Plant histories
The history behind a number of crop plants.
Looking at where they originated, their domestication, the introduction of these crops to Europe, how European attitudes to them changed over the centuries and ultimately how our changing demands have influenced the plants themselves.
How the potato has changed
From the very first humans to grow the potato we have been picking the 'best' potato plants (with the biggest or tastiest potatoes for example) to grow for our use. Just by doing this we began to change potato plants to suit our needs.
The potato has changed a lot since it was first domesticated but not always in the same direction. Over time different features have been considered important to potato growers. The earliest potato cultivation seems to have occurred in the upland valleys and plains of Bolivia. At these altitudes the ability of the potatoes to survive frosts would have been of major importance to farmers. As a result, after the initial domestication of the potato one of the first varieties to develop had a high frost resistance.
An example of the mountainous terrain in Bolivia (where the earliest potato cultivation is likely to have occurred). Frost resistance was an important trait for plants and farmers alike.
Photographer: NASA. Copyright: free.
Then as potato cultivation began to spread into other areas different qualities became important. In lowland areas there was less need to select hardy potato plants and farmers could concentrate on yield and eating quality.
As the potato spread from Peru further south it began to change in other ways. The days in the north of South America are always around 12 hours in length as these areas are close to the equator. Summer days in the South of Chile are much longer and potato plants from further north will not start to produce potatoes until autumn, when day lengths drop to around 12 hours. Over time potato plants in Chile were bred so that they would produce potatoes much earlier in the year.
Potatoes brought to Europe from northern South America went through the same change as Europe also has summer day lengths of longer than 12 hours.
By breeding and selection from just two varieties of potato, which were introduced to Europe in the 1500s, a wide variety of different potato plants were achieved in the following centuries. Potatoes were bred for improved yield, quality, texture and resistance to disease.
In the 1840s the Irish potato crop was devastatingly infected with potato blight. The resulting crop failures caused widespread famine, mass emigration to the USA and around 1 million deaths. The scale of this disaster drove plant breeders in the late 1800s to search for resistance to the disease in wild relatives of the potato.
A potato damaged by potato blight. The outside is shrunken whilst the inside is corky and rotten.
Photographer: ARS. Copyright: free.
A wild species, which was resistant to blight was eventually found in the early 1900s and after many attempts its natural resistance was bred into cultivated potato plants.
The use of the diversity of wild potato plants and ancient potato cultivars to breed desirable characteristics into modern potato crops has become commonplace but the variety of wild potato plants is still underexploited. This is because of the long time needed to breed a trait from a purely wild plant into a plant suitable for agriculture.
The fight against diseases is still an extremely important job for potato breeders but potatoes are also being bred to cope with new demands. They have become more resistant to bruising so that they can be dug by machines and have a more regular size and shape. These demands are changing as new challenges emerge. Attributes attractive to plant breeders in the future may include the ability to resist drought or grow in salty environments.
