Transcript Lecture 6- Light Acclamitization

Lecture # 13
Light
Acclimatization
ACCLIMATIZATION:
Adaptation of a Species
to a New Environment
What Is Acclimatization?
Favorable
environment
for
maximum
growth
:
Interior
:
environment
high light, high
nutrition,
high water supply,
high temperature
low light,
low relative
humidity
The Two Sides of Acclimatization
* Light Acclimatization
* Soil Acclimatization
reduce nutrient application,
reduce water frequency.
low light = less growth
= less need for nutrients
= less water need
Organ Level: Leaf
The Plant Leaf - An Overview of Structure
upper epidermis
palisade mesophyll
chloroplasts
spongy mesophyll
vascular parenchyma
xylem
vascular tissues
phloem
stomates
lower epidermis
Anatomical Differences Between
'Sun' and 'Shade' Plants
The Chloroplast - An Overview of Structure
Electron Micrographs
Of Chloroplasts
High Light
Low Light
Organelle Level : Chloroplast
Internal Organization
High light chloroplast
smaller chloroplasts
less thylakoids /
more stroma
More grana stacks
Taller stacks
less chlorophyll per
volume
Low light chloroplast
larger chloroplasts
more thylakoids /
less stroma
Fewer grana stacks
Spreadout thylakoid
more chlorophyll per
volume
Acclimatization
This Peperomia
went from a low
light environment
to a high light
environment.
Its appearance has
changed due inhibition of
chloroplast development
in light-sensitive cells.
Light Overload Can Cause Death!
Placing a low light adapted plant under very bright light will cause
chloroplasts to adsorb too much light energy. The will disrupt
biochemical pathways and they will cease to operate. Leaf scorch is the
result.
These three leaves were
subject to increasing
amounts of time for
acclimatization. The
smaller leaf was most
acclimatized and thus
could better handle the
light load.
Structural and Physiological
Differences Between
'Sun' and 'Shade' Plants
Changes in Natural Light Penetration Occur
Within Interior Spaces Because of Changes
in the Sun's Inclination
Summer sun
Winter sun
General Characteristics of
Sun and Shade Leaves
Descriptive
level
Morphological
Sun leaves
leaves thicker
Due to cuticle
and denser
cell walls
Shade leaves
often, a mosaic
leaf arrangement,
phototropic leaf
petioles, Thin
leaves
General Characteristics of
Sun and Shade Leaves
Descriptive
level
Sun leaves
more stomata
Anatomical Linear leaves
Fewer palisade
layers, shorter
cells,
tighter packing
Shade leaves
fewer stomata
Leaves broader,
More palisade layers,
longer palisade cells
more intercellular
spaces
General Characteristics of
Sun and Shade Leaves
Descriptive
level
Sun leaves
Shade leaves
larger
chloroplasts,
chloroplasts
fewer and
more grana,
smaller grana phototactic -
Ultrastructural smaller
-chloroplasts
General Characteristics of
Sun and Shade Leaves
Descriptive
level
Sun leaves
Shade leaves
Biochemical lower chlorophyll more chlorophyll
high respiration
high LCP
high light
saturation levels
low respiration
low LCP
low light saturation
levels
Differences Between Acclimatized And
Non-acclimatized Plants
Acclimatized
Medium to dark green
leaves
Large leaves
Flat leaves
Thin leaves
Leaves widely spaced
High Sun Grown,
Non-acclimatized
Yellowish to light green
leaves
Small leaves
Partially folded leaves
Thick leaves
Leaves crowded together
Differences Between Acclimatized And
Non-acclimatized Plants
Acclimatized
Internodes long
Thin to medium stems
Leaf position horizontal
or slightly reflexed
Few new leaves
Wide branch angles
Non-acclimatized
Internodes short
Thick stems
Leaf position upright
Many new leaves
Acute angles
Nursery:
6000-1000ft-c
85-95% RH
Greenhouse:
1500-2000ft-c Lighted Warehouse:
300-500ft-c
90-97% RH
40-50% RH
To
Job:
Time = x
1/2 x
xy weeks
Light Acclimatization Pathways
Initial Response.
 Improving Acclimatization Level.
 Reverse Acclimatization.

high
light
low
light
PS rates
R rates
Stored reserves
1 - 2 wks

beginning of acclimatization:
reorientation of chloroplast and grana;
increase in chlorophyll levels;
reduction in respiration rate;
production of new foliage.
2 - 8 wks
acclimatization complete
changes lead to
lower
compensation
point
plant lives
changes do not
lead to
lower
compensation
point
plant dies
Time Required for Acclimatization
 Depends on species, plant size, previous
treatment and magnitude of the change.
1 - 10 weeks or more;
Examples:
Philodendron, Aglaonema - very little time required;
Sun - grown Ficus benjamina and Brassaia
in 40 to 80 % shade - approx. 5 wks;
Ficus nitida in 50 % shade - 10 wks.
Acclimatization Strategies
fertilized w/
slow release
fertilizer
remove pellets
from the
surface;
leach
thoroughly
fertilized w/
soluble
fertilizer
continue with
the
new
fertilization
and water
schedule
underfertilized
continue with the
new fertilization
and water
schedule
continue with the new fertilization
and water schedule
ACCLIMATIZATION
Time line
60 %
Field Production
75%
Greenhouse
(INTERIM ACCLIMATIZATION)
100 %
ON SITE
Photosynthesis (rate)
Leaf life span varies with
species and cultivar
Palm
Dieffenbachia
0
6
12
18
Leaf life span (months)
24
Photosynthesis
+2
+1
Ficus benjamina
(acclimatized)
Ficus benjamina
(nonacclimatized)
0
LCP
-1
0
50
100 150 200
250
Light intensity (ft-c) 12 hours per day
!
Summary Tips:
* Learn as much as possible about the extent
of acclimatization of the purchased plants.
* Provide necessary conditions :
Light is the most important factor.
* Apply fertilizer and water at reduced rates.
The Cheapest Plant
To Buy Is
An Acclimatized Plant