Water is important to plants

1
Plant Environment Water

• Water is important to plants

• Water makes up 80-90 of herbaceous and 50 of
  woody plants

• Water critical for plant growth (photosynthesis
  6CO2 6H2O ---gt C6H12O6 6O2)

• Water needed to obtain nutrients from soil
  (nutrients dissolved in water)

• Water needed for cell elongation, one way plant
  tissues increase in size

2
Plant Environment Water

• How does water move through plants?

• From soil into root cells

• Water enters root hairs (projections of cells
  above root tip)

• Root hairs greatly increase surface area for
  water entry

• Root cells pump minerals into cells (using ATP
  energy)

• High concentration of minerals inside roots
  creates osmotic gradient (difference in water
  concentration)

• Water moves from high to low water concentration

• Adding minerals into roots decreases the
  concentration of water in roots causing water to
  enter by osmosis

3
Plant Environment Water

• How does water move through plants?

• From root cells to xylem in roots

• Water (and minerals) move between or through
  cells of cortex

• Casparian strips blocks water, force it through
  membranes of endodermal cells

• Endodermal cells selects nutrients that enter
  xylem

4
Plant Environment Water

• How does water move through plants?

• Xylem is dead, hollow, tubular cells

5
Plant Environment Water

• How does water move through plants?

• From xylem upward to leaves

• Water molecules clings to xylem and to each
  other

• Water in xylem is unbroken column

• Water evaporates from leaves pulling water up
  xylem

• Evaporative water loss through stomates of leaves
  is transpiration

• 90 of water absorbed by roots lost via
  transpiration in leaves

6
Plant Environment Water

• Other uses of water in horticulture

• Cooling turf or greenhouse (by evaporative
  cooling)

• Frost protection

• Modify local environment

• Irrigation

7
Plant Environment Water

• Water deficiency in plants

• Slight water stress causes stomates to close
  photosynthesis reduced

• Reduction in growth

• Smaller leaves

• Shorter internodes

• Smaller plants

• Slight water stress can effectively prevent fast,
  leggy growth

8
Plant Environment Water

• Water deficiency in plants

• Severe water deficiency

• wilting

• Dry leaf tips or margins

• Yellowing of older leaves

• Abscission of leaves, flowers, fruit

• Same symptoms can occur because of prolonged,
  excess water

9
Plant Environment Water

• Proper watering of plants

• Container plants

• Saturate soil with water let dry before next
  watering

• Watering completely encourages root growth
  throughout container

• Always use pots with drainage holes

• Water until some water trickles out of drainage
  holes

• Overwatering occurs from watering too frequently
  not too much at one time

10
Plant Environment Water

• Proper watering of plants

• garden plants

• Garden plants need regular water

• Deficits followed by excess water during
  particular growth stages reduces quality of
  vegetable

• beans with large air pockets

• Ruptures in tomato skin

• Growth cracks in carrots

11
Plant Environment Water

• Soluble salt problems

• Soluble salt problems result from

• High levels of salt in soil

• High level of salt in irrigation water

• Excessive use of fertilizers

• Symptoms include

• Wilting

• Drying of tips of margins of leaves

• Abscission of leaves, flower, fruit

(Symptoms same as lack of waterwhy?)

• Problem solved by flushing plant with water