Potato Growth and Development
Dr. Mike Thornton
Outline



Growth stages
Plant structures (leaves, roots, tubers)
Management
Potato Growth Stages
Reprinted from Potato Production Systems, University of ID
Plant growth types
Indeterminate – Continues to produce leaves
after bulking starts (late maturity)
Determinate– Leaf production stops after
bulking starts (early maturity)
 The
potato plant is basically a
starch factory
Over 90% of tuber dry matter comes
from photosynthesis
Components of the potato “factory”
Evaporative Cooling
CO2
Leaves
Leaves
Roots
Tubers
Water/Nutrients
Sugar
Photosynthesis - only in leaves
Sugar – a form of
stored energy
From Dean, 1994
Plants compensate for hail damage by being more
productive in the remaining leaves
Young leaves
Old leaves
From Rowe, 1993
Components of the potato “factory”
Evaporative Cooling
CO2
Leaves
Leaves
Roots
Tubers
Water/Nutrients
Sugar
What do we know about potato root
systems?
1 Ft
2 Ft
3 Ft
4 Ft
Modified from Weaver (1926)
Photo by M. Stalham, CUF
Potato roots pose some challenges
Proportion that is root hairs
60%
Total Root
Length
(km m-2)
30%
21%
Adapted from: Stalham and Allen, 2001 and Yamaguchi, 2003
Rooting characteristics by maturity class
Maturity group*
Mean growth
period (days)
Root dry wt
(g/plant)
Very early
76
1.3
Early
85
1.6
Medium early
95
1.8
Medium late
106
1.9
Late
115
2.2
Very late
134
2.8
* Population of 268 unselected clones
Source: Iwama, et al., 1981
Cultivar differences in rooting depth
3-Jun
0
24-Jun
15-Jul
5-Aug
26-Aug
Depth(cm)
-20
-40
-60
1
ft
2
ft
-80
-100
Source: Stalham, 2002
3
ft
Early
Late
Components of the potato “factory”
Evaporative Cooling
CO2
Leaves
Leaves
Roots
Tubers
Water/Nutrients
Sugar
Why do so many defects
show up on the stem end?
- Stolon (vascular
system)
- Composition (cell size,
no of starch granules,
sugars, enzymes)
- Age
Plant Characteristics

Vegetative propagation from tubers
- True seed used in breeding
Sprouting
 The
potato plant is basically a
starch factory
Over 90% of tuber dry matter comes
from photosynthesis
How do we make the factory
more productive?
Build it faster!
Sprout growth rate is directly related
to soil temperature
1
0.8
Sprout
growth rate
0.6
0.4
0.2
0
45
50
55
60
65
Soil Temperature (F)
Source: Kelmke and Moll, 1990
70
75
For the first ~40 days the seed piece is the
primary source of energy for the factory
600
550
Total Yield
500
(cwt/ac)
450
400
0.3
0.4
0.5
0.6
0.7
Weight of seed piece (oz) per stem
Source: Iritani and Thornton, 1984
0.8
Slow emerging crops
have shorter stems and
smaller leaves
80
14-Mar
11-Apr
12-May
60
% Ground
40
Cover
20
0
1-May
26-Jun
25-Jul
Date
Source: Firman, 1987
21-Aug
16-Oct
How do we make the factory
more productive?
Run it longer!
Yield Components
Production
per day
Yield =
X
Number of days
Example 1: 10 cwt/day X 50 days = 500 cwt
Example 2: 10 cwt/day X 70 days = 700 cwt
6-10 cwt/day is typical for ID
Effect on location on bulking rate
800
800
cwt/A
Parma
600
600
400
400
Aberdeen
200
200
0
0
35
60
72 63
85
99 9114
119141 155
147 169 175
130
184 198203
DAP
DAP
Location
Length of Linear Bulking
Rate of Linear Bulking
Period (days)
Rate (cwt/A/day)
Parma
118
5.9
Aberdeen
51
7.4
Effect of N fertilizer on ground
cover of Russet Burbank
Ground cover (%)
100
N0
N100
N200
80
60
40
20
0
1-May
1-Jun
We need to
maximize the
period of
100%1-Aug
light 1-Sep
1-Jul
capture
1-Oct
1-Nov

Relatively poor use efficiency of other nutrients
Species
External K requirement
(uM conc.)*
Internal K requirement
(% K in dry matter)
Potato
40.5
7.7
Wheat
6.4
5.8
Sugar beet
4.4
5.4
* For 90% maximum dry matter accumulation
Source: Trehan and Claassen, 1998
Relative Root Length
and N Uptake
Potato Root Growth in Comparison
to Nutrient Uptake (Russet Burbank)
Total
Tubers
Root Length
20
30
40
50
60
70
80
90
100 110 120 130 140
Days After Planting
Source: Pan, 1994
You can’t run the factory at full capacity
without intercepting sunlight
How do we make the factory
more productive?
Run it more
efficiently!
The factory has several critical processes
60
50
cloudy
40
30
20
respiratio
n
10
95
0
77
Net Ps Rate
sl.
overcast
sunny
59
The temperature
optimum for
Photosynthesis (energy
production) is around
75o to 80o F , Respiration
(energy use) continues
to increase with
temperature
41

Temperature (F)
Source: Winkler, 1961
Carbohydrate production is the critical process
100
Fewer carbs available to
drive tuber growth
75
70
75
60
55
Net Carb
Production
45
50
40
25
0
Day
Night
77
cool
cool
77
cool
warm
86
warm
cool
86
warm
warm
hot95
warm
95
hot
hot
90
85
80
75
70
65
Cool temperatures
during bulking
help the factory
run efficiently
A
10 pr
-M
25 ay
-M
a
10 y
-J
u
25 n
-J
u
10 n
-J
u
25 l
-J
10 ul
-A
u
25 g
-A
u
10 g
-S
ep
60
25
-
Ave Maximum Temperature (F)
Once the factory is running, sunny but cool (70 to 80 F)
conditions help make it more efficient
Source: Iritani, 1984
Low Yield Years
High Yield Years

What about “silver bullet” products that claim
to improve yield and quality?
Any product that is going to
increase yield has to:
- Build the factory quicker!
OR
- Run the factory longer!
OR
- Run it more efficiently!
Control of yield and quality is complicated
Environmen
t
Genetic
Potential
Managemen
t
Key Points




Potatoes undergo five stages of development
Leaves, roots and tubers are all key components of the
potato “factory”
Light interception (photosynthesis) is the key process
that drives productivity
Canopy development/duration and length of tuber
bulking determine final yield