Ruiru 11 is a compact, high yielding variety developed in Kenya to allow for more intensive coffee production with fewer losses from diseases and pests.
Ruiru 11 owes its existence to a coffee berry disease (CBD) epidemic in 1968 that lead to the loss of 50% of Kenya’s production. The crisis sparked action. In the 1970s, the coffee research station at Ruiru, which gives Ruiru 11 its name, began an intensive breeding program for varieties that were immune to CBD. This led to the development of Ruiru 11, which was released in 1985.
Breeders were focused on creating a compact variety suited to intensive planting, but one that had the high cup quality characteristic of the tall varieties predominant in Africa. Breeders spend many years crossing multiple progenitors to create what breeders call a complex hybrid that would gather the best attributes each of the chosen progenitors. This work resulted in the creation the male parent of Ruiru. The chosen progenitors of Ruiru 11’s complex hybrid male parent conferred resistance to CBD (coming from Rume Sudan, Timor Hybrid lines, and K7) and good cup quality (coming from N39, SL28, SL34 and Bourbon).
The female parent of Ruiru 11 was chosen to provide compactness (dwarf stature) and an additional layer of both rust and CBD resistance. A small number of Catimor (Caturra x Timor Hybrid) lines were identified to fulfill this requirement (including Catimor 129).
The final step in the creation of Ruiru 11 is to cross the tall male complex hybrid parent with the compact Catimor female parent. The resulting group of siblings produces Ruiru 11’s compact stature and resistance to coffee leaf rust and CBD. To mass propagate Ruiru 11, breeders manually pollinate the mother plants with pollen from the male parent lines to produce first-generation (F1) hybrid seed. This final cross results in hybrid vigor, hence high yield. The resulting seeds produce a set of siblings that are mixed together and distributed to farmers. This is called a composite variety.
Because Ruiru 11 relies on hand pollination for mass propagation, it has been difficult to produce adequate volumes of seed to meet farmer demand.