The environmental influence on grain yield and its relationship with leaf rust and leaf spots diseases was evaluated in the period 1994-2001, in Capão Bonito, State of São Paulo, Brazil, 24º02' S, 48º 22' W e altitude, 702 m. The genotype x year interaction was highly significant indicating that annual climatic differences have directly affected the grain yield. The averages of grain yield were the highest in 1998 and the lowest in 1994. The genotypes IAPAR 60, IAC 60, IAC 120 and BR 18 showed high grain yield means. IAPAR 60 did not present grain yield stability. The genotypes Anahuac, IAC 120, IAC 356, IAC 342 and IAC 373 are immune to the prevalent races of the fungus causing leaf rust. As the climatic conditions were favorable to the development leaf spot, its occurrence was generalized. Rainfall in May showed the best correlation with the occurrence of leaf spots.
wheat; genotypes; diseases; climatic variation
