Lecture 7 - Atmosphere-Plant-Soil Continuum

Question 1

osmosis

Answer 1

water uptake from soil to roots

Question 2

what does soil particle size affect

Answer 2

water movement
water retention

Question 3

how does water movement in large pore space vs small pore space in soil differ

Answer 3

large pore space - more gravitational pull (moves down faster)
small pore space - more capillary action (spreads out and down at a slower pace

Question 4

saturation

Answer 4

all pores are full of water. gravitational water is lost

Question 5

field capacity

Answer 5

available water for plant growth

Question 6

wilting point

Answer 6

no more water is available to plants

Question 7

what other factors affect soil interactions with water

Answer 7

organic matter, microbes, salinity, etc.

Question 8

root architecture

Answer 8

length of roots, branching, angle

Question 9

what is root architecture affected by

Answer 9

water flow into roots

Question 10

what are shallow root systems effective at

Answer 10

catching limited rainfall

Question 11

hydrotropism

Answer 11

root growth in response to water deficit

Question 12

examples of hydrotropism on root growth

Answer 12

in water sufficient environments, gravity makes the root grow down
in water insufficient conditions, root will grow towards water against gravity

Question 13

root pressure

Answer 13

positive pressure that forms in the roots as the roots uptake water from the soil via osmosis

Question 14

guttation

Answer 14

happens in the early morning when transpiration is not very high, Roots push water up and they need to release some water through the hydathode, forming water droplets on leaves

Question 15

different types of water pathways

Answer 15

apoplasmic, symplasmic, and transcellular

Question 16

what do the root hairs of the epidermis do

Answer 16

project into the soil, which increases surface for water and nutrient uptake

Question 17

who found out the significance of the casparian strip

Answer 17

Robert Caspary

Question 18

what does the Casparian Strip do

Answer 18

forces water to cross a plasma membrane

Question 19

what is the Casparian strip made of

Answer 19

lignin

Question 20

suberin

Answer 20

cell wall that is associated biopolymer found in endodermis

Question 21

what is the role of suberized endodermis in the roots

Answer 21

decrease the water permeability
xylem tensions extend further into the root system

Question 22

what is radial conductance

Answer 22

water flow from soil to stele

Question 23

what is axial conductance

Answer 23

water flow through the xylem

Question 24

what is radial conductance affected by

Answer 24

anatomy, morphology, cell wall permeability, activity of water channels

Question 25

what is axial conductance is affected by

Answer 25

number, diameter, and structure of the xylem conduits, and formation of embolisms