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Stress Management

Stress Management. Outline. What is stress and how does it affect potato plants? How does stress impact external tuber quality? How does stress impact internal tuber quality? How can you avoid or manage stress?. What is Stress?.

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Stress Management

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  1. Stress Management

  2. Outline • What is stress and how does it affect potato plants? • How does stress impact external tuber quality? • How does stress impact internal tuber quality? • How can you avoid or manage stress?

  3. What is Stress? • Any condition (moisture availability, temperature, fertility, etc.) that is above or below the optimum for plant growth and tuber production • The “ideal” temperature for growing potatoes is 77oF in the day and 54oF at night. “Therefore, potatoes grown in all regions experience temperature stress every year”

  4. What is Stress? • The impacts of stress tend to be cumulative - 10 days of heat stress is more damaging than 5 days - Two stresses together (ex. heat and water stress) tend to cause more damage than a single stress

  5. Moisture Stress and High Soil Temperatures Combine to Cause Damage No Stress Hot Soil Heat cables increase soil temperature by 6 to 9 F Source: Kleinkopf, 1988

  6. Environment (uncontrollable) Sources of Stress • Heat/cold/frost • Drought/excess rainfall • Hail/lightening • Air pollution

  7. Management (controllable) Sources of Stress • Soil moisture deficits or excesses • Nutrient deficits or excesses • Poor stand establishment • Compaction/root pruning • Physical damage to tubers

  8. Water Stress • Low moisture availability • High demand (heat, wind, excess N) • Low capacity (poor root system)

  9. Heat and Water Stress Occur Together • As temperatures increase, so does water use by the plant

  10. Effect of ET rate on level of soil moisture that can be used before development of stress High Low Data for a sandy soil in Egypt

  11. Stress–related problems Internal • Hollow heart / Brown center • Internal brown spot (IBS) • Sugar ends • Vascular discoloration External • Tuber size • Malformation • Second growth • Chain tubers • Growth cracks • Greening • Enlarged lenticels • Heat sprouts • Black heart • *Blackspot /shatter bruise • Low starch • High sugars • *Frost • *Chilling injury • Pressure bruise *Immediate

  12. From Hiller, WCS 19:169

  13. Stress-related problems Requirements for Expression • Susceptible variety + • Stress conditions • Weather or environment • Management mistakes

  14. Common Defects Triggers Malformations Heat, drought Growth cracks Moisture stress, erratic growth Sugar ends Heat Hollow heart Cold soil, low tuber set Stem end ?? Low solids Heat, early death Net necrosis PLRV Russet Burbank

  15. Outline • What is stress and how does it affect potato plants? • How does stress impact external tuber quality? • How does stress impact internal tuber quality? • How can you avoid or manage stress?

  16. During stress low availability of sugars and the imbalance in top/tuber growth can temporarily stop tuber growth. When growth resumes, it occurs at the site of most active cell growth. The end result is malformed tubers that may have knobs Around the eyes and bud end is where growth resumes

  17. 1. How does stress affect sugar development - Energy production and use • The temperature optimum for Photosynthesis (energy production) is around 65o to 75o F,Respiration (energy use) continues to increase with temperature Source: Winkler, 1961

  18. Plants Continue to Produce Sugars on Hot Days Temperature (F) • There is a period during the morning where photosynthesis reaches the optimum, even on very hot days 61 82 93 86 “Mid-day depression” Source: Dwelle, 1983

  19. Dry matter partitioning – two temps APJ 69:653 Harvest Index = .5 to .7 Harvest Index = .2 to .7

  20. Outline • What is stress and how does it affect potato plants? • How does stress impact external tuber quality? • How does stress impact internal tuber quality? • How can you avoid or manage stress?

  21. During stress there is less sugar available, and the tuber has a harder time converting sugar into starch. The tuber becomes a weaker sink, and the end result is lower specific gravity and more sugar ends Stems Sugar Starch

  22. Carbohydrate metabolism in potato tubers During normal tuber growth, metabolism is driven towards the production of starch. Stress (in-season or in-storage) changes enzyme activity and membrane function

  23. Effect of temperature on specific gravity of potatoes Air Temperature (oF) Cool (77/54) Hot (100/82)

  24. Comparison of soil temperatures at Oakes, ND High sugar ends

  25. Kincaid et al., 1993 R2 = 0.42 Irrigation Frequency “Soil temperature was directly related to percentage of sugar end tubers”

  26. E 0” W 36.6% 50.4% 4” 63.4% 8” 75.7% Impact of row orientation on Russet Burbank quality Percentage of 10 Tuber Sample with Sugar Ends

  27. Row Width Can Influence Sugar Ends Source: Shock, 1988

  28. The damage that occurs to the starch production system early in the season is permanent – The symptoms usually develop when the tubers are exposed to cold Storage at 48 F End of stress Harvest Source: Sowokinos

  29. Effect of a single water stress event on the incidence of disorders in Russet Burbank Source: Shock, OSU

  30. Stress event High or erratic N availability Pattern of hormone changes during tuber growth and storage

  31. Outline • What is stress and how does it affect potato plants? • How does stress impact external tuber quality? • How does stress impact internal tuber quality? • How can you avoid or manage stress?

  32. Principles of Stress Avoidance and Management • Maintain uniform and optimal conditions throughout the plant growth and tuber bulking growth phases • Minimize environmental stress • Avoid added management stress • Plant resistant varieties

  33. Don’t Contribute to Environmental Stress with Management Stress! • Poor root development • Compaction and late cultivation • Poor vine development • Erratic stands and early stress • Excess vine development - Too much N • Disease

  34. Plant root systems 21 days after emergence extracted from: compacted soil (left)uncompacted soil (right)

  35. By row closure a healthy potato root system extends more than 3 feet down and across the entire furrow Source: Modified from Weaver (1926) 1 ft 2 ft 3 ft Root Pruning Compact layer

  36. How does a stand like this impact row closure and soil temperature?

  37. Excess Nitrogen Fertility Can Lead to an Imbalance in Vine and Root Growth Vines with too much N Roots with too much N

  38. Stress (water, heat, nutrients, pests) can lead to premature plant death

  39. Impact of Resistance on Stress Management Intensity of Management Required Resistance Level Input Level High Low Moderate Moderate Low High

  40. Sugar End Susceptibility by Variety Parma, ID - 1994

  41. Varieties With Stress Resistance Heat and Drought Stress Ranger Russet Gem Russet Russet Norkotah Clearwater Russet Umatilla Russet

  42. Water Use Efficiency (WUE) 18 cwt/ in of water 15 cwt/ in of water

  43. Varieties With Stress Resistance Defoliation Stress Ranger Russet Alturas Gem Russet Bannock Russet Summit Russet Russet Norkotah (affects yield)

  44. Varieties With Stress Resistance Stresses Conducive to Hollow Heart Ranger Russet Alturas Shepody Umatilla Russet

  45. Ask questions – gain some wisdom!

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