A look back at this age-old method of raising potatoes.
The use of true potato seed (TPS) for growing potatoes is likely as old as the cultivation of the potato itself. Many potato cultivars in Andean highlands of South America — the region where potato was first domesticated — flower profusely and produce a lot of fruit. So it is only natural that the people in this area used TPS both to produce a crop for consumption as well as to develop better-adapted cultivars.
Today, the use of TPS by breeders around the world is routine in the development of new potato cultivars. There are several means of utilizing TPS to grow potatoes, each of which has its own set of pros and cons:
- Direct sowing in the field
- Use of seedling transplants
- Use of seedling tubers that have been raised in a nursery
Unlike seed potatoes, TPS is generally free from viruses, easy to transport and can be stored for several years without losing its germination. A disadvantage of TPS compared with seed potato tubers is that it is more labour-intensive to grow and it requires a longer growing season. Another disadvantage for commercial potato producers is that because TPS is the result of sexual reproduction, the crop is not genetically uniform.
It was because of the genetic diversity in progenies raised from true seed that a century or more ago that gardeners used TPS to raise novel potatoes that they exhibited at county fairs. This was often done in the hope of being able to sell seed tubers of their new cultivars to which various romantic names such as ‘Mortgage Lifter’, ‘Rot Proof’, and ‘Money Maker’ were applied. These hobby breeders were forerunners of modern potato breeders, and TPS was often featured in annual garden seed catalogs.
In the 1980s, research efforts by the International Potato Center (CIP) in Lima, Peru resulted in a flurry of activity among some North American seed companies that targeted home gardeners to either raise their potatoes from true seed directly, or to purchase young plants in plastic containers from garden centres.
In recent decades, the seed industry has made progress in pelleting seeds. This involves coating seeds with a thin layer of clay and/or other inert substances that results in a product with uniform size and shape. Pelleted seeds are easier to handle; this is especially the case for potato where the (uncoated) seeds are small and tend to stick together.
Some seed companies created extremely high expectations for TPS. One promotional brochure hailed TPS as “one of the most significant breakthroughs for agriculture in the last 50 years,” while another one stated that “conservative estimates by plant breeders indicate that potatoes grown from ‘eyes’ will be obsolete within the next decade. Home gardeners and commercial growers alike will realize millions of dollars of savings in transportation costs alone…”
Some even went so far as to claim they had developed the world’s first true seed potato variety. This initial enthusiasm for TPS, however, has faded in North America, where today only a few mail order seed houses still offer TPS to home gardeners.
TPS in Developing Countries
In Canada and other developed countries, the disadvantages of growing TPS on a commercial scale are seen by many to outweigh the advantages, which is why almost all commercial potato fields in North America continue to be planted with seed tubers.
But elsewhere, TPS has been promoted as an alternate means to grow potatoes for consumption in developing nations that lack the strong infrastructure needed to produce, transport and store high-quality seed potatoes. That’s because planting of one hectare of land can require up to 2.5 tonnes of seed potatoes in some instances, compared to only about 50 grams of TPS.
CIP has done a great amount of research on TPS for use in developing countries, including the production of the seed, agronomic practices and breeding. Some commercial seed companies have also conducted breeding trials with TPS.
These efforts have resulted in new TPS cultivars with greater genetic uniformity that are an improvement over previously available TPS and are better suited for certain conditions in some parts of the world. As a result, TPS has been used successfully on a commercial scale in several Asian, African and South American countries.