Selection of testing environments for winter wheat breeding

Stability of cultivars across different environments is one of the main goals in winter wheat breeding programs. Much attention has been devoted to analysing cultivar by environment (C x E) interactions to improve crop breeding efforts (Thomason and Philips, 2006 ; Sio-Se Mardeh et al., 2006 ; Hoffman et al., 2005 ; Pepo and Gyi ri, 2005). Ideal genotype would have, in all environments same high yield. Research work was conducted on four test locations in Eastern Croatia - Zupanja, Nova Gradiska, Kutjevo and Osijek - during four vegetation years, 2002/2003 – 2005/2006. Three winter wheat cultivars - Zitarka, Sana and Divana were chosen for the research due to their high yielding performance and good quality. Cultivars were planted in the randomised block design with four replications. Basic plot was 10 m2 with 25 rows and spaced 40 cm apart from other plot.Genotype-environment interaction proved to be very important in winter wheat breeding. For the selection of high yielding and stable genotypes several locations should be included in trials. Selection of locations should be made according to several stability parameters. In this research work all three stability parameters showed low stability of location Kutjevo. Also, there was high correlation between locations Kutjevo and Nova Gradiska. Therefore, location Kutjevo can be excluded from further winter wheat trials in Eastern Croatia.