Development of methods for bunt resistance breeding for organic farming

Abstract

Increased awareness of environment and eco-nomic advantages enhanced organic farming in Austria since joining the European Union. Accord-ingly the expansion of organic farming and the associated use of untreated seed, bunt diseases are on the rise. Common bunt of wheat, caused by T. caries (DC.) Tul. and dwarf bunt of wheat, caused by T. controversa Kühn, are major seed and soil-borne diseases in Austria. In addition to loss of grain yield, bunt reduces grain quality because it imparts a fishy odour to wheat and its products. Contamination with T. caries occurs all over Austria, whereas dwarf bunt, is limited to higher-altitude areas. A possibility for the decrease of bunt is the cultivation of resistant varieties. The objectives of this study were: (1) Evaluation of potential genotypes for T. caries and T. contro-versa resistance and (2) Recommendations for breeding programs. MATERIAL AND METHODS Experiments were conducted during the season 2005/2006 at two locations that commonly provide optimal conditions for bunt incidence. Most of the genotypes obtained from abroad have been already evaluated for bunt resistance and several genotypes were identified as resistant. Tilletia caries. An international assortment con-sisting of 98 resistant and susceptible winter wheat genotypes was evaluated for resistance to T. caries at the experimental field of Untermallebarn, 30 km northwest of Vienna, at 190 m above sea level. The average temperature and annual precipitation were 9.4°C and 642 mm. The soil type is loess. The seeds were artificially inoculated (1 g teliospores per 100 g seeds) with a bulk of teliospores collected from naturally in-fected spikes in Austria. Therefore the seeds were