This month, we shall learn about the different categories of seed potatoes in the country and improve our vocabulary in potato farming

1.Improved potato varieties

Improved varieties are defined as those that have been released or distributed by National Agricultural Research Systems (NARS) since 1970. Many of these varieties were developed from materials provided by CIP. They are usually considered to be superior in attributes such as yields, resistance to diseases, dormancy period, maturity period, taste or uniformity for processing purposes as compared to the ‘local’ or existing varieties (explained next) which they have tended to replace (KARI, 2000; KARI, 2005).

Note: “improved” refers to superior genetic composition of the variety compared to these local varieties and not to the health of the seed itself, which is considered under seed quality. Improved varieties also include those varieties originating from trials conducted by NARS and selected and adopted by farmers because of their superior qualities. However, they have not been with the farmers for more than 35 years.

2.Local potato varieties

Varieties with farmers whose origin is unknown or varieties released by NARS ,but which have been out with the farmers for more than 35 years without being screened and cleaned up against diseases.

3.Clean seed

Seed at farm level that originated from certified seed or basic seeds whose production has followed laid down guidelines after farmer training by MoA, KARI, GTZ, TOT, but that has not been inspected by KEPHIS. This seed category is not acknowledged by law and currently cannot be sold through formal market channels. It is also known as informally traded seed and it is categorized as non‐certified quality material that is tradable.

4.Positively selected seed

Seeds produced from ordinary seed through a process of positive selection by farmers trained on seed selection and management by MoA, KARI, GTZ (Germany Technical Corporation), TOT (Trainer of Trainers) or CIP. The process involves farmers identifying the healthy looking plants in the field and marking them using pegs. During harvest, seed potato is obtained from the marked plants only. This is as opposed to negative selection, where the unhealthy plants are identified and removed. Positively selected seed is classified as non‐traded seed and is not recognized by law.

5.Farmer/ Ordinary seed

Seeds sourced at farm level or market place whose production or selection is not done following any quality control procedure guided by either KARI, MoA, KEPHIS or any other potato experts. It is common with farmers where they use small ware tubers as planting material but it is classified as non‐ tradable seed although farmers sell to each other.

6.Breeders’ seeds 

  This is seed directly controlled by the originating or sponsoring plant breeder of the breeding Programme or institution and/ or seed whose production is personally supervised by a qualified plant breeder and which provides the source for the initial and recurring increase of pre‐basic and basic seed. Breeders’ seed is maintained genetically pure so as to guarantee that the subsequent generation (i.e. pre‐basic and basic seed class) conforms to the prescribed standards of genetic purity.

7.Prebasic and basic seed

This is the progeny of breeders’ seed or it can be produced from pre‐basic seed, which can be clearly traced to breeders’ seed. Thus pre‐basic and basic seed can be produced from pre‐basic. Pre‐basic seed is multiplied twice in the field to produce basic seed. In production the minimum seed certification standards are the same as for both pre‐basic and basic seed and it is supervised and approved by the certification agency (KEPHIS). It is handled so as to maintain specific genetic identity and genetic purity and it is required to conform to the certification standards specified for potato. Although mainly produced by the public sector, the private sector is potentially important in production of Pre‐basic and basic seeds

8.Certified seed

 This is the progeny of basic seed and its production is handled so as to maintain specific genetic identity and purity, according to the standards prescribed for certified potato. Certified seed may be the progeny of certified seed provided, this reproduction does not exceed three generations beyond basic seed stage. It is obtained from multiplying basic seeds under stringent supervision of KEPHIS. It is the only tradable seed potato under the Kenyan law. Although mainly produced by the public sector, the private sector has high potential of production and distribution.








Depicting manual planting of seed potato.There are various category of seed potatoes in the country. (Photo Courtesy of ADC Londiani satellite centre


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