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Harvest Operations. Tuber bulking vs vine kill timing Equipment operation Crop maturity Vine killing Bruise susceptibility. Potato Growth Stages. Physical Maturity (Skin set). Methods to measure skin set. High . Torque . Low . Low . High . Skinning damage . - PowerPoint PPT Presentation
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Harvest Operations
Tuber bulking vs vine kill timingEquipment operationCrop maturityVine killingBruise susceptibility
Potato Growth Stages
Physical Maturity (Skin set)
Methods to measure skin set
Torque
High
Low
High Low
Skinning damage
Water loss from a potato in storage98% through skin
2% through lenticels
Increases water loss by
3 to 5 fold
Days After Planting
60 74 88 102 116 130 144 158 172
Red
ucin
g S
ugar
s (m
g/g
dry
wt)
0
3
6
9
12
15
18
21
24
Spe
cific
Gra
vity
1.050
1.055
1.060
1.065
1.070
1.075
1.080
1.085
1.090
1.095Bud
Stem
Sp gravity
Reducing Sugars
R2= 0.84**
Changes in tuber composition with maturity
Physiological Maturity = 145 DAP
Knowles et. al., WSU, Pullman
Physiological Maturity (chemical maturity)
Defined as the average of date when:Maximum yieldMaximum specific gravityMinimum sucroseMinimum reducing sugars
Physiological Maturity DatesDays after planting
Cultivar Max Yield Max SG Min Sucrose Min Sugars DAP to PM
Ranger 160 146 130 130 142
Burbank 156 145 142 145 147
Umatilla 144 158 161 155 155
Alpine 169 153 155 143 155
Clearwater 175 175 130 135 154
Trailblazer 175 160 136 142 153
* All cultivars reached maturity between 2800 and 3000 degree days
130 DAP 145 DAP 160 DAP 175 DAP200
300
400
500
600
700
800
900
0
2
4
6
8
10
12
14
16
18
Trailblazer-Yield/vine wt.
cwt/ac vine wt. (lbs)
cwt/
ac
lbs/
5 pl
ants
130 145 160 1751.0550
1.0650
1.0750
1.0850
1.0950
1.1050
1.1150
-0.04
0.00
0.04
0.08
0.12
0.16
0.20
0.24
Trailblazer
Spec. Gravities
Days After Planting
Spec
ific G
ravi
ties
Redu
cing
Sug
ars
Phys. Maturity- (153DAP)
Harvest Time (days after planting)
155 169 174 179 185 193
Per
cent
Sug
ar E
nds
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0 Ranger Russet2005
R2= 0.96**
n = 7
Sugar Ends can Increase With Increasing Maturity of Ranger Russet
Courtesy Mel Martin, J.R. Simplot Co.
Crop MaturityFactors that influence crop maturity:
Variety (Determinate vs indeterminate)Emergence dateNitrogen fertilization IrrigationDisease pressure
Crop Maturity
Important reasons for correct maturity :Simplify vine killingMinimize harvest damageMaximize tuber solidsMinimize tuber sugarsMaximize storability
Vine Killing
Reasons:
Regulate maturityPrepare tubers for handlingControl tuber sizeCoordinate harvest with appropriate season
(need to balance equipment capabilities with climatic conditions)
One main focus of harvest management is bruise reduction - Estimated to cost the US potato industry $298 million annually (1996) - Processing contract incentives - Rejections at market (5% internal defects) - Storage losses (Shrink and rot) - Losses in productivity (processing and fresh pack)
Black spot bruise (a chemical reaction) occurs just beneath the vascular ring (not visible), and skin is not broken.
Shatter bruise breaks the skin, and is a physical damage.
Chemistry of Black Spot Bruise
Brook, R.C. 1996. Potato Bruising. National Potato Anti-bruise Committee
• Tyrosine (a substrate) and polyphenol oxidase (PPO - an enzyme) mix within a cell when cell membranes are damaged
• Oxidation (addition of oxygen) occurs forming intermediate compounds
• End result is melanin (black, gray, or brown color)
• Process takes 12 to 72 hours, depending on temperature
0 10 20 30 40 500
10
20
30
40
50
60
70
SusceptibleResistant
Variation from optimum operation (%)
% Bruise
Source: Thornton et al., 1973
Effect of tuber susceptibility and harvester operation on bruise damage
Tuber Physical Properties Affecting Bruise
• Tuber Sizeo Large tubers > damage small tuberso Small radius (end) > damage large
radius• Cell Sizeo Large cells > damage than small cellso Growth conditions play large roll in cell
size• AgeoBlackspot increases with vine maturity oTubers less susceptible after one month
curing – tubers can withstand 30-80% more impact
Brook, R.C. 1996. Potato Bruising. National Potato Anti-bruise Committee
Tuber Susceptibility to Black Spot Bruise
Brook, R.C. 1996. Potato Bruising. National Potato Anti-bruise Committee
Mineral Nutrition· N and P do not directly affect susceptibility.· Indirectly – deficiency results in earlier
senescence and more mature tubers.· Indirectly – high specific gravity > blackspot
than low specific gravity (N and P both affect specific gravity).
Research on Potassium and Black Spot Bruise
· Black spot bruise potential decreased with increased potassium application in excess of that needed for optimum yield.
· Shatter bruise increased with more potassium.· For each 100 pounds potassium, specific
gravity decreased 2.5 to 3.5 points.
Porter, Greg and P.C. Ocaya. Bruise susceptibility and potassium uptake of Russet Burbank potatoes in response to varied potash rate and timing. University of Maine. Presentation at 2005 PAA meeting. Calgary.
Two requirements for blackspot bruise:- Susceptibility to impact damage
- Potential to darken after impact0 = No
Damage5 = Most
Damage
Field Maturity as it Relates to Blackspot Bruising of Russet Burbank Potatoes
Blackspot Severity Group1 Field Maturity (%)2
Resistant (<2.5)Mod. Susceptible (2.5 – 3.0)Susceptible (3.1 – 3.5)Very Susceptible (>3.5)
19933
17334859
Corsini, D., J. Stark, and M. Thornton. 1999. American J of Potato Research. P.221-226.
19943
54596189
1. Abrasive peel test ratings where 0 = no blackspot and 5 = most damage.2. Percent dead vines in fields in late August.3. R-square values: 1993 = 0.37; 1994 = 0.21. Both significant at P = 0.01.
Mean36465574
Specific Gravity as it Relates to Blackspot Bruising of Russet Burbank
PotatoesBlackspot Severity Group1 Specific Gravity2Resistant (<2.5)Mod. Susceptible (2.5 – 3.0)Susceptible (3.1 – 3.5)Very Susceptible (>3.5)
Corsini, D., J. Stark, and M. Thornton. 1999. American J of Potato Research. P.221-226.
1.0741.0771.0811.083
1. Abrasive peel test ratings where 0 = no blackspot and 5 = most damage.
2. Average for all fields in the survey within a blackspot severity group, 1994. No relationship between specific gravity and bruise in 1993.
Soil Moisture as it Relates to Blackspot Bruising of Russet Burbank Potatoes
Blackspot Severity Group1 Soil Moisture (%)2
Resistant (<2.5)Mod. Susceptible (2.5 – 3.0)Susceptible (3.1 – 3.5)Very Susceptible (>3.5)
Corsini, D., J. Stark, and M. Thornton. 1999. American J of Potato Research. P.221-226.
51413334
1. Abrasive peel test ratings where 0 = no blackspot and 5 = most damage.
2. Available soil water at time of tuber sampling; average for all fields within a severity group. Data for 1994 only. Little to no differences in percent soil moisture in 1993.
Factors Increasing Black Spot Bruise Susceptibility
· More mature vinesRusset Burbank - 70% dead
vinesRanger Russet - 20% dead
vines· Higher specific gravity
Russet Burbank - Above 1.080Ranger Russet - Above 1.085
· Available soil moisture less than 60%
Management Through Harvest- Tuber hydration- Drop height- Pulp temperature- Drop surface
Series10
10
20
30
40
50
60
70
80
90
100
Black SpotShatterTotal
Tuber HydrationDehydrated (limp) Hydrated (crisp)
% D
amag
eTuber Hydration Level Effect on Black Spot and Shatter Bruise of Russet Burbank at
42ºF
Smittle, D.A., et al. 1974. Harvesting Potatoes with Minimum Damage. Am. Potato J. 51: 153-164.
Influence of Post-Vine-Kill Irrigation on Blackspot Bruise of Lemhi Russet Potatoes
Irrigation Treatment Percent Blackspot
No irrigation 1
4 days before harvest 2
8 days before harvest 2
512513
Stark, J. C. January 1987. University of Idaho Potato School Proceedings. P 82-83.
1. Soil moisture at 50% or less at vine kill.2. No effect of irrigation if soil moisture kept at 65% or above after vine kill.
Impact of temperature and drop height on bruise incidence
0 10 20 30 40 50 60 70 80 90 1000
2
4
6
8
10
12
14
16
18
20
50 oFLinear (50 oF)60 oFLinear (60 oF)
Total Bruise (%)
Drop Height (in)
Hyde, G., R. Bajema and R. Thornton, 1993
Impact of temperature and drop height on bruise incidence
0 10 20 30 40 50 60 70 80 90 1000
2
4
6
8
10
12
14
50 oFLinear (50 oF)60 oFLinear (60 oF)
Total Bruise (%)
Drop Height (in)
50 oF on coated chain
Steel surface
Relationship Between Soil Temperature and Tuber Bruising During a 24-Hour Period
More
Less
% B
ruise
MN 4 am 8 am Noon 4 pm 8 pm MNTime of Day
Smittle, D.A., et al. 1974. Harvesting Potatoes with Minimum Damage. Am. Potato J. 51: 153-164.
7
0
6
5
6
0
5
5
5
0
4
5Te
mpe
ratu
re
(°F)
% Bruise
Soil Temperature
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