Nutrition and Transport in Plants

Chapter 26

2Nutrition and TNutrition and Transport in Plaransport in Plantsnts

OutlineOutline

Essential Inorganic NutrientsEssential Inorganic NutrientsSoil FormationSoil Formation

Soil ProfilesSoil Profiles

Soil ErosionSoil Erosion

Water & Mineral UptakeWater & Mineral Uptake

Transport MechanismsTransport MechanismsWaterWater

Organic NutrientsOrganic Nutrients

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Plant Nutrition and SoilPlant Nutrition and SoilEssential Inorganic NutrientsEssential Inorganic Nutrients

About 95% of a plant’s dry weight is About 95% of a plant’s dry weight is carbon, hydrogen, and oxygencarbon, hydrogen, and oxygen

Primary nutrients are carbon dioxide Primary nutrients are carbon dioxide and waterand water

Essential nutrients have identifiable Essential nutrients have identifiable role, and a deficiency causes a plant role, and a deficiency causes a plant to dieto die

­MacronutrientsMacronutrients

­MicronutrientsMicronutrients

4Overview of Plant Nutrition

5Nutrient Deficiencies

6Nutrition and TNutrition and Transport in Plaransport in Plantsnts

Soil FormationSoil Formation

Soil formation begins with weathering Soil formation begins with weathering of rockof rock

Organisms also play an important roleOrganisms also play an important role

Lichens and MossesLichens and Mosses

Humus begins to accumulateHumus begins to accumulate

Under ideal conditions, a centimeter Under ideal conditions, a centimeter of soil may develop within 15 yearsof soil may develop within 15 years

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Nutritional Function of SoilNutritional Function of Soil

Soil is a mixture of:Soil is a mixture of:Soil particlesSoil particlesDecaying organic materialDecaying organic materialLiving organismsLiving organismsAir, andAir, andWaterWater

Roots take up oxygen from air spacesRoots take up oxygen from air spacesSoil particles consist primarily ofSoil particles consist primarily of

SandSandClayClaySiltSilt

8Absorbing Minerals

9Nutrition and TNutrition and Transport in Plaransport in Plantsnts

Soil ProfilesSoil Profiles

Soil profile is a vertical section from Soil profile is a vertical section from ground surface to unaltered rock ground surface to unaltered rock belowbelow

Parallel layers - HorizonsParallel layers - Horizons

­A (topsoil) - Litter and humusA (topsoil) - Litter and humus

­B (subsoil) - Inorganic nutrientsB (subsoil) - Inorganic nutrients

­C (weathered rock)C (weathered rock)

Because parent material and climate Because parent material and climate differ, soil profile varies according to differ, soil profile varies according to particular ecosystemparticular ecosystem

10Simplified Soil Profile

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Soil ErosionSoil Erosion

Soil erosion occurs when water or Soil erosion occurs when water or wind carry soil away to a new wind carry soil away to a new locationlocation

Worldwide, removes about 25 billion Worldwide, removes about 25 billion tons of topsoil annuallytons of topsoil annually

DeforestationDeforestation

DesertificationDesertification

Agricultural contaminantsAgricultural contaminants

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Adaptation of Roots for Mineral Adaptation of Roots for Mineral UptakeUptake

Important Symbiotic RelationshipsImportant Symbiotic Relationships

RhizobiumRhizobium bacteria fix atmospheric bacteria fix atmospheric nitrogennitrogen

­ Live in root nodulesLive in root nodules

Mycorrhizal association between fungi Mycorrhizal association between fungi and plant rootsand plant roots

­ EctomycorrhizasEctomycorrhizas

­ EndomycorrhizasEndomycorrhizas

13Water and Mineral Uptake

14Root Nodules

15Mycorrhizae

16Spanish Moss

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Transport Mechanisms in PlantsTransport Mechanisms in Plants

Transported in vascular tissuesTransported in vascular tissues

Xylem transports water Xylem transports water

­ Two types of conducting cellsTwo types of conducting cells

TracheidsTracheids

Vessel ElementsVessel Elements

­Water flows passively from an area of Water flows passively from an area of higher water potential to an area of higher water potential to an area of lower water potentiallower water potential

18Plant Transport System

19 Conducting Cells of Xylem

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Transport Mechanisms in PlantsTransport Mechanisms in Plants

Transported in vascular tissues, Transported in vascular tissues, cont.cont.

Phloem transports organic materialsPhloem transports organic materials

­Conducting cells are sieve-tube Conducting cells are sieve-tube membersmembers

Have companion cells to provide Have companion cells to provide proteinsproteins

End walls are sieve platesEnd walls are sieve plates

Plasmodesmata extend through sieve Plasmodesmata extend through sieve platesplates

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Water TransportWater Transport

Water entering roots creates a Water entering roots creates a positive pressure (root pressure)positive pressure (root pressure)

Pushes xylem sap upwardPushes xylem sap upward

­May be responsible for guttationMay be responsible for guttation

­Water forced out vein endings along Water forced out vein endings along edges of leavesedges of leaves

22 Guttatio

n

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Cohesion-Tension ModelCohesion-Tension ModelCohesion-tension model of xylem Cohesion-tension model of xylem transport suggests a passive xylem transport suggests a passive xylem transporttransport

Water molecules tend to cling togetherWater molecules tend to cling together

Polarity of water allows interaction with Polarity of water allows interaction with molecules of vessel wallsmolecules of vessel walls

Water column moves passively upward Water column moves passively upward due to transpirationdue to transpiration

­Column must be continuousColumn must be continuous

­Waxy cuticle prevents water lossWaxy cuticle prevents water loss

24 Cohesion-tension Model of

Xylem Transport

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Opening and Closing of StomataOpening and Closing of Stomata

Each stoma in leaf epidermis is Each stoma in leaf epidermis is bordered by guard cellsbordered by guard cells

Increased turgor pressure in guard Increased turgor pressure in guard cells opens stomacells opens stoma

Caused by active transport of K+ into Caused by active transport of K+ into guard cellsguard cells

26 Opening and Closing of Stomata

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Organic Nutrient TransportOrganic Nutrient Transport

Role of PhloemRole of Phloem

Phloem transports sugarPhloem transports sugar

Girdling of tree below the level of Girdling of tree below the level of leaves causes bark to swell just above leaves causes bark to swell just above the cutthe cut

Sugar accumulates in the swollen Sugar accumulates in the swollen tissuetissue

28Acquiring Phloem Sap

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Pressure-Flow of Phloem Pressure-Flow of Phloem TransportTransport

Positive pressure drives sap in sieve Positive pressure drives sap in sieve tubestubes

Sucrose is actively transported into Sucrose is actively transported into sieve tubessieve tubes

Water follows by osmosisWater follows by osmosis

Increase in volume creates flow that Increase in volume creates flow that moves water and sucrose to a sinkmoves water and sucrose to a sink

30Pressure-flow Model of Phloem Transport

31Nutrition and TNutrition and Transport in Plaransport in Plantsnts

ReviewReview

Essential Inorganic NutrientsEssential Inorganic NutrientsSoil FormationSoil Formation

Soil ProfilesSoil Profiles

Soil ErosionSoil Erosion

Water & Mineral UptakeWater & Mineral Uptake

Transport MechanismsTransport MechanismsWaterWater

Organic NutrientsOrganic Nutrients

Nutrition and Transport in Plants

Ending Slide Chapter 26