Potato Growth and Development Dr. Mike Thornton

Potato Growth Stages

Reprinted from Potato Production Systems, University of ID

Over 90% of tuber dry matter comes from photosynthesis

● The potato plant is basically a starch factory

Photosynthesis - only in leaves

Sugar – a form of stored energy

Roots

Leaves Leaves

Sugar

Water/Nutrients

CO2 Evaporative Cooling

Components of the potato “factory”

Tubers

From Dean, 1994

Roots

Leaves Leaves

Sugar

Water/Nutrients

CO2 Evaporative Cooling

Components of the potato “factory”

Tubers

What do we know about potato root systems?

Modified from Weaver (1926)

1 Ft

2 Ft

3 Ft

4 Ft

Photo by M. Stalham, CUF

Potato roots pose some challenges

Total Root Length

(km m-2)

Adapted from: Stalham and Allen, 2001 and Yamaguchi, 2003

21%

30%

60% Proportion that is root hairs

Cultivar differences in rooting depth

-100

-80

-60

-40

-20

03-Jun 24-Jun 15-Jul 5-Aug 26-Aug

Depth(cm)

EarlyLate

1 ft

2 ft

3 ft

Source: Stalham, 2002

Roots

Leaves Leaves

Sugar

Water/Nutrients

CO2 Evaporative Cooling

Components of the potato “factory”

Tubers

Sprouting

Why do so many defects show up on the stem end? -  Stolon (vascular system) -  Composition (cell size,

no of starch granules, sugars, enzymes)

-  Age

How do we make the factory more productive?

Build it faster!

Potato Growth Stages

Reprinted from Potato Production Systems, University of ID

Building the factory

Sprout growth rate is directly related to soil temperature

0

0.2

0.4

0.6

0.8

1

45 50 55 60 65 70 75

Soil Temperature (F)

Sprout growth rate

Source: Kelmke and Moll, 1990

For the first ~40 days the seed piece is the primary source of energy for the factory

400

450

500

550

600

0.3 0.4 0.5 0.6 0.7 0.8

Weight of seed piece (oz) per stem

Total Yield (cwt/ac)

Source: Iritani and Thornton, 1984

How do we make the factory more productive?

Run it longer!

Potato Growth Stages

Reprinted from Potato Production Systems, University of ID

Running the factory

Yield Components

Yield = Number of days X

Production per day

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

0

200

400

600

800

35 63 91 119 147 175 203

Location Length of Linear Bulking Rate of Linear Bulking

Period (days) Rate (cwt/A/day)

Parma 118 5.9

Aberdeen 51 7.4

Parma

Aberdeen

Effect on location on bulking rate

0

200

400

600

800

60 72 85 99 14 130 141 155 169 184 198

DAP DAP

cwt/A

Effect of N fertilizer on ground cover of Russet Burbank

0

20

40

60

80

100

1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov

Gro

und

cove

r (%

)

N0 N100 N200

We need to maximize the

period of 100% light

capture

Potato Root Growth in Comparison to Nutrient Uptake (Russet Burbank)

0

2 0 0

4 0 0

6 0 0

8 0 0

20 30 40 50 60 70 80 90 100 110 120 130 140

Days After Planting

Rel

ativ

e R

oot L

engt

h a

nd N

Upt

ake

TotalTubersRoot Length

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 temperature optimum for Photosynthesis (energy production) is around 75o

to 80o F , Respiration (energy use) continues to increase with temperature

0

10

20

30

40

50

60

41 59 77 95Temperature (F)

Net Ps Rate

cloudy

sl.overcastsunny

respiration

Source: Winkler, 1961

The factory has several critical processes

Carbohydrate production is the critical process

7570

6055

4540

0

25

50

75

100

Net Carb Production

77 77 86 86 95 95Day

Night cool warm cool warm warm hot

Fewer carbs available to drive tuber growth

cool cool warm warm hot hot

Once the factory is running, sunny but cool (70 to 80 F) conditions help make it more efficient

60

65

70

75

80

85

90

25-A

pr

10-M

ay

25-M

ay

10-Ju

n

25-Ju

n10

-Jul

25-Ju

l

10-A

ug

25-A

ug

10-S

epAve

Max

imum

Tem

pera

ture

(F)

Low Yield YearsHigh Yield Years

Source: Iritani, 1984

Cool temperatures during bulking

help the factory run efficiently

●  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!

Methods to improve skin color - Waxing (popular in the 1950’s) - Production regions (soils and climate) - New varieties (ongoing) - Growth regulators (use of 2,4-D described in 1949)

What do we know about 2,4-D?

ü  Auxin-like compound

ü  Herbicide: broadleaved weeds

ü  Stimulate cell growth in phloem

ü  Blockage starvation death

ü  Stimulate ethylene synthesis in potato*

- Could be direct or indirect

Arteca, R.N. 1982. AJPR 59(6):267-274

Mechanism of color enhancement

“Mechanism of 2,4-D enhancement of red color in

potato periderm is not known.” (Rosen, et. al, 2004)*

* Am. J. Pot. Res. (2009) 86:15-23

1

2

3

4

5

Check/ MCP/ De-blossom Ethylene/ 2,4-D Treatments

b

a

Influence of foliar applications of growth regulators on skin color for the cultivar Red LaSoda. Color rated on a scale from 1-5(darkest).

The darker color going into storage – the darker they come out of storage

Specialty varieties

Red Lasoda Purple Pelisse Yukon Gold

Terra Rosa All Blue Bintje

Effect of application timing on skin color or Red Lasoda

c

a ab

bc c

Acknowledgements