BIO1PS 2012Plant Science

Lecture 1Soils and Roots

Dr. Michael EmmerlingDepartment of BotanyRoom 410m.emmerling@latrobe.edu.au

ReferencesLadiges et al. (2010), "Biology", 4th Edition

• PART 3 - Plant Form and Function•Sections of Chapters 15 – 18 (pp. 317 - 420)• Good idea to read all chapters, but concentrate on the topics covered in the lectures

• PART 6 - Ecology •Section of Chapter 41, Australian Flora (pp. 1024 - 1026)

Knox et al. (2005), "Biology", 3rd Edition:•Chapters 14 - 17 (pp. 298 - 398)•Section of Chapter 41, Australian Flora (pp. 1008 - 1011)

Ladiges et al. (2010), 4th ed., Fig. 16.1

Leaves~4 Lectures

Soil and Roots~3 Lectures

Stems~2 Lectures

Hormones and Coordination~3 Lectures

Ghost gumEucalyptus papuana

Plant StructureLeafy, green above-ground parts (tops), absorbing light in photosynthesis

Ladiges et al. (2010), 4th ed., Fig. 15.22

Flowers and fruits for reproduction (spores in mosses and ferns)

Colourless below ground roots, absorbing water and mineral salts (nutrients)

Stems connecting the tops and roots

Typical Plant Structure

Ladiges et al. (2010), 4th ed., Fig. 16.9

•Soils•Nutrient Cycles•Root Development and Growth

•Meristems, root hairs, lateral roots

•Monocot vs. dicot structure

•Root Functions• Ion and water uptake

•Nodules (Rhizobia), Mycorrhizae

•Adaptations

•Root and Soils in Agriculture

Soil and Roots

Learning Objectives - Soils• Describe the soil horizons

• Describe the processes that give rise to soil

• Describe the nutrients that plants extract from the soil

• Introduction to soils:• Brady, N.C., Weil, R.R. (2008) The nature and properties of

soils. Harlow, Prentice Hall, 14th ed.

• Call number 631.4 B925n 2008

Quote

"Essentially, all life depends upon the soil ... . There can be no life without the soil and no

soil without life; they have evolved together." Charles E. Kellogg, USDA Yearbook of Agriculture, 1938

Soil - What Is It Good For?

engineering medium water supply and puri!cationhttp://www.roadtraffic-technology.com/projects/a688wheatley_hill/images/1-road-construction.jpg

http://www.nwas.org/meetings/nwa2006/Broadcast/Kelsch/watersheds/media/graphics/unit_5/soil_water_processes2.jpg

Soil - What Is It Good For?habitat

medium for plant growth

recyclingME

http://wps.prenhall.com/wps/media/objects/5309/5437119/Figures/chap01/Fig01-3.jpg

Brady, N.C., Weil, R.R. (2008), 14th ed., Fig. 01-3

http://www.organicguide.com/wp-content/uploads/2008/04/image54.jpg

Soil and Plant Growth• Physical support

• Water

• Nutrients

• Air

• Temperature moderation

• Protection from toxins

http://wps.prenhall.com/wps/media/objects/5309/5437119/Figures/chap01/Fig01-3.jpg

Brady, N.C., Weil, R.R. (2008), 14th ed., Fig. 01-3

Function of Soil

Source of all water and mineral nutrients (and then, mineral nutrients for all animals)

Sunlight Air

No soil - no plants (except for lichens) Furka

Soil

ME

• P is concentrated 1000-fold in plants compared with soil

• Water from apparently dry soil is absorbed and concentrated by plants

• Requires a !ne, extensive tissue system (‘roots’) penetrating soil• kilometres of roots per cubic metre of soil

• immobility of plants Extensive root

system

Please Concentrate!

Roadtrip, Anyone?

Secale cerealerye

http://www.agroatlas.ru/content/cultural/Secale_cereale_K/Secale_cereale_K.jpg

Essential NutrientsC.B. HOPKiNS CaFe

Closed Monday Morning and NightCu Zoon, the Mg

MacronutrientsMacronutrients Micronutrientsfrom air and water mostly from soil solids from soil solids

carbon (CO2) nitrogen copperhydrogen (H2O) potassium iron

oxygen (O2, H2O) calcium manganesemagnesium nickel

phosphorus zinc

sulfur boron

chlorine

molybdenum

Macronutrients

Micronutrients (trace elements)• made up of all the others

• relative concentrations in plant tissue of less than 5

• only very small (trace) amounts required from soil

Nutrient Relative concentrationN 1000

K 250

Ca 125

Mg 80

P 60

S 30

• is determined by the presence and availability of nutrients in soil for uptake by plants

• is the ability of the soil to support productive plant and, ultimately, animal (including human) life

Soil Fertility

Also called "horizons"

Soil LayersO

O horizon - leaf litter layer on surface of the mineral soil, often with high biological activity

D

D horizon - bedrock

C horizon - zone of weathering of bedrock

C

B horizon - zone of accumulation of !ne clay particles and mineral nutrients

B

A

A horizon - upper layer of mineral soil darkened by accumulation of organic matter and in which biological activity is greatest

Soils in Australia

http://www.anra.gov.au/topics/soils/maps/national/soil_atlas.gif

http://www.dpi.vic.gov.au/dpi/vro/vrosite.nsf/pages/soil-homeMore info on soils:

Soil FormationRock

physical breakdown(disintegration)

chemical breakdown(decomposition)

• temperature• abrasion, e.g. wind,

water, ice• plants and animals

• hydration• hydrolysis• dissolution• acid reactions• oxidation/reduction• complexation

http://blog.oregonlive.com/themombeat/2009/02/rock_solid_solutions_small.jpg

Generally nutrient-poorVery ancient soils

• long periods of erosion and leaching• no recent geological processes such as volcanic, glacial or

alluvial activity to build up ‘new’ soil rich in nutrients • low biological activity (because hot and dry)• very low in phosphate

Compare with very fertile soils in Java

• current volcanic activity

• heavy rains (alluvial activity)

• year-round biological activity

• supports large human population (100 million)

Australian Soils

• All the nutrient cycles are based in soil

• Pools of all nutrients on earth are limited

• Constant recycling necessary in order to provide nutrients to support continued life on earth

Knox p 357, 1185-1193

C, N, and P Cycles

Carbon• woody structures of vegetation (cellulose!)

• must be recycled to provide CO2 for ongoing photosynthesis

C, N, and P Cycles

C in forest biomass: 288.8 billion tGlobal Forest Resources Assessment 2010

Phosphorus• ATP, nucleic acids• easily immobilised in soil

Nitrogen• proteins etc. in plants and animals • must be recycled to give the N salts required by plants

Carbon Cycle

Ladiges et al. (2010), 4th ed., Fig. 44.19

C Cycle Animation:http://vro.dpi.vic.gov.au/dpi/vro/vrosite.nsf/pages/soilhealth_organic_carbon-cycle

Nitrogen Cycle

Ladiges et al. (2010), 4th ed., Fig. 44.20N Cycle Animation:http://vro.dpi.vic.gov.au/dpi/vro/vrosite.nsf/pages/soilhealth_nitrogen-cycle

Phosphorus Cycle

Ladiges et al. (2010), 4th ed., Fig. 44.22