35 ch37plantnutrition2005
Transcript of 35 ch37plantnutrition2005
AP Biology 2005-2006
Chapter 37.
Plant Nutrition
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Nutritional needs Autotrophic does not
mean autonomous plants need…
sun as an energy source inorganic compounds as
raw materials water (H2O)
CO2
minerals
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Macronutrients Plants require these nutrients in
relatively large amounts C, O, H, N, P, K, Ca, Mg, S
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For what & from where?C synthesis CO2
O synthesis CO2
H synthesis H2O
N protein & nucleic acid synthesis soil & fertilizer
P nucleic acids, ATP, phospholipids soil & fertilizer
K stomate control, water balance soil & fertilizer
Ca cell wall & membrane structure, regulation soil
Mg chlorophyll soil
S proteins, enzymes soil
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Local Long Island soil issues
Granite
Acid soils bind upmineral ionspH by adding lime
Quartz silica based soils- low in P- can be acid
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Micronutrients Plants require in very small amounts
primarily cofactors
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Nutrient deficiencies Lack of essential nutrients
exhibit specific symptoms dependent on
function of nutrient dependent on
solubility of nutrient
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Magnesium deficiency Symptoms
chlorosis = yellowing of leaves what is magnesium’s function?
Take 2 fertilizer pellets
& call me in the morning
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Chlorophyll
Why does magnesium deficiency cause chlorosis?
The chlorosis shows up in older leaves first, because plant moves Mg to newer leaves. Why?
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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
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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
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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
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Soil health as a global issueNot 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
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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
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Global issues fertility erosion irrigation forestry destruction
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Fertilizers “Organic” fertilizers
manure, compost, fishmeal
“Chemical” fertilizers commercially manufactured N-P-K (ex. 15-10-5)
15% nitrogen 10% phosphorus 5% potassium
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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
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Soybean root nodules N fixation by Rhizobium bacteria
symbiotic relationship with bean family (legumes)
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Increasing soil fertility Cover crops
growing a field of plants just to plow 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
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Some plant oddities…
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Parasitic plants tap into host plant vascular system
Indian pipe
Mistletoe
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Plants of peat bogs High acid environment
most minerals & nutrients bound up & are not available to plants must find alternative sources of nutrients
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Carnivorous plants
Are they really carnivores?
Pitcher plantVenus fly trapSundew
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Uses of peat
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Any Questions??