: flow through xylem highly efficient compared to living cells
        
        m^3 s^(-1)
        
        \( \Delta\) \( \Psi\)p / \( \Delta\) x
        
        drives flow
        
        pressure gradient
        
        smaller necessary through xylem than through living cells
        
        \( \eta\)=viscosity
        
        r=radius of tube
  - - - structure
        
        tube is a vessel
        
        vessels conected through pits
        
        connected by perforation plates
        
        dead
      - most angiosperms have
        
        most gymnosperms do not have
    - - structure
        
        numerous pits
        
        primary cell wall only, no secondary
        
        highly lignified walls
        
        dead
        
        hollow
        
        elongated
      - morphology
        
        torus only found in pines
        
        acts as valve to prevent spreading emboli
      - found in all vascular plants
- - - - dissolve gas bubles
        
        mitigate cavitation
      - consequence of ion accumulation
    - - probability \( \uparrow\)
        
        Rel. humidity \( \uparrow\)
        
        E \( \downarrow\)
      - through hydathodes
      - due to +\( \Psi\)s
    - - E \( \downarrow\)
      - soil \( \Psi\) high
    - - transport ions to xylem
        
        \( \Psi\)s xylem osmotic potential
    - - +hydrostatic xylem pressure
  - - - transmembrane
        
        may move through the tonoplast
        
        crosses plasma membrane twice
      - symplast
        
        must move so across the endodermis #
        
        permeability due to aquaporins
        
        respond to intracellular pH
        
        as pH changes, permeability decrease
        
        \( \downarrow\) temp \( \uparrow\) pH
        
        \( \downarrow\) aerobic respiration \( \uparrow\) pH
        
        genetic mutants low in aquaporins
        
        larger root systems
        
        wilt
        
        parts
        
        plasmodesmata
        
        cell cytyoplasm
      - in general water follows path of least resistance
      - apoplast
        
        prevented at Casparian strip
        
        located
        
        where xylem starts to mature
        
        distance behind root tip
        
        nongrowing part of root
        
        composed of
        
        hydrophobic
        
        lignin
        
        suberin
        
        no membranes to cross
        
        parts
        
        nonliving cell lumens
        
        intercellular air spaces
        
        cells walls
- - - - water fill interparticle spaces
        
        after rain
        
        sand retain ~15% water by volume #
        
        clay retain ~40% water by volume #
        
        may form film on larger particles
        
        small area fills first
        
        by capillary action
    - - clay
        
        +hummus \( \uparrow \) crumbiness #
        
        small interparticle spaces
        
        particle <2um
        
        large SA:Vol
      - sandy #
        
        interparticle space large
        
        particle >1mm
        
        small SA:Vol
  - - - hydraulic conductivity
        
        think of tiny strings of water along soil particle surface
        
        varies by
        
        soil type
        
        sand
        
        high hydraulic conductivity
        
        large spaces between
        
        clay
        
        small hydraulic conductivity
        
        minute spaces between particles
        
        water content
        
        replace water with air
        
        decreases with water potential
      - size of pressure gradient
    - - movement from larger pockets to smaller pockets
      - curved air-water interfaces
    - - most often in response to pressure gradient
      - mass flow
      - concerted movement of molecules en masse
  - - - proportional to elevation
        
        lower at lower elevations
        
        higher at higher elevations
      - roll in drainage
    - - soil dries, \( \Psi\)p becomes more negative
        
        can easily reach -2MPa
        
        =(-2T)/r
        
        soil particles assumed to be fully wettable
        
        r=radius of curvature of air-water interface
        
        clay, r <1um
        
        T=surface tension of water
        
        7.28 x 10^(-8) MPa m
      - wet soil ~0MPa
    - - saline soils <-0.2MPa
      - '> -0.2MPa
      - usually negligible
- - - - vertical shoots become a new plant
  - - - important no shading each other
    - - 2 per node
    - - 3 or more per node
    - - 1 per node
  - - - either a vegeative bud (branch or floral bud.
      - A mini shoot with a dormant apical meristem &several young leaves
  - - - The region between nodes
- - - - remain alive during differentiation
        
        Plasma membrane that lined the plasmodesma continues to line the sieve pore
    - - Sieve cells
      - sieve tube membrane
    - - occurs in groups ( primary pits fields);
        
        therefore; sieve pores also occur clustered together in groups called
        
        sieve area
    - - immature sieve begin to differ, their plasmodesmata enlarge to a diameter of more than 1 *m
  - - - is digested through a particular site if the primary wall, often removing the entire end wall
    - - an entire sack of vessle elements
    - - the most derived and strongest tracheary elements
    - - the 2ndary wall is deposited in the shape of a net as the name suggests.
    - - provides much more strength because the 2ndary wall underlies most of the inner surface of the primary wall and is fairly extensive
    - - the 2ndary wall exist as one to three helices interior to the primary wall
    - - does not provide strength
      - Simplest type of element, small amount of secondary wall, organized as a set of rings
    - - Vessel elements #
      - Tracheids elements #
  - - - because sugar is dissolved to be conducted water is transported simultaneously
      - Summer carries sugar into developing fruits and into the storage organs of perennial plants
      - Distributes sugar and minerals
      - living cells
      - pick up sugar from areas where it is abundant
        
        usually leaves during the summer and tubers or rhizomes in spring and transport to where sugar is needed
        
        growing tips of shoots, roots, young leaves and flowers
    - - once in shoots water evaporates from surface if stem, leaves flowers and is lost
        
        the minerals and a bit of water are used by surrounding cells
      - sap travels through dead, hollow cells not through living cells
      - water and minerals enter through roots and are conducted upward to leaves and stems
      - conducts water and minerals
  - - - an open tissue with large inter cellular air spaces
  - - - occurs in many shapes and sizes
        
        stinging nettle
      - create immobile air next to the leaf surface
        
        Allows water molecules to diffuse out of the stoma to bounce back in rather than be swept away by air currents
      - shade underlying tissues by blocking some incoming sunlight
      - epidermal cells elongate outward
      - make it difficult for animals to land, walk chew on leaf
    - - with a hole
        
        swell by absorbing water
      - stomatal pore
        
        in between them
        
        open up in the daytime letting CO2 enter the plant
      - work together to make the stoma
    - - Cuticle
        
        builds up as more or less pure layers
      - a fatty substance that makes the wall impenetrable to water
    - - leaves and stems that might be to close
      - passing animals
      - dust
    - - small insects
      - fungi
      - bacteria
    - - a single layer of parachyma cells
- - - - sugar must be transported down
  - - - cattails, lilies, palms, philodendrons, bromeliads
    - - roses, asters, maples,
    - - waterlilies, magnolias, laurels
    - - largest division in the plant kingdom
  - - - lay on top of the soil
      - for production of horomones
  - - - woody body
    - - Herbaceous body
    - - absorb moisture
    - - survival
        
        Above dies, under lives
      - Dispersal
        
        Runners, breaks, carried
        
        grow new plants
- - - - just 5 to 10 layers of cellulose micro fibrils
      - 80 to 100 nm thick
    - - little glucose used to build thin walls
    - - conduct nutrients over a long distance
        
        phloem
      - mass of parachyma tissues
    - - Transfer cells
        
        mediate distance transport by large plasma membrane
        
        capable of holding numerous molecular pumps
        
        increase surface area, having extensive knobs ridges, ingrowths on the inner surface of walls
      - chlorenchyma
        
        Thin walls let light and CO2 pass through
        
        to the chloroplast
        
        Numerous chloroplasts
        
        Involved in photosynthesis
      - Glandular cells
        
        Secrete nectar, fragrance, mucilage, resins, and oils
        
        Contain a few chloroplast
        
        have elevated dytosomes and Endoplasmic R.
        
        Transport sugar and mineral into themselves transform them and send the out
  - - - like air pressure to a tire #
  - - - flexibility would be a disadvantage example (brain and skull)
      - masses are hard, impenetrable
      - short
        
        strong walls in all 3 dimensions
      - Sclerenchyma tissues
        
        act brittle and inflexible
    - - other pests
      - fungi
      - insects
    - - strong enough to prevent the protoplast from expanding
    - - snow
      - wind
      - animals
    - - after no growth, achieved proper shape
    - - can be deformed, return back to original size and shape when pressure is released