understanding how fruit trees work “reviewing the...
TRANSCRIPT
Understanding How Fruit Trees Work
“Reviewing the Fundamentals”
Ted DeJong
The Fundamentals:
The overall objective of all cropping systems is to
maximize resource capture and optimize resource
use to achieve sustainable economic yields.
What resources are we mainly interested in?
• light energy• carbon • oxygen • water • nutrients
What are the three most
prominent chemical
elements in dry plant
parts?
Carbon C
Hydrogen H
Oxygen O
(Roughly in a ratio of
40:7:53)
Where does all that C H O
come from?
PHOTOSYNTHESIS!
The basic photosynthesis/respiration reactions(the most important processes for supporting life on the planet)
Carbohydrates + Oxygen(H2O) (CO2) (CH2O)n (O2 )
Photosynthesis
Respiration
Solar energy
absorbed by
chlorophyll
Chemical energy
To build and repair
Water + Carbon dioxide
Plants, nature’s
original solar energy
collectors
• What are nature’s natural
solar energy cells?
• Chloroplasts
• Problem: chloroplasts need an aqueous environment to function, air is dry and CO2
from air is required for photosynthesis.
• Solution: leaves with waxy cuticle to prevent dehydration and air control vents called stomates.
The primary function of tree structure is to support and
display leaves and the sole function of leaves is to house
and display chloroplasts for solar energy collection.
Carrying out photosynthesis is always a compromise between
taking up CO2 and losing H20.
Under non-stress conditions, canopy photosynthesis is a
direct function of the light intercepted by the canopy during
a day.
Rosati, et al. 2002. Acta Hort. 584: 89-94
Waln
uts
A
lmon
ds
Light interception
(that drives
photosynthesis) is
related to crop yield
but why then is there
so much scatter in all
of these points?
Lampinen, et al.,2012
Carbon distribution within the tree
The translocated
CH2O’s are mainly
sorbitol, sucrose and
glucose in almond
trees.
(This is a conceptual
diagram of where the
CH2O’s go but how
does that happen?)
What determines how and where CHO’s are used within
the tree?
This is a question that has received much attention over the past
50 years and scientists still disagree about it.
However, I believe it is relatively simple.
Carbon distribution is mainly controlled by the development and
growth patterns of individual organs and their ability to compete for
CH2O’s.
• A tree is a collection of semi-autonomous organs and each organ type has an organ- specific developmental pattern and growth potential.
• Organ growth is activated by endogenous and/or environmental signals.
• Once activated, environmental conditions and genetics determine conditional organ growth capacity.
• Realized organ growth for a given time interval is a consequence of organ growth capacity, resource availability and inter-organ competition for resources.
• Inter-organ competition for CH2Os is a function of location relative to sources and sinks of CH2Os, transport resistances, organ sink efficiency and organ microenvironment.
Bottom line: The tree does not allocate CH2Os to organs, organ growth and respiration takes it from the tree.
practical
examples of this
concept at work
is this type of
tree.
Five cultivars on one tree
Five cultivars on one tree.
What does this carbon distribution look like
through time as the plant grows?
Results from a new, 3-dimensional computer graphics based simulation
model called
L-PEACH
L-Peach Model
Input data
(Lpeach parameters)
Model components Output data
Hourly
Solar radiation
Temperature
Humidity
Irrigation
3D visualizatio
n
(L-STUDIO)
Quantitative data
(LPeachGraphing)
Architectural model
Commercial practices
CH2O and
H2O transport
algorithms
Functionality
of model
components
If we think of the tree as a collection of semi-
autonomous parts, what are the main parts of a
tree that we need to worry about from a CHO sink
point of view?
• Shoot growth
- both annual and daily
• Trunk growth
• Root growth
• Carbohydrate storage
• Fruit growth
In peach, length growth of
most shoots except water
sprouts (epicormic shoots) is
finished by June.
This is different in almonds.
Date
4/1/10 5/1/10 6/1/10 7/1/10 8/1/10 9/1/10
Leng
th (c
m)
0
20
40
60
80
100
high
medium
low
date
4/1/10 5/1/10 6/1/10 7/1/10 8/1/10 9/1/10
grow
th ra
te (c
m d
ay -1
)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
high
medium
low
Seasonal patterns of proleptic
almond shoot growth at three rates
of irrigation.
Note that shoot growth slowed down
by June but then there was a
second flush but addition of nodes
was more continuous.
date
4/1/2010 5/1/2010 6/1/2010 7/1/2010 8/1/2010 9/1/2010nu
mbe
r of n
odes
0
10
20
30
40
50
60
70
80
Contrary to popular opinion,
shoots grow most rapidly in
the afternoon when
temperatures are high and
stem water potential is
recovering form a daily
minimum.
Trunk diameter
growth continues
through most of
the growing
season.
Root growth tends to be
episodic in many species.
There is usually a burst of
activity in spring, a lull in mid-
summer and a second burst
in fall.
Peach example.
(mini-rhizotron data)
Mini-rhizotron data for walnut roots
Calendar day
80 100 120 140 160 180 200 220
Fru
it fr
esh
mas
s (g
/ fr
uit)
0
50
100
150
200
250
Control: no fertilizer applied
Spring N: 200 kg·ha-1
N applied April 1994
Fall N: 200 kg·ha-1
N applied September 1993
Split N: 100 kg·ha-1
N applied September 1993
+ 100 kg·ha-1
N applied April 1994
Peach Apple Almond
Describing fruit growth potentials
Re
lative
Gro
wth
Ra
te
(Co
mp
oun
d inte
rest ra
te)
The potential growth rate of all of
these fruit types can be predicted with
a relative growth rate (decreasing
compound interest rate) function.
Shoot and root biomass
CHO storage in shoots and roots
Fruit biomass
Canopy C assimilation
Supply
functions
Dem
and
functions
The L-Almond model
calculates all the
carbohydrate supply and
demand functions for each
hour of a day.
The model indicates that the
period corresponding to early
fruitlet growth is a time when
carbohydrate availability may
be particularly limiting.
This explains why there is a
fruit drop/abortion period in
late April/May/or early June
in many fruit species.
1 2 3 4 5 6 7 8 9 10
0.20.40.60.8
1 2 3 4 5 6 7 8 9 10
0.20.40.60.8
1 2 3 4 5 6 7 8 9 10
0.20.40.60.8
1 2 3 4 5 6 7 8 9 10
0.20.40.60.8
1 2 3 4 5 6 7 8 9 1000.20.40.60.8
Fra
ction o
f fr
uit d
istr
ibution into
cla
sses
Fruit dry weight classes
Unthinned887 fruits tree -1
Thinned 90 days after bloom
Thinned 60 days after bloom
Thinned 30 days after bloom
Thinned at bloom
220 fruits tree -1
220 fruits tree -1
220 fruits tree -1
220 fruits tree -1
0 50 100 150 200 250 300 350 400
75
100
125
150
175
200
225
250250
Crop load (no. fruits tree-1
)
Fru
it av
erag
e fr
esh
mas
s (g
frui
t -1)
5
10
15
20
25
30
35
4040
Tot
al C
rop
fres
h yi
eld
(Kg
tree
-1)
Fruit average fresh massTotal Crop fresh yield
Effect of crop load on fruit growth and crop yield
1 2 3 4 5 6 7 8 9 10
0.1
0.2
0.3
0.4
0.5
1 2 3 4 5 6 7 8 9 10
0.1
0.2
0.3
0.4
0.5
1 2 3 4 5 6 7 8 9 10
0.1
0.2
0.3
0.4
0.5
1 2 3 4 5 6 7 8 9 10
0.1
0.2
0.3
0.4
0.5
1 2 3 4 5 6 7 8 9 100
0.1
0.2
0.3
0.4
0.5
Fruit fresh mass classes
Fra
ctio
n of
frui
t in
clas
s
n = 350
n = 250
n = 200
n = 100
n = 40
Classes (g)
1 = < 30
2 = 30 - 60
3 = 60 - 90
4 = 90 - 120
5 = 120 - 150
6 = 150 - 180
7 = 180 - 210
8 = 210 - 240
9 = 240 - 270
10 = > 270
Thanks for your attention!
Questions?