Potato Growth and Development Dr. Mike Thornton

Potato Growth and Development Dr. Mike Thornton

Potato Growth Stages Reprinted from Potato Production Systems, University of ID

The potato plant is basically a starch factory Over 90% of tuber dry matter comes from photosynthesis

Photosynthesis - only in leaves Sugar a form of stored energy

Components of the potato factory CO2 Evaporative Cooling Leaves Leaves Roots Tubers Sugar Water/Nutrients

From Dean, 1994

Components of the potato factory CO2 Evaporative Cooling Leaves Leaves Roots Tubers Sugar Water/Nutrients

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 Total Root Length (km m- 2 ) Proportion that is root hairs 21% 30% 60% Adapted from: Stalham and Allen, 2001 and Yamaguchi, 2003

Cultivar differences in rooting depth 3-Jun 24-Jun 15-Jul 5-Aug 26-Aug 0-20 Depth(cm) -40-60 1 ft 2 ft Early Late -80 3 ft -100 Source: Stalham, 2002

Components of the potato factory CO2 Evaporative Cooling Leaves Leaves Roots Tubers Sugar Water/Nutrients

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 Building the factory Reprinted from Potato Production Systems, University of ID

Sprout growth rate is directly related to soil temperature Sprout growth rate 1 0.8 0.6 0.4 0.2 0 45 50 55 60 65 70 75 Soil Temperature (F) Source: Kelmke and Moll, 1990

For the first ~40 days the seed piece is the primary source of energy for the factory 600 550 Total Yield (cwt/ac) 500 450 400 0.3 0.4 0.5 0.6 0.7 0.8 Weight of seed piece (oz) per stem Source: Iritani and Thornton, 1984

How do we make the factory more productive? Run it longer!

Potato Growth Stages Running the factory Reprinted from Potato Production Systems, University of ID

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 800 800 600 600 Parma cwt/a 400 400 200 200 Aberdeen 0 35 63 91 119 147 175 203 60 72 85 99 14 130 141 155 169 184 198 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 100 Ground cover (%) 80 60 40 20 0 We need to maximize the period of 100% light capture N0 N100 N200 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov

Potato Root Growth in Comparison to Nutrient Uptake (Russet Burbank) 800 Relative Root Length and N Uptake 600 400 200 Total Tubers Root Length 0 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 The temperature optimum for Photosynthesis (energy production) is around 75 o to 80 o F, Respiration (energy use) continues to increase with temperature Net Ps Rate 60 50 40 30 20 10 cloudy sl. overcast sunny respiratio n 0 41 59 77 95 Temperature (F) Source: Winkler, 1961

Carbohydrate production is the critical process 100 Net Carb Production 75 50 75 70 60 55 Fewer carbs available to drive tuber growth 45 40 25 Day 0 77 77 86 86 95 95 cool cool warm warm hot hot Night cool warm cool warm warm hot

Once the factory is running, sunny but cool (70 to 80 F) conditions help make it more efficient Ave Maximum Temperature (F) 90 85 80 75 70 65 60 25-Apr 10-May Source: Iritani, 1984 Cool temperatures during bulking help the factory run efficiently 25-May 10-Jun 25-Jun 10-Jul 25-Jul 10-Aug 25-Aug 10-Sep 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!

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)

Influence of foliar applications of growth regulators on skin color for the cultivar Red LaSoda. Color rated on a scale from 1-5(darkest). 5 4 3 a 2 b 1 Check/ MCP/ De-blossom Treatments Ethylene/ 2,4-D

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

Specialty varieties Red Lasoda Terra Rosa Purple Pelisse All Blue Yukon Gold Bintje

Effect of application timing on skin color or Red Lasoda a ab c bc c

Acknowledgements