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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.
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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” CO2 Evaporative Cooling Leaves Leaves Roots Sugar Tubers Water/Nutrients
Photosynthesis - only in leaves Sugar – a form of stored energy
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” CO2 Evaporative Cooling Leaves Leaves Roots Sugar Tubers Water/Nutrients
What do we know about potato root systems? 1 Ft 2 Ft 3 Ft 4 Ft Photo by M. Stalham, CUF Modified from Weaver (1926)
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 * Population of 268 unselected clones Source: Iwama, et al., 1981
Cultivar differences in rooting depth 1 ft 2 ft 3 ft Source: Stalham, 2002
Components of the potato “factory” CO2 Evaporative Cooling Leaves Leaves Roots Sugar Tubers Water/Nutrients
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
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 Source: Kelmke and Moll, 1990
For the first ~40 days the seed piece is the primary source of energy for the factory Source: Iritani and Thornton, 1984
Slow emerging crops have shorter stems and smaller leaves Source: Firman, 1987
How do we make the factory more productive? Run it longer!
Yield Components Production per day X Yield = 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 Parma cwt/A Aberdeen DAP DAP
Effect of N fertilizer on ground cover of Russet Burbank 100 N0 80 N100 N200 60 We need to maximize the period of 100% light capture Ground cover (%) 40 20 0 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov
Relatively poor use efficiency of other nutrients * For 90% maximum dry matter accumulation Source: Trehan and Claassen, 1998
Potato Root Growth in Comparison to Nutrient Uptake (Russet Burbank) 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 75o to 80o F,Respiration (energy use) continues to increase with temperature Source: Winkler, 1961
Carbohydrate production is the critical process Fewer carbs available to drive tuber growth hot warm cool warm hot cool Day 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 Cool temperatures during bulking help the factory run efficiently Source: Iritani, 1984
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 Environment Genetic Potential Management
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