Abstract: For this study ten genotypes of spring wheat (Triticum aestivum L.) developed at three different breeding institutes were evaluated for two years at nine locations in Pakistan and Azad Jammu and Kashmir for various interactions. Genotype-location, genotype-year and genotype-location-year interactions were found highly significant (P<0.01) for flag leaf area, grain protein percentage and grain yield. The magnitude of interaction variance components viz., σ2gl, σ2gy and σ2gly reflected that relative performance of genotypes for these characters was more inconsistent across the locations than years. Thus, testing of genotypes at more locations for evaluation of these characters seems more effective than testing over more years. Flag leaf area showed significantly positive association with grain yield at two locations and non-significant association with grain protein percentage at all locations, whereas grain protein percentage indicated significantly negative association with grain yield at two locations, however, degree of correlation was inconsistent over the locations. It revealed that under appropriate agro-ecological conditions, concurrent selection for high grain yield based on flag leaf area is possible, whereas increase in yield may reduce grain protein percentage. The results suggest that for the development of superior and adaptable varieties, effect of environmental factors such as temperature, precipitation and soil fertility and their interactions on the expression and relationship of these characters should be considered greatly in breeding programmes.