Leveraging on germplasm acquisition for Arabica coffee improvement in Kenya
Gichimu, Bernard M.
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The low genetic variability within Coffea arabica species is a major hindrance to its improvement. The emergence of new pathogen races, especially for the prevalent fungus Hemileia vastatrix causing Coffee Leaf Rust (CLR) is a challenge to coffee production worldwide. Two accessions, namely Selection 5A and Selection 6 were received in 2008 from India as part of germplasm exchange in a Coffee Leaf Rust collaborative project involving India and four African countries namely, Uganda, Zimbabwe, Rwanda and Kenya. Seedlings of two Kenyan commercial varieties SL 28 and Ruiru 11 representing susceptible and resistant varieties respectively were also raised alongside the Indian accessions. The seedlings of the four varieties were planted at Coffee Research Institute (CRI) sub-centre in Kisii country and Agricultural Training Centre in Machakos country for field evaluation. Data was recorded on growth and yield parameters before and after crop bearing. Field records were also taken for infection by Coffee Berry Disease (CBD) and Coffee Leaf Rust (CLR). Growth parameters related to crop bearing had stronger correlation with actual berry count and hence yield confirming that potential yield of a coffee variety can accurately be predicted by combining early measurements of growth parameters and yield records. The yield potential of the Indian accessions was found to be lower than the standard Kenyan varieties. However, the accessions were outstandi ng in resistance to CLR which was only comparable to the resistant Ruiru 11 variety. The study confirmed that CLR, if not controlled can erode the high yield potential of elite varieties if conditions are favorable. It was also concluded that the Indian accessions provides an opportunity upon which traditional Kenyan commercial cultivars can be improved to withstand existing and new races of the rust pathogen.