The release is expected to raise prospects for manufacturers. Kari says they have been working in tandem with crisp-makers to "give us their standards."

Sherekea, Purple Gold and Kenya Mpya are disease-resistant, high-yielding and tolerant to viruses.
Trials are being conducted with the help of farmers in parts of Timau in Meru.

Sherekea is the highest yielding variety, capable of producing between 40 to 50 tonnes that can be harvested 100 to 120 days after planting. "This is going to benefit farmers the most," said John Onditi, a breeding specialist at Kari's Tigoni branch, where the breeds were developed.

The Purple Gold can yield 25 to 35 tonnes per hectare in mid-altitude areas, but thrives in high altitude where yields can be from 35 to 45 tonnes per hectare. It takes 120 to 130 days to be ready. The tubers are longer, said Mr Onditi.

The Kenya Mpya variety is suitable for mid- and high-altitude and can yield 35 to 45 tonnes a hectare in 90 days; it can be harvested while the plant is still green. "Farmers prefer such breeds especially for food," said Mr Onditi. "It's not necessary to wait for 120 days."

Kenya Mpya also has the shortest dormancy period of one to two months until shoots start sprouting.

The other varieties have longer dormancies. Sherekea's is two to three months and Purple Gold has three to four months.