Soil and Plant Nutrition

Page
7

Arbuscular mycorrhizae (endomycorrhizae)

Cortical cells

10 µm

(LM, stained specimen)

Slide 49

Agricultural and Ecological Importance of Mycorrhizae

Farmers and foresters often inoculate seeds with fungal spores to promote formation of mycorrhizae.

Some invasive exotic plants disrupt interactions between native plants and their mycorrhizal fungi.

Slide 50

Question: Does the invasive weed garlic mustard disrupt mutualistic associations between native tree seedlings and arbuscular mycorrhizal fungi?

EXPERIMENT

Increase in

plant biomass (%)

RESULTS

Invaded

Uninvaded

Sterilized

invaded

Sterilized

uninvaded

0

100

200

300

Soil type

Mycorrhizal

colonization (%)

0

10

20

30

40

Invaded

Uninvaded

Soil type

Seedlings

Sugar maple

Red maple

White ash

Slide 51

Epiphytes, Parasitic Plants, and Carnivorous Plants

Some plants have nutritional adaptations that use other organisms in nonmutualistic ways:

Epiphyte plants + 0 grows on another plant and obtains water and minerals from rain.

Parasitic plants + - absorb sugars and minerals from their living host plant.

Carnivorous plants are photosynthetic but obtain nitrogen by killing and digesting mostly insects.

Slide 52

Unusual nutritional adaptations in plants

Staghorn fern, an epiphyte

Slide 53

Unusual nutritional adaptations in plants

Mistletoe, a photosynthetic parasite

Slide 54

Unusual nutritional adaptations in plants

Dodder, a nonphotosynthetic parasite

Dodder

Host’s phloem

Haustoria

Slide 55

Unusual nutritional adaptations in plants Carnivorous plants

Slide 56

Unusual nutritional adaptations in plants Carnivorous plants

Pitcher plants

Slide 57

Unusual nutritional adaptations in plants Carnivorous plants

Sundews

Slide 58

Review

N2

(from atmosphere)

Nitrogen-fixing

bacteria

H+

(from soil)

(to atmosphere)

Denitrifying

bacteria