Genotype and environmental effects on resistance to late leafspot in groundnutB RNtareauthorFWaliyarauthorIn 1995 and 1996, 15 advanced breeding lines of groundnuts along with a local check were evaluated in a replicated trial for yield and reaction to late leafspot (Cercosporidium personatum [Mycosphaerella berkeleyi]) at Gaya in Niger and Bagauda in Nigeria. Variation among locations within years was significant for pod yield and late leafspot as well as among genotypes. The genotype×year interaction variance for late leafspot was one-fifth the magnitude of the genetic variance while genotype×location variance was larger that the genetic variance. The genotype×year×location variance was two-thirds the magnitude of the genetic variance. Broad-sense heritability was low for pod yield (46%), high for seed weight (84%) and shelling percentage (86%) and intermediate for late leafspot (53%). The results indicated the need to test breeding lines for resistance to late leafspot in more years and locations. High yielding late leafspot resistant lines were foundGroundnut1999African Crop Science SocietyArticle