Selection of new banana varieties for the cool subtropics in Australia

Abstract

The most destructive disease in the cool subtropics is race 4 Fusarium wilt caused by the root pathogen, Fusarium oxysporum f.sp. cubense (Foc). In many cases whole production areas have or are being destroyed. It was the need to develop Cavendish varieties resistant to Foc that stimulated banana screening and selection programs, as well as non-conventional genetic improvement programs, in Australia, South Africa, Spain and Taiwan. In Brazil, which also has a conventional breeding program, the primary target is to produce a superior AAB dessert banana that is resistant to race 1 Foc. Because of the focus on Foc resistance, selection of varieties better adapted to the subtropics has been a secondary issue. Some unexpected results have come from these selection programs. For instance, Goldfinger (FHIA-01), developed by the Honduran Foundation for Agricultural Research, has been found to be resistant to Foc and Sigatoka (Mycosphaerella fijiensis and M. musicola) but it also shows a remarkable tolerance to the climatic extremes experienced in the cool subtropics. What is even more interesting are indications that the flavour and texture of the fruit develops best in the cool subtropics of New South Wales and Queensland, but not in tropical Queensland. This demonstrates the need to assess genotype x environment interaction for specific traits in different ecological zones within a country.
The challenge for the subtropical industries is to develop or select bananas that are better adapted to the climate and pest/disease complexes of that region, but have flavour and characteristics that appeal to consumers. Preferably the fruit should have attributes that are not easily attained in more tropical regions. The introgression of genes may be targeted in some of these programs from cultivars with cold and drought hardiness (ie. Lady Finger (AAB), Mysore (AAB), Ducasse (AAB)). It is also important to study the genetics and heritability of important traits for the subtropics. Results from selection programs in Australia are discussed.