Which KR clones pollinate each other? We planted 3,500 trees to find out

One thing about coffee production that is not commonly known: Robusta largely can’t pollinate itself. A tree needs pollen from a compatible neighbour to set cherries. With 10 wilt-resistant KR clones available in Uganda, that leaves a lot of possible combinations.

Yet there is no published information available in the sector on which KR clones cross-pollinate well with each other. In practice, clones get mixed by what the nursery has in stock, not by compatibility.

So in September we planted a dedicated trial at Kawa Tamu. Five KR clones (KR1, KR3, KR4, KR5, KR6) are planted in bands of three columns, arranged so that each of the 10 possible pairings sits side by side twice, covering 3,500 trees. The seedlings came from Royal Plants & Nurseries (RPN Ltd) in Kyenjojo, ribboned by clone so nothing gets mixed up in the field.

From the second year onwards, we can monitor flowering, fruit set and yield, and finally give Ugandan producers an answer on which KR lines to combine.

We’ll publish the data as it comes in, including the pairings that don’t perform. If you know of compatibility data on KR clones that we’ve missed, we’d like to hear about it.