Breeding objectives, philosophies and methods in South Australia.
1996
Hollamby G. | Bayraktar A.
For a breeding program to be successful, a good knowledge of farming practices, soils, climate and market requirements is needed to set relevant objectives, use effective screening procedures, and ensure that yield and quality evaluation is carried out in representative locations using appropriate management. Wheat in South Australia is grown under semiarid dryland conditions in hostile soils, often with trace element deficiencies, boron toxicity and fungal and nematode root diseases. Genotype x environment interactions are large from year to year as well as from location to location. Most of the harvest is exported, so quality is critical. Breeding objectives are based on stress tolerance and marketable quality. The philosophies and strategies of the Roseworthy wheat breeding program are described with special reference to recent and future improvements. Essentially the program is a modified pedigree method with a large number of lines yield tested at the F4 stage after selection for foliar disease resistance has occurred but before any testing for grain quality. Multilocation evaluation of F5 (about 3000 lines) is carried out on survivors from the single replicate F4 trial on the basis of yield and a NIR reading calibrated for grain hardness, milling yield and extensibility. High and low molecular weight glutenin composition is also used at this time for culling. Two dimensional spatial analyses are performed to take account of within location variability. Across location and year variability is described by site sampling and the use of probe genotypes.
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