2/7/2008
Turf Growth and Development
Germination and Seedling
Development
Spikelet borne in Inflorescence
• Germination and Seedling Development
• Leaf and Stem Formation
• Inflorescence
• Roots
Spikelet
Florets
Floret
Floret
Apex
Caryopsis
Lemma
Palea
Base
of
Callus
Front View
Side View
Back View
Lemma
Palea
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Caryopsis
Caryopsis
Pericarp Seed Coat
Caryopsis
Aleurone Layer
Embryo
Endosperm
Fescue
Bluegrass
Scutellum
Bentgrass
Germination
Favorable seed-to-soil contact
Germinating Seed
Coleoptile
Colerhiza
Second Seminal
Root
First Seminal
Root
•
•
•
•
•
•
Endosperm Reserves
Planting Depth
Moisture
Light
Temperature
Light
Germination Process
• Enlargement of the coleorhiza
• Emergence of root-hair like
structures
t t
for
f anchoring.
h i
• Emergence of the primary root
(radicle)
• Emergence of the coleoptile
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Germination Process
• Elongation of first leaf within the
coleoptile
– Photosynthesis begins
• Second leaf emerges
– Growing point enclose in coleoptile
• Adventitious roots develop from nodes
at base of shoot
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2/7/2008
Growth and Development
• Germination and Seedling Development
• Leaf and Stem Formation
• Roots
• Inflorescence
Grass Shoot
Grass Shoot
Leaf Blade
Developing Leaves
Leaf Sheath
Crown
Grass Crown
Leaf
Sheath
Crown
Growing Point
Youngest Leaf
Apical Meristem
Growing
Point
Primordial Leaves
Internode
Apical Meristem
Axillary Bud
L f
Leaf
Primordia
Node
Adventitious
Root
Primary Root
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2/7/2008
Leaf Formation
Leaf Formation
• From leaf primordia
on top of crown
– New primordia
continually
ti
ll fformed
d
Emerging leaf
• Completely hidden
within several mature
l f sheaths
leaf
h h
Young Leaves
Apical Meristem
Young
Primordia
Leaf Formation
New Leaf
Young Leaf
Mature Leaf
Senescing
Leaf
Developing New
Leaf
Roots
Leaf Photosynthetic Rate
• Newly emerging leaves
– Use all the food they manufacture plus more
• Young fully expanded leaves
– Highest
Hi h t photosynthetic
h t
th ti rate
t
• Food for own growth plus storage
• Older leaves
– Maintenance production
Stems
• Three types
– Crown
– Flowering culm
– Lateral Stems
• Rhizomes and stolons
• Senescing leaves
– Recycling of essential building blocks
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2/7/2008
Crown
•
•
•
•
Crown
Highly contracted stem
Forms wherever new shoot develop
Develops leaves,
leaves roots
roots, tillers
tillers, stems
Stores carbohydrates reserves
Grass Crown
Youngest Leaf
Apical Meristem
Growing
Point
Primordial Leaves
Internode
Axillary Bud
Node
Primary Root
Adventitious
Root
Branching
Axillary Buds
• Tillers
– Intravaginal branching
• Builds shoot density in the immediate
vicinity of the parent shoots
• Lateral shoots
– Extravaginal branching
• Extend the plant population beyond the
parent shoots
Intravaginal
Lateral Shoots
Extravaginal
Lateral Shoots
• Stolons
Stolon
– Grow along the surface
– Form
F
new shoots
h
and
d roots at nodes
d
or at the stolon tip (terminal)
– Branching at the nodes forms
network of lateral stems
Rhizome
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2/7/2008
Lateral Shoots
• Stolonifreous Turfgrasses
– Creeping Bentgrass
– Rough
R
h Bl
Bluegrass
– Zosiagrass
Lateral Shoots
Lateral Shoots
• Rhizome
– Grows beneath the ground via stem
internode elongation
– Determinate and indeterminate types
Rhizome Growth
• Determinate rhizome
– Short
– Growth in three phases
– Aerial shoot formation upon reaching the
surface
• Indeterminate
– Long and branched at nodes
– Aerial shoots from axillary buds
Extensor rhizomes
Sprout rhizomes
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2/7/2008
Lateral Shoots
• Rhizomatous Turfgrasses
– Kentucky Bluegrass
– Creeping Red Fescue
Tillering
Tillering
• New aerial shoots emerge intravaginally
from axillary buds
Tillering
Inflorescence
Turf Growth and Development
Spiklet Borne in Inflorescence
Inflorescence
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2/7/2008
Inflorescence
Inflorescence
• Flowering portion of the grass shoot
• The basic unit of organization within
th inflorescence
the
i fl
is
i the
th spikelet.
ik l t
• The spikelet is composed of florets,
glumes and rachilla.
Callus
Rachilla
Floret
Glume
Inflorescence
Glumes
Types of Inflorescence
Floret
Floret
Glume
Bent Grass
Panicle
Raceme
Spike
Rye Grass
Types of Inflorescence
• Raceme
– Spikelets borne on short stalks, called pedicels,
coming off a main culm.
• Spike
– Spikelets attached directly to the main culm.
Grass Species
• Raceme
–
–
–
–
• Panicle
Zoysiagrass
St.Augustinegrass
Bahiagrass
Centipedegrass
– Bluegrass
– Bentgrass
– Fescue
• Spikes
– Ryegrass
– Wheatgrass
g
– Bermudagrass
• Panicle
– Spikelets spaced along spreading or
compressed branches.
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2/7/2008
Floret
Floret
Floret
Lemma
Palea
Glumes
Floret
Anther
Stamen
Turf Growth and Development
Filament
Root Growth
Stigma
Style
Pistil
Ovary
Turfgrass Roots
Adventitious Roots
• Grow from crowns as well as nodes
along rhizomes and stolons
p
• Variable lifspan
– May live as long as the shoot they
support
– Climate specific (cool-season versus
warm-season grasses)
– Species specific
Adventitious Roots
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2/7/2008
Root Tip
Turfgrass Root
• Root cap
– Protects the root meristem
– Senses up and down
– Aiding root elongation through soil with
slime sheath
Root Hairs
• Root hairs
– Specialized epidermal cells
– Absorb water and nutrients
Root Cap
Branch Root Formation
Longitudinal Section
of a Root
Cortex
Steele
Epidermis
Root Hairs
Meristematic Region
Root Cap
Root Growth
• Unfavorable soil conditions
– High soil temperatures
– pH <5.0
5.0 and > 7.0
– Oxygen deficiency
– High salt concentration
Root Growth
• Unfavorable cultural conditions
– Close mowing
– Excessive nitrogen fertilization
– Potassium deficiency
– Excessive thatch
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2/7/2008
Seasonal Root Growth
Turfgrasses
Cool-Season
• Perennials
– Dying shoots and roots are
continually replaced
Warm-Season
Spring
Summer
• Management facilitates
replacement growth
Fall
Root : Shoot Ratio
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