Post on 10-May-2015
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Plant physiology as a tool of productivity in different orchard systems
John Palmer, Plant & Food Research Ltd., Motueka Research Centre, New Zealand
The New Zealand Institute for Plant & Food Research Limited
Kerikeri 35o S
Auckland
Ruakura Te Puke
Hawke’s Bay
Marlborough
Lincoln
Nelson
Clyde 45o S
Palmerston North
Plant & Food Research
The New Zealand Institute for Plant & Food Research Limited
A Crown Research Institute
The New Zealand Institute for Plant & Food Research Limited
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.
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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.
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Fruit development pathway
Flower evocation
Flower differentiation
Flowering
Fertilisation
Fruit growth
Fruit maturation
Fruit harvest
Fruit storage &distribution
Consumer
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Orchard development pathway
Choice of cultivar
Choice of rootstock
Tree spacing
Tree quality
Tree training
Early yield and fruit quality
Mature yield and fruit quality
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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.
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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.
The New Zealand Institute for Plant & Food Research Limited
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.
The New Zealand Institute for Plant & Food Research Limited
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.
The New Zealand Institute for Plant & Food Research Limited
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.
The New Zealand Institute for Plant & Food Research Limited
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.
The New Zealand Institute for Plant & Food Research Limited
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.
The New Zealand Institute for Plant & Food Research Limited
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.
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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?
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Tree manipulation in the Tree manipulation in the nursery and the orchardnursery and the orchard
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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.
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A well-feathered tree of ‘Braeburn’/M.9
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Effect of concentration and frequency of application of BA sprays on ‘Fuji’/MM.106
BA concn. mg L-1
Number of feathers
Total length of feathers (m)
Mean feather 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
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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-1
GA4+7
400 mg L-1 GA4+7
200 mg L-1 GA3
400 mg L-1 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
(Simplified from Palmer et al. 2010)4 weekly sprays of BA followed by4 weekly sprays of GA
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Young ‘Scifresh’/M.9 treeshowing typical barewood
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Excessive axillary flowering, with poor quality spurs, particularly towards the base of the shoot
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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
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Effects of GA on floweringand 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.
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Extinct spurs
Blind buds
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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)
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TDZ (2500ppm) applied 3.5 weeks before budbreaktaken 7.7 weeks after treatment.
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Treated on the left with 2500 mg L-1
TDZ the previous year.
Untreated on the right.
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Carbon acquisition:Carbon acquisition:light into total dry matterlight into total dry matter
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The whole apple tree responds dynamically to changes in incident light
6 7 8 9 10 11 12 13 14 15 16 17 18 19 200
1
2
3
4
5
6
7
8
0
100
200
300
400 CO2 uptake Solar radiation
CO
2 exc
hang
e ra
te g
h-1
Time of day
Inci
dent
sol
ar ra
diat
ion
PA
R (W
m-2)
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0.0 0.5 1.0 1.50
5
10
15
20
25
sugar beet
potatoes
barley
apples
Tota
l dry
mat
ter p
rodu
ctio
n (t
ha-1)
Intercepted solar radiation (GJ m-2)
Relationship between intercepted solar radiation anddry matter production
Redrawn from Monteith (1977)
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Seasonal pattern of light interception by ‘Fuji’/M.9 apple in New Zealand
0 30 60 90 120 150 180 210 240 2700
10
20
30
40
50
0
5
10
15
20
25
30
35
Ligh
t int
erce
ptio
n (%
)
Time from September 15 (days)
Mea
n 5
day
sola
r rad
iatio
n (M
J m
-2 d
-1)
Redrawn from Palmer et al. (2002)
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Relationship between seasonal light interception and total dry matter production for apple
400 600 800 1000 1200 14000
5
10
15
20
25
30 Royal Gala Braeburn Fuji UK data
Light interception (MJ m-2 PAR)
Tota
l dry
mat
ter p
rodu
ctio
n (t
ha-1)
From Palmer et al. (2002)
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Factors influencing light interception
Tree factors – how we capture the light1. leaf area index2. tree height3. row orientation4. tree width5. cultivar
Site factors – what light is available1. latitude 2. cloudiness 3. frost-free period
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Relationship between LAI and light interception
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.50
10
20
30
40
50
60
70
80
90
100Li
ght i
nter
cept
ion
%
Leaf area index
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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.
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Harvest index: Harvest index: total dry matter into fruit total dry matter into fruit
dry matterdry matter
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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.
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Effect of crop load on partitioning of dry matter of ‘Crispin’/M.27 apple trees.
Palmer, 1993
0 5 10 15 20 25
0
10
20
30
40
50
60
70
80
90
100
% d
ry m
atte
r inc
rem
ent
Number of fruit/leaf area (fruit m-2)
Fruit
Leaf
Wood
Root
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Commercially, our harvest index may be less than that physiological possible because of:
1) young trees2) bienniality3) reduced crop load to achieve our
desired fruit size profile.
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Effect of crop load on partitioning of dry matter into fruit, ‘Crispin’/M.27
30 40 50 60 70 80 90150
200
250
300
350
400
450M
ean
fruit
wei
ght (
g)
Partitioning to fruit (%)
Data of 1982 taken from Palmer (1992)
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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 down4. PGRs
All by reducing vegetative vigour.
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Apple tree growth control by rootstocks
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A two year old treeof ‘Peasgood Nonsuch’apple on M.27 rootstock, showing a very high harvest index
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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.
Harvest index
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Fruit quality:Fruit quality:fruit dry matter into fruit dry matter into
saleable productsaleable product
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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
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Generalised effects of shade on apple fruit quality
Shade decreases:fruit weightfruit red coloursoluble solids concentrationbitter pit incidence and severitysunburnskin russetflower bud numbersfruit set
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Shady business is therefore to be discouraged in the orchard, for more reasons than one!
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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.
Certainly one of the major drivers in the adoption of intensive systems has been the desire for better light distribution within our tree canopies.
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‘Fiesta’/M.9 three-row bed
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Shaded fruit within the canopy
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Recent ways of manipulating light in the orchard
Reflective mulch
1. newer materials now available that can be run over with tractors.
2. importance of diffuse scattering.
Hail netting
1. need minimum shade coupled with effective hail control.
2. lighter colours increase scattered light.
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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
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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).
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Fruit dry matter and quality
Taste with apples has, until recently, largely been determined by fruit maturity, although for some cultivars a minimum soluble solids concentration is being specified.
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.
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Fruit dry matter and quality
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 integratedinto the development of fruit quality.
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Composition of the edible portion of several fruit (USDA website)
% of dry matter Fruit
Fruit dry matter
(%) Sugar + starch
Fibre
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
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Royal Gala from 4 orchards in Nelson and four orchards in Hawke’s Bay
10 11 12 1311
12
13
14
Hawke's Bay Nelson
Sol
uble
sol
ids
afte
r 12
wee
ks s
tora
ge (o B
rix)
Soluble solids at harvest (oBrix)
r2 = 0.41
From Palmer et al. (2010)
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Royal Gala from 4 orchards in Nelson and four orchards in Hawke’s Bay
12 13 14 15 1610
11
12
13
14 Hawke's Bay Nelson
Solu
ble
solid
s at
har
vest
(o Brix
)
Dry matter concentration at harvest (%)
r2 = 0.32
From Palmer et al. (2010)
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Royal Gala from 4 orchards in Nelson and four orchards in Hawke’s Bay
12 13 14 15 1610
11
12
13
14 Hawke's Bay Nelson
Solu
ble
solid
s af
ter 6
wee
ks s
tora
ge (o Br
ix)
Dry matter concentration at harvest (%)
r2 = 0.53
From Palmer et al. (2010)
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Royal Gala from 4 orchards in Nelson and four orchards in Hawke’s Bay
12 13 14 15 1610
11
12
13
14 Hawke's Bay Nelson
Sol
uble
sol
ids
afte
r 12
wee
ks s
tora
ge (o B
rix)
Dry matter concentration at harvest (%)
r2 = 0.82
From Palmer et al. (2010)
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Relationship between fruit dry matter concentration and soluble solids after 12 weeks storage of ‘Royal Gala’ and ‘Scifresh’. Samples from Nelson and HB
13 14 15 16 17 1811
12
13
14
15
16
Solu
ble
solid
s (o Br
ix)
Fruit dry matter concentration (%)
Royal Gala Scifresh
r2 = 0.97
From Palmer et al. (2010)
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Apple fruit dry matter concentration (DMC) and soluble solids
Redrawn from McGlone et al. (2003)
‘Royal Gala’ fruit from 3 orchards and two picking dates
r2 = 0.93
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Consumers’ scores for ‘Royal Gala’ apples from different DMC categories after 10–12 weeks of cool
storage.
Low Moderate High0
2
4
6
8
Liki
ng S
core
DMC Category
b b
a
Low Moderate High0
20
40
60
80
100
Acce
ptab
ility
%
DMC Category
bab
a
Low Moderate High0
20
40
60
80
100
Like
lihoo
d of
Pur
chas
e %
DMC Category
bb
a
From Palmer et al. 2010
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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.
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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?
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Key fluxes into and within apple fruit
Sor = sorbitolFru = fructoseGlu = glucoseSuc = sucrose
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Where to from here?Where to from here?
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Growing to product Growing to product specificationspecification
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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.
The New Zealand Institute for Plant & Food Research Limited
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.
The New Zealand Institute for Plant & Food Research Limited
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.
The New Zealand Institute for Plant & Food Research Limited
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.
The New Zealand Institute for Plant & Food Research Limited
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.
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Our traditional view of the orchard system
Modified from Bruce Barritt
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Our enlarged view of the orchard system
Sustainability
Carbon footprint
Water footprint
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SummarySummary
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.
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www.plantandfood.com
John.Palmer@plantandfood.co.nz
Thank you