Towards improved East African highland banana genotypes with resistance to pests and diseases

 W.K. Tushemereirwe, M. Pillay, M. Batte, T. Ssali, D. Talengera, K. Nowakunda, J. Namaganda & A. Kiggundu

Banana is the leading food and cash crop in Uganda.  It is estimated that about 9.5 million metric tonnes are produced annually from about 1.5 million hectares representing 38% of cultivated land. This level of productivity (6.3 tons/ha/year) is extremely low when compared to the yields obtained on station (60 tons/ha/year). The severe productivity decline has been attributed to pests (weevils and nematodes) and diseases (black Sigatoka, banana streak virus and banana bacterial wilt) as well as soil fertility decline, socio-economic problems and limited utilization options. Genotypes with pests and disease resistance were identified as the highest priority technology to be developed for control of the pests and diseases. It is estimated that yields of highland bananas can be doubled by using host plant resistance alone.  Efforts (joint between NARO and IITA) to develop resistant genotypes using conventional breeding started in 1994. The initial objective was to assess the potential of improving the banana group through conventional breeding. This was achieved through crossing the different banana cultivars with a diploid male parent (Calcutta 4) to identify female-fertile parents that could be used in the breeding programme.  About 50% of the 60 cultivars tested were female fertile. On-station evaluations of the progeny from the above cross for resistanc to black Sigatoka and acceptable cooking attributes yielded 16 promising hybrids. 4 of the hybrids had cooking attributes in the range of the highland banana controls. This suggested that any improved male parent was likely to result in some hybrids with disease resistance and acceptable cooking attributes. As a result of this information, a breeding approach involving 3X (female fertile, triploid highland banana cultivars) by 2X (improved diploid male parents) and 4X (tetraploid hybrids) by 2X (improved diploid male parents to get 3X (secondary triploids) was adopted. This paper elaborates the progress towards an improved highland banana genotype.