Fruit Growth
Ted DeJong
Fruit growth is made up a cell division 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).
AlmondPistachio 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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Frui
t fre
sh m
ass
(g /
fruit)
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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.
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.
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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Total fruit dry mass per tree
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n fru
it dr
y m
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uit -
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Mean individual fruit dry weight
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Grossman and DeJong 1995, Tree
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
uit d
istri
butio
n in
to c
lass
es
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
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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p fre
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ield
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Fruit average fresh massTotal Crop fresh yield
Effect of crop load in fruit growth and crop yield
1 2 3 4 5 6 7 8 9 10
0.10.20.30.40.5
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Fruit fresh mass classes
Frac
tion
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uit i
n cl
ass
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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ativ
e G
row
th R
ate
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-1 d
d-)
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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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row
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ate
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-1 d
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sFr
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ass
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
Day
s of
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t gro
wth
AndrossBowenCarolyneCarsonCoronaDavis
HalfordLoadelRossStarn
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).
Weather-Related Models & ServicesThese programs provide timely weather-related tree crop information specifically for California fruit and nut growers, researchers, and industry. Air temperatures, collected from the California Irrigation Management Information System (CIMIS) weather stations, are used for model calculations.
About CIMIS Weather Stations
About Weather-Related Models
Weather Links
Dormancy, chill accumulation, rest-breaking & freeze damage
Harvest Prediction Modelfor Peaches, Plums and Nectarines
Almond Hull-Split Prediction Model(in beta test stage: Fall 2011)
DaysafterBloom
Bloom DateFeb 15 Feb 15 Feb 15 Feb 15 Feb 15 Feb 152014 2013 2012 2011 2010 2009Accumulated Growing Degree Hours (GDH)
1 552 369 133 314 361 171 2 779 522 260 406 584 239 3 933 683 400 527 816 346 4 N 726 473 587 959 486 5 N 746 581 642 1,126 617 6 N 804 695 708 1,226 744 7 N 900 864 801 1,288 950 8 N 998 1,054 888 1,387 1,215 9 N 1,089 1,299 966 1,533 1,433 10 N 1,228 1,473 1,028 1,616 1,610 11 N 1,344 1,573 1,049 1,777 1,787 12 N 1,508 1,641 1,099 1,929 1,922 13 N 1,702 1,704 1,209 2,099 2,125 14 N 1,930 1,803 1,306 2,298 2,435 15 N 2,222 1,896 1,500 2,480 2,723 16 N 2,541 1,957 1,722 2,594 2,949 17 N 2,752 2,122 1,888 2,663 3,092 18 N 2,992 2,334 2,110 2,764 3,194 19 N 3,162 2,574 2,340 2,873 3,294 20 N 3,281 2,681 2,509 3,038 3,406 21 N 3,333 2,761 2,659 3,154 3,548 22 N 3,443 2,937 2,897 3,212 3,617 23 N 3,614 3,158 3,166 3,264 3,716 24 N 3,830 3,379 3,341 3,369 3,832 25 N 4,097 3,543 3,529 3,539 3,980 26 N 4,380 3,742 3,740 3,648 4,172 27 N 4,692 3,979 4,035 3,774 4,361 28 N 5,014 4,265 4,347 3,991 4,525 29 N 5,320 4,579 4,575 4,261 4,754 30 N 5,596 4,849 4,732 4,532 5,005
Harvest Prediction Model - Station #39 Parlier
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
Day
s of
frui
t gro
wth 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
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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
R 2= 0.6254
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Kingsburg
Modesto
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A
R D
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( m
m )
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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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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Degree-days after bloom
Frui
t RG
R (m
g g-1
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) Spring LadyCal Red
From Grossman and DeJong 1995
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199020042006
FullBloom
Spring Lady
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FullBloom
Cal Red
Day of year
Frui
t dry
wei
ght (
g fru
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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t abs
olut
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owth
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ay-1 fr
uit-1
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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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ulat
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men
t (g
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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
Sup
ply
func
tions
Dem
and
func
tions
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.
