Transcript Plant Growth Regulation of Herbaceous Perennials

Plant Growth
Regulators
Plant Growth Regulators
are naturally occurring or
synthetic compounds that
affect plant growth and
development
3 Types of Chemical Plant
Growth Regulators



Growth-inhibiting chemicals
Growth-promoting chemicals
Root-promoting chemicals
Plant Hormones
“Chemical Messengers”
 Auxins
 Cytokinins
 Gibberellins
 Ethylene
Rooting Hormones
 Auxin,
which stimulates rooting, is
the main component
 IAA (indoleacetic acid)
 IBA (indolebutyric acid)
 NAA (naphthaleneacetic acid)
Rooting Hormones
 Combination
of IBA and NAA
 Powder Formulations
 Hormodin
 Hormo-Root
 Rhizopon
 Liquid
AA
Formulations
 Woods
Rooting Compound
 Dip’ N Grow
Liquid Hormones
Powder Hormones
Cytokinins
 Responsible
for shoot initiation
 Present in rapidly dividing tissue
 Benzyladenine (BA)
 synthetic
cytokinin
 increases offset formation in hosta
Gibberellic Acid (GA)
 Promotes
cellular elongation
(stretched internodes)
 Increases fruit set
 Pro-Gibb: Enlarges flowers and
elongates peduncles (stems
supporting flowers)
Ethylene Gas
 Affects
cell division and
development
 Cause flowering
 Causes fruit ripening
 Causes leaf abscission
Plant Growth Retardants
(PGRs)
are any chemicals that
slow cell division and
elongation in shoot tissues
Why Control Growth?
 Blow-over
 Plants
out-grow pots
 Watering becomes difficult
 Increased shipping costs
 Leggy, low quality plants
Methods of Growth Control
 Pruning
 costly
and time consuming
 Genetics
 not
always available
 consumers wary of GMOs
Methods of Growth Control
 Environmental
Low
controls
fertility
Negative DIF (Temp)
Water Stress
Brushing, vibrations, and other
mechanical disturbances
Many growers find chemical
plant growth retardants to
be an effective and
inexpensive method of
growth control
How do they work?
Gibberellin
Inhibitors
Release
Biosynthesis
of Ethylene
Notice branching effects
Notice height control
Synergistic effects of two PGRs
Increasing PGR Effectiveness
In Non-responsive Perennials
Additional Benefits:
 Control
production schedule
 Increase branching
 Induce flowering
 Drought tolerant
 Pollution tolerant
Additional Benefits:
 Intensely
green foliage
 Resistant to mechanical damage
 Protection from some pests
(whiteflies)
 Overall higher quality and
aesthetic value
PGRs for use in Greenhouses:
B-Nine
Cycocel
Bonzi
Sumagic
Florel
A-Rest
Chemical PGRs
 B-Nine
(Daminozide)
labeled
for annuals and herbaceous
perennials
low activity (relatively safe)
 Cycocel
not
(Chlormequatchloride)
labeled on many crops
causes yellowing above 1500 ppm
Chemical PGRs
B-Nine/Cycocel
Synergistic
tank mixes
combination
Cycocel 800-1,500 ppm
B-Nine 800-5,000 ppm
Chemical PGRs
A-Rest
(Ancymidol)
intermediate
broad
label
activity
Chemical PGRs
 Bonzi
(Paclobutrazol)
 broad
spectrum label
 high activity
 Sumagic
 broad
(Uniconazole)
spectrum label
 most active PGR
Chemical PGRs
 Florel,
Ethrel, Pistill, (Ethephon)
causes
plant to release ethylene
narrow-spectrum label
PGR Efficacy
Application
timing
Dosage
Target
tissue
foliage/stems
substrate
PGR Efficacy
Environmental
Conditions
environment
at application
status of plant
post-application treatment
Application
Technique
Application
 Chemical
must be accurately
measured
 ALWAYS wear long sleeves,
pants, gloves, and shoes with
closed toes when mixing and
applying PGRs!!!!!!
 Media
Drenches
specific
volume/pot
 Foliar
Sprays
Specific
volume/area
(0.5gallons/
100ft2)
PGR overdose
 Example:
Bonzi overdose on pansies
 Ways To Reverse
 gibberellins
(Pro-Gibb)
 high-N nutrition
QUESTIONS?