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Site author Richard Steane
The BioTopics website gives access to interactive resource material, developed to support the learning and teaching of Biology at a variety of levels.

Potatoes, asexual and sexual reproduction

Potato growers plant small potatoes ("seed potatoes") in fields then let them sprout roots and shoots from which potato plants grow above the soil.

Why do they earth up potatoes in rows?
> to protect shoots against late frosts
> to increase stem length (potatoes are stem tubers, not roots)

Later on in the year they dig/pull up the plants and extract a crop of new tubers from under the ground.

Is the term "seed potato" is a good one?

> No as they are not seeds - just small potatoes
>Seeds may be formed if a potato plant flowers (often white or purple) and produces fruits looking like tomatoes (like tomatoes, they are in the Solanaceae which includes the deadly nightshade!). These poisonous fruits contain seeds which may germinate and grow into plants which vary from one another.

Why do seed potatoes from Scotland have good reputation?
> As they are grown in cooler places the parent plants are less likely to have been bitten by aphids which spread virus diseases - also they are more likely to be smaller

When potatoes are eaten, what is the main ingredient?
> starch

What do you lose if you peel potatoes before eating?
> Fibre, vitamin C, protein

Try to list some varieties of potato:
> King Edward, Golden Wonder, Arran Pilot (many more)
Potatoes were originally imported from different parts of South America and distributed to different countries in Europe. It is said that the Andean potato predominated in the 1700s, but the Chilean potato was introduced into Europe as early as 1811 and quickly became predominant. These varieties differed in their susceptibility to diseases.

In 1845-1852, a great famine occurred, principally affecting Ireland. This was caused by yields of potatoes being dramatically reduced by a disease called potato blight. Potato blight is caused by an organism Phytophthora infestans which used to included in the Fungi kingdom but is now classified with the Protoctistans. This, together with a number of political constraints, had major consequences including mass starvation, and resulted in the emigration of many Irish people to other parts of the world.

What weather conditions contributed to the spread of the disease?
> warm and wet in July

Why was the crop so devastated?
> There was no variation in the potato crop - they were all genetically identical

See if you can find out what variety of potato was grown on Ireland at the time, and how much potato per day did people in Ireland eat in the 1800s.

Web references

http://www.sacredearth.com/ethnobotany/plantprofiles/potato.php
Plant Profile: Potato (Solanum tuberosum) from Sacred Earth Ethnobotany site

http://www.eaprvirology2007.org.uk/26.%20ODonnell.pdf
The Scottish Seed Potato Classification Scheme

http://news.bbc.co.uk/1/hi/uk/7920199.stm
Plant diseases (caused by Phytophthora kernoviae and Phytophthora ramorum) threaten woodland (BBC news story)
Do you see the connection?



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