Twenty oat (Avena sativa L.) genotypes were evaluated for grain yield
stability and the effect of fungicide application on the genotype x en
vironment (GxE) interaction in four locations in southern Brazil durin
g 1986, 1987 and 1988. Eberhart & Russell's (1966) parameters (X, b an
d Sd) were adopted and analyses were performed according to three mode
ls: with fungicide application, without fungicide application, and, co
mplete model. Results indicated a strong GxE interaction, although no
genotype showed stable grain yield performance, as shown by the high r
egression deviations observed. Fungicide application caused an increas
e in mean grain yield performance, but did not affect the GxE interact
ion. UPF 7 and UFRGS 7 appear to be good genotypes for southern Brazil
because they are productive and insensitive to environmental changes;
on the other hand, UPF 6 and UFRGS 10 could be more useful for farmer
s, since they respond positively to the environmental improvements.