1 / 14

Plant water regime

Plant water regime. Introduction Adaptation, acclimation Poikilohydric and homoiohydric plants Water content, relative water content Water potential and its components Water and growth. Basic characteristics. Water content WC [%] = (FM - DM / FM)  100 FM - fresh mass, DM - dry mass

brac
Download Presentation

Plant water regime

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Plant water regime • Introduction • Adaptation, acclimation • Poikilohydric and homoiohydric plants • Water content, relative water content • Water potential and its components • Water and growth

  2. Basic characteristics • Water content • WC [%] = (FM - DM / FM)  100 • FM - fresh mass, DM - dry mass • cytoplasm 85 - 90 %, chloroplasts, mitochondria about 50 %, • ripe fruits 85 - 95 %, leaves 80 - 90 %, roots 70 - 95 %, wood 50 %, seeds , pollen grains 5 - 15 % • Relative water content • RWC [%] = [ 1 - (FMs - FMa)/(FMs - DM) ]  100, • FMs- mass after saturation, FMa- actual fresh mass • Plant water balance = absorption - transpiration • Effects of soil moisture and relative humidity

  3. Water potential and its components • w = (w -w0) / Vw • w - water potential, w - chemical potential of water in the system, • w0 - chemical potential of pure water, Vw-- volume per mole of water • = (G / ni)T,p,nj • G - Gibbs free energy, ni- number of moles of component i, nj - number of molesof other components, T - absolute temperature, p - pressure • w = s + p + m + g • s - osmotic potential, p - pressure potential, m - matric potential, g - gravitational potential • s = (RT / Vw) ln aw = -cRT • R - gas constant, aw- water activity, c - concentration •  = V (p / V) •  - volumetric modulus of elasticity , V - cell volume • Differences in w and its components inside cells and in apoplast (wall a tissue)

  4. Methods of determinationw - psychrometric methods, pressure bomb s - psychrometric and cryoscopic methodsp - pressure probeThermocouple psychrometer

  5. Pressure chamber

  6. Pressure probe

  7. Hofler diagram • The roles of individual components: • g - high trees • m - imbibition and germination (till water content about 60 %) • p - veins, apoplast, growth, movements of stomata • s - transport on cell and tissue level, plasmolysis, plasmoptysis, root pressure, osmotic adjustment, growth uplatnění

  8. Osmotic and elastic adjustment • Osmotic and elastic adjustment (growth, drought, salinity, low temperature, etc.), induction by decrease in soil water potential, air humidity, etc. • Osmotic adjustment – ion uptake, production and accumulation of osmotically active substances such as sugars (glucose, trehalose, saccharose), sugar alcohols (mannitol, sorbitol, glycerol), polyamines, aminoacids (proline), betaines (glycinebetain) • Membrane protection, source of C or N, defence against reactive oxygen species (ROS) • Dehydrines –ripenning of seeds or pollen grains, in plant vegetative parts during stresses, induced also by abscisic acid (ABA) • Elastic adjustment – expansin, endoglucanase, transglycosylase, peroxidase

  9. Changes in water potential and its components during water stress

  10. Water and growth • Elongation: • dV/Vdt  m(p - Y) • m - cell wall extensibility, p - pressure potential, Y - threshold pressure potential • dV/Vdt  Lp(wo - w) • Lp - hydraulic conductance, wo - water potential of water source, w- water potential of elongating cell • Lockart equation: • dV/Vdt = mLp/(m + Lp)  (w + p - Y)

  11. Model of cell wall and possible changes of its extensibility

  12. Aktivity of xyloglucan endotransglycosylase

  13. Comparison of shoot and root growth rate as affected by water potential of substrate

  14. Water stress and growth • Elongation rate (a) and pressure potential (b) in different distance from root apex in two substrates of different water potential

More Related