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Bijzet Z.,Institute for Tropical and Subtropical Crops ITSC | Sippel A.D.,Institute for Tropical and Subtropical Crops ITSC
Acta Horticulturae | Year: 2014

The avocado rootstock-breeding programme of the ARC-Institute for Tropical and Subtropical Crops aims to develop a range of avocado rootstocks tolerant to Phytophthora root rot. A detached root inoculation method (Van der Merwe, 1995) was only able to eliminate 45 of 91 original selections. An additional method was needed, as the remaining number of selections was still too high to be promoted to the field. The 46 seedling selections, remaining after the detached root inoculation method, were clonally multiplied by the method of Moll and Wood (1980). Of the 46, only 14 selections could be etiolated successfully and thus be multiplied for the trial. Comparison of feeder root percentage in non-inoculated and inoculated treatments was insufficient to facilitate the final selection of candidate rootstocks from a large number of potential selections with initial characteristics similar to that of the standard rootstock Duke 7. A new method for differentiation of the apparently similar selections on the assumption that a larger root system will be a better forager and thus enhance the horticultural aspects of the rootstock scion combination is discussed. The four best selections were identified. This method will identify the selections with an ability to maintain root regeneration in the face of P. cinnamomi pressure over time.

Sippel A.,Institute for Tropical and Subtropical Crops ITSC | Bijzet Z.,Institute for Tropical and Subtropical Crops ITSC | Combrink N.K.,Addo Research Station | Maritz J.G.J.,Addo Research Station | And 2 more authors.
Acta Horticulturae | Year: 2013

The Institute for Tropical and Subtropical Crops (ITSC) in Nelspruit Mpumalanga Province, South Africa, is one of the horticultural institutes of the Agricultural Research Council (ARC) with the mandate to do research, technology development and technology transfer on all tropical and subtropical crops in South Africa. Citrus is one of the crops on which there is a major research focus and for which there is a dedicated breeding and evaluation programme. As with all breeding programmes, the citrus breeding programme is faced with specific challenges and opportunities. Challenges influencing the programme range from external and internal issues as well as various technical aspects. The programme created environmental, social and economic advantages which have a macro influence on the community, whilst there are also specific advantages for the citrus industry in terms of knowledge created, gene banks and infrastructure established and availability of selections and breeding parents. The challenges and advantages of the citrus breeding programme are discussed.

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