5 tree biology fruit growth.ppt - fruit &...

Fruit Growth

Ted DeJong

5Tree_Biology_Fruit_Growth_DeJong 1

Fruit growth is made up a cell dvision phase and a cell enlargement

phase. The length of the cell division phase varies with species.


Shape of typical fruit growth curves


Growth curves for nuts can be quite different ‐‐hazelnut


Walnut


Almond fruit development

Note that the seed cavity is filled up the whole time that the fruit is growing. First with “cheap” nucellar tissue, then with endosperm (hashed lines), then with the seed cotyledons (clear white).


Almond


Pistachio fruit growth is quite different. The house is built first then it is filled.


Pistachio cont.


Presence of seeds can affect fruit growth


Fruit growth and yield are dependent on two separate, but interdependent sets of processes.

• Developmental processes (driving rates of fruit maturation and demand for carbohydrates and nutrients)

• Assimilation processes (determining the supply of carbohydrates and nutrients available to support growth and development)


What do we know about fruit developmental processes?

• The individual fruit growth potential of a given cultivar is governed by a relative growth rate (compound interest rate) function.

• Rates of fruit maturity (time between bloom and harvest) are mainly controlled by heat unit accumulation between bloom and 30 days after bloom.

• When early spring temperatures are high fruit development rates are rapid but fruit size can be negatively affected.


Calendar day

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Fru

it fr

esh

mas

s (g

/ fr

uit)

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Control: no fertilizer appliedSpring N: 200 kg·ha-1 N applied April 1994Fall N: 200 kg·ha-1 N applied September 1993Split N: 100 kg·ha-1 N applied September 1993 + 100 kg·ha-1 N applied April 1994

Peaches and other stone fruit are described as having a double sigmoid growth curve. This pertains mainly to the increase in fresh fruit mass of later (July – Sept.) maturing cultivars. These fruits are described as having three stages of fruit growth.

Stage I

Stage II

Stage III


When fruit mass is expressed on a dry weight basis the double sigmoid nature of peach fruit growth becomes less obvious and when early maturing cultivars are analyzed it disappears entirely.


When fruit growth is expressed as a rate per unit time the biphasic pattern of growth becomes clear even on a dry weight basis in late maturing cultivars but it is not apparent in very early maturing cultivars. It is generally thought that breeding for early maturing cultivars has cut out the middle stage of fruit growth.


There has been a lot of debate about the cause of the double sigmoid pattern of fruit growth but it is now clear that it is primarily just an outcome of the development patterns of fruit over daily (or smaller) time steps relative to their size or development state at the beginning of a time step. In other words the growth potential of an organ over any given time interval is a function of its size at the beginning of the interval and its development pattern over the interval.


Expressing fruit growth as a relative growth rate (RGR) (mass/unit mass/unit time) captures this concept. (RGR is essentially the same as a compound interest rate and the same principles hold—account grows as a function of the interest rate, starting principal, and time.)When analyzed in this way the curves of the early and late maturing fruit look similar except that the RGR remains higher, longer but is then truncated.


Why is this important? Because it provides a way to understand fruit growth and the responses of fruit growth to crop load, thinning and even weather in different years.The asterisks in the slides on the right indicate periods when the RGR of the fruit on heavily thinned trees was different than on unthinned trees. We assume that the fruit on the heavily thinned trees represent the fruit growth potential since resources should not be limiting growth of these fruits. The fruit on unthinned trees show the RGR response to excess crop load.


Note that in early spring the absolute growth rate (AGR) of the unthinned fruit departed from the thinned fruit curve at the same time as RGR became different in the previous slide. But in Cal Red the AGR of the unthinned fruit remained different than the AGR of the thinned fruit during Stage II even though RGR’s were not different. This is because even though the RGRs were the same, the fruit mass was different at the beginning of each interval and thus the AGR was different. 5Tree_Biology_Fruit_Growth_DeJong 19

Note that this results in an increasing departure of the cumulative dry weight of the unthinned fruit relative to the thinned fruit over the season. By reviewing the RGR and AGR curves we can see that this was the result of two interacting factors. Excessive crop load causing a lack of resources to support potential growth rates at specific time intervals, and decreases in potential growth rates subsequent to any interval when a potential RGR was not achieved.


What happens when crop load “stress” is relieved by fruit thinning at different times?Cumulative fruit mass never fully recovers because when growth falls behind potential for any interval, additional growth is compounded on the actual mass at the beginning of each interval, not on the potential mass. 5Tree_Biology_Fruit_Growth_DeJong 21

Back to the L-Peach model. Another feature of the model is that we can simulated fruit thinning. Fruit thinning can be done manually (as in the orchard) by selectively removing individual fruit or automatically by specifying the date of thinning and the minimum distance (number of metamers) between fruit at the beginning of a simulation.


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Crop load with no fruit thinning


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Total fruit dry mass per tree


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Mean individual fruit dry weight


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Grossman and DeJong 1995, Tree 5Tree_Biology_Fruit_Growth_DeJong 36

1 2 3 4 5 6 7 8 9 1000.20.40.60.8

1

1 2 3 4 5 6 7 8 9 1000.20.40.60.8

1 2 3 4 5 6 7 8 9 1000.20.40.60.8

1 2 3 4 5 6 7 8 9 1000.20.40.60.8

1 2 3 4 5 6 7 8 9 1000.20.40.60.8

Frac

tion

of fr

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istri

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Fruit dry weight classes

Unthinned887 fruits tree -1

Thinned 90 days after bloom



Thinned at bloom

220 fruits tree -1

220 fruits tree -1

220 fruits tree -1

220 fruits tree -1


Fruit yield data from four clingstone peach cultivars in commercial orchards near Kingsburg California that were thinned on two different dates in 1992. Data indicate means +- se for six, four-tree replications per cultivar and thinning date. Adapted from DeJong et al. 1992.

Cultivar/ThinningDate

Fruit size(gFW/fruit)

Crop Load(fruit/tree)

Yield(tons/Ha)

Loadel20 March18 May

113.3 ± 1.491.9 ± 2.4

1681 ± 641649 ± 40

56.7 ± 2.045.3 ± 1.6

Carson20 March18 May

127.8 ± 4.7108.2 ± 2.5

1576 ± 741427 ± 53

59.4 ± 2.046.0 ± 2.0

Andross21 March18 May

123.6 ± 2.1115.0 ± 1.7

1888 ± 961766 ± 58

69.3 ± 2.760.8 ± 2.7

Ross27 March19 May

163.9 ± 7.0163.9 ± 3.2

1862 ± 991638 ± 69

80.7 ± 2.572.2 ± 3.1


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Crop load (no. fruits tree-1)

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Fruit average fresh massTotal Crop fresh yield

Effect of crop load in fruit growth and crop yield


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Fruit fresh mass classes

Fra

ctio

n o

f fru

it in

cla

ss

n = 350

n = 250

n = 200

n = 100

n = 40

Classes (g)1 = < 30 2 = 30 - 603 = 60 - 904 = 90 - 1205 = 120 - 1506 = 150 - 1807 = 180 - 2108 = 210 - 2409 = 240 - 27010 = > 270


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Grossman and DeJong 1995. Annals of Botany 75:553-560.

The red curve on the right represents a peach fruit while the dotted lines is representative of the RGR curve of an apple fruit.


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lativ

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ate

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Adjusting the shape and the slope of the relative growth rate curve results in a fruit mass accumulation curve that is characteristic of apple fruit. Thus the basic RGR curve can be adjusted to fit many different fruit crops.


Environmental factors influencing fruit development rate and final fruit size

• Temperatures have a large effect on rate of fruit development and temperatures are primarily limiting during spring time.

• Growing degree hour accumulation in the first 30 days after bloom strongly influence harvest date for a given cultivar and year.

• Because of this, early spring temperatures also have a strong effect on peach fruit size.


Cling Peaches

y = -0.0066x + 215.55

y = -0.0080x + 190.87

y = -0.0063x + 180.23

y = -0.0035x + 179.41

y = -0.0068x + 173.52

y = -0.0066x + 168.16

y = -0.0086x + 207.37

y = -0.0066x + 207.36

y = -0.0076x + 218.74

y = -0.0106x + 218.81

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Sum of GDH one month after bloom

Da

ys

of

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it g

row

th

Andross

Bowen

Carolyne

Carson

Corona

Davis

Halford

Loadel

Ross

Starn


So what?

These relationships indicate that the spring temperatures in the first 30 days after full bloom govern fruit developmental rates and are a major factor in determining the harvest date for a specific cultivar in any given year. This relationship can be used as a tool, early in the season, for growers to estimate the approximate harvest date for stone fruits. This can be easily accomplished, 30 days after bloom, by going to the UC Fruit & Nut Research and Information Center web site (http://fruitsandnuts.ucdavis.edu).


Once there, select ‘Weather Services,’ then ‘Harvest Prediction Model.’Select the location of your nearest California Irrigation Management Information System (CIMIS) weather station and enter the date of full bloom. The data that will be shown are the accumulated GDH during the first 30 days after bloom. Using this number, you can estimate from Figure 1 how many days there will be from full bloom to harvest for this year.




Peaches

y = -0.0056x + 186.86

y = -0.0061x + 161.74

y = -0.006x + 136.76

y = -0.0058x + 108.82

y = -0.0036x + 89.57350

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Sum of GDH one month after bloom

Da

ys

of

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th FlavorCrest

Queen Crest

E.Lady

Maycrest

O'Henry

If the current year is like 2005 and there are 6,851 Growing Degree Hours accumulated between full bloom and 30 days after full bloom Then for Elegant Lady peaches you can expect harvest to be about 123 +/- 3 days from full bloom as indicated below. Keep in mind that weather near the time of harvest and local growing conditions (such as soil type, water status, tree nutrition, etc.) can also have some effect on the harvest date.


y = -0.001 x + 41. 55P < 0.001

R2 = 0.4117

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Kingsburg

Modesto

Yuba City

R D

F S

( m

m )

G D H 3 0 ( x 10 3 )

Higher temperatures in early spring also tend to reduce fruit size at reference date (at the end of Stage I of fruit growth). And because fruit grow according to a RGR function, average fruit size at harvest is also usually smaller, all other things being equal.

Why is fruit size at reference date negatively affected by early spring temperatures?


y = 0.2008x + 21.574

P < 0.001

R2

= 0.6254

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Kingsburg

Modesto

Yuba City

A

R D

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(

m m

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F B D to R D ( d )

Reference date fruit size is highly dependent on the time (days) between bloom and reference date, in other words the rate of fruit development. When development rates are rapid, fruit size at reference date is smaller.


y = - 0.0049 x + 101.45P < 0.001

R 2= 0.5944

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Kingsburg

Modesto

Yuba City

A

F B

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t o

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And, the rate of fruit development is strongly influenced by the temperature or heat accumulation (Growing Degree Hours) during the first 30 days after bloom (GDH30).

Basicly, when spring temperatures are very warm, fruit development rates are faster than the ability of the plant to supply resources to support the potential RGR, and because of the way the RGR function works early fruit size differences can be carried thru to harvest.


Using a computer model to see how warm springs cause smaller fruit size?

This is counter‐intuitive since we aren’t talking about temperatures above 30o C (86o F).


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Spring Lady

Cal Red

From Grossman and DeJong 19955Tree_Biology_Fruit_Growth_DeJong 54

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Spring Lady

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FullBloom

Cal Red

Day of year

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it dry

wei

ght (g

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it -1)

If we use the RGR functions shown on the previous slide to project potential fruit dry weight growth for three contrasting seasons we see substantial differences in the timing of potential fruit sink demands for carbon.


Cal Red

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Spring Lady

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The differences between seasons is even more apparent when potential absolute fruit growth rates of individual fruits are calculated for the first 50 days after bloom.


Cal Red

(2000 fruits tree-1)

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Spring Lady

(1000 fruits tree-1)

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Full bloom

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ulat

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When the individual fruit growth demands are compounded by pre-thinning crop loads during the first 50 days after bloom, the differences in potential carbon demand by the fruit among years is really apparent.

On the other hand how are the differences in temperature among years like to influence carbon supply?

• + effect on leaf Pn rate

• min. effect on canopy Pn because of lack of canopy development within 30 dab

• min. effect on starch mobilization

• greater competition for CH2O from vegetative sinks


Shoot and root biomass

CHO storage in shoots and roots

Fruit biomass

Canopy C assimilation

Su

pp

ly f

un

ctio

nsD

em

an

d fu

nct

ion

s

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 may help explain annual variations in yield that do not appear to be related to weather during bloom.

Take home lessons

• High early spring temperatures can be detrimental to fruit size and crop yield

• The potential negative effects are linked to temperature effects on fruit development

• Growers need to be advised to thin fruit early in years with high spring temperatures and heavy fruit set.

• Global warming is likely to have substantial effects on developmental processes in addition to assimilatory processes of fruit trees and some of these are likely to be quite negative.

• “June fruit drop” is caused by a lack of resources to fulfill the growth requirements of all the fruit that were initially set so some fruit abort.


5 tree biology fruit growth.ppt - fruit &...

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