2005-20061

AP Biology

2005-2006AP Biology

Chapter 37.

Plant Nutrition

2005-2006AP Biology

Nutritional needs

� Autotrophic does not mean autonomous

� plants need…

� sun as an energy source

� inorganic compounds as raw materials

� water (H2O)

� CO2

� minerals

2005-2006AP Biology

Macronutrients

� Plants require these nutrients in relatively large amounts

� C, O, H, N, P, K, Ca, Mg, S

2005-2006AP Biology

For what & from where?

soilproteins, enzymesS

soilchlorophyllMg

soilcell wall & membrane structure, regulationCa

soil & fertilizerstomate control, water balanceK

soil & fertilizernucleic acids, ATP, phospholipidsP

soil & fertilizerprotein & nucleic acid synthesisN

H2OsynthesisH

CO2synthesisO

CO2synthesisC

2005-2006AP Biology

Local Long Island soil issues

Granite

Acid soils bind upmineral ions↑↑↑↑pH by adding lime

Quartz silica based soils- low in P- can be acid

2005-2006AP Biology

Micronutrients

� Plants require in very small amounts

� primarily cofactors

2005-20062

AP Biology

2005-2006AP Biology

Nutrient deficiencies

� Lack of essential nutrients

� exhibit specific symptoms

� dependent on function of nutrient

� dependent on solubility of nutrient

2005-2006AP Biology

Magnesium deficiency

� Symptoms

� chlorosis = yellowing of leaves

� what is magnesium’s function?

Take 2 fertilizer pellets& call me in the morning

2005-2006AP Biology

Chlorophyll

Why does magnesium

deficiency cause chlorosis?

The chlorosis shows up in older

leaves first, because plant moves Mg to newer leaves. Why? 2005-2006AP Biology

Water & mineral uptake� Water uptake

� plants cannot extract all water from soil, only free water

� osmosis

� Cation uptake

� cation uptake is aided by H+ secretion by root

cells (proton pump)

� active transport

2005-2006AP Biology

The role of soils

� Plants are dependent on soil quality

� texture / structure

� relative amounts of various sizes of soil particles

� composition

� organic & inorganic chemical components

� fertility

2005-2006AP Biology

Importance of organic matter

� Topsoil

� most important to plant growth

� rich in organic matter

� humus

� decomposing organic material

� breakdown of dead organisms, feces, fallen leaves &

other organic refuse by bacteria & fungi

� improves soil texture

� reservoir of minerals

� organisms

� 1 tsp. of topsoil has ~5 billion bacteria living with fungi,

algae, protists, insects,

earthworms, nematodes

So don’t rakeyour lawn or bag your leaves

2005-20063

AP Biology

2005-2006AP Biology

Soil health as a global issue

Not taking care of soil health has far-reaching, damaging

consequences

� 1920’s Dust Bowl

� lack of soil conservation

� growing wheat

� raising cattle

� land exposed to wind erosion

� drought

2005-2006AP Biology

Soil health as a global issue� Soil conservation & sustainable agriculture

� maintaining healthy environment

� production of food supply

� economically viable farming industry

contour plowing crop rotation

“A sustainable agriculture does not deplete soils or people.”– Wendell Berry

cover crops

2005-2006AP Biology

Global issues

� fertility

� erosion

� irrigation

� forestry destruction

2005-2006AP Biology

2005-2006AP Biology

Fertilizers

� “Organic” fertilizers

� manure, compost, fishmeal

� “Chemical” fertilizers

� commercially manufactured

� N-P-K (ex. 15-10-5)

� 15% nitrogen

� 10% phosphorus

� 5% potassium

2005-2006AP Biology

Nitrogen uptake�Nitrates

� plants can only take up nitrate (NO3-)

�Nitrogen cycle by bacteria

� trace path of nitrogen fixation!

What will the plant use N for?

root

2005-20064

AP Biology

2005-2006AP Biology

Soybean root nodules

� N fixation by Rhizobium bacteria

� symbiotic relationship with bean family (legumes)

2005-2006AP Biology

Increasing soil fertility

� Cover crops

� growing a field of plants just toplow them under� usually a legume crop

� taking care of soil’s health� puts nitrogen back in soil

erosion control, too

Plow it under?Why would you

that?

A man…outstandingin his field

2005-2006AP Biology

Some plant oddities…

2005-2006AP Biology

Parasitic plants

� tap into host plant vascular system

Indian pipe

Mistletoe

2005-2006AP Biology

Plants of peat bogs

� High acid environment

� most minerals & nutrients bound up & are not available to plants

� must find alternative sources of nutrients

2005-2006AP Biology

Carnivorous

plants

Are they really

carnivores?

Pitcher plantVenus fly trapSundew

2005-20065

AP Biology

2005-2006AP Biology Pitcher plant 2005-2006AP Biology

Uses of peat

2005-2006AP Biology

Any Questions??