Palestra j palmer

The New Zealand Institute for Plant & Food Research Limited

Plant physiology as a tool of productivity
in different orchard systems

John Palmer, Plant & Food Research Ltd., Motueka Research Centre,
New Zealand

 Kerikeri 35o S

Plant & Food Research  Auckland

Ruakura   Te Puke

The New Zealand Institute for  Hawke’s Bay
Plant & Food Research Limited 
Palmerston North
Nelson


A Crown Research Institute  Marlborough

 Lincoln

 Clyde 45o S


I began my career in pipfruit physiology over 40 years
ago at East Malling Research Station, England.

Over those 40 years I have been privileged to work
with and to know many of the leading pipfruit
physiologists all over the world. Ours is very much a
world wide community, like all science we advance by
an interaction of ideas, tempered by our own
environment.

And that environment includes, not only the physical
environment, but the grower community and the
funding opportunities and limitations.


Crop physiology is all about understanding the
processes that control and determine plant growth and
development.

Horticulture is all about plant manipulation to achieve
desired ends. Physiological understanding enables us
to predictably manipulate our plants.

Classically, for example, the understanding of the
effect of daylength on flowering has enabled the
glasshouse flower industry to reliably programme the
production of flowers and flowering pot plants.


Fruit development pathway

Fruit growth

Fertilisation Fruit maturation

Fruit harvest
Flowering

Fruit storage &
Flower differentiation distribution

Flower evocation Consumer

Orchard development pathway

Tree training

Tree quality
Early yield and
fruit quality
Tree spacing

Mature yield and
Choice of rootstock fruit quality

Choice of cultivar

Key developments over the last 40 years

I believe that physiology has played, is playing and
will play a key role in the future of fruit growing.

In this talk I will inevitably be selective in the
examples I use of the contribution of physiology.
Many of those examples I have been involved in, but
I choose them just because I am so familiar with
them. Other speakers will cover other key
physiological contributions in their presentations.


Key developments

1. The importance of light interception and
distribution and the link to yield and fruit quality.
2. The widespread adoption of intensive planting on
dwarfing rootstocks.
3. An understanding of the orchard as a system.
4. A general move away from pruning to branch
manipulation.
5. The use of computer models to aid decision making.
6. The use of PGRs in nursery and orchard.
7. The need to apply physiological understanding to
new cultivars.

Key developments

1. The importance of light interception and
distribution and the link to yield and fruit quality.
2. The widespread adoption of intensive planting on
dwarfing rootstocks.
3. An understanding of the orchard as a system.
4. A general move away from pruning to branch
manipulation.
5. The use of computer models to aid decision making.
6. The use of PGRs.
7. The need to apply physiological understanding to
new cultivars.

Presentation overview

1) Tree manipulation

2) Carbon acquisition
- light into dry matter

3) Carbon partitioning
- total dry matter to fruit dry matter

4) Fruit quality
- fruit dry matter into saleable product

5) Where to from here?


Tree manipulation in the
nursery and the orchard


Tree manipulation in the nursery and
the orchard with PGRs

Interest in feathering agents to induce sylleptic
branching began in the USA and in Europe in the
1970s (Max Williams, Jim Quinlan, Bob Wertheim).

The physiological understanding underpinning
this was that the apex suppressed lateral bud
development but application of materials to either
slow the development of the apex or increase the
supply of cytokinins to the lateral buds would
induce axillary bud development.

This resulted in the release of products such as
Promalin, benzyladenine and recently Tiberon.


A well-feathered tree
of ‘Braeburn’/M.9


Effect of concentration and frequency of
application of BA sprays on ‘Fuji’/MM.106

BA concn. Number of Total length of Mean feather
mg L-1 feathers feathers (m) length (cm)
Control 0 1.0 0.6 62
4 sprays 100 4.3 1.9 47
200 8.8 2.5 25
400 12.0 3.3 27
6 sprays 100 6.9 2.1 29
200 13.4 3.7 26
400 15.9 4.1 25
5% LSD 2.78* 1.43* 12.9

* for comparisons within treatments, excluding control

Sprays applied weekly


Effect of repeat sprays of BA followed by
repeat sprays of GAs on the number of
feathers on ‘Comice’/QC

Gibberellin sprays
BA sprays None 200 mg L 400 mg L-1 200 mg L-1 400 mg L-1
-1

GA4+7 GA4+7 GA3 GA3
None 0.9 14.1 16.6 15.7 17.0
750 mg L-1 BA 2.4 12.9 15.3 15.8 17.4
1500 mg L-1 BA 3.5 10.4 10.2 12.7 16.8
Mean 2.5 12.1 13.5 14.5 17.1
P for main effect of BA spray = <0.001; P for main effect of GA spray = <0.001;
P for interaction = 0.001

4 weekly sprays of BA followed by (Simplified from Palmer et al. 2010)
4 weekly sprays of GA


Young ‘Scifresh’/M.9 tree
showing typical barewood


Excessive axillary flowering, with poor quality
spurs, particularly towards the base of the shoot

Tree manipulation in relation to
barewood

1) Prevention of flowering on one-year-old wood
on newly planted trees in the orchard by
using GA sprays in the nursery

2) Reinvigoration of blind buds in the orchard
using local application of thidiazuron

In both cases we were using physiological
understanding in our approach to this
problem


Effects of GA on flowering
and subsequent spur development

• GA3 at 400 mg l-1 applied on 3 January and 30
January on trees in their last season in the
nursery, resulted in a 46% reduction in flowering
the following spring.

• One year later the treated trees showed a 41%
increase in density of spur and terminal flower
clusters along the feathers.

• So by reducing the axillary flowering, we had
allowed vegetative buds to develop into spurs.


Extinct spurs

Blind buds The New Zealand Institute for Plant & Food Research Limited

Effect of timing, product and concentration
on % envigorated buds of ‘Scifresh’/M.9
BA = benzyladenine, TDZ = thidiazuron

Spray Conc. Weeks in relation to bud break Mean
(mg l-1) -2 0 +2 +4
Control 6
BA 500 7 5 9 8 7
BA 2500 3 8 10 7 7
TDZ 500 26 13 8 7 12
TDZ 2500 79 64 69 54 66
Mean 21 17 20 15

P for effect of chemical = <0.001: P for effect of timing = 0.100;
P for interaction = 0.004
Simplified from Palmer et al. (2005)


TDZ (2500ppm) applied 3.5 weeks before budbreak
taken 7.7 weeks after treatment. The New Zealand Institute for Plant & Food Research Limited

Treated on
the left with
2500 mg L-1
TDZ the
previous
year.

Untreated on
the right.


Carbon acquisition:
light into total dry matter


The whole apple tree responds dynamically to
changes in incident light
8 400
CO2 uptake
Solar radiation

Incident solar radiation PAR (W m )
7

-2
-1

6 300
CO2 exchange rate g h

5

4 200

3

2 100

1

0 0
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time of day

Relationship between intercepted solar radiation and
dry matter production

25
Total dry matter production (t ha )
-1

sugar beet
20

15 potatoes

barley
10

apples
5

0
0.0 0.5 1.0 1.5
-2
Intercepted solar radiation (GJ m )

Redrawn from Monteith (1977)

Seasonal pattern of light interception by
‘Fuji’/M.9 apple in New Zealand

35

Mean 5 day solar radiation (MJ m d )
-1
50

-2
30

40 25
Light interception (%)

20
30

15
20
10

10
5

0 0
0 30 60 90 120 150 180 210 240 270
Time from September 15 (days)

Redrawn from Palmer et al. (2002)

Relationship between seasonal light interception and
total dry matter production for apple
30
Total dry matter production (t ha ) Royal Gala
Braeburn
-1

25 Fuji
UK data

20

15

10

5

0
400 600 800 1000 1200 1400
-2
Light interception (MJ m PAR)

From Palmer et al. (2002) The New Zealand Institute for Plant & Food Research Limited

Factors influencing light interception

Site factors – what light is available
1. latitude
2. cloudiness
3. frost-free period

Tree factors – how we capture the light
1. leaf area index
2. tree height
3. row orientation
4. tree width
5. cultivar


Relationship between LAI and light interception

100
90
80
Light interception %

70
60
50
40
30
20
10
0
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
Leaf area index


Light interception has proved to be a
very useful physiological tool to
compare different production systems
with different tree heights, row
spacings and tree pruning and training
treatments.

Light interception sets the upper limit
for production.


Harvest index:
total dry matter into fruit
dry matter


Harvest index

Harvest index is the proportion of the total dry
matter production harvested in the fruit.

It is determined primarily by:

1. crop load

2. the strength of the alternative sinks for
carbohydrate, particularly vegetative vigour.


Effect of crop load on partitioning of dry matter of
‘Crispin’/M.27 apple trees.
100

90

80
% dry matter increment

70
Fruit
60

50

40
Leaf
30

20 Wood
10
Root
0

0 5 10 15 20 25
-2
Number of fruit/leaf area (fruit m )
Palmer, 1993

Commercially, our harvest index may be
less than that physiological possible
because of:
1) young trees
2) bienniality
3) reduced crop load to achieve our
desired fruit size profile.


Effect of crop load on partitioning of dry
matter into fruit, ‘Crispin’/M.27

450

400
Mean fruit weight (g)

350

300

250

200

150
30 40 50 60 70 80 90
Partitioning to fruit (%)

Data of 1982 taken from Palmer (1992)

Nearly all of our recent changes to tree
management have encouraged an
increase in harvest index e.g.

1. dwarfing rootstocks
2. minimal pruning
3. tying down
4. PGRs

All by reducing vegetative vigour.


Apple tree growth control by rootstocks


A two year
old tree
of ‘Peasgood
Nonsuch’
apple on M.27
rootstock,
showing a
very high
harvest index


Harvest index

We can consistently achieve up to 70%
harvest index, for trees at maturity.

Our limitations may be commercial or due to
problems with bienniality.

I do not believe we have reached the limit of
the biological system, particularly in relation
to the speed at which we reach full
production.


Fruit quality:
fruit dry matter into
saleable product


Fruit quality:
fruit dry matter into saleable product

This of course is the critical stage for we need to
present the customer fruit that is attractive, with
good texture and flavour that is typical of the
cultivar.

We are now dealing with hydrated dry matter in a
ready to eat, attractive, healthy, edible package.

There are, however, two key factors that we
have to get right – light distribution and fruit
dry matter concentration


Generalised effects of shade on apple
fruit quality

Shade decreases:
fruit weight
fruit red colour
soluble solids concentration
bitter pit incidence and severity
sunburn
skin russet
flower bud numbers
fruit set


Shady business is therefore to be
discouraged in the orchard, for
more reasons than one!


Certainly one of the major drivers in the
adoption of intensive systems has been the
desire for better light distribution within our
tree canopies.

However, intensive systems of production do
not necessarily mean we avoid the problems
of shading within our canopies.

Never forget the link between light and fruit
quality.


‘Fiesta’/M.9 three-row bed

Shaded fruit within the canopy

Recent ways of manipulating light in the
orchard
Hail netting

1. need minimum shade coupled with effective
hail control.
2. lighter colours increase scattered light.

Reflective mulch

1. newer materials now available that can be run
over with tractors.
2. importance of diffuse scattering.


The use and the misuse of light

High light interception is essential for high yield
per hectare.

Good light distribution is essential for high
quality fruit.

A successful system is one that combines both
of these.

Maximum use with minimum misuse


Fruit dry matter and quality

The packaging of dry matter into a fresh fruit
form is one of the most critical parts of fruit
growing.

Although eye appeal remains important in many
fruit, particularly colour and freedom from
blemish, taste is becoming increasingly
important. Initial purchase is based on eye
appeal but repeat purchase is based on the
eating experience.

Our production target should therefore be yield,
fruit size, appearance AND eating quality
(maturity and dry matter concentration).


Eating quality with apples is complex, as
crispness and juiciness are vital
requirements, as well as taste.

Each cultivar has its own characteristic
texture, flavour and taste.

Taste with apples has, until recently, largely
been determined by fruit maturity, although for
some cultivars a minimum soluble solids
concentration is being specified.



Carbohydrates (starch and sugars) and acids
make up the major proportion of the fruit dry
matter in many fleshy fruit.

Therefore the accumulation of carbohydrate
into the fruit is the key process that
determines the final fruit quality.

Traditionally, however, carbon acquisition and
distribution have not been closely integrated
into the development of fruit quality.


Composition of the edible portion of
several fruit (USDA website)

Fruit dry % of dry matter
Fruit matter Sugar + Fibre
(%) starch
Apple 14 70 17
Kiwifruit 17 55 20
Pear 16 60 20
Apricot 14 70 15
Peach 11 75 13
Melon 10 80 8
Tomato 5.5 50 22


Royal Gala from 4 orchards in Nelson and four
orchards in Hawke’s Bay
14
Hawke's Bay
Soluble solids after 12 weeks storage ( Brix)

2
Nelson r = 0.41
o

13

12

11
10 11 12 13
o
Soluble solids at harvest ( Brix)

From Palmer et al. (2010)

Royal Gala from 4 orchards in Nelson
and four orchards in Hawke’s Bay
14
Hawke's Bay
Nelson
Soluble solids at harvest ( Brix)

13 2
r = 0.32
o

12

11

10
12 13 14 15 16
Dry matter concentration at harvest (%)


14
Soluble solids after 6 weeks storage ( Brix) Hawke's Bay
Nelson 2
r = 0.53
o

13

12

11

10
12 13 14 15 16


Soluble solids after 12 weeks storage ( Brix) 14 2
r = 0.82
Hawke's Bay
Nelson
o

13

12

11

10
12 13 14 15 16


Relationship between fruit dry matter concentration
and soluble solids after 12 weeks storage of ‘Royal
Gala’ and ‘Scifresh’. Samples from Nelson and HB
16 2
Royal Gala r = 0.97
Scifresh
15
Soluble solids ( Brix)

14
o

13

12

11
13 14 15 16 17 18
Fruit dry matter concentration (%)


Apple fruit dry matter concentration (DMC)
and soluble solids

r2 = 0.93
‘Royal Gala’ fruit
from 3 orchards
and two picking
dates

Redrawn from
McGlone et al. (2003)


Consumers’ scores for ‘Royal Gala’ apples from
different DMC categories after 10–12 weeks of cool
storage.
100 100

8 a
80 ab 80
a b

Likelihood of Purchase %
6 b
b a

Acceptability %
60 60
Liking Score

b
b
4
40 40

2
20 20

0 0 0
Low Moderate High Low Moderate High Low Moderate High

DMC Category DMC Category DMC Category

From Palmer et al. 2010 The New Zealand Institute for Plant & Food Research Limited

Fruit quality and fruit maturity

The traditional harvest indices are indicators of
harvest maturity; fruit DMC can be viewed as a
complementary fruit quality index.

A high DMC fruit will only achieve its high
sensory potential if it is harvested at the correct
stage of maturity and then stored in a manner in
which firmness and acidity are optimally
conserved.


The control of DMC

If fruit dry matter concentration is a
useful fruit quality index, then the key
physiological question is then how do
we control and manipulate it to achieve
optimal fruit quality?


Key fluxes into and within apple fruit

Sor = sorbitol
Fru = fructose
Glu = glucose
Suc = sucrose


Where to from here?


Growing to product
specification


Future physiological challenges
– precision horticulture

1. “Every bud counts”
2. Improved rootstocks with resistance to biotic and
edaphic factors for apples and a range of dwarfing,
easily propagated Pyrus rootstocks to revolutionise the
pear industry.
3. Growing to product specification. Consistent high fruit
quality at point of sale, with greater emphasis on eating
quality rather than cosmetic appearance.
4. Increased development of multidisciplinary teams
including molecular biologists.
5. Orchard systems in a wider context.


Our traditional view of the orchard system

Modified from Bruce Barritt


Our enlarged view of the orchard system

Sustainability

Carbon footprint
Water footprint


Summary

I believe physiology has aided the development of
fruit growing in many ways, as I hope this
presentation has illustrated.

But the challenges that are currently with us and will
present themselves in the future will require even
more physiological input. Our fruit growing
industries need to continue to produce desirable,
healthy, saleable fruit, produced in sustainable,
reliable and predictable ways.

Only by understanding the way in which the tree
dynamically responds to its environment and its
own internal regulation can we achieve those goals.


Thank you www.plantandfood.com

John.Palmer@plantandfood.co.nz


Palestra j palmer

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