I. Topic

The white "Irish" potato is the world's most important vegetable crop.

	To become familiar with the origin and distribution of the potato.
	To understand the relationship between Ireland and the potato and the consequences of a one-crop agricultural system.
	To become familiar with the composition and nutritive value of the potato.
	To understand the climatic and edaphic requirements for potato production.

The potato originated in the Andes highlands of Peru or Bolivia. The potato was the basic food crop of the Ince, with over 52 separate varieties used by them. The potato arrived in Europe via the Spanish Conquistadores, but was slow to be accepted because of the myth that potatoes were posionous. By 1713 the potato had become the staple crop of Ireland. The potato supported a large increase in population in Ireland, culminating with the potato famine in 1845 and 1846. A fungus disease, Late Blight, infected the potatoes destroying the crop. This disaster caused one million people to starve to death and over 100,000 more to die of disease related to malnutrition. Over one million Irish emigrated mainly to the U.S.

The potato is the most important vegetable crop in the world. In total production, the potato falls in fifth place, after the major cereal grains. Potatoes are cool weather plants, optimum temperature for crop growth occurs when July temperatures average 70 degrees F. The most important areas of production are in Northern Europe and Northern U.S., but there is an increasing use of white potatoes grown in the cooler seasons of sub-tropical areas. The tuber grows best at 60 - 65 degrees F. Potatoes like deep, well drained soils. A silt, loam, or sandy loam are prefered. This is another crop like peanuts and sugar beets that mush be dug out of the ground, so heavy clay soils make harvest difficult. Potatoes are a hungry crop requiring very fertile soils or demanding a high fertilizer application to support the high tonnage produced.

The potato is a perennial grown as an annual. They are generally reproduced by tubers (seed potatoes are pieces of tuber or small tubers, not true seed). Therefore, potatoes, like sugarcane, is reproduced vegetatively. Potatoes are high in nutritional value. They are high in energy and protein and combined with milk, will provide nearly all the essentials for human nutrition. A potatp also has no more calories, ounce for ounce, than an apple. They are usually used for human consumption, but in parts of Northern Europe, they are fed to livestock. They work very well with a simple stomach animal like the hog.

1. Originated in Andes highlands of Peru or Bolivia.

• Many wild species found
• Selected over centuries by Incas
• Began cultivation long before 400 BC

• Uses: headaches, broken bones, rheumatism, indigestion
• Size: nut-apple color: gold, red, blue, black
• Chunyo - preservation by freeze drying

• Turma de tierra - truffle
• Fed to hospital patients in Seville, 1573

• Victim of myth and slander - particularly by French
• No production in England until 1796, but in Ireland 1663 - planted and appreciated!

• Grown almost to exclusion of any other crop
• Advantages:
• Maximum sustenance, minimum labor
• Cheap, abundant, few diseases
• Produced population explosion
• "Set - up" great Irish Potato Famine
• Complete crop failure 1845-46
• Disease - Late Blight, Phytophtora infestan
• 1 million starved, 100,000 died of disease, 1 million immigrated - most to U. S.

• Disease resistant - replenished Europe, N. America, stocks after blight
• "Rough Purple Chili" variety gave rise to at least 1/3 of N. American varieties today

1. World

• Maligned and misunderstood, this homely tuber is, in fact, the world's most important vegetable, after cereals.
• USSR has nearly 2 of total in production of white potato.
• 300 million MT on 48.4 million acres - average yield, 6 MT/A.

• Grown commercially in nearly every state
• Not a single month of year when not being planted or harvested somewhere
• 9.5 million MT annually - 1 billion dollars avg. Production 3.6 MT 91940) > 9.9 MT (1976)
• Consumption - high (1909-13) 182 lbs./capita ; low 110 lbs. (1960). Today 120 lbs.

• Ounce for ounce - no more calories than apple (76 for medium boiled potato)
• High quality protein
• High K
• Starch - alkaline - yielding, more digestible

1. Starch

• 65-90% of tuber dry wt. - in granules amyloplos
• Starch, total solids, specific gravity closely related
• Estimate starch from specific gravity % starch - 17.546 - 199.07 x (sp gr - 1.0988)
• Most mealy bakers - sp grav 1.085 + solids > 20%, starch N 15%
• Increase starch by:
• Planting high starch varieties
• Plant early - harvest late - permit full maturity
• Avoid excess NPK
• Adequate but not excess irrigation water
• Use slow-acting chemicals to kill vines
• Grow where late season climate sunny, < 70 degrees F

• Lignins, coumarin, flavors, anthocyanias, tannins mono-poly-phenolics
• Associated with tuber pigment and discoloration in raw potatoes
• Leaves, sprouts, embryonic tubers have most

• Steroid alkaloid, bitter, poisonous
• Normal concentrations 0.01% of dry wt.
• Concentrated in peel, eyes, sprouts
• May increase 20 x when tuber is:
• Undergoes wound reaction - corks over
• Is "sunburned" - turns green
• Is infected - solamino acts as "phytoalexin"
• Don't feed or eat tubers treated as above.

1. Solanum tuberosum- herbaceous, dicot belongs to nightshade family: Solanaceae

2. Perennial - grown as annual.

3. Generally reproduced by tubers.

4. Parts - vegetative.

• Stems - triangular cross-section 2-5 ft. High Stout, erect branched stems, 1-2 ft. Stolons, underground stems give rise to tubers
• Roots - fibrous, mainly in top 1 ft. Of soil
• Leaves - compound, l-2 ft. Long

• Inflorescence - cyme
• 5-lobed, bell shaped corolla - yellow, white, pink, purple, or striped
• 5 stamens on corolla tube - converge around single pistil - 1 stigma, 1 style, 2 loculed ovary
• Fruit - seedball "Small, green cherry tomato"

• Enlarged portion of underground stem or stolon.
• Eyes - rudimentary scale leaves or leaf scars which contain 3 axillary buds arranged in spiral fashion around tuber-like leaves around stem

• Commercial potatoes tetraploid, though highly self-fertilized do not breed true
• IPC Lima, Peru - investigating using botanical seed rather than tuber pieces for large scale plantings
• Advantage - cheap, would allow potato production in low-income tropical countries
• Disadvantages - lower potato uniformity

1. Temperature

• Cool weather plant
• Optimum growth - when July average 70 degrees F
• Grows mainly N. Europe, N. U. S.
• Tuber grows best 60-65 degrees F, is retarded by soil temperature above 68 degrees F, completely inhibited 85 degrees F
• In South, planted early spring or in fall or winter so grow in cool season
• Potato survives light frosts, freezes at 28.5 degrees - 29.5 degrees F, disintegration after total freezing

• Heavy veg. Growth: long days, high temperatures, high N
• Early tuberization - short days, low temperatures, N deficiency
• Flowering, seed germination - long days, cool temperatures

• Must have uniform supply.
• Fluctuations promote unequal vine and top growth
• If drought followed by good growing conditions - misshapen, growth cracked tubers, low spec. Gravity, poor processing quality
• Irrigation used in arid/semi-arid regions

• Ideal - deep, well drained, sufficient organic matter
• Silt, loam or sandy-loam preferred. Heavy soils may give misshapen tubers. If too wet - more conductive to disease of tubers
• Will grow at wide pH range 4.5 - 7. Optimum 6.5. Normally grown 4.8 - 5.4 because of scab

• Fertile soil or heavy fertilization needed
• Potatoes remove more total nutrients than most other important vegetable crops - particularly K and N (a 300 cwt crop contains 210 lbs. N, 26 lbs. P and 236 lb. K).
• On low pH soils of Atlantic Seaboard, Mn, Co, Cl also mg, B, Mo may be needed.

1. 1975 - > 60 cultivars certified in U. S.

2. Selection criteria:

• Appearance - bright skins, shallow eyes
• Disease resistance: Scab, Verticillium Wilt, Late Blight, Leaf Roll (virus), air pollution
• Yield
• Speciality purposes: early crop, chips, french fries, baking, starch recovery

• Russet Burbank
• Kennebec
• Katahdin
• Superior
• Norchip
• Marigold russet
• Norland
• Red pontiac
• Red ladosa
• Monoma
• Irish cobbler

Rotations

1. Potatoes grown in rotating to:

• Maintain loose friable soil structure
• Keep soil fertile
• Check weeds
• Reduce buildup of diseases, insects

Production

1. "Seed" potatoes - tubers not botanical seed.

• Certified seed - highly recommended
• Grown in N. U. S. and gives highest yields, quality. Least chance of disease
• Both field and bin inspections required
• Seed potato preparation
• Warm 2-3 week 65-70 degrees F
• Cut in blocky pieces with 1 eye, 1.5 - 2 ounce
• If cut before planting, store 60-70 degrees F in high humidity- promotes rapid healing, dust with fungicide
• No. 1B (1/2 - 2" diam.) Whole tubers planted give less rotting

• Fall or early spring plow deep - 2 inches more than 3-5" depth potatoes normally planted
• Compact, fine seedbed not necessary

• 2, 3, 4-row planters
• Automatic - picker-planter
• Cup-type planter - 1,2 operators
• Row-spacing in Virginia, 34-36 inches in-row 8-12"
• Planting date:
• Intermediate - plant late Feb.-April (harvest June-August).
• Late - plant late April - early June (harvest late August-late Sept.).

5. Vine killing:

• Rationale
• Done prior to harvest
• Stops tuber growth
• Hastens tuber maturity
• Thickens and firms skins making digging easier
• Limits potato size
• Reduces late blight virus spread from vines to tubers
• Facilitates mechanical digging
• Chemicals - des-i-cate, Dinitro, Paraquat
• Mechanical beaters, rotary mowers, flaming
• Slow killing promotes nutrient translocation

7. Storage - clean, dry, uninjured tubers.

• 38-40 degrees F for seed
• 45-50 degrees F for chips, french fries, requires sprout inhibitor spray
• Adequate ventilation, remove CO₂, heat
• High humidity - 95%
• Low temperature stored potatoes require conditioning at higher temp. to prevent damage

Potatoes are a very important human food. They are grown in the cool-temperate regions of the world, but there is increasing use of white potatoes in the sub-tropics. Potatoes are nutritious and high yielding. A small field of potatoes can produce high yields and will provide much of the primary carbohydrate needs to feed a family. This crop has the potential to contribute in the war on hunger. As potatoes become more adapted to a wider range of climate and soils, the utilization of this crop will also increase.

VI. Self Assessment
 

	What is the origin of the potato and what group of people first used the potato?
	How did the potato get to Europe? What limited its acceptance?
	Why did the Irish adapt the potato? What was the result of the dependence on a single crop? Explain the impact of this one-crop system.
	What are the climatic and edaphic requirements of the potato? How does this limit the distribution of the potato?
	Why is it important to produce varieties of potatoes that will grow in sub-tropical environments? Is this being done?